Chain and sprockets change HELP!

**warewolf** · 6th April 2009, 10:52

Definitely need to use a low gear for maximum resistance at the sprocket. Consider this practical view: any time you need to turn the engine over during servicing (eg find TDC) it is suggested you use a high gear because it is a lot easier to turn the engine via turning the back wheel.

I think the confusion is arising because under drive, we want to multiply the torque going from the engine to the sprocket to make it easier to turn the sprocket, so use 5:1 ratio (from previous example) engine:sprocket. When driving the sprocket, the ratio is inverted, but so is our desired effect: we want to reduce the torque going from the sprocket back to the engine to make it harder to turn the engine, so use 1:5 ratio, sprocket:engine.

The gearbox is just a torque multiplier, it doesn't care which end is drive/driven, and in each of the above examples, the gearbox ratio is the same one: 1st.

Originally Posted by cooneyr

If you leave the chain on and use the rear brake the gear the bike is in is irrelevant anyway. The XTZ uses the same system - big nut but with the right sized socket and a old torque wrench used as a leaver its a piece of cake to get off.

That's the trick with the Trophy. 36mm socket on a 400mm torque wrench, stand in the riding position so you can push down on the brake while pulling up on the socket. Hopefully the bugger comes loose before you pop a vein in your forehead...

**cooneyr** · 6th April 2009, 13:30

Originally Posted by warewolf

...That's the trick with the Trophy. 36mm socket on a 400mm torque wrench, stand in the riding position so you can push down on the brake while pulling up on the socket. Hopefully the bugger comes loose before you pop a vein in your forehead...

I have friends (actually a tolerant wife) so dont have this issue

Cheers R