How do you know if reach is too long?

Can you pop a manny? I really struggle to hold the front wheel in the air on LLS bikes.

Understeer and struggle to unweight the front

Understeer and struggle to unweight the front

This, long is great, as long as you can still actually move your weight forward for grip or back to lift it, if the reach is dictating your body position and you can't move around then it's too long.

Also factor in handlebar width.

I see a lot of people (particularly women and children( with uberwide bars, which both lock out elbows and pulls them forward.

Does the Atherton calculator include leg length, arm span and ideally height to shoulder? Because if it’s just in height it could be way out.

Does the Atherton calculator include leg length, arm span and ideally height to shoulder? Because if it’s just in height it could be way out.

Height, arm span and inside leg.

Came out fairly accurately for me, 503mm reach and I'm currently on the same size bike.

I changed back to a medium frame (Hightower)after riding a large (Jeffsy 29) for a couple of years (I'm around 5'8ish & use 760mm bars) and I personally find it's better about 95% of the time, especially steep/techy trails and jumps. The difference in reach is around 24mm, which doesn't sound a lot, but it allows me to move my weight around and feels like I have way more control almost everywhere (only place I prefer the bigger frame is flat out in a straight-line). It sometimes feels cramped when climbing, but I don't see myself back on a large frame in future

Can you pop a manny? I really struggle to hold the front wheel in the air on LLS bikes.

I struggle to hold the front wheel in the air on a BMX. Do I need a unicycle?

@sharkattack I've never been able to pop a manny on any bike, but that's just me being crap. I seem to be able to unweight the front when I need to but I do occasionally notice a bit of understeer.

I went from a steel hardtail to a Geometron. I thought I was a wheely king until I bought that thing. I lost my membership to the 12 o'clock club.

It also used to understeer but only when I was sitting back being lazy. You need to be on top of them actively riding them. My 520mm reach felt bang on but I never tried a longer one so don't know what 'too long' feels like.

That Atherton calculator puts me on 480mm reach, which is exactly what my latest bike has, and it is the best fitting bike I've ever owned.

Before that I was on a bike with 441mm reach and it felt short when out of the saddle. Front end felt squirrely (70mm stem didn't help but it was a pure XC bike).

Interestingly the calculator put me on a 640mm stack height. Current bike has 619mm stack with 20mm riser bars and it feels a tad low. Was going to order some 35mm risers to see what they felt like.

Interestingly the calculator put me on a 640mm stack height. Current bike has 619mm stack with 20mm riser bars and it feels a tad low. Was going to order some 35mm risers to see what they felt like.

I think stack and bar height is going to be the next geometry measurement that has the big realisation that most people over 5' 10" are probably on bikes with far too low bars. Much like reach has grown massively over the past few years.

I've just swapped around a couple of spacers on my bike, my bars are still well below the pedalling seat height and that's with a 10mm longer fork and a 35mm riser bar.

I'll be playing around with bar height on my next bike for sure.

I think stack and bar height is going to be the next geometry measurement that has the big realisation that most people over 5′ 10″ are probably on bikes with far too low bars. Much like reach has grown massively over the past few years.

I said something like this the other day in a handlebar thread. Front ends are generally way too low and it's been exaggerated by longer bikes which have the same stack heights. I benefited loads from a 40mm bar on the Geometron and I've done the same to the new Norco.

Bring your grips up to where your hands want to be.

I totally agree regarding stack height. I currently have 30mm of spacers under my bars and 38mm rise bars which almost feels high enough.

The reason I am asking is I have just put a deposit on a Curtis XR29 frame and have the oportunity to spec the geo to a certain extent so I want to get it right.

If I can lick the stem top cap it's likely a bit too long

Front ends way too low for what?

I don't understand what the downside of a lower front end is except if you don't like steering grip?

Front ends way too low for what?

Comfort for one. My average reach has gone up by around 100mm and a high bar makes it a nicer place to sit. I try to avoid stem spacers as they reduce your reach and move your hands back. A high bar maintains all that reach you just paid for and keeps your weight over the front axle.

I don’t understand what the downside of a lower front end is except if you don’t like steering grip?

If you have a bike with 500+ reach and a 63° head angle, raising your hands 30 to 50mm does not reduce your grip.

Front ends way too low for what?

I don’t understand what the downside of a lower front end is except if you don’t like steering grip?

