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. I have the same
problem with Schwalbe 20 inch tires. The rim manufacturers
and the tyre manufacturers are just a dinkleberries in
disagreement. I am on my third rim and tyre combo. Still
tight AF but will just fit.

Deflate the tyre. Lube up the bead with some soap. Inflate
to "Holy mother of god! How much?" PSI It may decide to pop
into its seat properly.

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.

I will try one of these tires on another bike with different rims,
see what I get, and report back.

It also seems like my best bet is to go with a different tire for
this bike. I'd like to stay with Conti's but don't want the
expense of the Grand Prix. Any suggestions?

--
Ted Heise West Lafayette, IN, USA

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.