Chain length advise

bikeit65

My bike has been having a few problems recently with gear shifting and the chain dropping down to the next lower rear cassette while you pedal backwards at lights, junctions etc,
So i have replaced the rear cassette, chain and middle front chainring, but this morning when out on a club run an old guy who done a bit of bike mechanics just said to me when we were stopped at the coffee shop that he thought the chain was too long, so could you look at the photos and let me know what you think regards the chain length.

desweller

Looks too long to me.

How To Set Your Chain Length

bikeit65

Found this http://www.machinehead-software.co.uk/b ... hcalc.html
and according to the calculations the chain length should be 53 inches but the chain is 52 inches?

arlowood

Don't know what experience your bike mechanic had that said the chain was too long but from what I've read it looks a bit short.

In your first pic with the chain on the big/big combo the general advice is that should still be a reasonably discernible angle to the chain pathway as it passes through the jockey wheels on the rear mech. Your pic shows that you are just about OK with the existing length. If the chain was any shorter there would hardly be any angle.

As you have pointed out using the calculator, I would add an extra inch at least to your chain and see how you go with the gear changes after setting up your rear mech again.

sungod

is that a shimano rear mech?

go to http://techdocs.shimano.com

choose groupset name, choose the si-*.pdf file for your model of rear mech, it contains instructions to set the correct chain length

fwiw usually with shimano, you put the chain on biggest ring, smallest sprocket, then set the chain length so that the axles of the two jockey wheels are vertically in-line - but there may be some models this doesn't apply to

if it's not shimano, go to maker's website and follow similar process

bikeit65

Followed the Shimano instructions and enclosed a photo so what do you think?

mercia_man

I agree with sungod. Chain on biggest ring and smallest sprocket and adjust length until jockey wheels vertical over each other. I use this Shimano method on all my bikes, triples and doubles, Campag and Shimano.

Looking at your latest pic, I reckon you've got the length right.

mercia_man

Just looked a bit more closely at your latest pic. If anything, the chain is slightly too tight.

I'd try putting one extra link to see if you can bring the lowest jockey wheel axle back until it is directly underneath the top one.

bikeit65

I will do that tomorrow and report back with a picture

Ben6899

Also, post a photograph of small-small.

cycleclinic

I find for a mech like that with normal size ockey wheels wrapping the chain around the big ring and the big cassette sporcket and bring the two ends together (inner and outer obviously) and add one full link (outer plus inner) then pass chain through mech and oin with a master link works very well.

Trying to do by mech position is more difficult. You know if the chain is too long when in small ring and smallest rear sprocket the chain rubs against the mech cage. If you have it so there is a bit of gap in this gear that you will never use the chain is the right length.