[Closed] Chris Porter Interview

I'm always interested in what he has to say. CP has spent so long looking at suspension that you'd be foolish to dismiss his opnions. On the other hand the counter arguments for tele forks are well established, the technology is understood, the products work acceptably for a good percentage of folk, and by and large they are reliable.

Also:
-Why does STW think I want to watch videos rather than read articles?

Shame the questions aren't a bit more probing on the fork thing.

If we take his word that the main drawbacks of current single-crown forks are bushing binding as they flex, why not just make them a bit heavier again like the old Marz RC3 ti - rather than piss about bodging expensive dual crown "solutions"?

I'm sure those Marz forks (55 and 66 anyway) were more fluid AND stiffer than current stuff. Though the new Debonair spring in the Lyrik gets a fair bit closer, TBF.

I think he argued well why "bodging solutions" rather than continually binning and buying a replacement design has its place.

New Z1 takes the heavier stiffer approach (and also has fewer controls/features and goes back to relying on the shim stack instead, as I think he was suggesting).

I appreciated having the video… I listened to it in the bath yesterday morning… might not have got around to reading a full interview for ages, if at all.

legend

-Why does STW think I want to watch videos rather than read articles?

They did kindly go to the trouble of transcribing the interview for you, in addition to providing the video.

That's a good point actually, if someone's already dropped close to £1,000 on a Fox fork, it might make sense.

I suppose I can't relate that easily as my limit is about half that, then I tend to sell on after a year or two when I see another bargain.

And I'm lucky I've not had any forks end up as scrap. Kudos to CP and Mojp for helping people avoid that situation, if that's what he's on about.

If we take his word that the main drawbacks of current single-crown forks are bushing binding as they flex, why not just make them a bit heavier again like the old Marz RC3 ti – rather than piss about bodging expensive dual crown “solutions”?

Because, we've all be conditioned to believing we need a 170mm travel trail bike to ride round Swinley forest, which weighs under 30lbs.

A 3kg single crown fork, isn't going to allow for that.

(The axle thing is still stupid… we should have gone fatter, not thinner, and properly clamped at both ends.)

I remember an interview with Fabien Barel back when he was racing endruro, testing, the then new Fox 36, with a 15mm axle and saying it was a stupid idea to have more travel and a less stiff axle. He didnt win with fox though as they wanted us to all buy new wheels and forks to meet the stupid new stupid standard.

its not rocket science to see why. My old dual headshoc, while the damping was shit and it had its own personal gravity it was so heavy, the suppleness of the fork was bonkers in the chattery stuff - it couldnt bind. the needle bearings (for the first run when they were set right) were amazing.

The problem witha floating bushing is that it need to run on something and fitting all that inside a fork leg would be hard - Kashima the inside of a fork leg? an USD fork with a smooth steel upper tube to run the bushing on is probably the way forward. untill you dent it.

Because, we’ve all be conditioned to believing we need a 170mm travel trail bike to ride round Swinley forest, which weighs under 30lbs.

A 3kg single crown fork, isn’t going to allow for that.

Won't a dual crown enduro fork be 2.5kg or more anyway?

More than one way to skin a cat I suppose, and I guess CP is focusing on what he can achieve and offer as a product.

Yep, but like he said, it's not the right answer, but it is an answer nevertheless.

All one big balancing act I figure. Much like riding a bike!

honourablegeorge

Member
They did kindly go to the trouble of transcribing the interview for you, in addition to providing the video.

Nothing loaded beyond the video first time.....i'll blame the "upgrade"

chakaping

CP is focusing on what he can achieve and offer as a product.

That's exactly it - he can't afford to design something liek that Dave Weagle fork with his small operation.

The problem witha floating bushing is that it need to run on something and fitting all that inside a fork leg would be hard – Kashima the inside of a fork leg? an USD fork with a smooth steel upper tube to run the bushing on is probably the way forward. untill you dent it.

Plasma coat the liners, although being the mtb industry, they'd do a shit job of implementing/validating it.

Without going to a dual crown fork (which makes fitting in a back of a car tricky and turning tight corners):

-1.5" straight steerer
-Intend stifmeiester (no point having a stif fork, if the system is a flexy mess)
-20mm axle with pinch bolts
-Linear bearings
-Decent amount of oil in the lowers, 10ml is a pitiful amount!
-Luftkappe debonair system, coil is an option (but more weight....)
-Shim stack system with adjusters that are used for polishing the damping
-Mudguard mount on the fork lowers
-180/200mm post mount, kill of this adapter nonsense (see system stiffness)

arnt we just forgetting that a bike isnt stiff.

