So, is it easier to turn over a big gear with a long crank arm (180mm) or a shorter one (170mm) ?

Longer crank = more leverage, but the tradeoff is in acceleration and high cadence. Short arm is less leverage, but easier to wind up and spin at high cadence.

For example, track sprinters use 165s, Pursuiters use 180's.

O dear lord you just opened a whole can of worms

:getspopcornandwaitsformassivedabate:

unless you're on a treadmill.

musket wrote:Longer crank = more leverage, but the tradeoff is in acceleration and high cadence. Short arm is less leverage, but easier to wind up and spin at high cadence.

For example, track sprinters use 165s, Pursuiters use 180's.

Really? I didnt know that about track sprinters. Ta.

Very intresting.

XCrazy wrote:O dear lord you just opened a whole can of worms

:getspopcornandwaitsformassivedabate:

Genuine question though.

My 2c from a sciencey perspective. The longer crank arm should give you more kick in your power zone. The issue becomes more complicated when you try think about accelerating the cranks, longer cranks mean your feet will move faster compared to shorter cranks at the same rpm. Longer cranks also lengthen your dead spots (whether its effectively any bigger than shorter cranks I don't know.

My conclusion. Longer cranks = more kick but will limit top speed if you are at risk of spinning out.

In reality you are best to try all and then decide what you like if possible.

OK heres a question..
seems a few new bikes are coming out with grease nipples on the BB...probably a bloody good idea, to keep the dirt/dust /water out,just pump in some grease.

so has anyone put one on their bike??? any issues...cracking etc(or not)?? warranty considerations(i presume that would be void)..anything else to consider?? and why don't all major bike companies put them in??

cheers...

Musket and XCrazy are on to it - but I would add that there is no absolute rule about crank length, no matter what anyone says. Many top cyclists have ended up running cranks the total opposite to what the many formulas have dictated because the theories didn't fit their style, and many of theories are contradictory anyway.

You've just got to try different lengths, and not just for a day or two - it has to be at least 6 months of all kinds of riding I reckon. Drags out the learning process a bit...

AFWIW, after extensive testing I discovered that I am happiest on 172.5s and have a 930mm inseam wtf!? I can push longer lengths (have tried 170s, 175s, 177.5s and 180s when I was fit(ter) for at least a year each, but my knees didn't like it (I think it's because I have a short femur in relation to my tibia) and as soon as I got tired my pedaling on climbs went to pieces. More than usual.

I can just turn shorter cranks easier even when I'm a sorry sack of shit.

HTH

I don't know anything about b/b grease niupples. Doesn't seem like it would work apart from pumping litres of grease into the b/b.

I like them on Manitou forks and Turner bushings though.

Oli wrote:I don't know anything about b/b grease niupples. Doesn't seem like it would work apart from pumping litres of grease into the b/b.

I like them on Manitou forks and Turner bushings though.

it would keep water out of the BB ..wouldn't it? ..i saw a pic in some magazine a wee while back...dammit cant remember..
i think all the Santa Cruz are coming out with Greasy nipples..but that might be on the bushes only..

i'll see if i can google a pic.

Oli..you think it would be pointless? ...would it crack do you think?

I just may not understand the concept - wouldn't be the first time!

It used to be done on old school cup and ball b/b's back into the 1800s. In more recent times I think the WTB greaseguard might have started on the hub then the b/b? If the bearings are designed for the nipples* then there's no reason why it shouldn't work, I guess?











*

I am here for the nipples

mitch7 wrote:

Oli wrote:I don't know anything about b/b grease niupples. Doesn't seem like it would work apart from pumping litres of grease into the b/b.

I like them on Manitou forks and Turner bushings though.

it would keep water out of the BB ..wouldn't it? ..i saw a pic in some magazine a wee while back...dammit cant remember..
i think all the Santa Cruz are coming out with Greasy nipples..but that might be on the bushes only..

i'll see if i can google a pic.

Oli..you think it would be pointless? ...would it crack do you think?

I think your getting mixed up, santa snooze and Intense run grease nipples for pivot bearings. Not BBs.