jumping chain

Thomson0

I have recently returned to cycling after a long break (now a lot older and fatter). I bought a second hand bike from ebay from a guy that was seriously into road bikes it started out as a 2007 specialized allez sport, but all that is left from the original bike is the frame, it now has a complete ultegra groupset and bontrager race lite wheels etc. The problem I have is that now that I have managed to increase my range to 10 miles per day without an oxygen tank! I am experiencing what I would call chain jumping when I am applying heavy pressure on hill climbing, is this just what happens or should I be looking for another reason for this the gears don't change and the cassette appears to be in good condition.

robd75

Sounds as though the chain has stretched/worn, be worth measuring it to check and replace asap if needed

le_boss

could be the gears just needing a tweak. a quarter turn of the screw may solve it.
or the chain may be worn.

if your not confident in tuning the gears drop in to your lbs.

Thomson0

Thanks for the info, I am confident enough to tweak the adjusters on the gears but the gears don't change when the chain jumps so would it be more likely that the chain is worn?

robd75

It sounds like the chain to me, either get a chain wear checker or lbs to measure it

saunaboy

I had the same problem. Took bike in for scheduled service & gear cable had stretched. This is normal on a new bike (or a new cable I guess...).

Cable was tightened slightly & problem disappeared.

Butterd2

This often happens when you change either the chain or the cassette. They wear together and work together ok but if you change one and not the other it can jump.
The trick is to change the chain before the cassette begins to wear otherwise you need to do both.
Check the chain for stretching - 12 links should be 12 inches long and look at the teeth on the cassette - are they lopsided. This should identify which is worn, or to be sure just do both.

Buckled_Rims

Yep, it could a few things that needs setting up or worn. Without seeing the bike I guess it is one or a combination of what's been answered.

1. Chain stretched.
2. Rear cassette worn
3. gear cable stretched
4. The indexing screw needs a quarter turn either clockwise or anti.

If unsure just go to the LBS, but this is good experience to try and do the job yourself

desweller

Or (worst case) freehub on its way out.

Thomson0

Firstly an apology for asking for advice and not being back on sooner, having spent the weekend with food poisoning I can say that the last thing on my mind was cycling, I am still feeling a bit manky but should be back on the bike soon.

Any way thanks for all the advice I managed after a long and interesting search through old tool boxes (its amazing the rubbish that I have stored over the years) , I found the chain measuring tool and after checking the chain I can confirm that it is knackered! I am going to order a new chain from the Ribble website can I assume that I can replace the ultegra 10sp chain with the equivalent 105 without any problems, the difference in weight won't be noticed by me but will it affect the cassette and chainrings?

Buckled_Rims

Generally a like speed for like speed is OK. so, 10sp Ultegra and 10sp 105 should be OK. Just make sure if you get a directional chain you put it on the right way. I'm not sure if 105 is directional because I've been using KMC for a while on my 105 bikes.

It might effect the chainrings or cassette if they have a fair amount of wear. But otherwise 105 and ultegra are fairly consistant and matching.