I don't know exactly where to put any threads I have questions with, but since I'm just a fat guy trying to get some exercise and reduce weight and cholesterol, I like this section. The amount of sections and information in this forum overall is overwhelming and I have a hard time sorting through the racer info vs. just exercise info.
So, last night I was curious and counted the teeth on my junk Walmart mountain bike job. Here's what I have...
25 / 33 / 42
13 / 15 / 17 / 19 / 21 / 24 / 28
Not sure what the standard is on rear cassette and how gearing is spaced on "good" bikes.
So I was curious about cadence and started googling around. Everything I read says to ride 85-90 rpm. Most of what I find googling seems to pertain to the "serious" cyclists. I'm not interested in being the fastest I can or how much distance I cycle, I'm just trying to get an hour of biking in a day for exercise. I'm perfectly happy riding my 12-14 mph for an hour every night.
Next I looked for information on calculating cadence from your gear ratios. I found a calculation and made a table in Excel to plug all my gears in and get a cadence at various speeds. When I'm on the relatively flat Allegheny River Trail I find myself generally between 12 and 13 mph for 6 miles out and 13-14 mph for 6 miles back. I ride in my highest gear. Trying to get higher than 14 mph, I'm pushing too hard and tire out, though I do sprint my final quarter to half mile and run 18-19 mph as long as I can for that last span.
From my calculation, between 12, 13, and 14 mph my cadence is 49 - 53 - 57 rpm. That feels right and pretty comfortable for me.
So reading about cadence, like I said, I see everything saying that you should aim for 85-90 rpm. What?!? That calculated on my top gear that I should be aiming for 21 mph! That is an absolute impossibility for me. I can hardly hit 19 mph for a quarter mile. The only time I've hit 21 mph was coasting downhill behind my house on around 11% grades. I tried to keep up with pedaling and couldn't catch that kind of spinning at 21 mph.
So, I look at my next gear down, 42/15. 85 rpm calculates to running 18 mph. Ok, so this was last night after my ride I was looking all this up so haven't tried going faster on a lower gear. I will try next time just going with the 42/15 and see what kind of speed I get out of it, but I feel like 85 rpm my legs will be flailing about uncontrollable. Also, again, no way I'm going to be doing 18 mph.
Ok, then I'll look at a 65 rpm cadence, perhaps for me that is a more realistic goal to achieve. When I have to slow down to get through the barriers that block motor vehicles, I generally down to 4th on the rear and move back up through the gears until I'm back in top gear. As I'm accelerating back up when I'm on the 42/15 (6th) I hit 12 mph when I move to the top gear. At 12 mph my cadence calculates at 56 rpm and I think I'm pedaling pretty darn fast and need to jump up to the top gear.
14 mph in that 42/15 6th gear calculates to 65 rpm. Times that I've done that before moving to top gear feels like the legs are flailing around way too much.
I'm just trying to learn and understand a bit about the techniques of pedaling a bike. I've read last night that lower cadence you will put more effort with your legs and that would be good for muscle building in the legs but faster pedaling at a given speed will be a better cardio workout. Also I read that the lower cadence and more effort would tire you out faster. Since losing weight and lowering cholesterol is my goal, seems that I want to pedal a higher cadence than I have been now for 3 weeks today. Feeling wise, the tiring out with lower cadence doesn't make sense to me. I will try out different gearing and pedaling faster my next ride, but my thinking right now is pedaling faster will be more tiring.
Like I said, just trying to gain some knowledge here and hope that some folks can shed some light for me thinking in a Clyde way rather than a 140 lb racer way, but maybe I'm thinking all wrong on the fact that I'm on a junk heavy mountain bike. I'm picking up a new bike next year, but I don't think I want the slung down low stance of riding a road bike and I'm researching some different hybrid bikes for later purchase (something like Specialized Crosstrain is what I'm thinking as I do have a ride I go on that is gravel road and a possible trail to ride that is cinder or hard pack gravel rather than paved, thus the not wanting a road bike.)