Slipping chain? hub? freewheel?

[Crackle]

You wouldn't think it was the chainwheel would you but you are beginning to run out of options. Did it start skipping after the cog change or the chain change or did you do both at once?

 

[Chuffy]

You wouldn't think it was the chainwheel would you but you are beginning to run out of options.

Aren't I just...

Oh and it's a TA track chainwheel and has probably done less than 5000 miles.

 

[MartinC]

Bump.

Did you manage to fix this?

 

[Chuffy]

REJOICE!

Andy Gates, for t'was he, has fixed it.

The fault? With me riding and Andy running behind, it was obvious that the tensioner was catching the chain in some way (we still haven't figured out how) causing the chain to skip. Andy introduced me to the concept of a 'magic gear' eg one that would work without a tensioner. The only one that was achievable with the bits that I've got was a 53x18. I'll be gurning up hills like a chimp treading grapes but at least I'll be riding.

NOT the freewheel
NOT the chain
NOT the chainwheel
NOT the sprockets
Just some weird random and totally inexplicable juju. Thanks for all the advice and suggestions though, they were appreciated.
In the meantime I'm going to develop thighs like Chris Hoy. Then I'm going to buy a new chain tensioner and go back to my nice comfy 46x16...

 

[mickle]

So a stiff link then.

 

[Chuffy]

So a stiff link then.

No. If it was just that, one of us would have spotted it.

 

[Crackle]

Yay, good stuff. Thank feck for that.

 

[NickM]

Clapped-out jockey wheel in the Doofer? Should be replaceable, I would think; maybe with something better.

Edit: like this, perhaps? Making it a Sooper Doofer

 

[MartinC]

Really glad you've got this working!

It sounds like the tensioner was intermittently not tensioning! Guess this might be because the jockey wheel was sticking (Mickle or NickM may have guessed why). When it sticks the tensioner arm moves upwards momentarily as the chain carries on round the sprocket, When it frees the chain isn't tensioned until the tensioner spring has reacted and restored tension.

It's always hard to diagnose problems when there's a combination of things happening. Sounds like the combination of a stiff link/duff jockey wheel and not enough wrap on the sprocket allowed this effect to happen.

 

[Chuffy]

Really glad you've got this working!

You're glad?

It sounds like the tensioner was intermittently not tensioning! Guess this might be because the jockey wheel was sticking (Mickle or NickM may have guessed why). When it sticks the tensioner arm moves upwards momentarily as the chain carries on round the sprocket, When it frees the chain isn't tensioned until the tensioner spring has reacted and restored tension.

Exactly what it was doing, although it took two people to see, because it doesn't do it on the workstand, only under load.

It's always hard to diagnose problems when there's a combination of things happening. Sounds like the combination of a stiff link/duff jockey wheel and not enough wrap on the sprocket allowed this effect to happen.

I'm going with the jockey wheel being knacked (thanks for the link Nick... ) as both the chains that I used were fine. Plenty of wrap on the sprocket too, as I'd used that combination before with no problems.