pedalmybike

Hi all,

Upon servicing my bike in the off season here I noticed that the plastic cup of the un-26 bottom bracket has a split in it. I have a metal cup from a un-55 lying around. My question is can I use this metal cup with the un-26? I suspect that I can but just checking to be sure.

thanks,
charlie

markjenn

I don't know for sure either, but I bet it can be used also. They look the same to me except for material. Wasn't that helpful? ;-)

- Mark

Kimmo

You'd be amazed how many different diameters I've come across on cartridge BBs; there'd have to be at least three or four different IDs for those cups.

Worth a shot, though.

davidad

AS long as it's shimano it will work.

Kimmo

I'm not sure all Shimano BBs use the same dimension...

lostarchitect 

There is nothing to be lost by checking. If it fits, you can use it. That's about it.

fietsbob

QBP sells an 'Up Cup' to replace the plastic ones too..

HillRider

I've substituted metal NDS cups for the plastic ones on several Shimano cartridge bottom brackets and it's always worked. Lucky? Maybe but give it a try.

pedalmybike

Thanks for all the replies guys. I had expected a more definitive answer, lol. but I'll give it a try and we'll see what happens.

charlie

Kimmo

That's reassuring, and reinforces my low opinion of the level of organisation at my co-op.

pierce

I'd just take the metal cup and the un26 and see if they fit on by hand (not on the bike. if it does, and it seems like a snug fit, then you're gold. but I tend to remove UN26's and replace them with UN55's as soon as there is any excuse

HillRider

For future reference, those plastic nds cup are functional and work well but you can crack them if you install/remove the bb incorrectly. The proper installation sequence is to install the drive-side cartridge first and torque it until it's snug, then thread in the plastic cup and tighten it snugly but not much and finally torque the cartridge to full spec. Do not over tighten the plastic cup as it will not tolerate anything close to the 25-30 lb-ft recommended for metal cups.

Removal requires removing the drive-side cartridge first, then the plastic cup. Trying to remove the plastic cup first almost assures breaking it. Guess how I learned this "secret"?

pedalmybike

Ok that's my mistake, I removed the plastic cup first. Lesson learned.

fietsbob

Yea the NDS sleeve has just a small stabilizing task, once the DS side is tight..
and the chance the plastic will rust or corrode Is Zero.

the Aluminum ones need a coat of grease,

or they stick like a used Ebay bargain bike stem/ seatpost..

pierce

and, DONT GREASE THE PLASTIC SIDE (says this all over the Shimano literature).

that alone is why I like the metal ones. they go on so much smoother with grease than the plastic ones go on dry, especially on an older frame where there might be a bit of surface corrosion on the threads

.