The issue is that it effects function so you could stiffen up or change the way in which it guides to solve that issue.

these look interesting.

https://www.bikemag.com/news/introducing-the-message/

The axle thing is still stupid… we should have gone fatter, not thinner, and properly clamped at both ends

Spesh E150

Presumably as head angles get slacker this problem gets worse as the bump force is hitting the fork at a shallower angle than before. Does this not mean that more of the force is not along the plane of the fork that the suspension move along

Plasma coat the liners, although being the mtb industry, they’d do a shit job of implementing/validating it.

therein lies the problem - Quality control and costs. you actually want something simple to implement and mass produce.

The current system is easy and allows for a bit of tolerance but forgoes outright performance. But who gives a toss about performance when you can 'design' a new one paint it red and charge a grand for it and still sell loads! we as consumers are muppets.

we as consumers are muppets

There used to be in the glory days factory race teams etc with stuff of dreams budgets

Nowadays as long as you look factory its ok

Watch the huck to flat videos on the new Pinkbike video reviews. Jesus, single crown forks are bendy!

Statement 1

"Suspension damping on a bike must be progressive because there is no chassis weight, the sprung weight vs the unsprung weight is almost the same. Digressive damping is bollocks. Progressive damping is really difficult to do with valves that give you an adjustment"

* First of all, the unsprung weight vs the sprung weight is clearly not almost the same. An average rider weighs, what 180lb? So that's about 20 times heavier than the unsprung weight. I'm not sure that the argument that a lighter chassis needs a more progressive damper setup holds weight either, Baja trucks and rally cars have crazy progressive suspension setups to deal with the huge forces imparted by the tonnes of metal flying around.

* The speed sensitive dampers can be made to be digressive during the transfer from low speed to high speed or progressive surely? See https://www.pinkbike.com/news/tuesday-tune-ep-5-high-and-low-speed-damping-part-1-2016.html Most high speed adjusters are based on preloading the shimstack, in reality your shimstack offers no extra benefits that a adjustable preloaded shimstack does not, they are exactly the same - one has a little more adjustability. Twin tube shocks are a little different, but these still have speed sensitive main piston shimstacks. The EXT shock is positionally progressive, as it works in a similar fashion to WRC and Baja truck internal bypass shocks. The damping ramps up towards the end of the shock stroke. This has nothing to do with the speed sensitive dampers, of which EXT offers just as many external adjusters as a DHX2.

Statement 2 "The fork twists due to the separate functions of the legs".

* Can we see the data that shows this effects what goes on in the real world? The MX race forks are all separate function forks, eg the Show S.F.F. Do they not have the same issues because they are overbuilt?

Statement 3 "Forks are too flexy"

* Dual crowns have always made sense to me - long travel single crowns seem silly, forks as rightly Porter insinuates aren't burly enough. But that doesn't mean to say that some flex isn't good.

5/10 for the interview - Porter knows his stuff but he shot himself in the foot in the first half of the interview IMO.

pretty much all of that is irrelevant to me - I'm such a crap rider that I wouldn't be able to tell the difference.

"e speed sensitive dampers can be made to be digressive during the transfer from low speed to high speed or progressive surely?"

I might add, by simply tuning the shimstack, as high speed adjusters simply alter the point at which the high speed circuit takes over.

I might add, do the EXT shocks really have progressive speed sensitive damping? As surely that is going to make small high velocity bumps harsh? The point of the EXT shock and internal bypass shocks on racing trucks and offroad vehicles is that the high speed can be allowed to blow off, so the vehicle soaks up small chatter but under deep impacts the compression ramps up massively?

An average rider weighs, what 180lb

I think you better take a closer look at the "average" MTB rider

Vorsprung has a much different take in terms of external adjustments or "features" as Porter likes to call them.

@10:23 "We commonly get requests from people for customer tuning stuff, which is fine - we can do that by the numbers but if you haven't managed to get the most out of your external adjusters, we can give you something that is better than that - but it's probably not as good as it could good be. What we really want to see from our customers is that they have made some effort to setup their suspension".

That sounds a bit different to Porters rant about "features" and the idea that everything can be done with just shimstacks and presumably his company tuning those for you.

Starting at 07:20

"Speed sensitive damping that will give you a plush initial stroke but ramp up to resist bottoming out. So ramp up how? Is it a more progressive damper curve in terms of generating disproportionally higher forces at higher speeds, typically not because that will give you something that becomes quite harsh and very unsupportive initially or is it something that ramps up towards the end of the stroke, obviously that is impossible (for speed sensitive dampers)? You cannot use any combination of shimstack that actually gives you less resistance at the start of the stroke than at the end of the stroke (you can of course use other types of damping setups to do this, eg internal bypass shocks".

Oooops.

I really wish that mtb journos knew enough to actually critically appraise what they are being told by people.

