crank length

I'm 6'1" and have always been on 175mm but am open to changing if my Zees ever need replacing on my trail bike.

Posted by: JBV

Posted by: cyclotoine

Posted by: craw

I'm 6'6" and tried 180s for a while. I liked the way they rode but the clearance issues were enough that I switched back to 175. 170 just felt too small. 175 is a good compromise for me.

Damn! What do you ride at that height? I would think almost all production frames are really too small for you?

i won't speak for Craw, but there are taller guys, and yes, some ride MTB. at least a couple of guys 6 7 in my area i know ride bikes and are good riders. about 5 yrs ago i ran into a guy about 6 7 (or more) and 300lbs and he was on a custom Zinn bike. strange as all hell. Zinn has a very different interpretation of how a tall person should fit on a bike (massively tall frame, way high up bb, etc. geometry from 20 yrs ago).  Craw will complain bitterly and endlessly about bike fit (as is his right to) but some of these local monsters are totally happy on modern xl's. the best guy had a Shinobi and he ripped on that thing. small buy today's standards (466 reach!).

I'd be curious to know how many of those guys went to bigger ostensibly better fitting bikes only to return? Or are they just used to small bikes?

My latest bike I believe is the first 175 mtb crank I've had. 170's previously. The extra leverage in the lowest gear is very nice if you're a faffer like me. Pedal strikes are a trade off.

I always assumed that everyone had been on 170mm cranks since always. The bikes I've built up at shops over the years in Vancouver were 170mm by default as that was all that was available in the high end

Hmm, I think I've always been on 175's on trail bikes but I could be wrong. Definitely have to pay attention to avoid pedal strikes climbing, but I'm also weird in that I have zero issue jumping off the bike and pushing through technical bits if I stall out or hit a pedal, I just don't care enough.

The big difference for me is foot speed while pedaling. I'm 6'2", used to ride 175s, and have happily switched to 170s. On the 170s, my feet trace a smaller circle, so for the same cadence, my feet are traveling slower. Which means I can get a slightly higher cadence for the speed at which my muscles/knees feel comfortable, which means I'm getting the same power as before, with less torque, which means my legs just last longer. One thing I've noticed is that people tend to get out of the saddle to climb/accelerate way sooner tend to be on crank arms that are too long. They're either too far behind the pedals to push hard, or can't get the power they need whole seated without getting to an uncomfortable foot speed.

Furthermore, shorter cranks move the point where you put power down in the pedals toward the back of the bike, relative to where your saddle is, which effectively steepens your seat tube angle. This, to me at least, is a huge benefit on BC's steep climbs, where being in position to sit balanced and push on the pedals on a sustained climb is important. I can handle 175mm cranks on bikes with >75° STA, but I'd still rather not.

170 mm for the last ten years to counter the mid range sag when pedalling tech with VPP bikes, the extra 5mm clearance seemed to help a bit. 

The science behind shorter/ longer is varied but essentially if you are a spinner then shorter is better and if you are a pusher (or like standing a lot) then longer cranks make sense.

The opening the hip angle is also a very valid reason for shorter cranks.

Just ordered a Pole Evolink, which I think will do nicely.

Very interesting. I’m 5’ 9” with a 32” inside leg (to floor) and I’ve often wondered about 170mm cranks. Every bike I’ve had has come with 175mm and I wonder if it could make a difference being of more, ahem, average height. I always feel that my feet are too widely spread when descending and it seems obvious shorter cranks will help with uphills in terms of reducing leg extension at the front of the pedal stroke.

I’m expecting my RF bottom bracket to go relatively soon and may change out the cranks with the BB when it does. 170mm with an oval ring is really appealing.

But I do wonder if a 5mm change on one leg can really make that much difference? Seems counter intuitive and part of me baulks at spending yet more on effectively an experiment. 

As a result I have to say part of me wonders - as Kenny has done - whether going the whole 165 hog may be the path to enlightenment.

I have 175 on my fat bike, 170 on my mountain bike (older Trance X), and 172.5 on my road bike. I prefer the shorter crank arms and bottom out less frequently on the mountain bike. Also get less knee pain from long rides. I would switch my fat bike to 170 as well but the season is nearly over so I will hold off for now.

I've been on 175mm on all bikes until last year when I switched to 170. Didn't notice a huge difference except far fewer pedal strikes. I'll be sticking with 170 for sure...

Sam Hill uses 165mm cranks...  /end of thread.

What are you using for 165mm cranks? 

Looking at picking up a cheap set to try. Seam Descendant looks ok and cheap