How much wiggle room in chainline / BB spindle length?

[FluffyChicken]

As far as I know the last letter if there will be S or L (or nothing) Nothing means left spindle is the same as the other, L = Longer, S = Shorter

Could just be a poor L

Annoyingly the 110 may vary with manufacturer and where you read
The shimano specific reference on sutherlands says the end factor (chainline difference) is 0.5 with reference to the UN series and shimano cranks. but elsewhere it has it at a different chainline by other people with other cranks. Joy of Joys.
Fit and if it works, doesn't feel odd. Forget.


(118 would be XL11

 

[Neil]

Measured the chainline with the 107 UN51 in, and an MC40 chainset on (I'd use either that chainset or new M570), and it looks about perfect. True test is when it's all cabled up and running.

So as that BB was stock in an identical bike, I'm going to go with 107 for the replacement for the original, since I'll probably put a new M570 on that (maybe the Sugino will go back on, but I'd stalled half way through polishing it), seeing as all the chainsets I'd currently run on there seem to work with that BB length.

I then checked the chainline on my 91 Axis that's been out and used for quite a while. Disturbingly, the chainline looks way over spec (somewhere around 55-57mm). The BB was in when I got the frame (it's not a Shimano one), and was very smooth, so I left it in, as I didn't have the non-cartridge type extractor tool. It runs a chainset from that era (91) a Deore DX one, I think. Front mech copes with all three rings. Rear shifting is OK - never been spot on since I built it up, but I've never bothered to do any more in terms of recabling it, I just tried to tweak / fine-tune it. It shifts OK going up the cogs in size, but sometimes can be a bit lazy going to the smaller ones. Trying to fine tune the cable tension didn't seem to sort it, it just pushed it the other way (ie better at moving down to the smaller cogs, more lazy going up to the bigger cogs).

Looks like it's the chainline that's fighting against it. Funny thing is, though - measuring it, it's way out of spec, but not absolutely awful - I've just never got it dialled-in perfect.