advice on fixing an old bicycle

marcco

I have an old Raleigh Stratos that I want to fix up. It needs a few bits but the main thing it needs is a new crank arm and sprocket. I don't want to buy the wrong one so I was wondering what do I need to know to get the right one or what do I have to measure? The sprocket has 46 teeth on it

Tonyandthewhale

By sprocket do you mean chainring (as in the toothed plate attached to the crankarm). There's nothing stopping you from replacing it with a different sized chain-ring (although if you go to a drastically different size you might want to lengthen or shorten the chain where appropriate).
Assuming the bike uses a square taper bottom bracket (and that you're not replacing this bottom bracket with something else) then you just need a crankset which is square taper compatible (ie. not hollowtech or ultra-torque or ISIS splined or octolink or anything like that).

marcco

Tonyandthewhale wrote: »

By sprocket do you mean chainring (as in the toothed plate attached to the crankarm). There's nothing stopping you from replacing it with a different sized chain-ring (although if you go to a drastically different size you might want to lengthen or shorten the chain where appropriate).
Assuming the bike uses a square taper bottom bracket (and that you're not replacing this bottom bracket with something else) then you just need a crankset which is square taper compatible (ie. not hollowtech or ultra-torque or ISIS splined or octolink or anything like that).

Ok thanks for that. Yes I did mean a chainring and it does have a square taper bottom bracket. I'm getting the hang of this lingo already:D. Is there more than one size square taper bottom bracket or are they a standard size?

Tonyandthewhale

Axle length can differ slightly, most common length is 113mm i think.

marcco

ok thanks

piston

If you have 5 or 6 speed derailleur gears with a single chainring, (as it appears from reading your post), I would go with a smaller chainring, about 38 - 42 teeth will work very well for most. Most bikes were over-geared.

marcco

piston wrote: »

If you have 5 or 6 speed derailleur gears with a single chainring, (as it appears from reading your post), I would go with a smaller chainring, about 38 - 42 teeth will work very well for most. Most bikes were over-geared.

i did think the bike was a bit slow. a smaller chainring would give a higher top speed wouldn't it?

denbatt

marcco wrote: »

i did think the bike was a bit slow. a smaller chainring would give a higher top speed wouldn't it?

Nope.

Tonyandthewhale

marcco wrote: »

i did think the bike was a bit slow. a smaller chainring would give a higher top speed wouldn't it?

Nope, it would just allow you to climb reasonable inclines and not fuck up your knees to badly.