Wogster

I asked a similar question way back around 2010, don't recall getting an actual answer....

Does anyone know if Raleigh bicycles made in Canada in the 1970's used 24TPI or 26TPI bottom bracket threading.... Everything looks like it is probably 26TPI. I know there were people at the time who milled out the 26TPI and threaded for Italian. Are there better solutions today? What about switching to press fit bearings? The options on newer cranks for square taper are getting a little thin.....

oneclick 

Get a pair of Italian-threaded alloy cups and a cartridge bearing unit that will fit them, take the 36mm threads off and cut 26tpi on them; a lathe, or a friend-with-a-lathe will be needed, but you will only have to do this once (per bike).

Charles Wahl

I don't know why you would do the above in preference to simply having the bottom bracket retapped to be Italian (and maybe milled down to 70 mm wide if you're picky about chainline). A Raleigh 26 tpi bottom bracket should be 71 mm wide, too, so an Italian BB spindle should work, or of course a cartridge BB provided in Italian. There are other 26 tpi issues with this sort of Raleigh frame, for instance having a 26 tpi headset.

There is this Sheldon Brown page for Raleigh weird threading issues: https://www.sheldonbrown.com/raleigh26.html

zandoval 

I get ya... Press fit bearings should be a reasonable option. Any body done it?

oneclick 

Well, aluminium is easier to machine (you can do the same trick with 25x1 alloy headsets), you might not have an Italian tap, and it keeps the frame/fork as is, which for some people is a thing.

Wogster

Okay, the issue isn't really thre BB, at least not for now.... I have two sets of cups and the spindle is tool steel, so the crank will likely outlive me, it's whether the chain rings are bolt on, or riveted on. It appears to be bolted on the inside, but not the outside, so maybe they threaded the spider, then used a bolt, or it could be some kind of blind pop-rivet, because it appears that the chain guard and spider are all one piece.

There may be a couple of options, if I find the right allen key, it appears to be an odd size, I could take off the chain rings, and replace them, with different ones. If it's a rivet, I could always drill it out, to a standard chainring bolt size, and just use normal bolts. It appears the larger ring hasa BSD of 104mm.... The RD, FD and the Freewheel that came with the bike are all Suntour, so it could be a Suntour crank as well. I think that Raleigh in Canada used a mix of Nottingham parts and standard parts to build these bikes, it's likely the frames, BB and headset came from Nottingham, and then they used off the shelf, Suntour parts for everything else.

So, they installed an off the shelf spindle, then put a cotterless off the shelf crank on it. Suntour not to be outdone, used off-the-shelf chain-rings, which is fine, but 52/42 is a little high when the motor is 60 years old, and not at the peak of efficiency . If I could run say 46/36 on it, that would work better for me, and 42/32 would be ideal...... I'll take some pictures tomorrow of both sides of the crank, with my "good" camera, and see if anyone has ideas......

Mods: If you want to change the subject line here, feel free.....

clubman 

Pictures of the crank are your friend. Off the cuff, it's unlikely this is all worth the trouble, even if it would work. The bcd will determine the range of rings you can use and when you see 52/42, it's rare that you'll be able to fit a small ring. Replace with a triple.

cudak888 

I've done the unthinkable and tapped a 26tpi Sports BB to 24tpi with no brass or anything. Didn't seem to affect a cartridge square taper I installed in it, but I didn't run it - I wound up installing an external bearing bottom bracket and crank in it.

I've beat on it quite a bit and neither of the Loctited cups are loose. Yet.






-Kurt

Dan Burkhart 

I have also done this. Worked OK, but I would not try it without a piloted tap set.

cudak888 

I did it with the 1970's-era VAR 380 set that one of the local shops gave to me. Worked a treat.

-Kurt