From: jobst.brandt@stanfordalumni.org
Subject: Re: Patching Tires - Tube Ridges - Remove or Not?
Newsgroups: rec.bicycles.tech
Message-ID: <CAlDd.419$m31.5515@typhoon.sonic.net>
Date: Fri, 07 Jan 2005 01:28:02 GMT

Alex Rodriguez <adr5@columbia.edu> writes:

>> I sand them off...carefully.  The real secret is to buy tubes
>> without these ridges.  There's really no excuse for them.

> Except for some latex tubes, which have problems of their own, I
> don't think I have ever seen a tube with no ridges.  Who makes this
> type of tube.  The ridges must be there for a reason.  I can't see
> the tube companies wasting rubber unnecessarily.

Anyone who has tried it will recall that the ridges are not readily
sanded off, so that method is out.  As was suggested, the plastic
razor is ideal for this and can't be beat.  Just cut the shaver handle
off and put the head in the patch kit.

The reason they are there are because the mold is separable to get the
tube out and the edges, if not relieved, will crack in use so there is
a radius that fills with rubber causing the ridges.  These are made
specifically to make the mold more durable and to put the cracks in a
known place, similar to concrete sidewalk cracks.

Jobst Brandt
jobst.brandt@stanfordalumni.org

From: jobst.brandt@stanfordalumni.org
Subject: Re: Patching Tires - Tube Ridges - Remove or Not?
Newsgroups: rec.bicycles.tech
Message-ID: <b%mDd.422$m31.5708@typhoon.sonic.net>
Date: Fri, 07 Jan 2005 03:04:39 GMT

Carl Fogel writes:

>> The reason they are there are because the mold is separable to get
>> the tube out and the edges, if not relieved, will crack in use so
>> there is a radius that fills with rubber causing the ridges.  These
>> are made specifically to make the mold more durable and to put the
>> cracks in a known place, similar to concrete sidewalk cracks.

> Elsewhere in this thread, Joe Riel asked about the densely packed
> cigar-band sections of ridges--a dozen or so ridges in an inch or
> two.

> Do they mark an especially tricky spot in the mold, or what?

No, that section is where the tube is spliced into a toroid from
straight rubber tubing.  This is indeed a bad joint, not only because
patching there is difficult, but because these heat sealed joints
occasionally leak spontaneously.  It seems to be another manufacturing
invention that reduces cost.  I have had a couple of failures there.

Jobst Brandt
jobst.brandt@stanfordalumni.org