Gear Jumping

[sndmn2]

So I had a rental tonight. It would jump gears on its own when pressure was applied but only on two or three of the rear rings. Is there anyway I could have remedied this or is this a case of a worn cassette ?

[Di_bear]

That's tricky. I've had several people check out my cassette because I've been having some major shifting problems. A friend adjusted my front derailleur tonight making it work GREAT. The rear is good, but still needs a little fine-tuning. It was *really* bad. In my case, it could be that I need new cables, but we're gonna keep working on the fine-tuning.

[john_galt]

It is tricky. I think it is Sheldon Brown who has a list of 100 reasons for shifting problems.

Jumping under pressure: If it was the middle rings it probably was worn. Another common cause for jumping under pressure is a bent cog. Any time I've had this problem a new cassette fixed it. Good thing it was a rental and not yours!

[Sherpaboy]

someone probably changed the old chain (installed new chain) on old worn cassette. Under load you'll get a slipping in usually only a few gears (the ones that get used the most).

If it is this there is no adjustment that can help...it needs new cassette too (or chain if it was the cassette that was swapped). And also as mentioned above a middle ring usually wears out much faster than big or granny...can also be an issue, but usually under load in more cassette cogs.

[Di_bear]

What if you have a new cassette *and* a new chain?

[Sherpaboy]

What if you have a new cassette *and* a new chain?

bent hanger or cable/housing issue.

[Di_bear]

What if you have a new cassette *and* a new chain?

bent hanger or cable/housing issue.

Yeah...I'm thinking I'm gonna have to break down and get it recabled.

[c0nsumer]

What if you have a new cassette *and* a new chain?

bent hanger or cable/housing issue.

Yeah...I'm thinking I'm gonna have to break down and get it recabled.

Get the hanger checked too. The shop should know to do that if you're having weird shifting problems.

Personally, almost all non-adjustment related shifting problems I've had been (slightly) bent hangers.

You could always go single speed...

[Di_bear]

[ignore]You could always go single speed...[/ignore]

The hanger isn't bent. That was one of the first things many people checked out. Jeremy V got the front derailleur to work great. The rear seems laggy.

[kyleRIG29er]

Go SS?

[Di_bear]

If I went SS, I would be walking my bike uphill, not going fast enough downhill, and my IT Band syndrome would pop up again. It doesn't match my riding style--which I enjoy, which is why it is my style--therefore, SS is not an option.

[centralRH]

[ignore]You could always go single speed...[/ignore]

The hanger isn't bent. That was one of the first things many people checked out. Jeremy V got the front derailleur to work great. The rear seems laggy.

"Laggy" = likely cable/housing problem...dirty housing, inner wire catching the cable, etc. There are other suspects (e.g., bad shifter) but I would start with a change of cables and housing.

[volklgirl]

Last time I looked at your Trek it had a cable unraveling inside the housing, IIRC.

New cables and housings tend to be a pretty inexpensive fix for a majority of the shifting problems I've encountered. I'd start there as well.

[JonathanGennick]

What if you have a new cassette *and* a new chain?

You can still get skipping if the rings are worn. Sometimes one must replace all.


Sent from my iPhone using Tapatalk. Typos and terseness are to be expected.

[Di_bear]

What if you have a new cassette *and* a new chain?

You can still get skipping if the rings are worn. Sometimes one must replace all.


Sent from my iPhone using Tapatalk. Typos and terseness are to be expected.

I upgraded everything this past fall. Everyone who looked at it also looked for wear, but it doesn't make sense that it would be worn by this point.