Help with chainring
 

I have what I believe to be an '88 Raleigh Technium Chill. I was wondering if I move the big chainring to the middle chainring spot, would I be able to go "big big" without issue, since it seems that isn't a good gear to try? I also realize there may be some alignment/ chain wear implications maybe? Also any info on this bike would be appreciated. I just bought it from a friend for $20. Shifts perfectly (friction) and brakes fine. There was a bolt coming loose from the inner chain ring (triple) and it caught on the chainstay, so what does he do? He kicks the pedal until the inner ring breaks:cry:, and still can't pedal it cause he doesn't have enough sense to screw in the bolt:twitchy:...So anywhoosit, he let me ride this before and I liked the feel of it, so I practically stole it from him to save it. It's my size too:thumb:. So any ways thanks for any help.

I don't understand. The little ring is broken right? Why not leave the middle and large rings alone? Just replace the little ring when you get a chance.

Well I did take off the small chainring, but I just wanted to use just the big chainring and not have to shift in front, just the back. I'm used to riding a single speed, and I think that the 48x30 I'd get from big to big would suffice for anything I'm going to be doing. However I just rode the bike for a couple miles, and I believe the other two chainrings are bent into an oval shape, which isn't easy to tell when I've got it flipped over, but when riding I can really tell. So I have another question. How or where can I figure/find out what the bcd is for the middle/big chainring? Btw being that I'm having to replace the chainrings, I'd still like to know if I put a big one on the middle if there would be any issues. I'd like to be able to buy just 1 chainring and that would suffice.

OK. So I've found out the bcd is 110mm thank you Sheldon. Is it possible the spider arms are bent too?

Do they say Biopace on them? :) Look up Biopace, I bet they were made like that if they're "an oval shape."

Yes, if the big ring fits on inside of the spider without hitting the frame you can definitely run it like that as a 1x6 or 1x7 or however many gears you have in the back.

If your outside BCD is 110, I'm 99.9% sure the BCD for the little ring is 74. This is a common size and you should have no trouble finding replacement rings if you decide to go that route.

yes they are biopace, and that's weird why would they be made to be oval shaped? Feew! I thought I was actually gonna have to put some dime into this thing to make it commutable. Yeah it's got a six speed freewheel, and I found out it's a 13-30 range. There's a website http://mombat.org/Raleigh.htm that has some information including a chart of different years of bikes made, and general componentry info. Although there are slight inconsistancies like on the website it says 46 teeth big chainring, and my bike has a 48 tooth, although I've seen slight variances on bikes direct bikes like that. Anyway, thanks for the good info.

The theory was to get more power into the drivetrain/fight the dreaded dead spot on top/bottom of the stroke to make the radius of the chainwheel sorta synch with the leverage offered by the crankarm.

yeah after i asked that question I followed fastjake's advice and googled biopace. I found a sheldon article that laid it out pretty well. I'm just glad I don't have to buy anything for this commuter/beater. :)