Chainline

Just had a new rear wheel built on a Surly flip flop hub and asked the LBS to fit a new bottom bracket while they were at it and get the chainline right.

Having got the bike back I reckon that the chainline is out by about 5mm (chainwheel further into centre than rear sprocket). How critical is this? Should I take it back? If so, what are my options to get it right?

It's a good LBS who I've used for ages so I'm sure they'll sort it no problem; just want to go back armed with knowledge on best way to fix it.

Thanks very much for your help.

5mm is quite a lot...

i think the best option is to ask them to fit another b.b. with a longer spindle length. shouldn't be a problem it's their fault and it's a new b.b. anyway.

Thanks for the advice. I'll ask them to do that. Cheers, Simon

and yeah really, dont ride it when the chainline is that off. throwing a chain on a fixed gear can be very dangerous.
it's quite rare that the chainline is so much in towards the frame.

I have the opposite problem, the sprocket is more inboard than the chainring, and that chainring can't be moved any further in to compensate as there is 3-4mm between it and the chainstay.

Is it ok to put spacers behind the sprocket to move it out? What other solutions do I have?

Cheers!

Simon - Make them do it properly this time!

Redeye - Spacers behind the sprocket sounds a bit dodgy, are there even enough threads on the hub to be able to space it out that much?

Might just have to get a new hub :-/

eeehhhh Redeye - Spacers behind the sprocket sounds a bit dodgy, are there even enough threads on the hub to be able to space it out that much?

Might just have to get a new hub :-/

So, my hub is spaced to fit into 120mm dropouts, but I've never seen hubs available that offer different "spacings" of the sprocket in relation to the axel.

It's the stock hub on a Flyer. I've heard there was a chainline problem, but there must be a solution. . . . I hope, without having to buy a new wheel! :/

I'm guessing the hub has the 'normal' track chainline? i.e. 41mm.

If you need it to be 3-4mm out, you could try a goldtec hub which has a chainline of about 45mm, then fine tune it with a slightly thicker or thinner cog.

Or you could just try thinner or thicker cogs (some cogs are thicker on one side than the other) on your current hub to try and shift the chainline slightly.

As long as the chainline is straight within one or two mm it'll be fine. Chains won't throw as easy as people seem to think.

the cheapest option is to either get a longer/shorter bb or to get a cog that sirs further in/out, different cogs have different spacings, sheldon brown has a list of cog measurements

Hmm... not hugely impressed with the shop's response. A slightly arsey "you want it further out than that?!" to which I could only really reply "yes, I want it straight".

Bizarre. Don't think they really get it. They've offered to "have a look at it" but I think I'll do it myself rather than waste any more time/ money.

Will check exact measurements and get a BB to fit. Does anyone know of a good adjustable one?

Cheers,

Simon

Just go mental at them. Be persistent and demand that it's done now otherwise you'll stand outside the shop telling every customer that goes in that they bodge jobs and don't do it properly when you pick them up on it.

They'll soon do it properly.

Simon - I think if the LBS was supplying the whole drivetrain they should be able to get the chainline right. However, lots of shops sell stuff without all the knowledge necessary to get it right but I think you should ask them to sort it out or give you a discount if you end up having to take it elsewhere.

What crank/BB do you have now?

redeye I have the opposite problem, the sprocket is more inboard than the chainring, and that chainring can't be moved any further in to compensate as there is 3-4mm between it and the chainstay.

As this is a new bike, again the LBS should sort it out for you. Really, a new 'track' bike should not have chainline issues.

How much is the chainline off btw? If its a few mm then I'd measure the 'shoulder' of the cog (ie the bit between the teeth of the cog and the hub body) and try comparing it to other cogs. I'd suggest an EAI cog as they're really decent cogs and tend to have a standard shoulder size (which may be wider than the cog you have esp if its a cheapo one).

Bottom bracket spacers can be used behind cogs, but they really should only be considered as a last resort.

Simon what shop is it?

Thanks guys. Current (fitted by shop) BB is a Shimano with a 115mm axle apparently. Crank is the original Sakae with the 42 fitted to the outside. Odd that it should still be too far in. I have a couple of other cranksets to try, just in case this one has an unusual chainline.

Am going to speak to the guy that did the work tomorrow as he was off today, but I'm tempted to just get it right myself rather than waste time driving it back over there. LBSs aren't that L out here in the sticks!

Simon

it is indeed really strange that a 115mm would have the cranks sitting closer to the centre than the hub... think the norm for track b.b. should be 103-107? correct me if i'm wrong guys.

yeah a lot of shops do suck. see how much more practical help you get here than from a bloody "BIKE SHOP"!!