[MMcG]

Figured I'd post here since there's way more traffic.

See this image?

Is the silver "spacer" on the bb the thing that converts it from a 68mm bb to a 73mm?? So if you were to remove the spacer, you'd have a 73mm bb??

 

[Brian HCM#1]

yes my child, you will have a 73mm.

 

[MMcG]

Many thanks!

I think i can remove it from the bb I installed last night then so that the one I put in will be inserted into the shell to a greater extent.

 

[Brian HCM#1]

What size is the BB shell on the frame?

 

[MMcG]

dunno -it's an old Schwinn Rocket 88 and I pulled out a RF Isis BB that was set up like in the photo. So then I threw in a Shimano BB and put that spacer on it. BUt the shimano BB I used was already a 68mm bb - so my take is that I don't necessarily need that spacer right?

 

[loco-gringo]

dunno -it's an old Schwinn Rocket 88 and I pulled out a RF Isis BB that was set up like in the photo. So then I threw in a Shimano BB and put that spacer on it. BUt the shimano BB I used was already a 68mm bb - so my take is that I don't necessarily need that spacer right?

Correct. RF, Truvativ and FSA all use the reducing spacers for a 68mm shell, on some models anyway. I have not seen Shimano do that. It is usually 68 or 73 mm.

Edit - the exception to that rule is the new external Shimano BB. It is a 73mm that uses spacers.

 

[MMcG]

I'll remove that spacer and see how everything fits.

 

[Brian HCM#1]

Just measure the shell on the frame, it's that easy. I believe the only Shimano ones that uses spacers are XTR.

 

[Biscuit]

FYI: a 68mm shell measures 2.677" or 2-11/16".
a 73mm measures 2.834" or 2-7/8".

(since not everyone has a metric ruler)

 

[loco-gringo]

Just measure the shell on the frame, it's that easy. I believe the only Shimano ones that uses spacers are XTR.

I'm pretty sure that they only used the spacer for chainline, but it's been a while since I ran those cranks and don't recall.

 

[Brian HCM#1]

I'm pretty sure that they only used the spacer for chainline, but it's been a while since I ran those cranks and don't recall.

Nope it's shell size, that's what different spindle lengths are for.

 

[loco-gringo]

Nope it's shell size, that's what different spindle lengths are for.

Cool. I just haven't had one in my hand for a while.

 

[buildyourown]

That doesn't look like a 5mm spacer to me, which is what it should be to convert from 68-73.

Many modern BBs come with a spacer for an e-type front derailleur. If you have a normal der, install the spacer. If you're installing an e-type der, remove the spacer.

 

[loco-gringo]

That doesn't look like a 5mm spacer to me, which is what it should be to convert from 68-73.

Many modern BBs come with a spacer for an e-type front derailleur. If you have a normal der, install the spacer. If you're installing an e-type der, remove the spacer.

It's a 2.5mm spacer. You only have to space the drive side since there is no flange on the non drive side. If it were a Truvativ, there would be an O-ring on the non drive. The cup will just thread in further on the non drive side.

 

[buildyourown]

It's a 2.5mm spacer. You only have to space the drive side since there is no flange on the non drive side. If it were a Truvativ, there would be an O-ring on the non drive. The cup will just thread in further on the non drive side.

I was going to call BS but then I saw the other spacer on the non-drive side.
On shimano BBs, the spacer is for e-type derailleurs.
MMcg, when you install the BB, make sure you remove both spacers.

 

[MMcG]

I didn't install that RF - I installed a Shimano, but used that RF spacer for some reason. Just need to remove the RF spacer that I paired up with the Shimano bb is all. Right?

 

[Brian HCM#1]

I was going to call BS but then I saw the other spacer on the non-drive side.
On shimano BBs, the spacer is for e-type derailleurs.
MMcg, when you install the BB, make sure you remove both spacers.

That's weird, as far as I know Shimano makes regular BB's as well as an E-type. I've never seen E-types come with spacers.

 

[MMcG]

I've got a Shimano E-type and it didn't come with any spacers.

Which reminds me - anyone need one? 73mm bb shell - I can't use it, and didn't realize it was gonna be an e-type when I bought it.

 

[Wumpus]

MMcg, when you install the BB, make sure you remove both spacers.

There is no mention of a second spacer in the instructions.

 

[Biscuit]

There is no mention of a second spacer in the instructions.

What the hell are thos things????