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Jumping gears


garyinoz's picture

By garyinoz - Posted on 24 March 2009

NB: Originally posted elsewhere on the Global Riders Network and appears via syndication.

As above, my gears are jumping all over the place, even with relatively low load on them. I had my bike serviced last month and so far I've taken it back three times and I'm reluctant to go back to the LBS again as I had similar problems after the first service (I wanted to give themn another chance). On the first ride after the service they were all over the place and they fixed this up in a couple of mins, subsequently I've had issues with my shocks but they are all good now.

So can someone enlighten me on the simple task of sorting out the jumping gears issue so I don't attempt it blindly. It did have a new cable put in during the service.

The chain is definately one link short as it broke on the first ride after the last service. Personally I think they should have put a new chain on then but they just fixed up the gears instead.

Cheers
Gaz

Tags
ar_junkie's picture

http://www.parktool.com/repair/ - they have some handy pointers...

Do you have a chain checker/indicator? Also check your cassette and chain rings, but if you have just had your bike serviced, they should be ok as one would like to think that they would have pointed it out to you if they needed replacing.

If all of the above is good, then the LBS simply may not have tuned you gears correctly. Check out the derailleur section (http://www.parktool.com/repair/byregion.asp?cati...) for pointers on adjusting your derailleurs.
This should enable you do minor adjustments and potentially encourage you to become a home mechanic... depending on what tools you have Eye-wink

Then again, if you have just had your bike serviced, you should take it back to them to fix.

LadyToast's picture

also check for twisted links... easy to miss.

garyinoz's picture

I'll check those things out, I remember looking at this after the last service when they were jumping. Chain and cassette appear ok but I'll double check and like you say they are quick to spot a worn chain or casette.

I can reach all the gears but it must just be the alignment so I'll check the hanger too. I'd be keen to get the chain length checked out, is there an easy way to do this?

And yes I probably should take it back but having been there every week since it was serviced I'm reluctant to do so. Worst case I'll take it elsewhere...and maybe get a new chain too!
Thanks

LadyToast's picture

"I'd be keen to get the chain length checked out, is there an easy way to do this?"

Two ways, either get a chain measuring tool, or use a ruler.

Good old Sheldon (RIP) to the rescue: http://www.sheldonbrown.com/chains.html

garyinoz's picture

Thats a good article.
Cheers

murray's picture

Hi Gary, I've had similar issues, using xt cassette and shimano narrow chain, firstly I replaced the chain, still didn't solve it, replaced the cassette, this solved the problem, the cassette wears to the chain and may not look particularly worn but will cause problems when a new chain is used. I don't think chain length will have anything to do with it (unless its stretched).

If all else fails you could always go S/S;)

garyinoz's picture

I went for a ride round the dam last night, and the alignment from the hanger to the casette was marginally out, even after I had it looking spot on as soon as I pedalled under pressure the chain just jumped. The other thing I noticed was that the bottom cog on the hanger seemed to have a fair bit of play in it. At the end of the ride I also noticed a broken spoke but I'm pretty sure happed on the final downhill.

I haven't got the legs for S/S, maybe a road bike?

Bruce's picture

A road bike is the way to go Laughing out loud

Damien's picture

Legs help with riding any bike not just SS you need them to reach the pedals.

Whisperer's picture

Most of the usual suspects have been mentioned but I'll add my 'bike whispering' comments...

* Chains wear, and should be replaced at 0.75% wear. A park chain wear tool is about $15 and a 'must have'.
The caveat to this is: Some people let their chain go, and replace the entire drive train in one go.
If you replace your chain when it is at 0.75% worn, your cluster will probably be good for around 3 chains.

* Clusters wear un-evenly. The middle gears of the cluster wears more than the higher and lower gears. A new chain may work fine on the higher and lower gears but jump on the middle ones. This may seem like alignment, but is a common problem. Rohlof make a great tool that I use and is about $25 (need to get it OS though).

* Check your cable outers have sufficient slack so they do not change the cable tension as the suspension moves through it's travel. Too long can have a similar effect but less common.

* Hanger alignment - a tool is needed, once again made by Park but pretty expensive. If your LBS does not have one, change shops.

* Adjustment - if everything else is ok, work with your cable adjustment. Get it close, then work with quarter turns of the barrel adjuster each way for fine tuning. Only quarter of a turn at a time, test, if worse, go the other way. Even the pros have to do this to get it 'just right'.

* If you continue to get poor service from your LBS, get them to ride it. And I mean properly, not just up and down the street with no load. Get them to ride up and down curbs, mounds, or something that is similar to the situation that it happens for you. Try to make a note of which gear it happens in, so you can give them a decent set of symptoms to work with.

There is a lot of bagging of bike shops at the moment - some of it very justified. But also some of it may stem from a lack of testing (by them or you) when bikes are picked up. In a perfect world, you could get on your bike and just ride, but that doesn't seem to happen any more with anything!
I recommend you don't just stick your bike on the car and hope for the best - TEST IT, and if there's still a problem, or you are not happy get them to fix it on the spot.
It's a lot easier for a shop to accept responsibility if it's at the time rather than bringing it back muddy after a lap of the Dam.

Brian's picture

if you are having to many problems it's the perfect excuse to just N+1 Eye-wink

garyinoz's picture

Trust me every time i'm in the shop I'm looking at the bikes and thinking that will solve all my problems, but having been out in a stinking hot car today that reminds me that I need to replace that first and then there is the road bike too.....I think I need a lotto win.

I'm certainly having a run of bad luck with it at the moment and it probably is due to be replaced.

garyinoz's picture

Well seeing as I broke some spokes the other night I figured I might get another shop to cast there eye over it. The anaylsis is that the cassette, chain, chain rings and jockey wheels are all stuffed along with the cable. Going to have to bite the bullet!

Jee10's picture

Great Blog:

http://www.nsmb.com/page/s/2923/adjust-your-rear...

This may not fix the issue, but this is very important to add to the memory banks!!

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