Originally Posted by
lazerzxr
Id quite like to try some 180mm cranks, im 6'2" and think that the 5mm reduced seat height would help cope with short head tubes on bikes these days. Also I struggle with reach generally so sitting 5mm further forward would also help. Of course there is the pedalling efficiency thing to take into account as well, so it kind of makes sence for all round bike fit for me.
The "pedalling efficiency thing" is a myth, imo. Longer cranks give greater leverage, yes, so you can probably push a bigger gear. But they slow your cadence, so you may not accelerate as well, there's a bigger "dead spot" at the top of the stroke (which is inefficient) and they'll be harder on your knees. If anything I'd say we should be investigating the benefits of shorter cranks for shorter cyclists rather than longer ones for us tall guys, because there are likely to be efficiency advantages in reducing the acuteness of the angle through which the knee has to bend at the top of the stroke.