Not enough stack height for us with long legs - consequently we've always our bars below the saddle when riding and on descents even with a long dropper, the saddle is still (too) high.

try to avoid stem spacers as they reduce your reach and move your hands back. A high bar maintains all that reach you just paid for and keeps your weight over the front axle.

It doesn't matter how you raise the bars, the effective reach will be reduced and your hands will move back, assuming you have the same effective stem length. It's the effective reach that really matters, this really should be calculated at the level you have your grips, not at the level of the top headset bearing.

Sorry but the term 'effective reach' is new to me.

I do know I'd rather have a bar that rises 40mm vertically (and can be rolled forward if necessary) than 40mm of stem spacers eating into my effective top tube measurement.

It also used to understeer but only when I was sitting back being lazy. You need to be on top of them actively riding them. My 520mm reach felt bang on but I never tried a longer one so don’t know what ‘too long’ feels like.

Yep, that's describes my first rides on a Geometron - as soon as I started moving my weight to where it should be I was fine. I'm on an XL with 535mm reach / 637mm stack and curious about trying the next size down, but buying secondhand I didn't get the chance to test different sizes beforehand. My other FSer has 519mm reach / 629mm stack (plus 15mm of spacers) and I need to try a higher-rise bar on that, but that's already the best-fitting bike I've ridden so far.

That Atherton calculator puts me on a 490 - regular. Hmm.

Oh, and +1 to this:

I do know I’d rather have a bar that rises 40mm vertically (and can be rolled forward if necessary) than 40mm of stem spacers eating into my effective top tube measurement.

i got measured at Ard Rock by atherton bikes, they put me on a 470 low.

my current bike (norco Optic) is 480 reach and feels absolutely perfect.

A friend also got measured, he was told a 470 regular would be perfect.

his current Starling Murmur is 485 reach and now he is on a hunt for a new bike with shorter reach, but he wants to go to 460. Feels like since he has had the Murmur he has been slower overall... possibly all in his head, but i can now beat him at a race and our other mate leaves him (and me) for dead.

I can't find the fit calculator on the Atherton site, just lots of mentions of it. Would anyone be kind enough to post a link?

My new bike is longer than any of my previous steeds, and I had a go on a mate's bike with the same reach (and similar other measurements) to see how it felt. That gave me a fairly accurate impression of what my new bike would be like.

Pros - mad stability and calm ride feel
Cons - Not so fun in tight corners, front can wash/understeer (if body position not adapted)

I had a smuggler, with 500mm reach and a 430 back end, ran it with a 35mm stem. Found the bike to be quite unbalanced, the rear end was far too short, so I had to actively push my weight forward onto the front wheel.
Conversely my G1 is 515mm reach with a 455 rear end (and can go longer), bike is way more balanced and can maneuver it far faster than the smuggler.

Swapping the smuggler for a stumpy, much better balanced with less reach.

Bike companies need to be offering different chainstay lengths for different sizes to maintain the balance.

his current Starling Murmur is 485 reach and now he is on a hunt for a new bike with shorter reach, but he wants to go to 460. Feels like since he has had the Murmur he has been slower overall… possibly all in his head, but i can now beat him at a race and our other mate leaves him (and me) for dead.

Ha, the new bike I just mentioned is a large Murmur too. Sometimes I'm faster on it, sometimes slower. Mostly faster though.

Experience tells me my ideal reach is probably 470-475mm, but I really wanted to try the Starling and a nice S/H frame came up.

Personally I'm sold on slacker head angles too, so I'm thinking I'll probably pop an angle headset in at some point, which will reduce the reach a little too. Just a thought for your pal.

I can’t find the fit calculator on the Atherton site, just lots of mentions of it. Would anyone be kind enough to post a link?

It's on the bike product page, select the frame details and it'll give you the option.

It’s on the bike product page, select the frame details and it’ll give you the option.

Thanks, it suggested a 450 Low, which def would be too short for my preference.

Sorry but the term ‘effective reach’ is new to me.

I do know I’d rather have a bar that rises 40mm vertically (and can be rolled forward if necessary) than 40mm of stem spacers eating into my effective top tube measurement.

It's the reach measured at the level of your grips. If you raise the grips by using riser bars, putting spacers under the stem, or using a stem with more rise, but have the same effective stem length, then you have reduced the effective reach. This is because the steering axis is not vertical so the point at which your hands rotate around moves backwards as you raise the bars.

