Is there a difference between the small and large chainring assuming you're using a similar gear ratio?


#1

Seems my quads are burning in the large chainring while my calves are cramping in the small.

My FTP went up from the last block so cant use the small ring because I spin too fast for my comfort. So now I have to use the small chainring and even at 95 rpm, my quads are getting sore…

Im using a cheap 7 speed road bike so the jumps are large in the gears…Maybe time for a new bike??


#2

Gear ratio should be all that matters - front chain ring wouldn’t meaningfully change anything if the gear ratio was the same due to using different cogs in the rear


#3

In a simple sense, an equal ratio will be the “same” work.

In reality, there are VERY SMALL differences in drivetrain efficiency between the two. I am not entirely confident in this summary, but usually… small sprockets are less efficient than large sprockets.

That said, in the context of training it matters less about which you choose. What matters most is using the same setup each and every time for the sake of consistency in power data and workout effect.


#4

Yeah. Bigger gears are more efficient. To the tune of 500mW to 700mW. I’ve got some data somwhere around here. Definitely not something you would notice.

If you throw in the impact of cross-chaining the difference can creep up to 2.5W to 3W. Again…probably not something you would notice. The error in a typical smart trainer would gobble that up anyhow.


#5

@chrismilk I assume you’re not on a smart trainer, but most “dumb” trainer have some sort of resistance adjustment. If yours does then increase the resistance a little, then you can stay in your favourite gear.


#6

I used to run an old road bike with Shimano 8-speed gearing on a dumb trainer and that was really frustrating with the jumps in cadence. My solution to it was to buy an even cheaper older bike with friction shift and then fit an old 11 speed wheel / cassette. I’ve can now spin at more or less the right cadence, or at least one that matches my road / CX bikes, and on a trainer it really doesn’t matter if the shifts take a few seconds.

Of course this could just be the reason you need to upgrade the bike and/or get a smart trainer! :wink: