UKC

I'm haveing a bit of trouble setting up my gears. With the chain on the largest chainring and the either of the two smallest cassette sprockets the chain clips the next largest cassette sprocket. This is worse when the chain is on the smaller chainring and I'm trying to use any of the three smallest cassette sprockets.
To me it looks like the chain line is wrong but measuring from between the two chainrings to the centre of the BB shell seems correct (~47 mm) so I'm a bit stumped. The chain is a KMC XXSX 10 speed chain that came on the bike and the bike on the whole has done about 200 miles.

Any suggestions?

Thanks,

Gethin.

In reply to gethin_allen:
Front mech needs adjusting.

In reply to gethin_allen:

Sounds like an index problem. I would look at re-indexing and see if that resolves the problem, this is to take account of any stretch in the cable.

In reply to andymac:


It's not rubbing on the front mech

In reply to gethin_allen:

I don't think I explained the problem well above, the chain is contacting the neighbouring larger sprocket on the top tensioned side, not the bottom where the chainline is guided by the deraliure (sp).

In reply to gethin_allen:

You say chainline is right but might still be a chain line problem. Depending on your set up you can change that with spacers.

Also, check that rear wheel is sitting square in frame.

In reply to gethin_allen:
Is your wheel in straight? Stupid q and I hope the answer is yes...

In reply to gethin_allen:

Everything is square and true with the wheels and fitted as it was when I got the bike. The gears change and index fine (give or take a bit of cable stretch and outer cables bedding in a bit) it's just this bloody rubbing clicking that's driving me nuts.
I'd say that it needs a spacer on the drive side of the BB axle between the crank arm and the bearings, but it's a push fit BB and I'm not really sure what I'm up to with them or even if it is a viable thing to fit such a spacer.

I never had any problems with my old 9 speed setup and really wouldn't miss the 2 extra gears if i could just have a nice quiet ride where all the useful gears were available.

In reply to gethin_allen:

Is the gear hanger bent or are the screws loose? you shouldn't be cross chaining, smallest chainring to smallest rear sprockets or big to big, is the rear mech too close to the sprocket? the B screw may want adjusting

In reply to Mr Moac:

Everything is tight and square and new. As stated, it's not the derailleur positions that's the problem, with the chain on the largest up front an either of the two smallest at the rear the chain rubs against the next largest sprocket on the cassette.

In reply to gethin_allen:

What groupset? As indexing is usually undertaken in the largest chainring and smallest sprocket first, I'd still go with that. It's possibly just a small adjustment needed.

In reply to gethin_allen:

...bike on the whole has done about 200 miles.

Return to shop and get them to sort it and explain what's wrong.

In reply to gethin_allen:

Are you a midget? Chainline clearances are tighter for small frames with short chainstays.

In reply to Removed User:


I was wondering about this. Is there much difference? I've just measured 10 bikes in the garage ranging from Mrs. Ent's 48cm to a client's 60cm and the distance from the centre of the BB to the centre of the rear axle was 41cm on every single bike.

E

In reply to gethin_allen:

similar problem here turned out to be a kink in the gear cable (possibly):
http://forum.ctc.org.uk/viewtopic.php?f=5&t=47125&sid=f78287bd5a7da...

In reply to gethin_allen:

Sound like a bizarre problem as there are no adjustable parts that will make any difference to the chainline and you've already checked everything is straight and true. So, these ideas are all long-shots:

Are you absolutely certain it's a 10 speed chain?

Does the spacing between the sprockets appear to be equal the whole way down. It could have been fitted incorrectly but this is a very long shot as missing a spacer would make such a large difference it would be obvious.

Perhaps there could be too many spacers between the cassette and the hub, but this would only make a 1-2mm difference, not enough to cause your problem.

In reply to Oujmik:

Is the cassette locking nut actualy done up tight? If it's not, then the cassette may be wider than it should be. Clutching at a passing straw here by the way, but it's worth giving the cassette a waggle to see if it's all held together tightly (being a block of 4 gears (or is it 3?) and a stack of loose gears and spacers.

In reply to Enty:

I'm guessing there is if you are running 26" wheels? Maybe not much variation across frame size though.

In reply to Removed User:


Not a midget but I was wondering about the chainstay length thing.
The bike is a 2014 spec Giant TCR3 medium/large with 10 speed Tiagra groupset.
http://www.giant-bicycles.com/en-gb/bikes/model/2014.giant.tcr.composite.3/...
(chainstay length stated as 40.5 cm)

The chain is definitely 10 speed compatible as it has it stamped on the links and I even measured the width of the links with some callipers to check.

The cassette is on tightly, I've taken it off and looked at it and put it back on etc, and the wheels run in the centre on the stays suggesting that the spacers on the hubs are correct or that the wheel was dished to fit the frame spacing after the initial wheel build (probably by a machine) which would be highly unusual.

The only reason I'm trying got sort this out myself is because of the complexity of getting it back to the place that sold it to me; it was a internet mail-order place specified by my employer for the cycle to work scheme.

In reply to gethin_allen:

The cogs are the right way round on the cassette aren't they? I made that mistake putting a cassette back together. Not saying you have but I have no other ideas!

In reply to gethin_allen:

I,ve always understood that chainsets were not designed to route the chain from an inside chain ring to the smallest rear sprocket as the angle of chain to sprocket is too great. Also, you may have a longer bottom bracket designed for a triple chain ring.

In reply to Baz47:


But if you read my post, it isn't right with the chain on the largest chainring and the smallest on the cassette. Also, the Bb axle is integral to the driveside crank arm and the Bb itself is push fit into the bb shell.

I called the company that sold me the bike and they've agreed to let me take it to the LBS to sort it and they'll catch the bill.
It was a shame I couldn't have got it from them in the first place but I couldn't afford to buy it without the cycle to work scheme.

In reply to gethin_allen:

It seems as though the chain line needs to be more than 47 mm from centre at the chain rings? Maybe there is a spacer missing on the drive side of the BB? A spacer would move the chain rings out a bit, lessen the chain angle and reduce the risk of clipping the next sprocket in from a small one.