Rolling the bars forward just increases the effective stem length.

Think about it like this. Imagine that you extend the heat tube length by 50 mm, so the top headset bearing is higher. Then the measured reach would be shorter, even though the actual frame geometry has not changed. If you fit the same fork and use some combination of riser bars, stem spacers, and riser stem to get your handgrips into the same position with regards to your bottom bracket, your hands will follow exactly the same arc as you turn the bars, despite one bike having a shorter measured reach than the other.

What this shows is that the effective reach is what determines your hand movements, not the measured reach. It doesn't matter whether you use stem spacers, riser bars, or whatever, if you have your grips a the same height and distance in front of the bottom bracket, your hands will follow the same arc as you turn the bars.

How do you know if it’s too long? From experience, try a few big bikes for as long as possible (as it takes a while to adapt) & find out what works & what doesn’t for you.

I’m 186cm, similar wingspan & normalish 86cm inner leg - I’ve tried a load of big bikes (500+mm reach) and have been consistently slower on every single one of them. I have from experience, ascertained, around 485mm is the sweet spot for me in terms of reach with a sensible stack height. Chainstays (or rear centre) I’m not that fussy over, as there are benefits to long, and short - it depends on the sort of trails you ride & how you like the bike to react in certain scenarios.

I value speed when riding, as going fast is fun, but also appreciate there is a balance between outright speed & a bikes ability to deal with steep, tight & nadgery stuff (especially when racing) - ultimately you have to decide where the compromise is. No doubt according to the internet, I’m riding a bike too small for me these days, but then apparently according to Pinkbike 95% of people racing the EWS are the same & would be better riders on a bigger bike 😆

Going back to the original question

The reason I am asking is I have just put a deposit on a Curtis XR29 frame and have the oportunity to spec the geo to a certain extent so I want to get it right.

What's your height and current bike reach?

Within a certain size range it'll be down to preference - longer will feel more stable, faster at speed over rough terrain, better down steep rough stuff - more 'predictable' in corners. Short is the opposite - more agile, easier to throw around, less stable in fast rough stuff, better in the corners.

For me, my next bike will be chosen to help my weak areas, which are primarily super steep/rough trails - hence I'll probably be trying to get quite a high front end to help with being able to weigh the front in steep stuff while not feeling like I'm about to be ejected over the front!

At 6ft 3in I could easily ride anything between a 480mm and 540mm reach - I'm very likely to be going for an XL size G1 in 535mm reach (I'm booked in for a demo day in 5 weeks). Current bike is 510mm reach but with 10mm extra fork which has reduced it by about 5mm or so.

i find the whole reach numbers game can become quite confusing. As mentioned, Norco put me on a large, with a reach of 480 (im 175cm tall), yet if i went to a Vitus Sommet the reach for my height is 443mm. I would have to 'size-up' to a large to get 471mm. A nukeproof Mega i could ride a medium at 455 or a large at 475.

So each manufacturer can have a vastly different figure for a persons height. Obviously there are other measurements that come into play too.. like stack etc. Headtube angle and wheelbase, along with chainstay length can change how a bike rides or how you have to ride a bike.

I wouldnt know where to start if someone told me i could change the geo?!?

It also used to understeer but only when I was sitting back being lazy. You need to be on top of them actively riding them.

I second this. You realise quite quickly that to go fast, you have to be aggressive - long bikes are a PITA to ride lazily.

You’d probably realise that a bike was ‘too long’ if, towards the end of a normal (for you) length ride that the front wheel starts to go astray as you tire.

Try riding a bike with similar geometry and sizing. Bike size is very subjective

I value speed when riding, as going fast is fun, but also appreciate there is a balance between outright speed & a bikes ability to deal with steep, tight & nadgery stuff (especially when racing) – ultimately you have to decide where the compromise is. No doubt according to the internet, I’m riding a bike too small for me these days, but then apparently according to Pinkbike 95% of people racing the EWS are the same & would be better riders on a bigger bike 😆

Riding and Racing are two totally different concepts

And:

So each manufacturer can have a vastly different figure for a persons height. Obviously there are other measurements that come into play too.. like stack etc. Headtube angle and wheelbase, along with chainstay length can change how a bike rides or how you have to ride a bike.

