in message <[email hidden]>, Antony
(') said:Hi, I've not owned a bike for a long time and never have
done anything other than basic maintenance. Yesterday I
bought a £20 hack to get about on. It's just a bog-
standard mtb-style thing with 15 gears, but needs a bit of
work. It needs a new chainwheel as teeth are missing so I
have a few questions . . .
Do I have to replace chainwheel, rear cogs and chain
together?
You don't have to but it's usually better to,
particularly if they are in poor conditions - which yours
sound as if they are.
Quoted message said:What is involved in replacing the chainwheel?
The chainrings usually bolt onto a 'spider' on the drive-
side crank. There are, unfortunately, a number of
different patterns of spider - the five-spoke ones and two
different patterns of four-spoke ones are quite common but
there are others.
However, if they're all fscked, it may be more
straightforward to get a new chainset (i.e. cranks with
chainrings already fitted) which you can get for twenty
quid upwards
Quoted message said:Are there standard fittings (screwthread sizes etc) for
chainwheel/bottom bracket etc?
Most bottom brackets these days are the square taper type.
There are a few splined ones around but they rare. Having
said that where the chainset sits laterally on the taper
varies... so you can have lots of fun with this.
There's what's called the 'pitch circle diameter' - this is
the diameter of the circle which passes through the centre
of the bolt holes. Usually the big and middle chainrings use
the same bolt holes (often 110mm PCD) and the small ring
uses different boltholes. There's a useful chart here:
<URL:http://www.sjscycles.com/boltcirclediameter.asp>
Quoted message said:What should I expect to pay for a steel chainwheel and
rear cogs?
Between a fiver and about fifty quid for the chain ring,
depending how posh it is. The problem with your five speed
rear cogs, they're probably a 'freewheel' rather than a
modern cassette. About a tenner for a reasonable basic one.
You won't get a really expensive one, because the new bikes
are all on cassettes. Note that freewheels are famous for
being a complete bugger to remove.
Quoted message said:Where's the best place to get the parts?
If you've got a good Local Bike Shop it may be worth
frequenting because it is a source of high quality advice.
It will be more expensive than...
Quoted message said:Any good sources on the net?
Plenty.
<URL:http://www.sjscycles.com/>
<URL:http://www.chainreactioncycles.com/>
<URL:http://www.wiggle.co.uk/> <URL:http://www.edinburgh-
bicycle.co.uk/>
--
[email hidden] (Simon Brooke)
jasmine.org.uk~simonOpen ↗
;; lovely alternative to
rice.
