Hi, for a given level of effort is there any good data defining the dropoff in overall efficiency as cadence drops?

I ask because I recently wore out my 11-36 cassette and threw on the 11-28 the bike originally came with. I then went on my usual routes which have some pretty serious climbs, 10%-15% for sections, which require me to go pretty slow, sometimes under 4mph. (I'm 63-yo and a recreational cyclist, not a racer, so I'm not one to push myself to redline on hills - I just like getting up them without blowing a gasket.) At 3.5 mph, I was surprised that my perceived effort grinding away on a 34t front, 28t rear at 40 rpm didn't seem much different than doing the same with the 36t rear at 50 rpm. In some ways, I kinda prefer the slower cadence.

If my knees are Okay with the strain and I can pedal smoothly at these low cadences, I'm tempted just to continue using my 11-28 rather than getting a new 11-36.

- Mark

Have you looked Yourself ?

Efficiency goes up with lower cadence. Oxygen use goes down. But you start drawing from non-aerobic metabolism and straining muscles. There is a lot of data out there. Maybe try googling aerobic and anaerobic cycling.

Ben

It varies by individual depending on the ratio of slow-twitch to high-twitch muscle and other physiological factors, but I wouldn't worry too much about the precise efficiency. Optimum efficiency tends to be at a considerably lower cadence than most of us choose to ride at since there are other factors such as muscle fatigue and strain that come into play. These tend to be worse when a low cadence is used for extended periods at a given power output. The higher gears on your current cassette probably aren't hurting your efficiency by much at all, but they do put a greater strain on your muscles and knee joints. Probably not a problem in the short run, but your current cassette will wear out too and you might want to replace it with one with a bigger cog when it does.

No, I haven't searched for data. I think I'll put some wear on this cassette and see how it goes. Might go 1x... Put a 38t on the front and 11-36 on rear... this will get me a low gear about halfway between the 28 and 36 with my current 34 front. I won't have any gears above about 25 mph but I don't ride in groups.

~90" (38/11) is a great gear for going 25 MPH+ if you know how to turn those pedals.