3 piece to one piece conversion? Impossible?

[Thxcuz]

Is it possible? I doubt it but I figure if anyone would know, it's you folks. I like one piece cranks for it's simplicity It would be awesome to chuck all the spindle length, bb threading and all that jazz out the window and just set some cups where the threads are and shove in a one piece.
I doubt it't a thing but it would be cool if there was an adapter that could do that.

 

[user 135]

Not possible as the bottom bracket shells are different sizes.

 

[mitchelangelo]

The one piece would never thread through the smaller bottom bracket size.

 

[Thxcuz]

One of my frames has a Swiss bottom bracket. Finding spindles for these are a pain. Plus I have to take in account spindle length when buying a crankset. The only options for sealed bb are from velo orange for $66 or Phil wood for $200.

 

[Sinner4]

For $36 you can get a thread less BB and slide it it.. I posted it before, Sunlite i beleive. To go to a 1 piece you would have to cut the old BB out and weld in a new 1 piece unit.

 

[cave12man]

I know Truvative also sells this guy for about $25. Still not 100% sure how you install these things though.

Coupled it with this Sunlite Sealed BB also for $25.

 

[cave12man]

Curious if these would work for say a motorbike frame? Looking to go 3 piece on my next build.

 

[Thxcuz]

I have that adapter. It works great BUT if it doesn't fit exactly you'll have to grind the outside a little. No biggie.

 

[frameteam2003]

I think the closes you could come to what your asking is a Thompson BB
http://classic-cycle.de/en/Hubs-Axles-C ... aring.html
and I think they take a special tool to reem the threaded BB to fit the pressed in cups.

 

[Thxcuz]

I've been looking at those threadless bb. Why the odd sizes. 122.5? I would need a 123 for many lower end shimano cranksets. I don't see a 123 threadless anywhere.

 

[Sinner4]

I think I'm lost now, you want to drop the 3 piece crank and go to the ONE piece crank.... Right? If so you must enlarge the Bottom Bracket Shell to fit it the one piece in. Or Am I lost. If so you don't need all of the above high dollar stuff. You need the simple one piece BB shell installed in the old small 3 piece BB place.

 

[Thxcuz]

Sorry to confuse everyone.
I have a bike with a Swiss bb and I was looking for a simple solution. Once being told that no 3 to one adapter exists nor could it ever exist I was looking for an inexpensive solution for a bottom bracket that requires swiss threaded cups and 70mm spindles. It's all a big mess and I regret removing the cottered cranks and destroying them repair in the process.

 

[Sinner4]

Ok, Got ya. Go with the the spindle I posted. Its like plug and play. Get a nice alloy used or new crank set and pedal away. Dont know but I think it will work.

 

[alecw35]

It might be that a threadless bb cartridge wont fit the Swiss bb shell. I know Italian BBs are larger diameter. Thomson BBs are smaller diameter than English BBs that are the most common for 3 piece cranks.
As for them being different sizes. It might be the engineers were experimenting with theories they had. Or that they just wanted to be difficult and sell lots of different products, where one design might have done most customers.

 

[Thxcuz]

Swiss bbs are weird...they are like the French bb (Motobecane used swiss a lot) but the fixed cup is threaded opposite of the French. I think they are still 68 mm BUT for whatever reason if you want to replace the spindle your best bet is to use a Japaneese 70mm spindle. Sheldon explained why somewhere.
So my choices are Phil wood (too expensive) velo orange (better, but more than I want to spend) or find a spindle to match whatever crankset I end up with. (Not impossible, but not as simple as going to amazon)

 

[Thxcuz]

Now I feel stupid...they DO have some 70mm spindles on amazon.