Fixing Play in Bottom Bracket
 

Hi, Thanks for your help.

I have an older-style shimano octalink bottom bracket (Shimano 105 BB-5500 Bottom Bracket). It is installed in a Cannondale CAAD9 with a Ritchey cranket. There is some lateral play in the bottom bracket that concerns me.

The bottom bracket is lightly used and fairly new so if it is simply wear I am really surprised - although it could be. The bottom bracket is threaded all the way into the frame and very snug. Same for the adjusting cup on the non-drive side - very snug and threaded all the way in.

What could be causing the play? Is it simply worn out bearings? Is it that 105 BB-5500 is generally a crappy/loose bottom bracket? Can it be that for some reason that the adjusting cup cannot be tightened enough in my frame to remove the play? (From what I remember, the sealed units such as the BB-5500, do not provide any adjustment for play with the adjusting cup. It simply tightens into the frame and that is it.)

Any PRO tips are appreciated (including telling me I should just upgrade to a newer crankset and BB).

Thanks.

How much play?
Where is the play -- that is, what is moving relative to what?

There is a reason the Octalink Bb has been moved on from. To get the larger diameter spindle inside the same diameter shell Shimano used much smaller diameter rolling elements, which do wear at a faster rate then larger diameter ones, all other things being equal. Additionally many feel that the sealing of these BBs isn't as effective then the tapered square units.

Now I would ask if the slop/play is a functional issue. Does it effect shifting? Does the chain rub more now then when first assembled (and the der cable tension adjustment having been kept up with)? Bearing slop/play that doesn't effect other functions can be considered a non issue in many cases. In fact most radial contact/preassembled/cartridge bearings need some end play to avoid premature wear.

The only Shimano Octalink BB that is adjustable for end play, AFAIK, was the Dura Ace version 1st generation. Shimano went away from this design soon though as the floating bearing cone would cause creaking and sometimes crack. To give Shimno credit they were trying to solve the problem of poorly maintained tapered square crank arm retention bolts and the resulting arm becoming wallowed out and coming loose. That they could also claim a stiffer BB spindle sure helped in the market place, too bad this has so little actual benefit in real life. Andy.

I had this happen recently when I forgot to install the washer when I put the 8mm internal hex head crank bolt in.

I can move the crank arms in a different direction than the circular path they should follow, i.e., closer and farther from the frame rather than parallel to the frame.

This "lateral play" seems to be inside the bottom bracket, not at the attachment to the frame or at the attachment of the cranks to the bottom bracket, which is why I am suspecting the bearings.

Glad to know it was not just to change everything to make money.

It does not seem to be a functional issue. Shifting is fine. No detectable chain rub. The drive train, cables, derailleurs, shifters are all in very good functional condition.

I was mostly concerned that the slop/play might damage the frame. What do you think?

I pulled the cranks and checked the cup tightness. Both sides were very snug. After reattaching the cranks the slop/play was the same.

Sure, bearings need some play. My other bike, with an external bottom bracket, probably has the necessary play but it is not at all detectable by lateral movement of the crank arms.

I had one of those Dura Ace BB. Very nice I thought.

So I guess I should either get a new octalink BB or convince myself to upgrade the crankset and BB!

Thanks for your help Andy.

Thanks! But that is not it. I just pulled the crank arms to check things were snug and the washer was on the 8 mm crank bolt, both sides.