Bottom bracket shell cutouts
 

Many of the better steel road bikes of the 1970's and 1980's (Raleigh Professional, Colnago, Masi, etc.) had decorative cutouts on the bottom side of the bottom bracket shell. First of all, what was the purpose (if any) of these cutouts, and secondly, how do you maintain the bottom bracket on such bikes? Seems like an awful lot of water and road junk has an easy way into the working parts of the bottom bracket.

TSapp

There were no sealed bearing cartridge type bottom brackets until recently so, rather than having grease get all gunked up in the bottom of the frame, cutouts solved the problem. You don't see them on track bikes because grease on the track would be a bad thing.

As for maintenance, I guess that a little frame saver sprayed around the edges couldn't hurt. To be honest, I never thought about it. I don't think much water gets splashed up in there but I could be wrong...

Now I am not certain but the cut-out was there to let water out. You will likely not see the BB cutout on a bike that sported pre-sealed sleeve or sealed bottom bracket days.

With a sleeve or sealed cartridge, if water did manage to get into the bottom bracket housing, it could pool and collect. In days gone by, before sealed this or that, water could get in through the spindle/cup opening. However, it could also get out through that same opening. With that in mind, it could not pool up.

If water is allowed to pool up, it can fill up chain stays and the like. Best to not have it there by allowing any that gets in, absolutely free access to leave. The sleeve or or seal will protect the bearings, so an opening in the bottom is not going to negatively impact the integrity of the bearing cavity.

Of course, I could certainly be wrong but that is what a local vintage bicycle guru told me.

I should say that there were sealed bearing type of BBs back in the day but they were not in popular use as they were pretty expensive. Does anyone know how much a Phil Wood BB cost in, say, 1985?

The reason they're there is they look bad-ass :)

Can't argue with this:

http://farm7.staticflickr.com/6007/5...ef1c5e21_b.jpg

I don't know how much water can get in there through the cutout, but even if it did the opening would allow for evaporation. FWIW, I've never had a rust problem with any bike that has a BB cutout.

EDIT: According to my Palo Alto catalog, a Phil Wood BB cost $54.98 in 1981. That's compared to a Stronglight Ti at $89.98, Stronglight steel at $39.98 and an Avocet II at $44.98. Those were the only sealed units being offered in that year's catalog.

DD

To keep the bottom bracket shell from getting greasy? I'm not buying that one!

I worded it poorly, I should have written something like "old gunky grease and/or other fluids"; randy wrote it out better than me.

Made your frame lighter, too.

Or to help them make your wallet lighter.

Sealed bearing bottom brackets have been around for over half a century but didn't become common until relatively recently. Cut-outs are more a vanity thing -- something the builder does to distinguish their frames from others.

Yup. Back in the day, plenty of high-end bikes had cut-outs and plenty of equally nice, expensive bikes did not. Had nothing to do with drainage (unless you submerge it, not much water can get into a built-up bike frame anyway). Some BBs came with sleeves and some didn't. Sleeves would help keep out dirt from the road if the BB had holes, but just as important, it would keep rust from the frame tubes & BB away from the bearings.

Also, track frames had BB cut-outs: here's a 1977 Cinelli track:

http://bikeforums.net/attachment.php...hmentid=234219

Drillium!

My '74 Raleigh track has "CC" cutouts in the bottom bracket.

Do all Carlton bikes have these cutouts?

mmm, my '78 Raleigh Pro does not, it just has a 2 slot cutout. The serial number of both bikes are "W" based (worksop), which I think means Carlton/Raleigh.

I still haven't seen many (one) comments about servicing a bottom bracket where the BB shell has cutouts. Do you regulary flush it out to remove dirt? What do you use? How often? What about lubing it? And I definitely agree that they look "bad ass"!

TSapp

No different than servicing one that doesn't, though if the BB doesn't have a sleeve I'd make one. Dirt gets in around the spindle & drops out of the frame tubes as well as comes in through BB cutouts. I've made sleeves out of aluminum cans, plastic anti-freeze bottles and such. I never had much trouble with BBs, and once I started using Campagnolo (whose proprietary sleeves tended to split) I never had BB problems at all.

I spread a thin coating of lube around the interior of the shell on my bikes with cutouts; I clean and re-apply each time I service the BB.

DD

Just checked my '79 Raleigh track, it has a 2 slot cutout.

+1

I actually read the directions on a Campi cartridge BB I installed last winter. it actually recomemded ensuring there was a hole in the shell for drainage

I personally think a shell with cut outs is superior to a fully closed one. With how I treat my bikes both wouldn't be an issue, but from I have heard and seen open is better.

Why'd you go & do that?
Sounds like a CYA thing from Campy. Might be useful on a cyclocross bike. Otherwise, not so much...

I can see an advantage if the bike is ridden in the wet a lot, but otherwise....

...an entry and exit point for small rodents :)

DD