Well this has opened my eyes on how to really enjoy my occasional solo evening pootle when the kids have gone to bed and I've done all the chores.

Perhaps it's not relevant to you.

I do think mtbers should get a bit more clued up though, I used to ride with a bunch of motorsports engineering unergrads when I was at uni - so silly bollocks annoys me.

Hmm. I used to have boxxer teams on one bike and lyric dhs on another bike- very similar forks to the point of having interchangable parts, both 35mm, both 20mm axle, one dualcrown 200mm and one singlecrown 170mm, used to ride the same things. Could I tell any difference from bushing bind through flex? Nope. Maybe I would have, had someone on the internet told me I should though.

Now I'm no pro but I can say I ride harder than most people (not that hard a target) so I figure if it's not a problem for me it's not going to be a problem for most people. But if it is, isn't it a shame that Fox won the bloody stupid standards war and 15mm became the universal fitment (except ironically on Fox 36s).

Oh, and Chris Porter happily sold them for years. Call me a cynic but I doubt he'd be saying this if he was still making a living selling Fox 34s to people.

Northwind, I've felt for a while that there are only a few players in the industry that will go and try to give you a detailed technical breakdown of why a company is doing things the way they are and treat you as an adult instead of simplifying our spouting silly nonsense.

Darren at PUSH Industries, Steve at Vorsprung and to a lesser extent the guys at TF tuned. Steve is particularly great, it never feels like he is trying to sell you a product that he doesn't think won't make a difference to you (his attitude towards custom tuning is telling) and his pinkbike tech Tuesday videos are just great. On top of that, if you have more technical questions in regards to his video - you will get an essay back as a reply. He also rides a high pivot point bike, so I like him hahah! He's also a proper engineer.

It feels like Porter is trying to sell me something, which is a shame as I quite liked the technical aspect of the EXT Arma V3 shock. Sometimes I feel like going an setting up my own mag, as it appears that no one in the UK mtb media cares for critical technical appraisal of various ideas and products in the industry.

* First of all, the unsprung weight vs the sprung weight is clearly not almost the same. An average rider weighs, what 180lb? So that’s about 20 times heavier than the unsprung weight.

You are suspended weight though, to some extent. Depends on the situation but I see what CP and you are both getting at.

Ride an E-bike or a loaded up bike and you see how much difference adding a fairly small amount to the chassis weight makes. 5-6kg has notable inertia there and builds up plenty of momentum at 15-20mph.

You are suspended weight though. You balance your weight between hands and feet, ride light and move around and have really good adjustable suspension.

You can only use your weight like that on low frequency inputs, on high frequency chatter you essentially become a rigid mass and the suspension does the work.

The only thing that I can think of that Chris might have been banging on about are the high speed rebound adjusters in twin tube shocks, which causes linear to digressive damping curves. Not quite optimal according to some including vorsprung, not a huge pain either. Steve still rides a CCDB, despite having the technical know how and kit to custom tune any shock on the market for his needs.

Sorry, I'd already edited that to be a bit less egg-suck sounding (the bit you quoted) ^

True about low/high frequency impacts being different, overall though I don't see the rider as being a rigid mass in the same way a heavier main frame with lighter suspended ends would behave. Shades of effect rather than absolutes.

Damping curves etc to suit ... I'll happily leave that to others to think about : )

and to a lesser extent the guys at TF tuned.

Steve is particularly great, it never feels like he is trying to sell you a product that he doesn’t think won’t make a difference to you (his attitude towards custom tuning is telling)

Flooksy was actually exactly the same if you spoke to him in person. He'd completely understand what you wanted from a shock tune and why you wanted it no matter if some of those traits were completely the opposite in some respects to what was fashionable/current thinking with suspension at the time or the products he sold. I heard he's no longer at TF though. Shame. The guy's a true gent. I've no idea if TF still have a similar ethos to Tim's having not used them in a decade.
CR has always been the opposite of that. Very absolute about what's wrong with everything other than his thinking and tends to get his own way. Whether that's advisng WC racers to run their rebound so slow it never fully recovers through an extended rock garden or getting punters who can barely handle their current bike onto one a foot longer that they'll never be able to handle properly in a million years. His blinkered thinking has tripped him up more than a few times (Boxxcart anyone?) and yet folk still blindly listen to him.
The body language in that interview was made for radio.

I used to have boxxer teams on one bike and lyric dhs on another bike- very similar forks to the point of having interchangable parts, both 35mm, both 20mm axle, one dualcrown 200mm and one singlecrown 170mm, used to ride the same things. Could I tell any difference from bushing bind through flex? Nope. Maybe I would have, had someone on the internet told me I should though.

