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View Full Version : Raleigh Twenty bottom bracket... Solved!



andy_is_me
08-24-06, 01:24 PM
Since day one the bb on my Twenty has been a pain in the posterior. It started with the removal of the original cups. Serious elbow grease and a homemade tool ala Sheldon Brown got them out. Next was the hunt for a suitable replacement. With the help of this here forum I got my hands on some sort of Euro bb with 24tpi plastic cups that could allegedy be forced into the 26tpi threads. I think it would have worked, but the thickness of the cups coupled with my chainline's need for a 110mm spindle rendered that solution useless. I finally spent the big wad of cash on those Phil Wood cups and found a cheap UN-72 sealed bb. This worked okay, but the threading was just a little too shallow and my bb always had a tiny bit of play that made me crazy as well as nervous (wobbly chain... fixed gear... chain flies off... crash... die...). I attempted to fabricate some sort of washer/spacer thing out of a tin can lid to solve the wobble but while I was doing it, I thought I'd call around to the local shops and see if any old timers still had a 26tpi bb tap. And I was in luck! I spoke to the mechanic on the phone and he said he could easily add a couple mm to either side of the bb threading. I dropped the bike off and was told to return in a couple hours. When I got home, I got to thinking that I hadn't been completely clear with the guy, so I called the shop. The shop owner told me that it was probably normal English threading (24tpi) and I assured him that no, I was certain it was 26tpi. He said that he'd pass on my clarification to the mechanic and he'd see me in an hour. When I got there the mechanic was gone for the day and the owner told me that he had tapped it to 24tpi! The mechanic claimed that it was already 24tpi and he just added some new threads. I was sceptical so the owner guy grabbed a standard bb and threaded it in for me to see with mine own two eyes. Perplexed yet somewhat relieved, I went home, found the cups that I had removed from the UN-72 and installed the thing. So there you have it, after spending an unholy amount of money on the Euro bb and then the Phil cups (not to mention the instalation tool) my six or eight months worth of frustration is solved with $20 worth of labour and a $5 bottom bracket.

randya
08-24-06, 01:47 PM
I believe retapping the 26 TPI BB to 24 TPI is one of Sheldon Brown's alternative techniques for dealing with Raleigh 20 BBs. You shouldn't have been too surprised that it took a 24 TPI cup after the mechanic had retapped it to that thread pitch!

:)

juan162
08-24-06, 02:32 PM
Like you, I too tried several solutions for my raleigh twenty's bb and ended up having it retapped...I've been happy ever since. Happy riding,
Juan

LittlePixel
08-24-06, 04:42 PM
Verr interesting...
I'll keep that in mind if I ever do another Twenty (heh). Then I can go serious weight-weenie with a titanium/carbon crank combo—Yay! (I know, I know... a fast pig may be fast but still a pig and never a greyhound ;)

MnHPVA Guy
09-05-06, 06:06 AM
I had a local framebuilder retap my Raleigh Sports to 24tpi and the threads look like they had been cut that way originally. No sign they'd been buggered with. IMHO the retapping worked so well I feel this is "Plan A" for cotterless cranks.

He also faced the ends down till the width is now 68mm instead of Raleigh's usual 70mm. The threads of the Shimano BB are so long that most of them engage threads cut into fresh metal, so it doesn't matter how strong the threads are where the 26tpi were recut to 24tpi. (Though I think they are pretty good).

I'm looking for a Twenty. Could someone tell me if they have the same 70mm BB width? My Raleigh built 1970 Moulton has a 73mm width BB.

LittlePixel
09-05-06, 09:11 AM
My twenty has a 77mm shell. Yes - 77. This is UK frame for 451 wheels so there may be a difference on US frams. In not you might want to face 3.5mm of the collar off on both sides.

MnHPVA Guy
09-05-06, 01:45 PM
My twenty has a 77mm shell. Yes - 77. This is UK frame for 451 wheels so there may be a difference on US frams. In not you might want to face 3.5mm of the collar off on both sides.Or take 2mm off each side and use a 73mm BB.