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I hear a lot about bikes designed to be stable at speed or for going fast round corners, but what about just plain confidence inspiring? Is it the same thing? Say you want a bike that will get you safely down a steep rocky descent. One that will make you feel confident about that descent. Say you are not worried about how fast you get down, but about how secure you feel on the descent. What design characteristics would help. Long chainstays? Slack head angles? Long Top tube? Big wheels ? etc
Yes, I know, skill is the major factor in confident descending. But skill is the main factor in going fast too, yet certain design characteristics improve high speed stability. I'm just interested in whether the same characteristics improve confidence on steep descents too.
On a steep descent, for me it would have to be (in order of importance) stand over clearance, a long top tube, slack head angle, wheel base, good cockpit layout. Faith in my tyres would be paramount too.
No single feature will be worth much on it's own. People bang on all the time about needing a slacker bike for this or that (and 6 years ago I did too) but without a long enough top tube a slack head angle is worthless. 300mm top tube and 59 degree ha anyone?
anything that helps keep your weight behind the front axle.
so I guess taken to extremes a 29er front wheel with a 12" rear one with a very long front centre on the bike, very short seat stays and a saddle that's behind the back axle.
Slack angles and a reverb...
Why slack head angle. Aren't they mainly for high speed stability? If it's just about staying behing the wheel wouldn't a longer top tube do the same job? Also, if you are descending more slowly wouldn't you rather have quicker steering?
In the current horrendous mud, fat tyres http://a-pic-a-ride.blogspot.co.uk/2015/02/ruined-by-fat.html?m=1
the on one fatty, although not a downhill machine & doesn't go fast just gives me loads of confidence on downhill or technical stuff. Got to praise Brant & shaggy's geometry. If there was a "normal" bike with that amount of stand over and geometry I'd be buying it
No single feature will be worth much on it's own. People bang on all the time about needing a slacker bike for this or that (and 6 years ago I did too) but without a long enough top tube a slack head angle is worthless.
I'd disagree. On a really steep slope I want a shorter top tube to get my ass over the rear wheel, I don't want to be stretched out. I'd also like a high bar / stem. Something like the highpath bikes can go down very steep stuff with ease.
Slack head angle.
Agreed. The BB on a highpath is quite high though and the bars aren't that far behind the axle. Security / safety on a really steep descent comes from a low BB relative to the axles and bars well behind the front axle so you can keep your weight back (rather than a slack HA in isolation, the bars coming back relative to the axle is a big reason for slackness imo). All that puts your c of g further behind and lower relative to the front axle. Think of the lever diagram of front tyre contact, axle pivot and where your weight is.Something like the highpath bikes can go down very steep stuff with ease.
A longer TT (for a set stem/bar) doesn't improve the relationship between your weight and the bar + f axle as long as you're holding onto the bars, it lenghtens the front of the bike but puts your weight further in front of the BB, that's not ideal as you're more stretched and less able to get all your weight onto the back wheel.
Relatively, yes (personally) but if your weight is balanced well I think it makes little odds, just preferences. A slack HA / a lot of trail is great for speed and stability but there's no point going long-trail for the sake of 'that slackness feel' for more normal speeds or slo-mo tech, imo. Longer trail just means the wheel hitting or moving over things has a bit more more feedback and influence into the steering, plus more 'flop', so it needs wider bars etc to compensate, which also slow the steering reaction due to a bigger steering radius at the grips etc. but it's no big deal really. Big bars for speed/from the hips cornering are great and the wider balance stance is also good on slow techy stuff. Get yourself and your bike well weight-balanced and the rest is just handling/feedback preferences, taking into account other uses and speeds and so on.Also, if you are descending more slowly wouldn't you rather have quicker steering?
I'd say the combination of slack head angle and short stem - basically geometry that puts your hands well behind the front wheel axle. A long top tube on its own doesn't do that!
Actually I suppose axle-crown length, head tube length and fork offset have quite a big contribution to how the slack head angle moves the axle in front of the top of the head tube. Without doing the numbers I don't know how much they matter though...
Why slack head angle
Slack head angle gives (me) the ability to feed the front wheel into an obstacle before fully committing to it, a bit like steering a wheelbarrow. There's a momentary indication of what it feels like before I actually get there iykwim
Other than the usual stuff about C-o-G and geometry, for me silence is a big factor. If the bike doesn't sound like it's going to explode on a rattly descent, I'm good
Stevet1 - MemberNo single feature will be worth much on it's own. People bang on all the time about needing a slacker bike for this or that (and 6 years ago I did too) but without a long enough top tube a slack head angle is worthless.
