Jumping gear..

Schoie81

I've developed a problem on my bike. When i'm in top gear (50/11) the gear seems to 'slip' roughly every two turns of the pedal crank. It only happens in this gear combination, all others run fine and I have no problem switching between gears, even into top gear, it changes quickly and smoothly. Its as if the chain just misses a tooth somehow?

Problem is I can't see what happens, because it only does it when I'm riding - if i get off and lift the wheel off the ground and spin the pedals, all runs smoothly with no problems. I assume with the wheel free to spin so there's no loading on the chain this stops the problem occurring?

Anyone any ideas?

farrina

Not sure if this fit's your circumstances but here might be a good point to start

http://www.bikeradar.com/forums/viewtopic.php?t=12885926&p=17944870

Regards

Alan

Yossie

Oh - I thought you meant the special clothes you wear in the bedroom. Sorry. Personally I have a string vest and some yellow pants that always do the job - TDV can't resist a man in a string vest and yellow pants. Gonna try the look out on Nina from Nina and the Neurons at this Christmas' panto time.

Schoie81

It does sound like exactly the same problem, although I haven't changed anything on the bike - last week it was fine, this week it's not...? Only thing I've done is taken the chain off, cleaned and re-lubed it. I haven't changed or adjusted anything else?

slowbike

How is the chain joined ? Sounds possible stiff(er) link to me.

If its not a quick link and your using a chain removal tool to refit the pin then I push it through, flip the chain over and push it back a fraction so te side plates are not squashed together.

Schoie81

Slowbike wrote:

How is the chain joined ? Sounds possible stiff(er) link to me.

If its not a quick link and your using a chain removal tool to refit the pin then I push it through, flip the chain over and push it back a fraction so te side plates are not squashed together.

This did cross my mind as it doesn't coincide with every rotation of the cassette or every rotation of the cranks but does seem to be pretty regular at about every two rotations of the cranks - so it seems its not just happening randomly. Also as the chain is only thing i've done anything with on the bike this week. Would that also make sense with it only doing it on the 11t gear - because thats where the chain's turn is at its tightest?

That said, the chain IS joined with a quick link which I put on there 2months (about 250miles) ago - and its been fine until this week.

For information, I don't normally run big-big or small-small, but just to try it, i changed to the small chainring on the 11t this morning and it jumps in that combination too - but still ok with small chainring on all other gears.

Schoie81

I've just had a thought - the quicklink isn't quite symmetrical, and should be installed with the smoother curve on the inside - I can't remember paying much attention to this when I put the chain back on last weekend, so if I've put the quicklink on the wrong way around - could that be causing this?

keef66

Schoie81 wrote:

I've just had a thought - the quicklink isn't quite symmetrical, and should be installed with the smoother curve on the inside - I can't remember paying much attention to this when I put the chain back on last weekend, so if I've put the quicklink on the wrong way around - could that be causing this?

Indeed it could.

slowbike

Schoie81 wrote:

Would that also make sense with it only doing it on the 11t gear - because thats where the chain's turn is at its tightest?

I think you've already got your answer from the possibility of the quicklink being installed the wrong way round (didn't know they were handed ... perhaps mine aren't?) ...

but yes - if it was a stiff link problem then the 11t cog is the smallest and the chain will have to turn round its tightest there - less teeth are available to grip the chain - so if it wasn't supple then it has a potential to stand up and not roll round properly - hence the skip - where as a 26t cog has more teeth and the chain doesn't have to turn quite so tightly - so there is a bit more tolerance in there.

Schoie81

Yes - the quicklink was the wrong way around - swapped now so will have to wait until I can get out again to test it - see if that was causing it - seems likely though.

I have Wipperman Connex quickinks on my bikes - they're a slightly different shape on one side to the other and it says the smoother curve should run against the chainrings/cassette - don't know if other makes of quicklinks are the same or can be used both ways? Could be my problem though in this instance.

keef66

Schoie81 wrote:

Yes - the quicklink was the wrong way around - swapped now so will have to wait until I can get out again to test it - see if that was causing it - seems likely though.

I have Wipperman Connex quickinks on my bikes - they're a slightly different shape on one side to the other and it says the smoother curve should run against the chainrings/cassette - don't know if other makes of quicklinks are the same or can be used both ways? Could be my problem though in this instance.

I think the upside down Wippermann link is the likely explanation. They are quite insistent it has to be installed the right way up. One of the reasons I use the KMC links; less scope for a cock-up.

Schoie81

keef66 wrote:

Schoie81 wrote:

Yes - the quicklink was the wrong way around - swapped now so will have to wait until I can get out again to test it - see if that was causing it - seems likely though.

I have Wipperman Connex quickinks on my bikes - they're a slightly different shape on one side to the other and it says the smoother curve should run against the chainrings/cassette - don't know if other makes of quicklinks are the same or can be used both ways? Could be my problem though in this instance.

I think the upside down Wippermann link is the likely explanation. They are quite insistent it has to be installed the right way up. One of the reasons I use the KMC links; less scope for a cock-up.

Simple fact is, someone suggested i got the Wipperman links to enable quick removal of the chain - seemed like a good idea, so I did just that without looking into it any further, so at that time I didn't know there were different makes of quicklink - but have since become aware of others. Anyway, not a big issue so long as you don't just stick them on blindly (like I did last weekend!!)

Problem solved though - links installed correctly and 'jumping gear' problem is no more - successful test ride today! Lesson learned and muppet of the week award accepted!