Gear Jumping - Freehub?

Fantasia

Hi - been having a prob with my bike - when starting off from stop and my weight on the pedal my bike seems to jump gear - just had a new chain and mech fitted, so its not that - could the freehub cause this prob?

nicklouse

What do you mean by jump a gear?

Your words imply that it has been poorly set up.

If the freebody has gone then the cassette will be slipping and not feel like jumping a gear.

But what you say has been done points to a worn cassette.

But what is acrually happening?

Fantasia

Hi - thanks for your reply - was having probs with my gears, bike is used a lot so wear and tear and needed attention - new parts fitted. Bike now going really well, ZOOOOM, except for this prob. When stoped on a slight incline and then start off with my weight on the right pedal to take off instead of taking off smoothly its as if it drops a gear, although it hasn't, the pedal drops like something has slipped. It's going back in for sorting out on Monday - just trying to figure out before hand if that is the problem.

rjkflyer

If you're now certain it's not a gear change, and have ruled out the RD 'sticking' in any direction (which could cause the chain to 'snatch' when you apply load) then you are probably right that the free hub is either worn, stuck or broken.

Inside the free hub there are usually 3-4 spring-loaded 'pawls' that engage in the toothed track that runs around the periphery, thus transmitting drive.

1. Worn: one or more of the pawls is worn to the point where it no longer can 'catch' the teeth in the free hub, or,
2. Stuck: the grease in the free hub is either gone or congealed (or replaced with one far too thick if recently overhauled) so much that it's stopping the pawls springing back to their required position to catch the freehub teeth, or,
3. Broken: the spring that pushes the pawls back out is broken/defective.

Either way it's an easy maintenance task. Pawls should be replaced every so often, and re-greased (although beware the mistake of putting in ultra-heavy grease that prevents the spring action happening properly).

mattv

Feel if there is any "wobble" in the freehub by holding the big sprocket and rocking it in and out from the wheel. A tiny amount of play is acceptable, but any more than half a mm couldindicate wear in the freehub. What wheel/ bike is it on? All weather daily commute or fair weather ride? Basic wheels do not have repairable freehub bodies, you can only replace the entire unit (around £25).

jimothy78

If you've just changed the chain, then the prime suspect for a slipping chain (which is what it sounds like) is cassette wear - the teeth of the sprockets wear to match the old, stretched chain, so they don't mesh properly with the new one.

paulbox

nicklouse wrote:

But what you say has been done points to a worn cassette.

Still this.

If it's not the cassette, I would then check that it's not a front chain ring.

njee20

Agree with Nick/Paul, worn freehub is very unlikely. Worn cassette (assuming you didn't change it when you changed your chain?), is very likely.

paulbox

Don't bike workshops take bikes for a little test ride before handing them back to their customers? I would never change my chain and not run it up and down the road to make sure that it wasn't slipping, it's such a common issue.

Maybe they were just trying to keep the costs down for the customer, but I still think they should check really. It's a bit of a PITA having to take your bike back in to be fixed.

Fantasia

Hi Guys

It sounds like the freehub, cause there was some movement when it was checked out - not much but obviously enough to cause the prob.

When the chain was replaced all the other associated bits and bobs were done too - the problem was only obvious when taking off from stop on a slight incline with all your weight on the one pedal.

Thanks for all your help and comments, my bike knowledge is just a wee bit further along - I'll let you know how it goes when the freehub is sorted out - fingers crossed it solves my problem.