I'd disagree. On a really steep slope I want a shorter top tube to get my ass over the rear wheel, I don't want to be stretched out. I'd also like a high bar / stem. Something like the highpath bikes can go down very steep stuff with ease.
Oh yeah, that old chestnut. What happens to your front end grip, steering and braking while your hanging your weight over the back wheel? If you think a shorter top tube is better for descending then imagine how your bike would descend if the top tube was as short as it could possibly be. front wheel, just shy of the back wheel. Now add your big high bar and stem. Sounds great.
Well if you're going to extremes imagine your top tube is 5' long and you're stretched out superman style...
Personally I prefer a bike with a middling length top tube and a short stem. If the front end is too long I can't weight the front tyre enough, it becomes wandery and vague. If its too short as in your example then of course wheelbase starts to become an issue.
Slack angle (which keeps the wheel foreward rather than under you
low BB (which keeps your feet low/behind the front wheel)
Long TT and short stem (gets the front wheel foreward without taking you with it).
Reasnoble chainstays, too long and your weights on the front wheel, too short and you'll not roll over stuff as easily.
SPEED! Almost everything, regardless of steepness is easier with a bit of momentum. Plan your line choices, and what you're going to do, then let of the brakes and do it! If you can make it through a section on the brakes, then it'll be even easier off the brakes.
Why slack head angle?
Simples... if you think about it, the steeper the descent, the more force will be perpendicular to the forks axis of travel, causing it to flex rearward rather than go through it's travel.
On a slope, a slacker head angle lets the fork work more and flex less
Toe studs help stop me slipping
slack head angle
tight rectum
My own personal design feature of being 5 ft nothing and having a saddle at most peoples knee height.
Airbags
Skill, commitment and self belief.
Head angle doesn't really matter at all.
the only bike specific things that do are decent front tyre grip and a slammed saddle.
A fork that is setup not to dive into its travel, causing the bike to stop and the rear end to unload as you continue to move forwards and help your shock send you out the front door.
Big balls.
beaten to it by fd3chris 🙂
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Edit:Great minds
small balls in a nice tight scrotum or the ability to ninja them up inside at will would both be better than a large set.
Confidence inspiring. It doesn't matter [i]how[/i] it inspires confidence, it could even be something that's really performance impairing as long as you trust it. Nothing else is as important imo, steep stuff usually goes wrong when you run our of confidence not bike.
Decent brakes that dont just lock up.
Need to keep rolling and modulate your braking.
Look at DH bike design as what you want. Then find what elements of that you can transfer while keeping all around usability.
things like tyres with a good braking edge, short stem, wide bars, good brakes, well set up suspension, low saddle. Just look at the evolution of 'enduro' bikes.
The main thing is confidence so experience and learning lines etc, keeping your body in the right position. i.e not too far back or forwards.
A broken front brake that doesnt have enough power to stop the front wheel plus a lack of awareness of the consequences should it all go wrong.
[i]the only bike specific things that do are decent front tyre grip and a slammed saddle.[/i]
Troll is spot on
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Dark-coloured underpants.
A slack head angle and a long TT both move the front wheel forward of your centre of gravity. What this means is that you can ride down steeper stuff without worrying about going over the bars. If your CoG passes beyond a line over your front wheel, you go over. Now, in practice you need a pretty steep slope to do this but when you get close to that point things get rather sketchy. Also if you are close to that point and your forks dive as you hit something, it can rapidly tip you over, as I'm sure we've all experienced 🙂
If the 'steep stuff' you are talking about is steep enough to put you near this point, then a slack angle or long TT will help. However if it's not that steep then something else might help more and have less downside.
I've done several things to my bike to make riding steeper descents less likely to end in failure.
Dropper seatpost, greater travel fork ( taller front end , added maybe 12mm to ' front centre') which isn't set up to blow through easily, slightly shorter stem, better tyres, run tubeless and at fairly low pressure for grip.
Of course, I still need the thing to be rideable for all the thousands of mile, where it's a climb, or nowt remotely techy !
BUT... I don't think any of these things have made a blind bit of difference to confidence in myself. Some days I find, usually challenging downs easier than on other occasions.
There are a few ' bits' on our local stuff, which still allude me, although many others which I've successfully dealt with in the last couple of years , of which I was scared before.
Most of those were dealt with by ' sessioning' them. That's what does wonders for confidence. Success,
I also think levels of confidence are linked to many variables like, weather, trail conditions, extent of hangover, if you aren't on your own, the folk you ride with etc.
Skill or training.
Did a skills course last week, now better understand body position etc and far happier going down really steep stuff.
FWIW Need weight on the front, and low down.