Ignore what they say, Marketing are involved, just focus on the nos.

Thanks all for the comments and suggestions. As for trying other bikes which would be the ideal, location, time and a lack of riding mates makes that a little difficult.

@ta11pau1 I'm 183.5 in riding shoes or a shade over 6' in old money, which always surprises me as I used to be well over 6'1" in bare feet but time seems to have shrunk me.

When I got the HB130, I demoed it in L and XL and eventually chose the XL. The L felt more comfortable seated as I wasn't so stretched out with my stiff back but standing the XL felt more like I was "in it" rather than "on it" which I preffered. So, I specced an XL with shorter stem and a stack of spacers under the bars which sorted the seated position to something more comfortable but not absolutely perfect. When I first got it into the rougher stuff I must admit I found it a bit of a handful but I put that down to me not knowing how to ride modern bikes having come from a 2006 Stumpy in size L.

For a long time I rode it in standard guise on the high setting as I was getting a few pedal strikes and didn't want to drop it lower. Eventually I put it in the lower setting and upped the fork travel from 140 to 150 and fitted shorter cranks. This took the reach from 495 to 485 and generally made the bike much more manageable for me and I started to feel much more at home with it in the rough stuff. The Atherton calculator recommends a 480 reach for me which isn't miles shorter than my current reach but seems like it might make sense. It also recommends a 15mm taller stack which also makes sense to me.

@intheborders - yup, i am very much this way of thinking these days. Numbers rather than height charts. Plus geometry geeks has helped when looking at bike options.

@Jordan at you height you're going to be between L and XL for a lot of bikes - Atherton bikes do seem to reccomended a slightly shorter reach within the size range - 500mm for me whereas I prefer 510-520mm in a 'normal' sized bike with regular seat angle.

They also don't seem to give the ETT which I find is important to make sure I'm not feeling hunched over when pedalling.

The Atherton calculator recommends a 480 reach for me which isn’t miles shorter than my current reach but seems like it might make sense. It also recommends a 15mm taller stack which also makes sense to me.

@Jordan, all sounds sensible to me given your current bike sizing and feel etc. I'm wary of the recommendations from any manufacturer re size recommendation, but the Atherton calculator doesn't seem too far away. I just redid mine using height and inside leg in riding shoes (I didn't read the guidance first time...) - now suggesting a 500 Regular for me using 190cm in riding shoes, 88cm inside leg (with shoes) and 192cm arm span.

Rode my 'smaller' 519mm/629mm reach/stack bike last night after several weeks exclusively riding my XL Geometron with 535mm/637mm. Beginning to think I may have (pun intended) overstretched myself with the Geometron as I'm definitely more comfortable all-round with the shorter reach. Might just be I've got my Nicolai dialled in more but it shows how effing difficult bike sizing can be without decent length demo rides, which are near-impossible for me.

They also don’t seem to give the ETT which I find is important to make sure I’m not feeling hunched over when pedalling.

@ta11pau1, I always look for that too but looking at reach and ST angle combined I've got a decent feel for how a bike will feel when seated. I'm 188cm barefoot (nearly 6'2) so marginally shorter than you so very likely you'll likely be best on an XL Geometron rather than L, glad to hear you're doing a demo with them as it really comes down to personal preference. If I ever consider swapping my G15 for a G1 I think I'll need the demo day with them to thoroughly test out a large. Saying that, Deviate Bikes are local to me and an XL Claymore really appeals (not the price though).

Is this a good thread to discuss head and seat tube angles or does it deserve it's own thread?

As standard the XR comes with 64HA and 77STA seems pretty bang on trend for Enduro bikes. Strangely, the Atherton AM150 comes with 65HA which is pretty conservative for a modern Enduro bike, maybe if you have Atherton riding skills you don't need the security of a slack HA?
I realise there are compromises everywhere but when does HA become too slack for general techy trail riding with the odd Enduro race once or twice per year?

Is this a good thread to discuss head and seat tube angles or does it deserve it’s own thread?

As standard the XR comes with 64HA and 77STA seems pretty bang on trend for Enduro bikes. Strangely, the Atherton AM150 comes with 65HA which is pretty conservative for a modern Enduro bike, maybe if you have Atherton riding skills you don’t need the security of a slack HA?

They're all related, you can't just look at one measurement in isolation.

