Joshua Putnam may have said:In article <[email hidden]>, [email hidden] says...
Quoted message said:Surveying the collected bikes in the back yard, none of which are high-end (or even mid-level,
for that matter), *not a single one* has a drain hole below the BB.Food for thought...though I agree that if the ability for water to get in is present, the
facility for it to get out logically should also be present. I can't read the designers' minds,
though, so I have no definitive answer as to why it appears that this is not the case or is not
regarded as a problem.For the same reason almost no headsets or hubs are designed to hold up well in the rain -- bicycles
are fashionable high-end toys to most buyers in the U.S., and they simply don't get ridden in the
rain, so most of them aren't designed for it.
The US Post Office used bicycles to deliver the mail for about 50 years IIRC. I used to see quite a
few of them, and to the best of my recollection, none had any weather sealing on the head, and they
were used and parked ourdoors (in swampy climates like Miami) continually. The lack of sealing
didn't seem to be much of an issue there; I believe that because the amount of water which got into
the bearings was small, and the water was able to drain out immediately, and because the speed of
motion of the bearing was miniscule, simply having it well coated with grease was adequate to keep
the failure rate to an acceptable level. The bottom brackets on those bikes were also unsealed, I
should note, with relatively few resulting problems. Thus, it may be that the engineering decision
was that sealing the assemblies added extra cost for little gain, and wasn't worthwhile.
Current BB designs are mostly sealed on the outside at the very least, but the designers apparently
regard the probability of water getting into the BB via the frame as being ignorably low. Someone
with far more daily experience in current bike repair issues could address whether the record shows
that water is causing a significant failure rate in that area, but I cannot confirm the existence of
such a problem with my limited exposure. On the other hand, I've seen a few reports of head tubes
that were so corroded inside that they couldn't be fitted with a 1 1/8" headset without reaming the
crud out first...and still, they hadn't experienced a failure in the bearings. From all of that, I'd
say that with rare exceptions, it looks like the bike designers know what they're doing, from a
purely practical standpoint.
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