Chain ring and cassette sizes and torque.

janwal

Hope someone can enlighten me on this.I have had a compact 34/50 and 11-32 cassette for some time and had no problems climbing the hills around Huddersfield on the 34.I have recently converted to SRAM 1x11 with 42 front and 11-42 cassette.This is equivalent to about a 12/13-33 . Anyway I can still climb just fine but I feel as though I have more torque and probably climbing a bit faster if anything. Even though using nearly the same overall ratios in each system should the effort be the same or does the bigger front chain ring give more torque or am I just imagining it?
Your thoughts.

sungod

torque is the result of you applying force through the leverage of the crank arm to act against the leverage of the wheel

only the ratio between the chainring and cassette counts, not their absolute size (leaving aside impact on drivetrain losses)

the lowest gear on old is 34/32 (f/r), the lowest gear on new is 42/42, c. 6% easier, that's easily noticeable

assuming the old/new crank arms are the same length, for the same gradient on 42/42 you need less force to maintain the same cadence, or you can apply the same force at a higher cadence to go up quicker

on steep climbs, i'd suspect the latter is what you are experiencing

imposter2.0

janwal wrote:

does the bigger front chain ring give more torque or am I just imagining it?
Your thoughts.

As mentioned above - torque is a component of how much force you are applying to the pedals - so if you think that a change of crankset is giving you 'more torque' then unfortunately you are imagining it.

ElectronShepherd

You don't say one way or the other, but if you changed the bottom bracket at the same time for a new one, maybe the new BB, with fresh bearings, is spinning more freely?

Also, never underestimate the "I have a shiny new bike (or parts), so I'll put more effort in" psychological effect.

Having said that, as pointed out already, the lower gearing is the most likely reason.