Upgrade Chainset?

Gerry Attrick

Can anyone help? I have a hybrid with which I am more than pleased except for the TX71 chainset. I know it is Shimano's budget triple, but I didn't expect the middle ring to be so noisy! Everything is adjusted perfectly but I still get a metallic "chain type" rattle every pedal revolution on the middle ring only. I have stripped and checked the usual culprits, bottom bracket, pedals, front and rear derailleurs etc, but nothing cures it. Is it time to consider an upgrade? If so to what? I would like to keep the 48-38-28 ring sizes. Anyone any experience of this problem?

MarvintheAndroid

This might be more a function of the front mech.

Marv

Gerry Attrick

Marv, thanks for response but I've checked both mechs thoroughly and nothing is rubbing even under heavy stress. In fact the noise is there even when spinning the pedals by hand with the rear wheel off the floor.

MarvintheAndroid

Worn chain or rings maybe ? Has it done this from new, or become worse over time ?

If you are really unhappy with the chainset you could certainly upgrade it, but I would suggest you rule out wear and tear first because replacing just one component in a worn drivetrain can make things worse.

Marv

Gerry Attrick

Hello again, Marv

The bike is only a few weeks old and did not make this noise from new. I know I should take it back, but the dealer is 75 miles away! I live in the sticks somewhat here.

Thanks anyway.

supersonic

Check that none of the teeth on the middle chainring are bent though do note some are shaped to aid shifting).

Gerry Attrick

Thanks for that suggestion Supersonic. I've just been out to check but no sign of bent teeth. Sure some are oddly shaped, but I'm assured by the dealer that is to assist changing. The noise appears to occur just as the chain moves over the pick-up pins particularly when sprockets 5,6,7 and 8 are in use on the cassette. Does that give a clue to anyone?

supersonic

Could be a chainline problem ie the angle of chain from front to rear. Good article in Sheldon below on this.

Gerry Attrick

Thanks again Supersonic. I looked at the alignment by eye initially and thought you had found the problem, but careful measurement after reading Sheldon Brown's article gave me a front line of 47mm and a rear line of 44.5mm. Aaaaaaargh!

Gerry Attrick

Thanks to all you fine people who tried to help. I finally took the clicking beast to the LBS (not where I bought it!) and they fitted a SRAM chain in place of the Shimano fitted. Guess what.........silence, blissful silence. Don't know why, the Shimano was only as old as the bike (a few weeks), but who cares?