Now I’m no pro but I can say I ride harder than most people (not that hard a target) so I figure if it’s not a problem for me it’s not going to be a problem for most people.

I think you're missing the point here somewhat. Chris was talking about the bushing bind from a stiffer dual crown fork chassis. No disrespect to you but you most certainly don't ride harder than most people a 200mm DC fork is intended for. I weigh a lot more than you and ride harder on a 100mm hardtail than you do on a 200mm DH bike and I wouldn't consider myself as someone who rides half as hard as the intended user of a 40 or Boxxer. (I'm talking about top 20 World Cup DH racers and Crankworks/Fest/Rampage riders incase I'm not making that clear). Bushing bind very much is a thing with the current DC forks at that level. It's still apparent under an old guy like me who weighs 2st more than most of those riders only I just don't happen to care about it.

For most folk bimbling down local enduro stages No. You're right they absolutely do not need to worry about it. But that doesn't mean it's not present or that folk will buy a smoother system if it was put into production. Look at this forum for evidence. Consistant whining from not particularly skilled or hard riding punters about Lyriks/Pikes etc. needing improved and folk happily shelling out hundreds on top of the cost of an already overpriced fork for slightly different air shafts, dampers and coil springs. That won't change. it's golf.

Very absolute about what’s wrong with everything other than his thinking

Just so we're clear, you're talking about Chris Porter, not yourself?

I'm actually openmindedAF. I just happen to be right an awful lot 😉

Geex, Porter had me run my DHX2 almost closed on the low speed rebound an wide open on the high speed rebound once. Which would be completely the wrong way round to what Vorsprung suggest, maybe Porter was having a bad day or I misheard him?

Again, I really don't get him sometimes - quite a few of his ideas work, quite a few don't.

"I wouldn’t consider myself as someone who rides half as hard as the intended user of a 40 or Boxxer. (I’m talking about top 20 World Cup DH racers and Crankworks/Fest/Rampage riders incase I’m not making that clear)"

Aye, right. The intended users are the paying public, rockshox and fox only care about top 20 wc racers and the like for marketing, not as actual users. And likewise Porter couldn't care less about them, and he surely doesn't expect to influence them through this video.- he's after Bob Slowlaps's credit card details.

You're spot on about the golf side of it, mind. Which is weird because of how that contradicts the other stuff.

I think Geex might be right about the dual crowns to be honest, he just put it badly and rather meanly towards you there Northwind tbh.

A lot of issues would be solved if those on long travel single crowns gave up the ridiculous notion of having a 170/180mm fork in a 2kg package and then wondering why the crown debonds and creaks. You get lower axle to crown lengths with ducal crowns as well.

If durability of the product is important to people we shouldn't be riding single crowns.

I actually like Chris. The first time I met him he gave me a shock bolt from an intense M1 at the bottom of a muddy Welsh DH track back when he was their importer to sort out my bike. I've had a laugh with him and a mutual friend a few times since but he's one of those guys that came from motorbikes so sometimes has worse bike handling ideas than silly old TJ.

I quite like him as well, I just think he's bonkers, I never know quite where he's at with his thinking - he's a bit hit and miss sometimes.

Porter is right. The telescopic fork is a kludge - a highly refined kludge, but nonetheless a kludge.

Everyone is used to its characteristics so the flaws tend not to be commented on.

One big one is brake dive. It's possible to minimise it and then your fork does not need so much travel, and so can be lighter. So why isn't it done? Probably because brake dive is seen as a feature now and not a bug.

You can't cut down travel because you've eliminated brake dive. All forks and shocks pack down to an extent in repeated hits, even when rebound is setup properly. If you cut down the travel the fork will not be as comfortable or as grippy, period. There is no replacement for displacement when it comes to off-road suspension. Steve goes into detail about rebound, pack down and fork harshness in his videos - watch them.

The problem with linkage forks is that no one has managed to get a good axle path that mimicks the rearward path of a telescopic fork on a bike with a slack head angle, in a package that is stiff enough, has an equal amount of travel for a given axle to crown, is not crazy heavy and is reliable. Axle path matters - Commencal have shown that, Steve at Vorsprung knows it as well and bought a Deviate (as has our own TomHoward).

Someone one day will do it, but I had Antonio at Linkagedesign knock me up an axle path analysis of that linkage fork mentioned in the interview. It's rearward for the first half and then vertical - not great for attenuating hard hits that go deep into the travel that are not directly upwards. I'm sure the STW journos will sing it praises when they ride it for 2 days in Spain or wherever though....some of them might even buy one and will then be seen a year later skipping about on telescopics again after they realize it's shit.

