chain length for gears ?

General Help
1

i used the technique to calculate chain length that seemed the simplest for my 1x8 friction shift setup.
So chain round the front chainring and round the largest rear cog, overlap the ends of the chain and allow one complete male-female link in excess before trimming to length.

it seems to shift fine though i need to use a fair bit of force on the shift lever, but i feel aesthetically ( and probably mechanically) there is too little chain to allow the derailleur to take up as much slack as it wants to, it might be a “little” overstretched. but not really sure with it being an early 80’s derailleur, maybe they liketo work like this?
here’s a picture on the big and little cog, i have two segments of chain i removed from the chain as bought, should i put them back in?

cheers
Liam

2

Chuck a short cage Shimano mech for starters. Will shift much better.

Then check that the mech isn’t stretched to far when in the lowest gear. Your method is fine for a 1x. Other methods will end up with a too long chain as they expect a double crankset. The mech doesn’t rotate back further because it doesn’t have the small-small combo.

3

Yeah for a 1X system you should have measured it differently as there’s heaps of capacity to play with, so no need to have it so stretched out.

Put it in the smallest cog on the rear and add links (use new pins) so the bottom of the chain sits about 10-30mm below the top pulley.

Like this:

4

thanks for the help guys,

i really like the look of the old galli derailleur, that’s why i’m using it, at least till i feel i need something smoother.

are you two mildly contradicting each other? i don’t have new pins/links so would prefer to leave it as is for a few days and see what happens if that is a viable option. there is still swing/spring in the derailleur when on the largest gear, so it doesn’t seem to be fully extended yet.
i’m sure it will be frowned upon at the traffic lights, but the fender line will probably draw most of the attention. this is my winter bike for last winter so i’m a slow worker

5

More stretch equals more chain tension. As long as you’re not beyond the limits of the mech, this is a good thing, decrease slap and the chance of throwing the chain.

Edit: no problem reusing pins on a fat eight speed chain.

6

You can go for different things I guess, my recommendation would result in:

  1. better shifting as the top pulley will be closer to the sprockets and wrap around better (also b-screw dependent, not sure if your derailleur has one of those)
  2. it won’t wear out the springs in the derailleur as much
  3. it’ll be easier to change gears due to less cable tension
  4. it won’t look like it’s about to snap off

also, chain slap isn’t a real issue on a road bike and you’ve got a front mech on there to stop it falling off anyway.

but listen to blakey about reusing the pins :slight_smile:

7

well, if i can reuse the pins i will put the 4 links back in, it will surely look neater and if it changes a bit smoother it wouldn’t hurt

thanks for the education on the dark arts of derailleurs and chains - both of you.

8
  1. I’d prescribe b screw adjustment over using chain length to get jockey the right distance from the cluster
  2. I should probs store my geared bikes in small small to minimise tension on springs/cables/shifter ratchets. but lazy.
  3. I’ll give you this one, but I reckon a matched shimano geometry mech would solve this and more
  4. looking isn’t doing, as long as it’s within an acceptable range, but if you like the look of it rotated back more, who am I to stop you.
  5. ask xbbx how the chain drop on the townie went for him :wink:

Do an experiment Liam, assuming it’s not currently going to asplode the mech, ride it for a few days, then refit the links and compare the shifting/chain tension/etc. Report back, with charts preferably.