Landgolier

This is an odd one, thought I'd ask if anyone has ever tried it. I'm working on a singlespeed that would be happiest if it had a 105mm Italian bottom bracket. Normally I'd say 103 + spacer, but 103 cartridge BB's are basically nonexistent as far as I can tell. There are some out there (old DA, some others), but nothing in current production and I don't want to base a build around parts I can't replace. If I'm wrong and there's a 103 italian cartridge BB out there with JIS tapers, problem solved, thank you all and good night. Also, I know there's a man named Phil Wood who could make all my problems go away, but that's just out of the $$$ range for this bike.

So it occurs to me that one ought to be able to install cartridge Italian BB's backwards, since all the threading is the same. This might actually be better, since the side actually doing all the work would be threaded "correctly" and couldn't unscrew itself as is otherwise possible with Italian setups, but it might be worse since the drivetrain would be on the side with the cheesy spacer cup rather than on the side that is properly screwed into the frame. The point here would be that I could use a 107mm BB, which are easy to find, put it in backwards with a 1mm spacer on the left side, and bingo, same chainline as the hypothetical nonexistent 105mm Italian.

Anybody got any thoughts? Ever tried this before?

vpiuva

It's still right hand threaded no matter which way you install it, so it's possible you've overthought this 'benefit'. But I've installed a BB backwards for a while until I found one with the correct spindle length and it worked. Can't say it was a long term test, however.

Retro Grouch 

Diameters aren't the same.

top506

I installed a UN-52 backwards to make a cheap crankset fit on a bike and ran it for a year with no problems.
Top

Landgolier

Huh? Italian is 36x24 both sides. I'm talking about using an italian threaded BB put in from the left rather than the right.


I think you're talking about flipping a spindle, not a whole BB, which is impossible on British threaded setups. Italian thread BB's unscrew because the right side is right hand threaded, which is wrong from the standpoint of bearing precession. Right hand threading on the left is "correct," so a cartridge bottom bracket installed this way should not unscrew. Jobst Brandt argues that left side cups don't precess meaningfully anyway, the effect comes from the forces of the chainring. It's those forces that I'm concerned about.

vpiuva

Is he saying the forces aren't great on the left side of the BB because they are the left or because they are on the non-drive side? The drive side cup is right (wrong) threaded whether it is the "left" or the "right" side of the BB.

jjvw

Yes they are.

Wannashmooze

I know this is an old thread, im planning on doing this to avoid having my italian bb unscrew. I ordered a UN54 and guess what?? It came with a metal non-drive side cup! That should avoid the whole plastic cup problem on the drive side that happens when you flip a shimano cartridge bb.

fietsbob

Phil Wood.. only the mounting rings are different.
and the spindle can be pushed thru the bearings to fine tune chainline ,
if the shifting alignment, with the mounting rings wont satisfy

HillRider

The OP knows all of that but clearly said the PW was out of his price range.

Burton

Noted that you`re reserrecting this thread snd that your post is completely unrelated to the original post except in principal.

So the questions are:

(A) Did you work out an axle size that will maintain your chainline when you reverse the cartridge?

(B) Do you really think that driving with the resulting completly screwed up Q-factor on a continuous basis is a solid alternative to either LocTite on the threads of the bottom bracket or simply gropping the crank assembly on a regular basis and retorquing the BB assembly - or both?

LesterOfPuppets

He might have saved up enough for the Phil Wood over the last 4 years.

JohnDThompson 

Aren't the same as what?

Depending on the the of cartridge, the OP may be able to adjust chain line with the rings that hold the cartridge in place -- set the drive side ring in deeper and the non-drive side ring less so to move the chain line inboard.

JohnDThompson 

IIRC, the Phil rings can be used with some other cartridge BBs.

fietsbob

yup, Older Phil BBs used a SS tube, half the bearing sticks out of the tube ..
the mounting ring fits on the other end part of the bearing.
match any uses the OD of that, a standard cartridge bearing size...

Wannashmooze

Shimano BBs are symmetrical, they don't know that they are installed backwards.

Frkl

I know that this thread is long quiet, but does anyone here have long term experience to share? I recently did the same thing on a bike build.