Aye, right. The intended users are the paying public, rockshox and fox only care about top 20 wc racers and the like for marketing, not as actual users. And likewise Porter couldn’t care less about them, and he surely doesn’t expect to influence them through this video.- he’s after Bob Slowlaps’s credit card details.

Sorry dude. missed your reply.
There was no contradiction. My point was that 99.9% of punters don't need a DH bike or a DH fork. DH racers do. (And I don't mean Bob the eventist but racers who live and breath DH aiming for success). Same as Bob Sliceshot doesn't need phase one blades to play half a round on a Sunday with his old mate Wullie Sandtrap but it doesn't stop the two of them popping in the Pro shop to deek at them and splaff shit about them in the bar and end up buying a set when they see an offer they can't refuse in golf monthly or a PSA on www.Golffairwayworld.com

Ps. poor Bob.

Porter had me run my DHX2 almost closed on the low speed rebound an wide open on the high speed rebound once.

Yes, I didn't get on with his rebound settings at all. They obviously work for him, and he thinks they make him quicker (a lot of his stuff comes from stopwatch timings rather than feel).

on a DHX2 he was advising LSR of 4-9 (against fox 17-19). I was fiddling with LSR and HSR without ever being completely happy until I used a shockwiz in the end and got to 16. Other settings were close to Chris' recs.

Likewise for the 36RC2 He was recommending rebound at 14-17 (against Fox 7 and my current 9)

geex

Member

My point was that 99.9% of punters don’t need a DH bike or a DH fork. DH racers do. (

Sure, and I agree- but since the 99.9% are the market that makes it possible for Fox and Rockshox to make dh forks (and for Chris Porter to sell Geometrons) and the 0.01% aren't buying what he's selling or probably watching his videos, it's kind of irrelevant. And I think it's pretty bloody obvious that when I talk about myself I'm part of the 99.9%!

"You can only use your weight like that on low frequency inputs, on high frequency chatter you essentially become a rigid mass and the suspension does the work."

I'm only a few rides in on mine, but try an ebike and you'll immediately see (feel!) that that's wrong - it's quite remarkable how much better the suspension works!

I agree with Chris that telescopic forks the way they're making for MTBs are a bit of a bodge - they're fine for someone like me but I shouldn't be the target audience. I also agree that he a has long history of contradicting himself!

on a DHX2 he was advising LSR of 4-9 (against fox 17-19). I was fiddling with LSR and HSR without ever being completely happy until I used a shockwiz in the end and got to 16. Other settings were close to Chris’ recs.

Yeah, I have a Geometron with a Float X2. Chris’ recommended way more LSR than Fox’s recommendations. I started with Chris’ recommended settings and I’ve been gradually winding out the LSR and the bike, to me at least, keeps feeling better. I’m sure he has his reasons, but interesting that you found similar to me.

“You can only use your weight like that on low frequency inputs, on high frequency chatter you essentially become a rigid mass and the suspension does the work.”

I’m only a few rides in on mine, but try an ebike and you’ll immediately see (feel!) that that’s wrong – it’s quite remarkable how much better the suspension works!

I agree with Chris that telescopic forks the way they’re making for MTBs are a bit of a bodge – they’re fine for someone like me but I shouldn’t be the target audience. I also agree that he a has long history of contradicting himself!

I've ridden a lot of HEAVY downhill bikes, with good suspension (either coil or very well looke after air) I've never thought that the suspension was working better because of the weight. The bikes simply get thrown off line a little less because of the weight.

Granted, E-bikes can still be a bit heavier than those! So I can't be certain of my own experience compared to yours Chief!

I'm not sure the answer to suspension woes is to add 10kg to a bike anyway or for us all to jump on e-bikes, a better response would probably be to run coils and improve coatings and seals.

99.9% of punters don’t need a DH bike or a DH fork. DH racers do. (And I don’t mean Bob the eventist but racers who live and breath DH aiming for success).

Yes and no really. People who race DH for fun* would probably find that they were quicker and enjoyed it more with 8 inches of travel, but the only bikes in that sector are DH bikes designed for the fast end of the field. Ideally they would like a different bike. But nobody is making bikes and forks for the slow end of the field so it's hobson's choice.

* presumably they still do and haven't all gone enduro? When I raced (slow old git category) DH, enduro didn't exist, and although racing on my trail bike was OK, a DH bike was more fun and faster. But I got a secondhand one, I wouldn't have splashed out on a complete brand new bike**.

** would have been something like an Iron Horse Sunday.

"I’ve ridden a lot of HEAVY downhill bikes, with good suspension (either coil or very well looke after air) I’ve never thought that the suspension was working better because of the weight. The bikes simply get thrown off line a little less because of the weight."

