Author Topic: Chain Skipping on MTB  (Read 196 times)

Chain Skipping on MTB
« on: September 22, 2017, 01:26:17 pm »
I have an old (~2007) Genesis Core 30 hardtail which has recently started to suffer from really bad chain skipping every time I put it under load. It seems independent of which gear it's in (it's an old 3 x 9 format). Most of the gear is Deore.

I've looked around on Google and narrowed it down to the chain, or the cassette , the chainrings or maybe the hub. i.e. just about anything. The rear mech also looks a little twisted and the jockey wheels are very worn, with a couple almost completely missing. I can't adjust the L screw enough to stop it crashing into the spokes so it probably needs replacing anyway.

I've replaced the chain and it made no difference, does anybody have any suggestions ?

I'm a bit reluctant to start throwing parts at it, especially if I end up replacing the entire drivetrain. Rather than doing this I'd rather just upgrade it to either 3x10 or maybe 1x11, as the only additional expense as I see it would be the shifters.

Any suggestions anyone ? If I end up swapping parts out, then I'd like to do it in a way that, if possible, I end up with an upgraded bike (for instance can I swap the rear mech for a 10 speed mech ? Will it work on a 9 speed cassette with 9 speed shifters ?

My plan would be something like :

Rear mech (-> 10 speed).
Cassette (->10 speed)
Chainrings
Shifters

Would this work ?

PaulF

  • "World's Scariest Barman"
  • It's only impossible if you stop to think about it
Re: Chain Skipping on MTB
« Reply #1 on: September 22, 2017, 01:59:40 pm »
Looks like you've identified all of the likely culprits but most likely is the rear mech given your description of its condition. But I'd guess that the cassette has also passed its useful life span

Out of the box there's limited compatability between 9 and 10 speed. The chain's a different width for a start and the cable pull is different so you would need:

- New shifters
- New mech(s)
- New cassette
- New chain

Re: Chain Skipping on MTB
« Reply #2 on: September 22, 2017, 02:34:39 pm »
Thanks Paul,

Since posting that, I've just swapped out the cassette with another 9 speed from a road bike and it's made no difference, it's still skipping. Next step is to swap the derailleur from the same bike (a fairly recent Ultegra) and see what difference it makes.

I know that I'd end up changing everything if I do go 10 speed, but figured if I'm going to have to change most of it anyway, then I'd rather end up with a 10 speed than a 9 speed. I'm just not sure if the 10 speed mech will work in a 9 speed configuration in the meantime.

PaulF

  • "World's Scariest Barman"
  • It's only impossible if you stop to think about it
Re: Chain Skipping on MTB
« Reply #3 on: September 22, 2017, 02:44:59 pm »
I'm pretty sure that it won't. Think there may be a magic of road mech and mtb shifter that does work across 9 and 10 speed but I don't remember what it is I'm afraid

Re: Chain Skipping on MTB
« Reply #4 on: September 22, 2017, 04:16:09 pm »
AFAIK, 9sp MTB shifters will work with 9-sp MTB mechs and 9 or 10sp road mechs, as will 9 or 10sp road shifters. (The newest Tiagra ones, both mech and shifters, are different.)

10sp MTB mechs and shifters need to be paired.

Re: Chain Skipping on MTB
« Reply #5 on: September 22, 2017, 04:42:26 pm »
The fact it skips under load in any gear and still does it on a new cassette and chain makes me suspicious of the freehub.  My 3*9 Deore MTB failed like this.

Try borrowing a wheel off another bike.

Re: Chain Skipping on MTB
« Reply #6 on: September 22, 2017, 05:14:56 pm »
I've been playing in the shed.  :)

I swapped the Ultegra mech onto the Core and low and behold. It still skipped. However I also noticed that it didn't look aligned either, so I took out the hanger and when I laid it on a flat surface it was slightly bent.

I straightened it as best I could in a vice, but couldn't get it perfect, however even at that when I retried it, it didn't skip.

This is with the Ultegra mech and the 9 speed cassette off a road bike.

Next stage is to get a new hanger and see how it works. I can then swap everything back and make a call whether to upgrade it to a 10 speed or not.

Thanks all so far.

PaulF

  • "World's Scariest Barman"
  • It's only impossible if you stop to think about it
Re: Chain Skipping on MTB
« Reply #7 on: September 22, 2017, 07:01:48 pm »
AFAIK, 9sp MTB shifters will work with 9-sp MTB mechs and 9 or 10sp road mechs, as will 9 or 10sp road shifters. (The newest Tiagra ones, both mech and shifters, are different.)

10sp MTB mechs and shifters need to be paired.

That was the magic that I dimly remembered