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A while back I guilt up my Longitude (29er) as a 650b+ bike.
The BB height is about 15mm lower as a 650b+ than it would have been as a 29er.
Its not rocky around here but I've noticed clipping my pedals and crank arms more so with this bike than others. This may be an imagined "thing" as I am aware of the lower BB but ......
Would 5mm crank are change from 175 - 170 or even 165 make much difference to pedal motion?
I have the ability to go up 5 or 10mm with the saddle to compensate(?)
Worth a try or forget about it?
And as everyone likes a pic ......
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The ideal crank arm length depends on your leg length I think.
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I went from 175 to 170 on my Intense for a bit more clearence, I'm sure I felt the difference pedalling, but it was mild and probably more in my head than anything.
Been on there 3 months now, Kitten fatalities holding steady at 0.
I doubt your BB has dropped 15mm - there's about 10mm or so diameter between a plus tyre and a 29er (varies with different tyres) - so that's only a 5mm drop.
I've gone from 175 to 170 a few weeks ago. Very pleased, no change in saddle height, much easier on my dodgy knees. Wish I'd done it ages ago. Only a few kittens have died, but they were younger, weaker ones that I don't think would have made it anyway.
Pedal action will be improved, effectively you're raising the gearing so you could reduce your chain ring size to get it back to normal.
I am sure BB height is supposed to be 300mm.
Its currently 285mm IIIRC.
Keen to avoid kitten fatalities if possible. If unavoidable then so be it!
Went from 175mm on a 26er to 165mm on a 650b (to try and alleviate some knee niggles when I got a new bike).
Kept the same chainring size and getting up to speed is noticeably a little bit harder, but spinning a higher cadence once cruising is noticeably easier.
Swings and roundabouts...
Kept the same chainring size and getting up to speed is noticeably a little bit harder, but spinning a higher cadence once cruising is noticeably easier.
+1 stick with 175mm on mountain bikes but 170mm on road bike, got a commuter with 175mm cranks & can feel it in the knees * & want to swap them as soon as i can
* could have transferred from mind....
I've gone from 175mm to 165 on my FS, took a few minutes to adjust, yes torque is a little down when you really need to crank but this is more than made up for by the increased ground clearance.
Still running 175 on my hardtail and can't say it bothers me jumping between them.
I have 175 on the mountain bikes,
I have 170 on the road bikes
I can't tell the difference.
Went from 175 to 170 when I got a new crankset. Can't tell any difference.
I was kinda skeptical about feeling any difference between 170 and 175, given I have both [on different bikes] and didn't think I could tell the difference.
However ... going from 175 to 170 on both my Peregrine, and on my Vaya made a noticeably positive improvement in comfort: I'm assuming the BB drop is the key thing.
My Osprey tho' is still on 175's and is very comfy as it is, so will be staying on 175's. Doubt any of that will help you tho'
😀
(My kittens are nine now! 😯 ).
I've changed to 170mm on my 5, I noticed that I'm getting a good pump In my quads now.
I wouldn't have thought 5mm would make any difference..
I've tried 170, 172.5 and 175 on both road bikes and mountain bikes. Much prefer the 175s, so have them on everything now. Just didn't feel like I could get the acceleration off 170s that I can off 175s. I know it's only a 2.9% increase, but I can feel the difference.
I've run 175, 172.5, 170 and 165 cranks on various bikes. Haven't died of terminal knee rot yet. 165s definitely help with pedal strike.
Maximum is pretty much a fixed point based on limb length, body dynamics and flexibility. Too long and you damage knees and restrict breathing. Minimum length is just restricted by comfort and preference.The ideal crank arm length depends on your leg length I think.
Given how BB has lowered 15mm, you better get a set of 160mm cranks to compensate. 😉
Too long is generally worse than too short, ghostlymachine pretty much nails it. Most people may not notice a 175 -> 170 switch (with saddle adjusted) but if you were to go the other way then the probability of having unhappy knees increases a lot unless you have quite long legs.