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I have 105 Cranks/BB, will an Ultegra crank work with my BB(7 posts)

I have 105 Cranks/BB, will an Ultegra crank work with my BBSwat Dawg
Mar 16, 2003 8:54 PM
I just snagged an ultrgra crankset off ebay for a good deal, and am curious if I will also need to get a new ultegra BB. I have 105 cranks and I think 105 BB. Also is the Ultegra BB stiffer that the 105. Currently, I can flex the 105 when I am cranking, but I'm not sure if the flex is coming from the BB or the cranks themselves. If the ultegra is compatible, I'll just slap on the new cranks and then find out if it was the cranks, but a heads up would help. Thanks in advance.

Swat Dawg '04
no problem!the bull
Mar 16, 2003 9:46 PM
Just make sure its the new stuff-It will be easy to tell!
Do you have the cranks that have the built in puller.
Its like a washer that screws into the crank so when you loosen the crank bolt it works as an extracter.
Huh???Swat Dawg
Mar 16, 2003 10:12 PM
Extractor tool? Built in puller? I am going to install the parts at the bike shop and maybe if I need something extra I guess they'll have it. But what do you mean the new stuff? I am confused a little.

Swat Dawg '04
Mar 17, 2003 2:57 AM
A crank puller or extractor is just a fancy bolt that screws onto your crank and pulls it off by pushing on the bottom bracket at the same time. The fit between the two is so tight that you definitely need one. Your bike shop will have one for both old and new cranks. Ultegra and Dura Ace cranks have a "dust cap" that covers the bottom bracket bolt that acts as an extractor. There's a hole in the middle so that you can unscrew the bb bolt and once it comes out far enough, it pushes the cap from the inside, thus separating your crank from your bb. 105 level cranks do not have these, but you can order them separately if you want (for about $20 I think). Only the newer cranks come with them. I'm not sure if they work with older ones, although I don't see why they wouldn't. They're a handy way to avoid buying an extra tool (although a crank puller only costs about $8).

I assume that by old and new he meant square taper vs. splined. Older 105 and Ultegra used the square taper, newer ones have a splined or "octalink" interface. Some people insist there's a difference in stiffness, but I think you'd have to be pretty dang big and sensitive to tell the difference.

Hope that helps...
re: I have 105 Cranks/BB, will an Ultegra crank work with my BBNASA Noddler
Mar 17, 2003 4:48 AM
I have a Ultegra Crank on a 105 BB. Both are splined and work together no problem. I wouldn't change the BB. Very little weight difference or performance gain.
Depends.Spoke Wrench
Mar 17, 2003 5:45 AM
You didn't mention the age of either crankset. If they're both nine speed pipe billet stuff, fine. Other combinations maybe not.
Usually a matter of splined or notFez
Mar 17, 2003 7:45 AM
The compatibility issue isn't 105 to Ultegra.

Its usually a matter of whether you are using a splined BB/crank or not. All Ultegra 9 speed stuff used the splined BB/crank. Some early 105 9 speed stuff was not splined. Around 2000 or 2001 all 105 stuff became splined.

You just need to know what 105 stuff you have and pick the compatible bottom bracket from there. Also, triples need a triple specific BB.

Its relatively cheap either way. An Ultegra BB is around $40, a 105 one is around $20-25. A bigger deal is can you install it yourself? About the "flexing" you say you experience, start by making sure the BB is installed properly and see if it goes away.