On Wed, 19 Sep 2018 11:17:47 -0700 (PDT),
wrote:
On Wednesday, September 19, 2018 at 9:04:52 AM UTC-7, Theodore Heise wrote:
On Wed, 19 Sep 2018 07:07:49 -0700 (PDT),
jbeattie wrote:
On Wednesday, September 19, 2018 at 5:21:05 AM UTC-7, Theodore Heise wrote:
On Wed, 19 Sep 2018 07:33:24 -0000 (UTC),
dave wrote:
On Wed, 19 Sep 2018 01:40:46 +0000, Theodore Heise wrote:

I've used mostly Continental tires for over 20 years
and nearly 100K miles of road riding. Recently I got
a half dozen Ultra Sports (700c x 25), and after
putting a new on on the front noticed a definite
bounce as it rolls. I've tried three now, with the
same results. The wheel is very true and round, with
no flat spots.

The bead is probably not seated right.

That's possible, but seems unlikely for *three* different
tires mounted at least five times. Also, I inspected the
seating of the tires pretty carefully, and there is no
apparent difference in tire placement around the rim. On
top of all that, wouldn't the bead either seat or blow out
on riding for hundreds of miles?

Your options are a defective tire or a tire that is not
beading. Some tire and rim combinations a just bad, and
you can get a tire that will not bead without soaping,
beating, prying, pumping, etc., etc. Untreated, the tire
will not bead no matter how long you ride it. Ultra Sports
are an unhappy combination on my Sun CR18 rim which has a
shallow rim well. They're tight, but they do bead and are
round. I quit using them because of poor sidewall
durability. I never had one that was mismanufactured.

Thanks, Jay (and dave). I suppose there is some small chance that
I got a group of defective tires from a bad manufacturing run, but
the non-beading point does seem more likely. I should have added
that getting the tires off takes some active inward pushing to get
the bead out of the hook on the rim. In some spots, a surprising
amount of force is needed. So this too points to bead seating
problems.

Ted, this is quite easy to see - there is a line that would
normally be showing above the rim edge. That is symmetrical so
if that isn't showing in about the same height above the rim all
the way around you've discovered your problem.

Yes, that is my understanding too. In my earlier post, "there is
no apparent difference in tire placement around the rim" referred
to observation of this line--though I did not explicitly say so.

Is it possible for the bead to not be fully seated without showing
as a difference in the tire seam/markings' distance from the rim?

--
Ted Heise West Lafayette, IN, USA