I’m trying to put a cheap Barracuda bike back into some kind of rideable condition for a friends son.

Its not come up too bad with a bit of oil,elbow grease and some fettling.

Here however is where the final problem is p’ing me off!
Its a cheap as cheap 3×7 with gripfhift. All the gears can be found, ans i’m surprised at how well! The rear mech appears straight. The chain isn’t worn out.
BUT, when i try to ride it it is fine in every gear except the 7th, now matter what ring at the front.
Its fine on the stand, but any slight load its jumps. Even 6th is fine with loads of load. This would suggest everything’s OK with the freewheel itself, wouldn’t it?
Nothings been invested in it but time, and i don’t think its worth spending anything on, but i don’t want to say its knackered unless it really is. But right now i can’t stop it jumping!

I can make my MTB and Roadie work fine, oh and every other bike i’ve done.
just not this little bugger!

Any helpful suggestions would be appreciated!

Is the 7th cog bent – or simply worn?

Completely guess but maybe the chainline simply won’t allow it?
WIth a BSO, I’d suggest 6 out of 7 is pretty damned good.

Yeah, use the limit screw to tune out 7th, and you’re done.

I’d say you’ve done a good job

APF

Maybe i’ll try that.
It goes into it fine,just won’t ride in it.
Nothing seems particularly worn, thats whats bugging me!

Is it rubbing on the frame? Cheapy frames sometimes interfere with the bottom sprocket.

WIth a BSO, I’d suggest 6 out of 7 is pretty damned good.

It’s just plain showing off is what it is! 🙂

I’ve had a similar experience with one working perfectly in the stand but not when ridden. The solution was as I discovered the realisation that life’s too short.

Probably just worn out.

Ill bet the gears havnt worked for some time so the kid just used the front gears and the 7th cog.

Have you checked for stiff links in the chain? sometimes it will only show up on the smaller cogs as the angle the links have to rotate to is more acute and on the bigger cogs it’s not an issue.

Go through the chain link by link and rotate fully from this -o-o-o- so that the links are like this -o/°\o- to each other to check properly, should be no binding or stiffness.