PDA

View Full Version : Changing the BB standard


saab2000
09-24-2005, 09:08 AM
I just saw on cyclingnews.com an article about the top o' the line Specialized. They have a new crank design which looks to use a new BB shell size. In one way this is too bad because it limits the frameset to using that crank/BB. But in another way it is about time someone deals with this. Many people would agree that the Shimano outboard bearings was a defacto method of increasing the BB shell size, but with a compromise or two.

Is it time for a larger shell size standard to keep the bearings inboard? Anyone have a more knowledgeable guess on this? It seems like it would make sense to me.

jpw
09-24-2005, 09:40 AM
Is this the 'Overdrive' standard?

SPOKE
09-24-2005, 05:44 PM
i think Cannondale has the OS BB shell on their top of the line six-13 that uses their crank.
the ISIS open standard BB bearing/axle was a good attempt at standardizing the crank arm connection but it really didn't address the bearing loading issue that causes some failures with the smaller diameter bearings.
if i'm not mistaken, Cees Beers (ADA composite wheels fame) makes a BB assembly that uses roller type bearings (ground cylinders instead of balls). it spins so well that you can make the axle spin by simply blowing on the axle. (i can just imagine the comments from that last statement :D). the old campy super record BB's were almost capable of this with a little extra polishing but since these BB's had ball bearings they just didn't last as long unless you really did alot of maintainence on them.

Jeff N.
09-24-2005, 06:55 PM
I know Chris King has been toying with an oversized BB designed for an OS BB shell. I'd say that something like that could eventually become a standardized item, but probably not within my cycling lifetime. Cannondale has their design, and it has gotten pretty positive reviews. But its purely proprietary, pressed-in (I believe), and way far from ever becoming standard. It's kinda like the integrated headset in that you'll see bikes here and there with that design but no real standardization. The BB area DOES seem like the next logical place for bike designers and component engineers to futz around with though, although the added weight of a larger BB shell and resulting larger BB spindle/bearings etc. might become an area of concern from a design standpoint. Heck, I wouldn't be surprised to see them eventually widen the rear to 135! Or 140! Get 15 gears (or more) back there! Know whum'sayin"? Jeff N.

mdeeds71
09-24-2005, 11:46 PM
In the day the pre-Trek Kleins had a pressed in bottom brackets that were the top of the notch in terms of rigidness...Never had a problem with them except now days very few can actually change the pressed in bearing out properly...Yet I have no need to do the old bike yet. The bearings were huge and of aircraft spec...I actually got part number for my bike and they specified an part number boeing uses for a toque tube bearing on the 737.