Evening all.

I’ve got a Lapierre Zesty which is a cracking bit of kit. However, having owned a Lapierre Spicy for a couple of years previously, I had a problem with my heels rubbing on the rear swingarm and wearing the paint.

Not that this was a particularly huge problem, other than being unsightly.

So, when I brought my Zesty, I decided to ditch the standard SLX 10 speed and slap on the newer 10spd XTR kit – and use 165mm XTR cranks – mainly because I managed to blag them (understandably) for a bargain price…

Now, I’ve been pretty unfit recently, and have been struggling to get fit due to baby/work/DIY commitments – so bear this in mind while I get to my question:

Having read Sheldon Browns advice and a few others, the consensus is that crank length matters not when it comes to geared bikes (read here: http://sheldonbrown.com/cranks.html). Also, most sites mention shorter cranks help alleviate knee issues.

So my question is this: Am I just being an unfit faffer complaining when my mates drop me again because I’ve got to a hill and decided to start spinning my way nowhere – or is it because I’m genuinely finding it harder as I’m spinning more? (for clarity, I’ve 38/26t)

The cranks help my feet not clip the swingarm, they were cheap, and are (slightly) lighter – but if I’m likely slowing myself down, I’m keen to change.

Or as I said, am I just being a moany unfit spod who should MTFU and change into a bigger gear?

change into a bigger gear

how tall?

i have 175s on all mtbs. i did have 170s before & they were awful – felt like i couldn’t put any power down – changed to 175s and the bike was much improved.

run 170s on my ss road bike & can’t tell the difference to the 175s on my geared road bike.

make of that what you will!

just being an unfit faffer

different crank length will not make you faster, end of thread.

For info: I’m 6′ 3″, but have diddy 33″ legs – I ride a Medium, well, er, everything.

I’m leaning on the unfit faffer bit, but I am interested in how people perceiev crank lengths.

Change down a gear or two and up your cadence to compensate.

If you’re long legged, and/or a pedal masher, go for longer cranks. If you’re shorter of leg, and/or a gear spinner go for a shorter crank.

Sheldon Brown’s site is absolutely right, but… As I’ve found different things do suit different people. I can’t get on with 175’s despite having average to long legs (for my height anyway), so I run 170’s. 165’s do feel quite short though, but like I say, drop down a gear or two and pedal faster!

EDIT: 33″ is not diddy, that’s how long my legs are! Mind you, I’m more than 4 inches shorter than you, so everything is relative… Maybe see if you can borrow some 170’s to try out, might be a happy middle ground. If you’re anywhere near me I’ll let you have a go with some 170’s.

My understanding is if cranks are longer than optimal the rider looses power at th top of the stroke because the knee comes too high.

Seems to me that’s valid for a geared bike.

I have 170s on my Soul and 175s on my Blur, it feels like the Soul spins up faster especially in fast power moves (eg up a steep muddy bank) but there are so many differences in the bikes I couldn’t swear it’s to do with the cranks.

For info: I’m 6′ 3″, but have diddy 33″ legs – I ride a Medium, well, er, everything.

Maybe you are too big for it, and your body isn’t able to ‘breath’ – plus, wrong geo. Longer cranks for longer legs, not sure though what the ideal is.

At 6′ + I think you’d be I’ll advised to run anything less than 175 tbh.

Been Useing some 165 xtr on my hard tail to try and help a knee problem.
Can’t see any performance differnace since I fitted them and was not exspecting to
Knee does seem better though

165 on one bike. 175 on another. Littler perceptible difference apart from far less pedal strikes.

That’s interesting orangeboy; I’m obviously expecting to lose some leverage, which will be noticable on standing up climbs, but as I’ve got older I’m keen to spin more to stop myself mashing the pedals like I used to (and killing my left knee in the process).

Do you find normal ‘riding’ (i.e. give and take riding) is about the same?

@b_r I’ve always ridden smaller bikes – I used to have a 16″ GT hardtail, and my Charge Duster is an 18″ – it’s just a personal choice due to my riding style. I run a 70mm stem on my bikes though, just to give a little teeny bit of extra room. I did have to convince Wheelies when I ordered my Zesty, they wouldn’t have it that I was my height buying a medium – ‘just give me my sodding medium!!!’

@muddyfunster that’s the other thing I’ve also noticed – something that I did wonder would be a benefit – it also helps in that you can get a few pedalstrokes in berms where other people can’t.

I do sometimes wonder if it’s a trick we’re missing – I heard that Gee Atherton runs 165mm on his DH bikes for this reason.

It’s one of those noticeable but actually inconsequential things.
I’m short (and not as fat as I was because bread is no longer my friend) but I’ve got 175s, 172.5s, and 170s and can’t notice the difference in performance.

I really can’t say I’ve noticed any differnace at all but I do tend to sit and spin at the moment
Rather than stand and attack the hills like I used to.

I will be getting more 165 for the fsr so it strikes less as I can’t see a down side

I heard that Gee Atherton runs 165mm on his DH bikes for this reason.

