PeterAnker

Hello guys,

I just bought a second hand road bike.
And I have the following issue:

The crank is a triple ultegra 6503 with octalink V1.
The previous owner put in a octalink V2 bb because he is a an stupid idiot.
The v2 bb is also shorter then the original bb which would be a 118.5mm. That resulting in the removal of the small ring, because it was rubbing on the frame.

What can I do?
I need a longer bb, so I can use all the 3 chainrings.

The crank splines are probably deformed from the v2 bb.

Should I get a V1 bb with the correct length: 118.5 mm. I'm afraid that the v2 bb damaged the splines and the crank will have play on the v1 bb. I don't want to waste more money.
Or should I buy a longer v2 bb, like a Octalink BB-ES25 which is 118 mm. The damage is done, and just try to make a useable bike.

Please help!

Thanks!

bradtx

PeterAnker, If you want a double crankset, replace the 6503 with a V2 compatible crankset. If you want a triple crankset, replace both the BB and the crankset.

Brad

bobotech

I had a crankset with almost the same situation as you do. I got a crankset a while back from a friend. It was a Ultegra V1 Octalink triple that he had mounted to a V2 octalink BB. Once he tightened it down, it only engaged about 1 or 2mm instead of the full 5mm depth of the spline.

He used it like that and had no problem but didn't like the triple and gave me the crankset. I am picky and new about the incompatibilities between v1 and v2 splines so I researched the part numbers only to discover that he had screwed up.

So I had this crankset with the splines deformed for about the first mm or so. The entry to the splines on the crankset are beveled so the V2 BB splines can sort of wedge in there. The v2 splines are slightly wider than the v1 splines. 2.8mm vs 2.4 or something like that. Since the entry point on the crank splines are slightly beveled, he managed to jam the v2 splines in there and they held for him. The crank didn't slip but there is zero safety buffer in there and chances are it would have eventually slipped and ruined the crank.

So i found the proper 118.5m V1 bb and with it off the bike, I gently worked the crank onto the bb and after a few minutes, I mananaged to clean up the deformation present and the V1 crank fit flawlessly on the V1 bb. The splines then looked good.

So provided the V1 crank has never slipped on the v2 BB, chances are you can get the V1 crank to engage the V1 bb without much trouble and it will work well again.

bobotech

Don't buy another V2 bb in hopes of using the crankset, when you use a V1 crankset on a V2 bb, only about 1mm of the spline is engaged and eventually it will slip and ruin the crank.

HillRider

Absolutely get the correct V-1 118.5 mm bottom bracket. The 105-level BB-5500 is still readily available and modest in cost.

PeterAnker

Sorry for the late reply, I've been away.

I got the cranks out, and they splines look like this:










and the v2 octalink bb:






From what I see the crank splines have engaged the bb all the way.


With pictures presented, you think I still might get away using a new BB-5500 ?


Thanks everyone!

bobotech

No, they do not look like they have engaged it all the way. They look more damaged than my cranks using the wrong v2 BB but not by all that much. You can try getting a new V1 bb but I'm not going to say its going to work as well as mine did. If it were me, I would source a new V1 bb and try it and see how it works. It might work just fine. You will want to work the crank on the new bb slowly and back it out several times to try to clean up the splines as much as possible. Then make sure you securely torque the crank down and see how it goes.