If you were an engineer or physicist you'd see the contradiction in your statement. 😉 Every time you hit a bump that bump tries to throw the bike off line. If that impact is perfectly elastic then it'll be moved off line the same amount regardless of the mass of the bike - in the case of hitting large rocks then anything which absorbs or damps the collision will be part of the bike, mostly the tyres and suspension (obviously there's a small amount of wheel and frame flex too).

If a heavier bike is thrown off line less then that means the tyres and suspension are adding additional compliance by working better. QED.

Good point.

Are we sure that some of the difference, is that a little bit of extra mass holds speed better as well? I'm still not convinced that a bit of extra weight overcoming seal friction makes the huge difference that everyone claims it does when they move to a heavier bike. Or whether something else is going on with the ride quality that they are feeling?

If weight improves the ride quality of the suspension, then surely lowering friction by moving to coil would have the same drastic effect that everyone talks about with e-bikes - or even just reducing the spring rate. But moving to coil doesn't have a drastic change on chassis balance during hard repeated hits, you just get a little bit more grip and midstroke support, along with a bit less harshness through the bars.

Then again, as you rightly point out I'm not a physicist or an engineer, I'm good with maths though - so if you send me a link I could get my head around it.

I’ve ridden a lot of HEAVY downhill bikes, with good suspension (either coil or very well looke after air) I’ve never thought that the suspension was working better because of the weight.

Yeah. but you've missed the glaringly obvious difference between a 50lb DH bike and a 50lb Ebike.
Let me spell it out for you.
a 50lb DH bike has a 13lb tops frame incl cock shock a heavy fork, heavy wheels, tyres and tubes, heavy components. so that weight is distributed fairly evenly. Without ading weight somewhere intentionally there's no other way to get a DH bike over 46lb
Whereas a 50lb Ebike has a 21lb frame with much lighter wheels, tyres and components.
But that's not the whole story.
DH frames are overbuilt throughout with heavy coil shocks sat centrally (say 1lb heavier than the Ebike's air shock)
(using shimano steps as example as it's the lightest Ebike motor system by a fair way) Ebike frames also have the shock weight positioned centrally but also have 14lb of motor and battery mounted low and centrally.
Weight distribution makes a huge difference.

This summer I had been riding my Ebike far too much and neglecting some of my other bikes. I had a holiday to the Alps booked so took my DH bike out for a shakedown/get aquainted again uplift day the weekend before the trip and it felf crazy light. (it's 35lb, the Ebike is 47)
As a little experiment on the first day in the alps after the first mornnings riding I put a Dakine hotlaps bag filled with spares and DH tube onto the DH bike below the BB. the bag weighed 2.5lb. The increase in stability and improvement in grip and suspension was instantly noticable. I'm a cynical bastard and wouldn't have believed it if someone had told me this.

The thing is I would have re-calibrated my riding to the lighter DH bike anyway. and as it happens the Dakine bag was hit by a rock on a highspeed section of DH track 4 days later and split so I ended up riding the DH bike again without the extra low weight just fine.

I owned 48-51lb DH bikes for well over a decade and rode the shit out of them so I know very very well how one handles. it's NOTHING like my 170mm 47lb Emtb handles. And I'm talking about when descending with no assistance or pedalling UPHILL with it switched off.

Running the same tyres my 47lb Emtb is more stable and offers more grip than either of my 35lb DH bikes but is far far more nimble, easier to popt and lay over in the air than those old DH bikes of around the same weight were . For me. the sweetspot for Emtb handling would be something around 42-45lb in weight. Everything is a compromise but that sort of weight for me would offer the best mix of nimbleness and stability. There are already Embts aroind that weight but they either aren't burly enough or use less powerful motors and smaller capacity batteries.

FWIW I think when Emtbs get much over the 50lb mark they start to handle more and more shit all round too. Stable though obviously.

God damnit, I want a ****ing e-bike now.

Look at what you've gone and done.

So, any high pivot e-bikes out yet? 😀

Edit

The Bergamont still has one of my favourite suspension systems on an eMTB, and I thought we would see more designs like this, but it turns out that Haibike have a patent for high pivot idlers on e-bikes and they are featured on many machines in their range.

Aghhh!

Hahahhaha 😀

sure as day every time Chris Porter opens his mouth in public discussion ensues, wallets open and money gets spent elsewhere.

Lucky he has his music and art

a 50lb DH bike has a 13lb tops frame incl cock shock

Is that a special thing that provides extra knob fiddling?

raybanwomble
You can’t cut down travel because you’ve eliminated brake dive. All forks and shocks pack down to an extent in repeated hits, even when rebound is setup properly. If you cut down the travel the fork will not be as comfortable or as grippy, period. There is no replacement for displacement when it comes to off-road suspension...

I'm not going to argue that's there's no replacement for displacement. That's a given.

