I'm looking for bearings in a cage for a bottom bracket overhaul and chainrings for a 5 arm crank, I'm fed up with going to the local bike shop to be told they haven't got any bearings - didn't have any loose ones even - and with a sharp intake of breath "nope you can't get them any more" and don't want to fit a cartridge bottom bracket or new crank. Ta.
Found some bearings and calmed down a bit now. Anyone know how chain rings are measured? If they are shimano rings for a 5 arm crank are they universal or not?
Bolt Circle Diameter (BCD) i.e. the diameter of the circle scribed by the bolts (5 in your case) holding the chain ring onto the crank.Originally Posted by Grouse
If the chainset is not more than 15 years old and is from one of the mainstream manufacturers then they will have the tables on the tech areas of their web sites. But to be honest if it was nothing too exotic, GENERALLY they will accept newer components from the same manufacturer. But I would always check first because, as somebody is bound to point out in a moment, there are exceptions.If all else fails, ring Charliethebikemonger who appears to have old copies of all sorts of tech stuff and is very helpful.
Thanks for that. I just had a look at Sheldon Brown's site and if I've done it right my BCD is 110mm - does this mean any chainrings of 110mm will fit?
Looking at his site now. It's looking good - soon be back in vintage bike heaven. Managed to get bearings from Halfords after ordering some on the net - the ones my local bike shop didn't have.
Right. Have I got this right: middle and outer have bcd of 110mm and inner has bcd of 74 mm (its a mountain bike triple) - so if I get rings of these sizes with right no. of teeth I'm sorted?
I'm still at work but will try to have a look/measure later.
Yes, 110 BCD are MTB size, 130 BCD is (generally) road
Sounds about right. What size rings are you after as I'm having a garage clearout and think there's a big bag of rings in there...
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