From: jbrandt@hpl.hp.com (Jobst Brandt)
Newsgroups: rec.bicycles.tech
Subject: Re: Rolf Vector Pro wheels analysis
Date: 13 Apr 1998 19:23:09 GMT

dlkouba writes anonymously:

>> What tire in particular are you trying to defame?  The dirt tires that
>> Avocet produced were tested by three bicycle magazines, each on
>> separate occasions, with invited riders who rode the Avocet tire and
>> other leading brands down a measured dirt course with timing lights.
>> The ten best runs of each tire were recorded and in each test the
>> Avocet tire was the fastest through the section.
>>
>> These tires were also tested for road traction and achieved close to
>> the same lean angles as the best cornering slicks.

> And we all know that magazine tests are a true indication of what the
> riding public wants and needs.

The test was an Avocet test with riders from the magazine.  The timing
lights and course was set up by Avocet and to avoid bias is rider
response, sports editors and their riders were invited to perform the
test.  You didn't hear this from the bike magazine as an endorsement
but as measured results.  The accompanying texts did not praise the
Avocet tires in deference to their major advertisers but merely listed
the results in the articles that chose to show them.

> Alas, I have never heard of a mag being influenced by a new hyped up
> product.  If I listened to mags I'd be riding a URT with biopace
> rings, a suspension stem, riser bars, and these ill-fated Avocet
> tires.  Of course the Avocets would have babypowder in them because
> I HEARD through rec.bicycles.lore that the talc makes it easier for
> me to take the tires off and pitch them into the trash.

Now now.  Keep your temper.  Why do you take this so personally?

Jobst Brandt      <jbrandt@hpl.hp.com>

From: jbrandt@hpl.hp.com (Jobst Brandt)
Newsgroups: rec.bicycles.tech
Subject: Re: Rolf Vector Pro wheels analysis
Date: 14 Apr 1998 00:03:51 GMT

Mark Weaver writes:

> I'm supposed to believe 3 different mags conducted scientific tests?
> That's pretty out there, but I suppose if I had the names and dates
> of the articles I could check it out. how 'bout it.

That's not what I said.  I said Avocet constructed the test (June
1997) and invited three bike magazines to try the tires.  Subsequently
little or nothing appeared in the press, Avocet at the time, not being
a major tire advertiser.  The results were presented in a less than
informative article.  I was disappointed in the objectivity when the
three tires for soft medium and hard dirt were tested.  They were more
than just another variation of directional tread or the like.  That
these tires also cornered well on hard surfaces didn't seem to appeal
to the riders or editors who themselves participated in the test.

> The only mag article I saw where tires were actually tested on a
> course for speed was in MBA I think, and they concluded that
> Bontrager revolts were the fastest, with Conti double fighters and
> some others close behind. I personally don't remember seeing the
> Avocets in that test, but they coulda been there.  Unlike der
> jobst-meister I admit to being fallible.

Who is "jobst-meister"?

Scott Nicol of Velo News, Jeff Drake of Bicycling, and Charlie
Cunningham of MBA were there with their staff.  Of the riders
Cunningham, editor of MBA, was the fastest and all posted their best
times with Avocet tires.  The ten best runs were averaged.  VN and
Bicycling didn't find an opportunity to report on the test while MBA,
in an elegant side step, gave someone who wasn't involved in the test
the article assignment.  I assume this avoided biting the hand that
feeds (those who have faithfully advertised their tires in MBA).  That
the tests were done under the auspices of Avocet was not apparent in
the article and no times were given but rather the usual "responsive,
quick, good tracking..."  evaluation.  Your suspicion of magazine
articles is not without basis.  The MBA article was accurate although
the reader probably drew incorrect conclusions.

> I still say it's pretty darn likely those tires suck.  I sure don't
> see too many of 'em on bikes around northern California.  Most of the
> expert racers I know have to buy their own tires, so either we're
> all stupid and blind (which is actually pretty believable), or jobst
> is a pompous, grandstanding fool, trying once again to replace a
> large amount of testing and evaluation with a small amount of
> engineering.  That also seems pretty likely.

I doubt many of them ever heard of an Avocet dirt tire.  For example,
in spite of the continued failings reported on wreck.bike, Continental
tires are still the most popular tires on the road in my area,
probably because they have an advertising presence and sponsorship.

> How bout it?  Is there anyone who actually rides a mountain bike who
> thinks the Avocet MTB tires don't suck?  I would love to hear some
> opinions of riders who have some race time on them.

Thanks for asking.  I too would like to know who tried them.

Jobst Brandt      <jbrandt@hpl.hp.com>

From: jbrandt@hpl.hp.com (Jobst Brandt)
Newsgroups: rec.bicycles.tech
Subject: Re: Rolf Vector Pro wheels analysis
Date: 14 Apr 1998 15:22:49 GMT

Dan (who?) writes:

> I am being 100% honest when I ask this:

I didn't realize your honesty was in question until you mentioned it.
What problems are you having telling the truth?  Let's hear about it.

