Originally Posted by
AnthonyG
Leisesturm, where are you coming from?
Are you an industry insider?
I'm 5'2" with a long torso and short legs. I have owned and ride many km's on bikes with, 110mm cranks, 125mm cranks, 135mm cranks, 140mm cranks, 152mm (6") cranks, 165mm cranks and 170mm cranks. I've ridden bikes that have seat tube angles from 69 degrees to 78 degrees.
When I say that I haven't lost power from shorter cranks, this isn't just theory to me. 110mm cranks probably are a little short, but still WAY better for me than 170mm cranks. When I say that longer cranks make it harder to get through top dead centre, I know from personal experience that this is so. My torque delivery with 165mm and 170mm cranks is VERY choppy. With 125mm and 135mm cranks I can feel the extra torque that I can deliver through the whole stoke.
When I was riding on 165mm cranks and a seat tube angle of 75-78 degrees I couldn't use the drops to save myself. My knees rose into my chest and I couldn't bear my weight on my hands (I do have weak arms and hands). With 125-135mm cranks and a seat tube angle of 70 degrees or so I have NO problems riding along in the drops. in fact I find it comfortable.
And the cold hard truth is, I haven't developed anything new at all. I've owned and seen numerous small vintage bikes that are EXACTLY the same as what I recommend. Short cranks, relaxed seat tube angles, small wheels and short front centre distances.
The knowledge has been around a LONG time. In modern times the knowledge has been deliberately forgotten.
Anthony
I, I, I... me, me, me...
your observations are duly noted. I really don't know why the bicycle industry would have it in for riders on such a massive scale as to deny the general public access to a useful tool. If very short cranks were of massive benefit to the majority of riders they would be available. Sooner or later some manufacturer will come up with an adjustable crank that the rider can set to whatever crank lenght they feel works for them based on complicated biometric analysis or simply how they feel that day. Two of my bikes have quick release seatpost collars. I didn't order them they just came that way. But I do use them. I mess with seat height on those bikes where I pretty much leave it alone on the bikes that require me to go find a crescent wrench to adjust the saddle height.
Years ago Shimano did considerable reasearch into human power delivery through the entire 360* pedal stroke. They observed the fall-off in power delivery, not torque, near TDC. Their answer was to reduced the diameter of the chainwheel near TDC (and BDC) and keep it at full diameter elsewhere. Remember Biopace cranksets? Neither do many people. Interestingly another company, I forget which, came to diametrically opposite conclusions about what to do about human uneven power delivery and their 'biopace' chainrings were small exactly where Shimano's were large and vice versa.
Neither company and many other companies have offered very short (or very long) cranks to the public. I'm not going to worry about it.