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hopefully one of the engineer type stw members will see this.
when running a 1 x set up, say 30/42 or bigger, is a rear hub and it's internal workings designed to work with torque that will be going through them?
What makes you think more torque is going through the hub?
Torque through the wheel hub won't change just because you change the gearing 🙂
Simple answer is no, it's no worse than using a granny ring in the same overall gear.
There is however more torque in 1x11 than 1x10 or 1x9 owing to the lower gears available (mashing uphill in 32-42 is more torque than walking up hill with 32-36).
Bigger wheels (29ers, fat bikes) do however put more torque in the hub, shimano actually made/make 29er XT hubs with stronger freehubs.
Well, it certainly feels like you're pushing more torques into the hub, doesn't it :)?
I can see where the OP is coming from though.
Spinning up a hill in a nice low gear can be done at a reasonable cadence. So, there's a certain amount of "effort" per revolution of the crank/wheel
Take away the lowest gears and cadence is lower, therefore the amount of "effort" involved with each revolution of the crank is greater. When cadence gets really low (you're gurning up the hill), each downstroke of the crank is producing acceleration, with a moments deceleration between each stroke.
That [i]feels[/i] like there's a higher torque going through the hub.
Of course, all this assumes that the 1x gearing can't go as low as the 2x, 3x or whatever was there before.
reason I am asking, when I had my spesh enduro, it came with a 30 front and a 12/36 cassette. I changed the rear to fit a 42 hope trex. I was told that the rear hub was not designed for this. so I then thought I would do a test. I fitted a 22 inner ring on the front.
the hub died on the 2nd ride.
How did the hub die?
it sheared internally.
Lots of freehubs survived the singlespeed years.
Anyway, don't spend money on new freehubs if you dont have to, because, as they say, torque is cheap.
Sorry 😳
Your torque will only increase if you put on weight or your change to a longer crank.
There's also the physical leverage applied by a bigger cog to consider, especially as it has a significant side loading on 1x systems. There's a good reason Hope increased the bearing size on the Pro4
It's the immense power that Ton generates.
Some say he once stood up on a climb & caused a land slide.
Don't confuse RPM and torque...
It's all about mechanical advantage provided by the drivetrain.
The lower the gear ratio, assuming the same load is input at the pedal the more torque you can apply to the rear hub, (worst case being the full body weight of a chunkier rider on the end of a 180mm crank say) 24-36 would apply more torque than say 32-42... In theory at least...
What cookeaa said.
Also think about the units of torque. Newton metres (for the metricated).
Oversimplifying...
Newton's is a measure of the force you can apply along the chain. This is a function of the riders strength and potentially weight.
Metres the distance from the hub body to the edge of the cassette tangentially.
Multiply N x M gives you the torque applied
So bigger cog at rear = more torque applied to hub.
Basically yeah, It's easier to think of it as a static load case, it's just a few levers...
your input lever is a crank arm the smaller your chainring radius the more mechanical advantage you have and the more tensile load is applied to the chain for a given input.
That tensile load is then applied to the rear sprocket, which again acts radially converting that tension, to torsion eg torque, the larger the sprocket the more advantage it has on the FH body...
Interestingly the new Eagle 1x12 kit provides the opportunity to have a 28-50 ratio... That probably applies more torque to a FH than anything would have done previously.