> Did Jobst have a hand in the design of the Avocet MTB tires?

That sounds heavier than what happens in such design.  It is the tread
pattern that gets designed, the tire is a conventional casing used by
other models made by IRC and is nothing new.  I, in a committee of two,
came up with a tread pattern that had good traction for dirt while having
a tread edge that would not roll over under hard cornering on pavement.

> Weren't these the tires that kept coming off the rim?

If they were, then all other IRC tires of that size came off, however,
I think IRC knows how to make tires that stay on.  I have relied on
their ability for years of riding and have not been let down.  I have
not heard of any tires coming off.  Where was this observed?

Jobst Brandt      <jbrandt@hpl.hp.com>

From: jbrandt@hpl.hp.com (Jobst Brandt)
Newsgroups: rec.bicycles.tech
Subject: Re: Avocet Tires (was Re: Rolf Vector Pro wheels analysis)
Date: 14 Apr 1998 18:01:47 GMT

Alex Wetmore writes:

> Does IRC make the Avocet tires?  Besides the tread pattern is there
> any difference in the casing material or tread material?

IRC makes several types of casings with different cords.  If you
compare the cored count and casing walls and find them the same, then
you are probably looking at identical casings.

> I'm trying to figure out why Avocet tires are much more expensive
> then similar IRC models.  For instance compare the IRC Metro with
> the Avocet Fasgrip (both are available in 559 sizes).  They are very
> similar, except that the IRC Metro has a useless tread pattern (and
> probably a slightly thicker tread).  The Avocet is almost $10 more
> though, at around $20-$25, compared to $12-$15 for the IRC tire.

I am not familiar with the Metro but I doubt that the casings are
the same if there is that much price difference.

> Should I just look for similar IRC tires instead.  My tandem has the
> IRC Smoothie (basically a 559-32 version of the IRC Metro) and its
> also a nice tire.

I'm not aware that IRC sells a smooth tire under their label.  What is
that tire called.

> However its hard to compare it to the Avocet tires since there are
> such large differences in riding a tandem and a single (although
> when I get a chance perhaps I'll swap tires with my girlfriends
> bike, which has the 559-32 Avocet Fasgrip 20s on it).

I'm not sure what you expect to notice unless you test the limits, and
that isn't easy.  The maximum lean angle in a curve could be painful
to test and the rolling resistance is imperceptible to a rider
although measurable.  The ride quality is primarily a matter of
inflation while to determine wear rate would require some statistical
results to reveal a trend.

In contrast, test machinery has determined that smooth tread corners
better (greater lean angle) and that it has lower rolling resistance.
However, rolling resistance (at a given inflation pressure) is
strongly dependent on tread thickness, so that riding worn out tires
is slightly faster.  I don't think the advantage is worth buying thin
tread tires unless you are competing at the top level in a time trial
race.

Jobst Brandt      <jbrandt@hpl.hp.com>

From: jbrandt@hpl.hp.com (Jobst Brandt)
Newsgroups: rec.bicycles.tech
Subject: Re: HELP! Which direction tire treads?????
Date: 3 Dec 1998 23:24:00 GMT

Greg Thomas writes:

> If you are talking about offroad tires used offroad have you
> experimented with running a front specific tire, like an old dart,
> backwards?  With the tire mounted backwards there is much less knob
> face providing braking traction.

Yes?  I notice you didn't say that there is a measured difference in
traction.

> Also, offroad there are much different traction requirements between
> the front and rear tires so front or rear specific tires are
> effective.  the front needs much more turning traction than the
> rear.

I don't believe that.  Side load on a rear wheel is greater than the
front, proportional to the load carried.  There is no doubt that a
slipping front wheel is a greater hazard than on the rear, but that is
not in contention, only that directional tread has shown no measurable
difference.

> The knobs on the front should be designed to balance turning
> traction and straight ahead braking traction while the rears can be
> balanced more towards straight braking traction with a little bit of
> side traction to prevent the rear from coming around on sharp,
> slippery corners.

That sounds reasonable but how does one do that?  The Avocet dirt
tires have something better in that they corner nearly as well as a
road tire on hard surfaces while having plenty of dirt traction.  When
leaned over hard, there are no fore and aftaccelerating forces, so
this part of the tread should be designed for side loads only.  In the
middle of the tire there are no cornering loads so it should be
designed for fore and aft traction.

I think the Avocet tires accomplish this better than others and
demonstrated it in timed tests on a dirt s-bend.  Riders from various
bicycle magazines rode the tires through timing lights and averaged
their ten best runs.  The Avocet tire performed better than the main
competitors.

> I prefer the same tire front and rear more because i can put a new
> tire on the front and then put the front on the back.

That is always a consideration and one that I make use of on my road
slicks.

Jobst Brandt      <jbrandt@hpl.hp.com>