Folding Bikes - Raleigh Twenty - help needed re. Bottom Bracket size (*** / Kinex BB)

This is a question to the real experts in this forum...

I just bought a used Twenty and want to upgrade it. I found some very good info already on various parts.

What I am still not sure about is the bottom bracket - I do not really want to spend a fortune on a Phil Woods bb, especially as on the website "http://www.rhizomes.nl/articles.html" someone has found a cheap standard 24 tpi bottom bracket that can be forced into the existing shell. This works because its rings are plastic - it can of course be done only once, but that's okay for 15 bucks...

What I am not sure about is if that can really work with the oversize bb shell of the Twenty. I read several times that the Twenty has a 73 mm (or even a tad larger) bb shell. When I look at the manufacturers websites (*** and Kinex ), the bottom brackets they offer today are all in the 68/70 mm range.

Maybe there is someone in this forum who has used these brackets before, and can tell me if it will still work, or if this could have been wider version that is now out of production? When I look at the description from *** (which is very clear and precise, almost like a do-it-yourself manual), it looks to me as if a 68mm BB can probably not be tightened securely into a 73 mm shell.

Any ideas if this can be made to work are highly appreciated... thanks.

Link to Manufacturer's website with specs:

http://www.***.com/content.***.de/en/branches/industry/consumer_products/sports_fitness/prod_sports/bottom_bracket_b/bottom_bracket_b.jsp?
(details can be downloaded in the SERVICE section on the right side)

http://www.kinex.sk/english/index.php?page=katalog_36a&p=1

The guy that wrote that article does pop his head in here from time to time - look for posts by v1nce as that's his name; you might even find PMing him about the width would be helpful.

I would offer my own help but I went the Phil route (this was before the *** route was known) so haven't really got the raw experience.

Someone here was posting about adapting another shimano (A un-53 perhaps? I'm not 100% on that) bottom-bracket by stripping some of the threads from the cups so it would fit which seemed like another good hack. You might have to dig around a bit to find that one - I think it was posted this spring though.

Good luck with the upgrades though - you've found the place where twenty's never die ;)

Thanks for the hint, LittlePixel, I have just dropped him an e-mail. It's almost a pity to modify the one I got from ebay, it's really in an excellent condition for a 1976 bike, most of it is still original. I even did a 2-hr tour already without any problem. Just the handlebars hurt my hands, they're far too small. And you cannot pack it very well since the handlebar cannot be removed... so I have decided to modernize it. Guess it'll be a great bike once that's done.

The guy that wrote that article does pop his head in here from time to time - look for posts by v1nce as that's his name; you might even find PMing him about the width would be helpful.

I would offer my own help but I went the Phil route (this was before the *** route was known) so haven't really got the raw experience.

Someone here was posting about adapting another shimano (A un-53 perhaps? I'm not 100% on that) bottom-bracket by stripping some of the threads from the cups so it would fit which seemed like another good hack. You might have to dig around a bit to find that one - I think it was posted this spring though.

Good luck with the upgrades though - you've found the place where twenty's never die ;)

'Twas me that stripped the threads off a UN 54. It was still working fine, no creaks, still tight after maybe 500 miles (I swapped the square-taper one back to the original one so I could use the original chainguard). Here's the link (3rd post down): http://www.bikeforums.net/showthread.php?t=410958&highlight=

Standard "English" bottom bracket shells come in 2 widths: 68mm and 73mm
Italian is 70mm
Let's not discuss French and Swiss bottom brackets, right now...

The Raleigh Twenty bottom bracket shell is approximately 78mm.

I've used a few 68mm cartridge bbs in 73mm frames, so I figured that I could use a 73 in the 78mm frame.

When I built the Evil Twenty (which Phatatude posted about on 9/29/08), I took a 122.5mm (spindle length) by 73mm Shimano UN52, and threaded the non-drive cup deep into the frame, until it snugged the body of the bb. The alloy cup I used lacked the ring which you find at the end of the threads on the plastic cups, so it threaded right in.

If you have the plastic cup, filing that ring off will alow the cup to thread fully into the frame with distorting.

DISCLAIMER: I haven't put any significant miles on this bike. I built it for an art show, this coming Friday, and have only test-ridden it around the neighborhood for a few miles. Time will tell if this conversion will hold up. As I said, it has worked with standard mtb frames, in the past, so it should work just fine in this instance.

Also, I think a longer spindle (127.5mm) would be required to use a more modern crank. The 122.5 just worked with the old-school SR crank I used.

Check here for more details: http://grinderswheels.blogspot.com/2008/09/more-art-evil-twenty.html