Fixer question

"Tim Hall" <[email hidden]> a écrit:

Quoted message said:

I currently run a double chainset on my fixer, using the inner ring.
It's a bit knackered, so one option is to splash out on a new! shiny!
chainset, most likely a single.

Quoted message said:

Will this screw up the existing chainline? ie does a chain ring of a
single chainset run in the same space as the inner ring of a double?

In general, you need to choose your bottom bracket and cranks together to
achieve a given chainline. If you replace your current cranks without
changing the bottom bracket, it's very unlikely you'll end up with the
correct chainline.

If you're currently using a typical road double crankset, the inner
chainring will give a chainline of around 40mm, give or take a millimetre or
two. That's close to the intended chainline of a typical track crankset.
Track cranks tend to be expensive, however.

You can acheive the same chainline using the outer position of a road double
with a shorter-than-normal bottom bracket axle, but getting it right can
take some trial and error.

Single chainsets designed for off-road use usually give a much wider
chainline - around 52mm

http://www.sheldonbrown.com/chainline.html

Square taper cranks give the most options for tweaking the chainline, as
bottom bracket axles are made in a wide variety of lengths. That tends not
to be the case with the more modern splined systems.

James Thomson

in message <[email hidden]>, Tim Hall

(') said:

I currently run a double chainset on my fixer, using the inner ring.
It's a bit knackered, so one option is to splash out on a new! shiny!
chainset, most likely a single.
Will this screw up the existing chainline? ie does a chain ring of a
single chainset run in the same space as the inner ring of a double?

If you're going for a fixer, it will be fine. Just space your single cog
out on the cassette with spacers until it lines up with wherever the chain
ring comes to. If you're running a full cassette and derailleur at the
back then it won't be perfect but you will most likely get away with it.

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

;; Woz: 'All the best people in life seem to like LINUX.'
;; <URL:http://www.woz.org/woz/cresponses/response03.html>

In article <[email hidden]>, Simon
Brooke
[email hidden] says...

Quoted message said:

If you're going for a fixer, it will be fine. Just space your single cog
out on the cassette with spacers until it lines up with wherever the chain
ring comes to.

Are you confusing single-speed with fixed-wheel, perchance?

in message <[email hidden]>, Rob Morley

(') said:

In article <[email hidden]>, Simon
Brooke
[email hidden] says...

Quoted message said:

If you're going for a fixer, it will be fine. Just space your single cog
out on the cassette with spacers until it lines up with wherever the
chain ring comes to.

Are you confusing single-speed with fixed-wheel, perchance?

Comes to the same thing, as far as chainline goes. At least it you're
hacking it up from bits of old bike. The difference is that with a fixer
you deliberately knacker the freehub mechanism, with a singlespeed you
deliberately don't.

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

... a mild, inoffensive sadist...

Simon Brooke said:

in message <[email hidden]>, Rob Morley

(') said:

In article <[email hidden]>, Simon
Brooke
[email hidden] says...

Quoted message said:

If you're going for a fixer, it will be fine. Just space your single cog
out on the cassette with spacers until it lines up with wherever the
chain ring comes to.

Are you confusing single-speed with fixed-wheel, perchance?

Comes to the same thing, as far as chainline goes. At least it you're
hacking it up from bits of old bike. The difference is that with a fixer
you deliberately knacker the freehub mechanism, with a singlespeed you
deliberately don't.

Sorry, I wasn't quite clear.

It's already a fixer, I just feel the need to get a new (or s/h)
chainset, and thought I'd do it properly. Afterall, it's been running
on a double for 6 years at least, as a temporary measure.

It's a screw on hub, so no problems about knackering up, deliberately
or otherwise, a freehub, just buy another screw on sprocket. I see
there's a nice Miche one on Ebay, going for what Parker sell them for.
Money/sense imbalance strikes again.

This fit of fettling came about because the bike was dirty, so I
cleaned it. Then I thought I'd better clean the chain. Then I thought
I'd better put new balls in the hubs. Then I noticed a loose spoke.
Then I noticed how shagged the chainset is. Ho hum.

Anyway, thanks for the responses, sounds like I'll be fine.

Tim

In article <[email hidden]>, Simon
Brooke
[email hidden] says...

Quoted message said:

in message <[email hidden]>, Rob Morley

(') said:

In article <[email hidden]>, Simon
Brooke
[email hidden] says...

Quoted message said:

If you're going for a fixer, it will be fine. Just space your single cog
out on the cassette with spacers until it lines up with wherever the
chain ring comes to.

Are you confusing single-speed with fixed-wheel, perchance?

Comes to the same thing, as far as chainline goes. At least it you're
hacking it up from bits of old bike. The difference is that with a fixer
you deliberately knacker the freehub mechanism, with a singlespeed you
deliberately don't.

You're assuming that the OP is bodging a cassette hub, which he isn't.