Most pro DHer’s run 165’s for pedal clearance reasons. If they could get hold of shorter cranks, they probably would too. Pedalling power is about the least important aspect of DH racing, more important is getting a low BB height to aid with stability and cornering, which will increase pedal strikes unless shorter cranks are used. If Shimano made a 150mm long Saint crank, people would buy it!

mboy: Makes absolute sense – of the times I’ve raced DH, you’re absolutely right in that power means nothing if you can’t get the bike through the tough stuff.

I must admit, BB height isn’t something that’s an issue on the Zesty/Spicy, but was on my Commencal Meta 5.5 – I was forever clouting the pedals on that bike.

165, 175 and 180 on my bikes
I can tell the diff when I go from 165 to 180 but it doesn’t feel weird – then again, I don’t ride all that much. Guess it could be different if you ride hundreds of miles a week

Pedalling power is about the least important aspect of DH racing

Tell that to the guys who just raced at Petermaritzburg 🙂

Depends on the course of course chrisdw, but for the most part in DH racing, stability and corner speed is way more important than pedalling. Look at Danny Hart’s World Champs winning run for instance… Not much pedalling in that!

Totally agree with you. Just thought I’d be a bit pedantic and point out an exception 🙂

A good way of explaining the effect shorter cranks have; is that they allow a greater transfer of torque due to the smaller circular path the pedal takes. This has the effect of ‘down-gearing’ the bike.

I’ve always ridden smaller bikes

Neil, maybe you have – only based on myself when I went from a 18.5″ to a 20″, and on my first long ride it suddenly made sense.

Like I say, it could be your whole (or part) body position that is wrong. Try this:

http://www.ebicycles.com/bicycle-tools/frame-sizer/mountain-bike

Or more measurements:

http://www.competitivecyclist.com/za/CCY?PAGE=FIT_CALCULATOR_INTRO

OP, I don’t think the crank length on it’s own would cause your problems, but the fact that you’re riding a bike that’s too small for you with cranks that are also too small, just might.

Pedalling power is about the least important aspect of DH racing …if you like going slowly.

B_R and Euro: as lovely as those sites are, they don’t even account for my 33″ legs against my 6’3″ height – so I think they’re a little out – and they’re also telling me I need 180mm cranks if I choose 33.5″ as my inside leg – go figure :s

At the end of the day, I’ve spent over 15 years riding/racing/falling off mountain bikes, and I’ve tried an awful lot of different bikes, one thing that I’ve always found is that I just do NOT get on with longer top tubes – causing me back pain and ending up dulling the speed of the bike in tighter stuff.

I prefer a bike that’s smaller mainly because of it’s handling traits – and as such I’ll never be convinced of the “you’re 6’3″ so you MUST ride a fapping huge 20″ frame”.

I tried a 20″ Lapierre once. I couldn’t even step over the top tube. An 18″ is not much better.

So, when advising people they’re too big for a bike without reading all the stat’s they give is a bit silly…

I had same problem. Moved my cleats. Try that first. I think having them more central to the ball of my foot increased stability and power. They were right forward below. Anyway it’s a no cost change, try it.

I prefer a bike that’s smaller mainly because of it’s handling traits – and as such I’ll never be convinced of the “you’re 6’3″ so you MUST ride a fapping huge 20″ frame”.

You’re preaching to the converted here Neil. I’m over 6’4″ and all my bikes* are slightly too small for me because I like them that way.

* My first proper fitting (20″) bike was purchased a few months back and I have to concede that it’s far easier to cycle – but not as much fun to ride.

Neil

Mate, not a problem, but I guess Euro and I have had the same experiences ourselves so just trying to help out.

Once I’d accepted that I needed a longer TT suddenly I felt comfortable, and after much experiment with stems/bars/saddle and positioning I’ve got a bike I’m happy with.

Maybe look for something not so tall, but with a longer TT?

I’ve tried that, having even gone for the specific Genesis range from Gary Fisher in order to see how it goes.

However, being more DHy in my style, and a 4 time Mega, er, rer, I’m naturally going to be running a short smaller bike.

On top of this, I’ve spent many years riding longer bikes than mates, having been pointed at, laughed at, generally shunned, until I finally cracked and gave into the 50mm stem way – and I’ve never looked back. However, as I’m doing more XC now, and given I knew the Zesty would be a medium, I’ve given myself an extra 20mm over my Spicy which I ran a 50mm stem (and that was a BITCH to ride anything other than down, with all the kit on it).

With that, and the fact that I used to work in a bike shop maaaaaany years ago as a Sales Manager, sizing up triathletes and many a MTBer, I’m more than aware of how sizing works on a variety of different types and manufacturers of bikes. Just sayin’ like 🙂

Either way, I’m happy enough that I’m just an unfit faffer I suppose.

I might have a mooch at my cleat location, they may well be a bit out – but I’ve always ridden them ever so slightly to the rear of the ball of my foot.