Now here's an interesting question

Kieran_Burns

http://www.scoobynet.com/non-scooby-rel ... stion.html

Anyone?

Dropzone-dog__

It could be argued that any grit on the chain leads to a grinding paste developing.

The more you have to pedal in order to keep the same avg speed up then, your chainrings, sprocket, chain etc are subject to a higher cadence thus the grinding paste will have more effect due to pushing a lower gear & all parts of the affected drive train coming into contact with each other more frequentley.

You could also argue that trying to push a higher gear stresses the bb bearings etc.

Good luck solving that one :idea:

nwallace

hm,

Not done physics/engineering since school so i will probably be way off.

As we are going up hill there is no scope for freewheeling.
To move 10m you must turn the wheel 10/c times where c is the circumference.
Regardless of the gear you therefore also need to put in the same amount of kinetic power (in Tech studies we referred to it as Work Done) (ignoring any differing resistance in the gearing).
And to create that same amount of power you need to put the same amount of force over the distance.

So for the big gear you put in more force over a shorter period than for the smaller gear which needs less force but over a longer period.

Therefore I reckon it's roughly the same.

2nd gear is the one that is likely to fail on a road car, but that's due to needing to change in/out of it more often (jucntions, queues etc) than say 5th (you just go into it and then cruise)

Dropzone-dog__

The posed question was really one of wear though.

Kinetic considerations outside of a sterile lab enviroment we need to consider drive train contamination as a limiting factor.

Beeblebrox

Meh, the options are low strain but more revolutions or high strain with fewer revolutions. I think there's probably only a knat's testicle in the difference it would make, even over a long period of time, so stick with the fastest option :twisted:

prawny

Don't smaller combos wear faster? I read on the singlespeed thread that the smaller you go front and back wears quicker than an equal GI but using more teeth.

So for less wear you'd want big ring, big sprocket but then your crossing the chain :roll:

I don't know how you can ride up a big hill and think though, this is obviously a hypothetical question.

gtvlusso

Err - I have far too many things to do to be bothered.....ride fixed, problem solved!

c12345

wear is proportional to => number of chain inches consumed / number of teeth used in the consumption.

I haven't thought too deeply about this, but I'm an engineer so I'm prepared to be wrong, but it seems pretty straightforward at least for first order effects.

nwallace

sent it to a mate who is a meccy engineer of some form.

"Using a lower gear is better - otherwise you have to crank harder which puts excessive strain on the chain, the ratchet or sprag clutch in the freehub &c."

Jay dubbleU

On the other hand lower gear means a greater number of rotations so presumably more wear on chain and cogs ?

prawny

But when you strech your chain it kills the teef!

I go for lower gear every time. No love i'm not changing down because i'm weak and feeble, I'm prolonging the life of my drivetrain 8)