Chain slipping at chainset

Cubic

Hi,

Occassionally, when going up steep hills, my chain slips from the middle ring to the little ring on my 105 triple.

Does this indicate that I just need to change the chain or should I replace the chainrings too?

The bike is about 18month old and gets used pretty frequently.

Bugly

it indicates your chain is stuffed and more then likely the chainring you are using is worn because of that.

sungod

if the chain is badly worn you'll probably have to change the cassette too, as the chain wears it accelerates wear on the cogs and chainrings, eventually a new chain will no longer fit properly (it'll skip like crazy)

see here for how to measure chain wear (aka stretch)...

http://www.sheldonbrown.com/chains.html

...or you can buy a gauge to do it for a few quid


have you checked the front mech alignment? for shimano you can find the service instructions on...

http://techdocs.shimano.com

adjustment might let you put off the painful day for a while (buying a new chain, cassette and rings will cost a bit)

it really is best to keep an eye on chain wear and replace the chain before it causes excessive wear to the other parts

bexley5200

most likely chainset worn,and you need a new chain too.

amaferanga

Before you start throwing money at your bike....

Is your front mech properly adjusted? If its not sitting far enough out when the chain is on the middle ring it may be knocking the chain down to the small ring as your frame flexes under load on hills. While riding normally the chain may just be clearing the mech. You could try moving the mech out a tad using the cable adjusters.

Cubic

Thanks for the replies.

I'll have a look at my front mech adjustment tonight as that could well be the problem.

I actually picked up an Ultegra 6600 chain and cassette in the January sales and am just waiting for the weather to improve before fitting them.

My chainset is an FSA Gossamer triple. If it's not the mech that's causing the problem, could I just replace the middle chainring, as this is the one that gets by far the most use? Or should you replace all three?

Also, if I did decide to get a new chainset e.g. http://www.chainreactioncycles.com/Models.aspx?ModelID=11789 would I just need to get the matching BB or is there anything else I'd need?

Thanks for your help!

sungod

if adjustment doesn't sort it...

try new chain, but it's possible the new chain will skip on the cassette so badly the bike is unridable, so new cassette

then if the chainring still has issues, just one ring might be enough, all depends on the wear

if you decide to get a new chainset then either get one to match the current bb, or replace the bb too

btw after 18 months, did you service the hubs and headset yet? (grease early or repent at leisure!)

Cubic

Errrrrn no! Hubs and headset - I was only just getting my head around the drivechain! :shock:

I'll take your advice regarding the skipping chain. Thanks!

I think I'll wait till spring and then get the lbs to do a full service as I'm sure I'd cock up the headset if I tried myself.