After see Tom’s post on compact cranks and a number of other posts on the same topic over the past few months… What the hell are compact cranks? What do they accomplish?
Also can some please explain gear ratios? I just operate on the change gears until reach desired level of effort? Why would I change my gears? What is the range in sizes?
Currently I am very weak when climbing. (Actually I am weak in general on the bike but it is worth on the hills). But I still find I am spinning on downhills when in my biggest gear. Would compact cranks help me? Or should I get a different size for my bike?
A compact crank is a regular crank but the boltholes for the chainrings are drilled in closer to the spindle, thereby allowing a smaller (more compact) chainrings.
The rationale is that most people do not generate the same power as professional cyclists so they do not need the same gearing as a professional cyclist.
I’m sure someone will respond more intelligently and also mention the numerous threads on this question. A compact crank is has a 110 BCD(bolt chain diameter?), as opposed to a 130 or 135 BCD for “normal” cranks. It basically allows you to run a 50/34 chainring, rather than a 53/39. this gives you lower gears for climbing and less gear overlap between the big and small rings, while still giving you the larger gears for the flats. That way, you don’t have to run a triple. There is an excellent site for information on gear ratios, someone help me out - Harris cyclery?