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-   -   121.5 mm Bottom Bracket? (https://www.bikeforums.net/bicycle-mechanics/319929-121-5-mm-bottom-bracket.html)

cooleric1234 07-11-07 08:02 PM

121.5 mm Bottom Bracket?
 
I just took off the bottom bracket on my 2002 Giant Hybrid. I looked at the cartridge, and it says it's 121.5 mm long. But after looking at Nashbar and other common cycling sites I can't find a bottom bracket that long. Is this old and outdated or am I missing something? Any advice on what I can get as a replacement?

Here are two photos for you to see what I'm talking about:

http://s71.photobucket.com/albums/i1...01624Small.jpg

http://s71.photobucket.com/albums/i1...01621Small.jpg

JanMM 07-11-07 08:47 PM

The axle is 121.5 mm long. The bottom bracket is 68 mm wide.
Nashbar lists a 68x122 right now.

cooleric1234 07-12-07 05:17 AM


Originally Posted by JanMM
The axle is 121.5 mm long. The bottom bracket is 68 mm wide.
Nashbar lists a 68x122 right now.

Okay, so I imagine it's not a big deal if the axle length is a little bit different then. But I suppose I wouldn't want to go down to 113 or anything like that. Thanks for clearing that up.

C_LOGAN 07-12-07 05:34 AM


Originally Posted by cooleric1234
Okay, so I imagine it's not a big deal if the axle length is a little bit different then. But I suppose I wouldn't want to go down to 113 or anything like that. Thanks for clearing that up.


It is a big deal because your cranks are made for a specific bottom bracket axle length. If you go out too much, your chain line will be off center.

Stacey 07-12-07 07:13 AM

A half a mm is NOT a big deal. :rolleyes:

C_LOGAN 07-12-07 08:01 AM

Maybe not half a mm, or a mm. But you can't ignore the axle length - it makes a difference and it is better to go with the specs. Why bother getting something of a different size if you can buy the correct size quite easily?

cooleric1234 07-12-07 08:07 AM

Because it's not that easy. First of all, I don't see the 68x122 mm BB on Nashbar previously mentioned (maybe I'm blind). I've searched across the Internet and I think I MAY have finally found a 68x121.5mm BB, but I'm not totally sure (it doesn't look like square spindles...are those just covers on the last item on the following page?):

http://www.bicyclefitness.com/info/intsale.html

DMF 07-12-07 08:13 AM

Don't worry about it. Half a millimeter won't affect anything.

C_LOGAN 07-12-07 08:18 AM


Originally Posted by DMF
Didn't you read this?

I read it. I just don't believe it.

BB SEARCH 121.5

C_LOGAN 07-12-07 08:21 AM


Originally Posted by cooleric1234
Because it's not that easy. First of all, I don't see the 68x122 mm BB on Nashbar previously mentioned (maybe I'm blind). I've searched across the Internet and I think I MAY have finally found a 68x121.5mm BB, but I'm not totally sure (it doesn't look like square spindles...are those just covers on the last item on the following page?):

http://www.bicyclefitness.com/info/intsale.html

Just give your local bike shop a call. They will be able to order one in for you. As DMF said, a very small amount won't make a difference though.

Stacey 07-12-07 10:07 AM

I got lucky today. My not so LBS had exactly the BB spindle I needed... a 3U, 124.5mm.

Stacey 07-12-07 10:09 AM


Originally Posted by C_LOGAN
Maybe not half a mm, or a mm. But you can't ignore the axle length - it makes a difference and it is better to go with the specs. Why bother getting something of a different size if you can buy the correct size quite easily?

Of course.

JanMM 07-12-07 04:37 PM


Originally Posted by cooleric1234
First of all, I don't see the 68x122 mm BB on Nashbar previously mentioned (maybe I'm blind). ):

http://www.bicyclefitness.com/info/intsale.html

Shimano UN53 68X122 isn't listed as being in stock. My bad. Nashbar/Performance: They don't always have what you need.
Bikeman lists a UN54 68x122. http://www.bikemannetwork.com/biking...QRSHMTN/CR5371


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