poorly gearbox or something else?

[blueflag]

Take the caliper off when you try it with the chain on, if it's free then the problem is your brake...

[amorti]

Check the cush hub. Two main things can and do go wrong, the cushes wear and shrink, and at that point the hub moves laterally and the bearing fails. The failed bearing makes a nice graunchy noise. You can test it on the bike same as you would with testing wheel bearing by grabbing it at 6 and and 12, but it is easier to take the wheel off and stick your finger in.

Or, the rear caliper is in some way damaged. Repack the sliding pin with red rubber grease and check if all the pad retaining springs are in place and in good condition.

Or, it's your chain, which is dead. Watch it go round, and check for anywhere you can see links that don't run straight but keep a kink in them.

Or your engine or gearbox has bigger issues, but chances are it'd be leaking oil out the output shaft by now.

[amorti]

what would the symptoms be of a fcuked gearbox?

strange rumbling sound?
if coasting in neutral it feels like a rear brake binding at the same point?
if on a paddock stand, notchy to and difficult to turn the rear wheel?

I have just replaced the rear wheel and sprocket bearings but i am now a bit worried it could be something more costly.

I will have a good look at it tonight so some pointer on what i could check out would be appreciated.

Ah, this will be the thing. I've read it better now.

If you've changed something recently, and now it doesn't work, what does that mean? It means you probably did it badly. Did you put the middle spacer back in? And the spacer between the hub and wheel bearings? And all other spacers back in their right places? I am guessing no to one of the above.

[The Novice]

it spins freely after taking the chain off.

I agree - i touched the bearings, must be them? however no problems at all when i checked - and yes all spacers etc etc are in. spacer in the middle, new bearings, new seals, and hub/sprocket spacers are on.

I have checked the chain, thats fine, brake isnt the issue, i have today put the wheel back on with chain on it now.

Havent gone out on it again yet - might get some time tomorrow, but its not making the same noise it was, nor am i feeling the same resistance i was before.

Maybe a bearing wasnt seated properly and taking wheel off and retorquing has sorted it? Either that or it needs the weight on it to before i can tell if its ok.

[amorti]

it spins freely after taking the chain off.

I agree - i touched the bearings, must be them? however no problems at all when i checked - and yes all spacers etc etc are in. spacer in the middle, new bearings, new seals, and hub/sprocket spacers are on.

I have checked the chain, thats fine, brake isnt the issue, i have today put the wheel back on with chain on it now.

Havent gone out on it again yet - might get some time tomorrow, but its not making the same noise it was, nor am i feeling the same resistance i was before.

Maybe a bearing wasnt seated properly and taking wheel off and retorquing has sorted it? Either that or it needs the weight on it to before i can tell if its ok.

Again don't know your level of experience just throwing ideas out-
could it be as simple as an over tensioned chain? If there's no tight spot in the chain (YET!) but the chain is seeming to make the noise, then it could be that. Do bear in mind that chains will actually always make a bit of noise, sometimes it is hard to tell what's normal?

[The Novice]

I just do not know what it was exactly, could have been a bearing not sitting right although I think you might have hit the nail on the head, the chain was too tight, i have slackened it off a bit (within the tolerence), cleaned it again and relubed it.

I have been out on it for a few miles on sunday and it seemed fine, hopefully it will be ok - tell you what the noise before was horrendous so i am amazed its making no noise now.

Thanks for the pointers