And you're probably right in that the Atherton bikes are going to be designed for and by very skilled riders - much like pro enduro riders going for short bikes because they don't need the extra stability of a long bike.

I realise there are compromises everywhere but when does HA become too slack for general techy trail riding with the odd Enduro race once or twice per year?

Well... Lots of people are very happy with 62.5 degree HA on the G1. For a modern enduro bike (160mm rear travel or more) I'd want 64 degrees or less. My current bike is at around 65.5 and feels a bit out of date, although it is a trail bike.

Folk quoting geometry numbers of their own bike - have you actually measured it?

And for those that have, how did you actually measure Reach - as I've had a couple of go's based on Googling (what Reach actually is), and got nowhere near the stated numbers (nowhere as in, inches out, never mind millimetres)?

I realise there are compromises everywhere but when does HA become too slack for general techy trail riding with the odd Enduro race once or twice per year?

I took my previous bike down to about 63deg or just under. I was surprised that it still pedaled and climbed really well, just felt a bit more lazy on flat trails.

For a trail / enduro crossover bike I'd want a 64deg HA at least, and I bet that's what the Atherton will have when they revise it next.

And for those that have, how did you actually measure Reach – as I’ve had a couple of go’s based on Googling (what Reach actually is), and got nowhere near the stated numbers (nowhere as in, inches out, never mind millimetres)?

Very tricky to measure, you'd need a perfectly flat floor, then a perfectly vertical line to line up with the bottom bracket, then you'd be able to measure front that line at the top of the headtube.

Folk quoting geometry numbers of their own bike – have you actually measured it?

Not with my current bikes, but I did with a previous fleet and it's bloody hard to do accurately! I used the dining room for a flat floor, dangling bits of weighted string from the ceiling aligning with the centre of the BB and top of head tube, then a spirit level strapped to a long bit of wood to measure the horizontal.

Previous bikes were fairly close to quoted geometry. I can't be arsed doing my current bikes TBH, so far at least.

I realise there are compromises everywhere but when does HA become too slack for general techy trail riding with the odd Enduro race once or twice per year?

Personal preference, but I've not found a downside to the 63.3deg HA on my big bike or 64.5deg on trail bike (both measured as I'm running 10mm longer fork travel than 'book' figures for both). I do prefer how my trail bike feels locally but I think that's down to the slightly shorter reach and me getting the fork dialled in far better.

Head angles... practical performance improvements or marketing departments dream, as everyone wants slacker and slacker? Some enduro bikes are slacker than downhill bikes. For good reason? Or because its 'rad'?

When does a 65 degree head angle become un-rideable? On the steepest gnar of British Colombia? Or the steep south welsh trails of Barry Sidings? Or the flats of Swinley?

Or is it a case of you can charge harder on a slacker bike? Be it due to physics or placebo effect? Therefore you can get away with more which allows you to be more confident/quicker?

Atherton bikes are being perceived as 'conservative' with a 65 degree head angle, but maybe they know going slacker adversely effects the bike in other ways? The recent Enduro Bike magazine group test would suggest the Atherton wasnt held back by such a 'steep' head angle on the rails or compared to other enduro bikes. You could argue in this day and age of super enduro bikes, is 150mm rear even enduro... bro?!

Its hard to know without riding the same bike back to back with a significant change in the head angle... something most folks are unlikely to be able to experience.

PS. i am not saying they are good or bad, right or wrong... just throwing some points of view into the mix for discussion.

Or is it a case of you can charge harder on a slacker bike? Be it due to physics or placebo effect? Therefore you can get away with more which allows you to be more confident/quicker?

Mostly this, I found things just calmed down nicely when I got to about 63deg, with an extra-planted feel.

And the bike wasn't trying to pivot me over the front wheel on steep trails any more - which has always been an issue for me 'cos of my body proportions.

Not a placebo, as I wasn't expecting some of the changes at all.

intheborders

Folk quoting geometry numbers of their own bike – have you actually measured it?

This got me thinking and it is indeed hard to measure accurately but I tried. Using the entirely unscientific method of spirit level and straight edge and bits of masking tape on the floor mine measures about 20mm short of published figures. That kind of innacuracy could have easily been introduced by my technique though so I wouldn't stand by it.

However, if I input all the published figures into here, many of which I have been able to check then the calculated reach and stack come out pretty spot on with published figures.