So, my ultegra rear mech doesn't seem to hold enough tension. Although it is moving fine between all the cogs on the cassette it isn't springing back enough to hold the chain taut. I had this issued about 6 weeks ago so cleaned the mech with degreaser and gave it a good clean / lube. All seemed fine (over about 3-4 rides) until the other day when I went to use it. Any advice? fixable or buy a new one?
thanks.
How old is it and what gear do you leave it in when not being used? Based on nothing more than observation I've come to the conclusion that rear mechs loose spring strength if left in the bigger rings/sprockets.
If you are dexterous enough then you can dismantle it and clean/lube the main pivot too. It's putting it back together when a third hand is useful.
I would strip, clean and grease the pivots.
Some mechs you can also increase the tension by moving the spring to a second hole.
If it's an old cable, it might be hanging on by a thread in the lever where it does a very tight turn not far from the nipple.
Is your chain too long?
I would strip, clean and grease the pivots.
Yes. Mechs don't lose their spring strength, but the main sprung pivot can become sticky and stop the mech from returning properly and maintaining tension.
Before dismantling everything (which can be a bit tricky if you have not done it before) it's worth giving the mech and mounting point a good clean, and carefully spraying some lube like GT85 around the pivot where the pivot bolt enters the mech body. Waggle it back and forwards until you are sure it is moving freely under its own spring tension.
yeah I think its just the pivot that is sticky. have doused it in GT85 and it moves.....its 5 years and thousands of miles old though so have bought a new one.....along with a new chain set after noticing the drive side crank was cracked all the way through!