Noisy top-gear (Claris)

Pointy boy

Well-Known Member
Hi,
I've got a bit of a grinding noise when in top gear on my Claris-equipped Allez. All the gears are perfectly indexed (I think), as all changes up and down are silky-smooth, but there is a bit of a rubbing noise when in the highest gear. I can't seem to pin-point it, but I think it's the rear mech. The noise is very minor, and most people would probably just live with it, but if there's a simple tweak, I'd love to know!

Cheers.
 

T.M.H.N.E.T

Disc brakes - Stopping things since 1902
Location
Northern Ireland
Back out the H screw a little if the indexing is ok
 
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Pointy boy

Well-Known Member
Ok, one more stooped question: the front derailleur barrel adjuster: which way do I turn to slacken. I it's know anti-clockwise, but looking at the bike from the front or from the riders position? So far, fettling and YouTube have only made matters worse... I think the LBS may be beckoning... ;-)
 
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Screw it in - so clockwise looking at it from the cable end. There's usually a threaded hollow bolt that goes into the shifter frame (what the brake/shifter lever pivots in) - the cable runs through this hole in the bolt. The bolt is (usually) surrounded by a plastic 'nut' - which is what you turn. The nut runs up and down the outside of the hollow bolt along ridges up the outside surface of the bolt. Screwing it in takes tension off the cable.

We can help you but you'll need to tell us exactly what's making the noise - there are several possibilities. Suspend the bike of the ground somehow and turn the pedals whilst looking for what's catching - it can be hard to locate it but take your time. There's no need for the LBS - chain noises are usually adjustment related and easily solved once you understand how the system works. There are 2 limit screws on the rear mech to stop the mechanism from going too far to each side (H and L screws).These don't affect the indexing - just the range of travel of the mech.

There's then a (B) screw which bears on the rear mech hanger and sets the limit of rotation of the mech - if it rotates too far forward the top jockey wheel can touch the cassette. Best not to 'fiddle' until you work out what it is that needs adjusting! Cable tension affects the indexing. The cable should be just about slack when in top gear assuming that the mech is sprung such that it 'wants' to go to the highest gear (i.e the smallest sprocket on the outside).

I'm no expert (many on here are) but with a bit of analysis you'll soon learn how to do it. I set up my own mechs simply by working out what's catching and making the appropriate adjustment. Once you've got it right it'll only need occasional tweaking.
 
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Pointy boy

Well-Known Member
Thanks, but the front derailleur barrel adjuster is on the frame down-tube, not at the shifter, hence my confusion about clockwise vs counter-clockwise:blush:.
 
Imagine that you are looking along the front derailleur cable, away from the shifter towards the bottom bracket. If you turn the adjuster counter-clockwise you will tighten the cable. The noise you describe just might be the chain making light contact with the front derailleur guide. If you change to the inner chain ring the cable will slacken. If you can find exposed inner cable somewhere, you should be able to feel some slack in the cable, but not too much. The down tube barrel adjuster is used to trim out most, but not all, of this slack. It's also worth checking the setting of the high stop screw on the front derailleur. This wants to be set to allow just enough travel to make for a crisp change to the dog ring, but not so far that the chain gets thrown off toward the pedal. However good you get all this on the workstand, it's out on the road where it matters, so after you get it perfect in the shed, take it for a test drive to confirm your good work!
 

sgl5gjr

Senior Member
Location
Huntingdon
has it always been like that?...... before you mess with cables and tweaking.... check the chain for wear... often a worn chain can lead to front mech rub... and everyone rushes to mess with front or rear mechs.... You tube gets a good watch and all things can end up worse...and then a call to the likes of me to fix it...lol
I had one yesterday with the same symptoms...and a guy who loves his bike and it must run quiet and smooth... chain checker showed he was worn...new chain and all is well again....being worn they can just go out of alignment enough to rub, contrary to belief some bikes are set very close tolerances on the front mechs and can be a b*st*rd to sort, especially the supermarket/halfords/own brand ones and cheap end with twist shifts and cheapo unknown front mechs....
 

screenman

Legendary Member
Every thing gear wise should start with rear mech alignment first.
 
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