Chainline Issue

in message <[email hidden]>, Tony B

(') said:

The cranks have captive bolts in them to draw them onto the BB splines
but when I do them up pretty tight using a T handled hex key they still
seem to be quite a bit off. The BB had some other screws with it, the
more usual (to me) loose screw complete with rubber and steel washers
on them, would it help me get the damn thing in line if I changed
screws? Are track chainsets supposed to just line up or do I need a new
BB? Ambrosio don't even list BB's and chainsets on their websiteso
that's not much use, TD's are closed on weekends, yadayada... bloody
cycle standards...

Track BBs are usually adjustable laterally to fine tune the chain line -
but 10mm sounds way too much.

Quoted message said:

any advice anyone? Am I missing something?

Sounds to me as if you're probably missing the right bottom bracket for
the job. If it were me I would phone Dolan's for advice - in my
experience they're friendly and helpful.

--
[email hidden] (Simon Brooke) http://www.jasmine.org.uk/~simon/

The Conservative Party now has the support of a smaller proportion of
the electorate in Scotland than Sinn Fein have in Northern Ireland.

Tony B said:

Hi all,

I'm building myself a new fixie based around a Setavento frame with
track ends :-) but have a bit of a chainline issue, as follows:

Yesterday I got some Navigator track wheels from Terry Dolan's in
Liverool, I also got myself an Ambrosio Pista track chainse and ISIS BB
for the bike. Bugger me but they don't line up, in fact they seem to be
10mm (ish) out.

The rear wheel seems to have a 40mm chainline dimension, the BB 50mm.

The wheel is 120mm OLN which suits the track ended frame perfectly
(doesn't seem to be much latitude for spacing or messing here at the
back though), I (stupidly) assumed the track chainset would just
immediately line up.

The cranks have captive bolts in them to draw them onto the BB splines
but when I do them up pretty tight using a T handled hex key they still
seem to be quite a bit off. The BB had some other screws with it, the
more usual (to me) loose screw complete with rubber and steel washers on
them, would it help me get the damn thing in line if I changed screws?
Are track chainsets supposed to just line up or do I need a new BB?
Ambrosio don't even list BB's and chainsets on their websiteso that's
not much use, TD's are closed on weekends, yadayada... bloody cycle
standards...

any advice anyone? Am I missing something?

Have a look at the rear sprocket - some (like dura-ace) have an offset
flange which means if you removed it and replaced it the other way round
it would change your chainline by 5mm or so. Also, the thread on the
rear hub is the same size as a standard bottom bracket, so you could use
a bottom bracket ring to provide a little more spacing, if there is
enough thread on the hub, and if it will still fit in the frame. Those
are your cheap solutions. If they don't work, its shorter bottom bracket
time, but 20mm shorter is a huge difference.

JimP

--
Let's think the unthinkable, let's do the undoable, let's prepare to
grapple with the ineffable itself, and see if we may not eff it after
all. - DNA

Jim Price said:

If they don't work, its shorter bottom bracket
time, but 20mm shorter is a huge difference.

JimP

I have measured the BB, it's already a short one - 108 over the axle,
the BB shell is 67mm and the Ambrosio BB came with the pigging cranks.
Sheldon says the 40mm chainline dimension for the wheel is OK so I guess
the actual crank itself must be plain rubbish, or else made for a frame
with 130 spacing or sommat, or else I need a longer allen key....

I'll call Mt Dolan on Monday and see what he thinks. I should be out on
the bike now, not rattling these keys. Doh!

bfn,

Tony B