But if your brakes are diving, you're using up displacement that could be used for suspension.

IN many ways it's a shame that cartridge forks became so popular. In the 70s, I used to tune motorbike forks for myself and mates by fiddling around with shims, drilling ports, and making up magic potions for suspension fluid. It's amazing what a few small adjustments can make, and they can be done for pennies if you don't mind getting your hands oily, ie accessible to any mechanically competent rider.

Epicyclo, the Grip 2 damper cartridge would be great in that regard if Fox UK were actually willing to provide the spares for home servicing - as it self bleeds!

Do you think we could package Tom Killeens head to hub idea to eliminate bushing bind, on an mtb fork?

https://books.google.co.uk/books?id=84hF-qoR5I8C&pg=SA7-PA30&lpg=SA7-PA30&dq=telescopic+fork+that+resists+brake+dive&source=bl&ots=F-z2uGS9Lm&sig=EwfkEChpDGlkSuR1eStCtTUarbY&hl=en&sa=X&ved=2ahUKEwjV8pqK3JffAhWMqaQKHd7eCgUQ6AEwCnoECAAQAQ#v=onepage&q=telescopic%20fork%20that%20resists%20brake%20dive&f=false

Scroll down a bit to find the description. It seems like it would add a lot of complexity an weight to a bike still - and the frame would have to be designed ground up for it.

For interested parties, here's a quote from Steve on his Pinkbike tele vs lever video

There was no need for the rectangular stanchions on that, it had the scissor link that kept everything aligned. The problem with that design was the axle path was a bit whack and didn't follow the steering axis. Never got to ride one unfortunately but having an anti-dive characteristic alone also doesn't guarantee that it's actually better under brakes. What happens if you have so much anti-dive that it actually extends? What happens if you have exactly 100% anti-dive and the front end doesn't move but the rear end rises due to the forward weight shift? What happens if that anti-squat rate varies in a particular way, does that make it more harsh or less? What if the damper isn't low enough friction, or isn't reliable, or blah blah... there are a ton of variables involved!

He also seems to think that an axle path that follows the steering axis is desirable as well.

Isn't that Killeen thing basically just a McPherson strut?

Edit: Which if I'd read the next page I would have noticed that's what it said.

RaybanW, sorry, do you have a link to the article? I wouldn't mind reading it

https://www.pinkbike.com/news/tuesday-tune-ep-8-why-were-riding-telescopic-forks-2016.html

The comments are worth wading through as well, Steve usually delves a bit deeper when he posts on the various forums.

It's interesting that Motion-Ride came out shortly after this video, with their own video responding directly to Vorsprung essentially stating that although their C shaped axle path was not what riders wanted now (not that C shaped axle paths are ****ing terrible) - they could move to a linear one on the production sample. Now it's almost 2019 and they are rocking a slightly rearward to vertical axle path, because.....stability (totes not that they can't design a fork worth a ****, that has sensible anti-squat values with a more linear axle path).

EDIT

To get rid of dive you basically need a linkage style fork, or a linkage on a tele. The problem with them is the links are far too short, and usually leading instead of trailing, with the result you have an axle path that results in very fast change to the steering geometry once out of the sweet spot.

But the telescopic fork, being the kludge that it is, can benefit from another kludge, assuming it is suspended on air. All that is needed is an auxiliary air chamber and a cutoff valve operated by the front brake lever. This can be tuned to vary the amount of dive to the rider's preference. Again, something I used to do to try and get decent performance out of the dire forks fitted to 1970s motorbikes.

There was a good factory implementation of this on the H-D tourers like the Electraglide which made it surprisingly capable for hard riding.

My personal favourite is the Telelever system on the oil cooled BMW twins. The suspension does not have to be compromised for the braking. Implementing that on bicycle frames may be a problem because they are not 3 dimensional enough to get enough lateral rigidity - or do they need that rigidity?

I think they do need it, there isn't enough rigidity in my 36 - I feel much more at home and confident behind a set of dual crowns.

To get rid of dive you basically need a linkage style fork, or a linkage on a tele. The problem with them is the links are far too short, and usually leading instead of trailing, with the result you have an axle path that results in very fast change to the steering geometry once out of the sweet spot.

I wonder if that's partly why Motion have stated they haven't tuned out all the dive. They don't provide any of the numbers for anti-dive, leverage ratio or axle path on their website though (I wonder why?) - look at this video - does that look like considerable dive to you before he/she stops at the stream?

On top of that, the fork is completely unservicable by home users, we know little about how the damper works and the spring is only adjustable on preload.

But of course, STW raved about it on their 1 day test - without mentioning any of this.

