Converting a cottered crank bike to square taper?
stickman
Posts: 791
Can it be done? I'm referring to my Raleigh.
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Gears - Obscuring the goodness of singlespeed
http://www.flickr.com/photos/21720915@N03/
More stuff:
http://www.flickr.com/photos/65587945@N00/
Gears - Obscuring the goodness of singlespeed
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Comments
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Can't think why not! At simplest, just a replacement axle. More expensively, a complete new b/b (though depending on age may need to watch out for Raleigh-specific threading on the cups). Oh and new cranks obviously!d.j.
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Yes, the threads of the bottom bracket are what matters, being a Raleigh they are English so all you need to do is remove the old cottered chainset and bottom bracket and fit a new tapered English bottom bracket. Note Italian and French threaded won't fit as they are threaded differently . The critical thing is to get the right length of axle for the chainset you are going to use ! Also the taper of the new axle needs to suit the chainset as well.
Shimano a Japanese taper, Campag a Italian taper. Other chainsets check whats needed !0 -
Thanks for the replies.
Is it an English thread that ordinary Shimano etc. bottom brackets have?Bikes, saddles and stuff
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Gears - Obscuring the goodness of singlespeed0 -
stickman
have a read http://www.sheldonbrown.com/gloss_bo-z.html#bottom
as you can see some Older British-made Raleighs, especially 3 speeds had their own set up.
but some quick measurements will soon sort that out."Do not follow where the path may lead, Go instead where there is no path, and Leave a Trail."
Parktools :?:SheldonBrown0 -
Thanks.Bikes, saddles and stuff
http://www.flickr.com/photos/21720915@N03/
More stuff:
http://www.flickr.com/photos/65587945@N00/
Gears - Obscuring the goodness of singlespeed0 -
STD english 24tpi, Raleigh 26tpi. Does depend on year, though it is obvious when you compare cups.0
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Thanks. It's approx. 1990. I think.
Update: I checked the gear hub and it's dated 1991.Bikes, saddles and stuff
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Gears - Obscuring the goodness of singlespeed0 -
Stickman iIt should be 24tpi at that year, if you put two cups (say a shimano cartridge and your cup) together thread to thread you can see any pitch error clearly.0
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Thanks, that sounds encouraging.Bikes, saddles and stuff
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1990 and cottered cranks?! Is it worth saving?d.j.
"Cancel my subscription to the resurrection."0 -
If I couldn't fit a modern BB maybe I would get an Archie frame and transfer the parts over to that. (same 650a wheel size)Bikes, saddles and stuff
http://www.flickr.com/photos/21720915@N03/
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http://www.flickr.com/photos/65587945@N00/
Gears - Obscuring the goodness of singlespeed0 -
Finally took it apart today, checked a spare Shimano cup in it and it matches. I'll go to my lbs tomorrow and hope they've got a modern bb in my size in stock.Bikes, saddles and stuff
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http://www.flickr.com/photos/65587945@N00/
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Found out that because they fit in diffent ways that bb axle lengths are different - so is there an axle length conversion chart for going from cottered to non-cottered?Bikes, saddles and stuff
http://www.flickr.com/photos/21720915@N03/
More stuff:
http://www.flickr.com/photos/65587945@N00/
Gears - Obscuring the goodness of singlespeed0 -
hello the axle length will depend on the new chainset, it will need to set the ring(s) at the same distance from the seat tube as the previous chainset, what is the new chainset that you are fitting? each one has a preffered botom bracket axle length (and specification) for perfect alignment
Cf0 -
Thanks,
I should have updated this. The chainring is a Mighty-X 46 tooth, common to see on ebay, I found I had an old bb axle and did a mock-up, found out i'd need a 127mm which I bought and there's no problem.Bikes, saddles and stuff
http://www.flickr.com/photos/21720915@N03/
More stuff:
http://www.flickr.com/photos/65587945@N00/
Gears - Obscuring the goodness of singlespeed0