Doncha just love it when second hand advice is passed on chinese whisper style by keen noobs after skills training.
keep COG low & weight centred (which by default becomes further back the steeper the angle of the line between your bike's wheel axles).
some right nonsense is being spouted here on this subject.
keep COG low & weight centred (which by default becomes further back the steeper the angle of the line between your bike's wheel axles).
tbh, that's what a decent coach will be telling folk (No, I'm not saying you're a decent coach - you are shit)
However, I've never seen or heard of a coaching day actually taking place on properly steep terrain, as it just isn't practical to trying a section stuff you can barely walk up or stop on when coming the other way.
Good tyres and go easy on the brakes.
He he... you know I do actually coach?
when would you like a booking? there's a space in the 8-12yr olds group this Saturday 😛
How much coaching does ones need to gain their Level 1 Skids award?
L1 is just theory, You'll probably be fine with that 😉
Sweet 🙂
Now, you might laugh, but probably my most confidence inspiring bike on steep, slow, nadgery stuff is my Singular Hummingbird. Rigid forks, so no brake dive, 29" front wheel, forks with a fair bit of offset.
Add a dropper post and it's just the job.
On faster stuff my Alpitude with 170mm Marzocchi 55RC3 Ti Evo 2 is as good as I can handle.
I've noticed that 29 is far less OTBey than 26. However the lack of suspension on mine does seems to erase that advantage 🙂
Most useful thing to have for descending steeps? A complete lack of imagination........
(closely followed by comprehensive Medical Insurance and a Helivac waiting in the wings) 😉
More seriously, i think the modern trend for short chain stays, the rear wheel tucked tight to the seat post, and a low bottom bracket make huge difference in feel when going down things. Look at pics of a modern full susser with someone hanging off the back, and the sag in the rear suspension (cause all their weight is on the back) means the BB is really very low indeed, compared to HTs of just a few years ago.
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low saddle. if i know its really steep i might even drop my dropper even lower.
same for jumping. or any fun messing about in the woods.
Imagine a line coming up vertically from the bottom bracket and try to keep your body mass in that line. This will distract you from the horrendously steep rutted descent criss crossed with polished slippery roots in front of you.
However, I've never seen or heard of a coaching day actually taking place on properly steep terrain, as it just isn't practical to trying a section stuff you can barely walk up or stop on when coming the other way.
Jedi has some stuff around the old quarry at Hertshore which is pretty steep.
Thanks for the comments folks; very interesting.
I was just struck by the way that magazine reviews often praise a bike for being stable at speed (so we now have bikes that are stable at speeds I'll never reach). They'll also sometimes claim that a new bike allowed them to clear a tricky climb that they'd never managed before. But I've never heard any reviewer say that a new bike gave them the confidence to ride down something they didn't have the nerve to tackle before, which is strange as I thought that would be a good selling point for mere mortals.
Maybe the design of the bike has no bearing on the issue (although the responses so far would suggest that isn't the case). Maybe the reviewers just don't want to admit that they didn't have the nerve to ride down something. Although that would be strange as we all have stuff we wouldn't ride down and they seem quite happy to admit to not being able to get up stuff.
You simply need to learn how to filter out the dross. Both here and in your magazines.
The shortest steepest adult bikes you'll find are BMX's (Which also have relatively high BBs) and they're designed for dropping into vert ramps. once you've dropped into a few properly tall vert ramps you won't be phased by sledging down steep chutes on your mountainbike.
Steep only becomes difficult when you add in corners and cambers and it's the terrain that dictates what bike/tyres will ride it those best not the gradient.
they're designed for dropping into vert ramps
Yes but a vert ramp is absolutely nothing like a steep MTB descent!
Get hold of Pulp Traction and marvel at Brett Tippee and Richey Schley Decsending real steep stuff on ancient Stumpjumpers and cantilever brakes.
Your modern will ride a million times better than those 'classics' and your local trail won't be anywhere near as steep.
a steep chute on a trail can be [i]exactly[/i] the same molgrips.
Slack HA, reverb, grippy pedals and decent brakes.
a steep chute on a trail can be exactly the same molgrips
Can be, but usually isn't 🙂
For me, it's wider rims. I was out on Saturday with a couple of handy mates on their Enduro style (you know what I mean!) bikes while I was riding on my rigid fat bike. It was steep and sloppy but the fat tyres with their huge amounts of traction meant that I had the confidence to ride over off camber roots and down some genuinely steep trails where they were struggling to stop their front wheels from breaking out and depositing into the nearest tree. I guess for me, the ultimate dh bike has to be a fat bike taking this to a logical conclusion.......once I have one to play with, I'll be putting the theory into practice. 😀