I wonder if that’s partly why Motion have stated they haven’t tuned out all the dive. They don’t provide any of the numbers for anti-dive, leverage ratio or axle path on their website though (I wonder why?) – look at this video – does that look like considerable dive to you before he/she stops at the stream?

I don't think the axle-path and anti-dive aspects of the linkage are particularly linked, so you could achieve as much as you wanted of the latter without affecting the former, if you see what I mean.

And, proponents of these forks rather play up the ability to play with the axle path. I have never quite seen why the axle path must be exactly parallel with the steering axis even on a telescopic fork. (Although of course it isn't any way given the amount the things flex, to replicate that on a rigider linkage fork you would have to build some offset/curve in).

That Motion fork - my first thoughts are no thanks.

It looks like brake dive would depend on where in the arc of suspension movement the brake was applied. (I'd like to see a side on drawing of the brake side to be sure)

Reminds me of the problem Vincent Girdraulic forks used to have in racing when they had been modified for more travel. They'd go stotting off into the undergrowth on zigzags if you transitioned from full throttle to full braking instantly. What was happening was the fork was at the top of its travel (beyond factory recommendation) and the angles were wrong, so the braking force overpowered the suspension and locked it up. It only happened in those circumstances if I remember it right, so it was a puzzle for a while. Lesson: never try to outsmart Phil E Irving's designs. 🙂

A trailing link fork is always going to be more prone to brake dive unless there is a linkage to feedback the brake forces to the non-suspended part, ie solidly bolting the brake to the fork arm is not optimum. (Eg Vespa scooters). The advantage of a long trailing link is it is easier to design for less radical geometry changes. That works to some extent for a long leading link too, and it's easier with leading link to cancel braking forces.

(NB I am specific about long links, short is another story).

The thing is though, a lot of the anti-dive things fitted to motorcycle forks were blanked off by riders who [i]wanted[/i] the bike to dive on the way into corners. It can be a good thing.

Exactly what Kayla said.

There's no way I would want to switch to a fork that didn't compress under braking after 25 years of riding one that does and knowing exactly how my fork behave under braking forces.

also. Other than these guys...

Who on earth is braking in any situation ever while their fork is using full travel?

.
And, proponents of these forks rather play up the ability to play with the axle path. I have never quite seen why the axle path must be exactly parallel with the steering axis even on a telescopic fork. (Although of course it isn’t any way given the amount the things flex, to replicate that on a rigider linkage fork you would have to build some offset/curve in).

The parallel axle path with current head angles leads to nicely rearward axle paths, that are good for most of the bumps apart from very vertical or very horizontal inputs. My opinion, is that the human body is much better biomechanically equipped to handle and offset geometry and centre of gravity changes, so we shouldn't be moving away from prioritising bump attenuation. My Commencals rear axle path attests to that, since moving to a high pivot point bike I have been consistently quicker though regular sections - by quite a considerable margin. I simply don't get the same harshness transferred through the bike that I have done with other designs.

The thing is though, a lot of the anti-dive things fitted to motorcycle forks were blanked off by riders who wanted the bike to dive on the way into corners. It can be a good thing.

I've mentioned this before, but TJ was adamant that the change of weight distribution was not down to the fork dive.

@Raybanwomble
Top tip: Stop listening to motorcycle handling advice from a man who loses motorcycle handling arguments with motorcycle riders on the internet and doesn't actually own or ride one.

I’ve mentioned this before, but TJ was adamant that the change of weight distribution was not down to the fork dive.

They're linked though, surely? One can cause the other and vice versa, at least that seems the case from the dozen or so trackdays and handful of races I've done 😉

The parallel axle path with current head angles leads to nicely rearward axle paths, that are good for most of the bumps apart from very vertical or very horizontal inputs.

Well yes, so why weren't more rearward paths considered when things were steeper? Why stick with exactly 0 degrees when you could experiment with a degree or so either way built into your crown forging(s)? You would of course also affect trail. But you would think that the ideal trail for when you have maxed out your fork travel might well be different from when you are cruising along smooth ground. I am just curious why this doesn't appear to have been experimented with in the field of telescopic forks. (Maybe it has?)

Change of weight distribution happens with rigid forks, dive doesn't.

I thought they were, but maybe a physics type can educate us.

PM me if you guys ever want to go and set up your own magazine, with blackjack and hookers.

Well yes, so why weren’t more rearward paths considered when things were steeper?

They were, DH settled on around 63 degree head angles well over a decade ago not just for handling reasons but bump absorption as well. Steep bikes do feel harsher on steepish terrain, but supposedly once you start getting past 62 degrees then the fork starts to flex upwards and shock absorption is compromised. Santa Cruz has stated this as a reason for not going past 63.5 to 64.5 degree head angles in the past and that these numbers seemed to be the sweet spot.