+1
We used the unit of measurement a bunch when I was in the Navy.
JimD
Precision in all things.
On Apr 18, 2012, at 10:11 AM, William wrote:
> Perhaps we should develop our own quantitative metric for the narrowness of
> the hair being split? Inspired by the well known engineering unit the RCH.
>
> SHPI -- splittable hairs per inch?
>
> On Wednesday, April 18, 2012 10:07:07 AM UTC-7, HappyCamper wrote:
> You can say that every post on this group ever has been splitting hairs. It's
> part of the fun :)
>
> - Ryan
>
>
>
>
>
> On Wednesday, April 18, 2012 10:03:07 AM UTC-7, Jim Thill - Hiawatha Cyclery
> wrote:
> MichaelH illustrates how little difference it makes. Three minutes is his
> largest variation in his 18 mile ride on a variety of different tires with
> different bikes, and that variation wasn't even reproducible in a second
> trial. I spent seven years in grad school doing science, so I can see that
> there are confounding factors in Michael's research that muddy the waters.
> But his over all consistency from tire to tire and bike to bike suggests (if
> not proves) that tire differences play much less role than, say, the rider's
> day to day energy level and attitude, wind direction, and countless other
> factors. Comparing one lightweight 700x28 tire to another is really splitting
> hairs.
>
> On Tuesday, April 17, 2012 7:16:05 PM UTC-5, MichaelH wrote:
> Another single data point.
>
> Along with the post on where the Rambouillet fit in the Riv line up, I rode
> an 18 mile loop from my home on my Ram with a pair of Continental GP4, 23 mm
> tires. (A gift). The course has 900 feet of climbing and includes 4-5 miles
> of dirt roads, with the rest equally divided among good pavement, bad
> pavement, and atrocious pavement. After the ride I recorded my time &
> subjective impressions (painful). I also discovered a cut in the sidewall
> of the rear tire, so I decide to replicate the ride with a variety of bikes
> and ties. I rode it twice on my Ebisu with Jack Browns. The first ride was
> 3 minutes slower but the second was identical, although a lot more
> comfortable. I rode it once with my Trek & T Serve (30mm actual). My time
> was right between the faster and slower rides & the comfort just a nudge
> below the JB. Now the wind has shifted around from the south to the west (
> it has been blowing at 20 -25 mph, making this very real world test) and the
> dirt road has been graded, leaving it's surface full of rocks and loose sand,
> so it's really hard going now. Hard to make comparisons. I'm in Boston for
> the weekend and heavy rain forecasted for next week so this test will be
> suspended for a while.
>
> I'm not sure where this leaves me. I'd like to put the Grand Bois Green on
> my ram but am wondering if the perceived advantage is worth the added flats.
>
> Michael
>
> On Tuesday, April 17, 2012 4:29:48 PM UTC-4, William wrote:
> I'm in the same boat with Pari-Motos. I flat almost every ride with
> Pari-Motos, and almost never with anything else. I've put them back on with
> Foss tubes to try again. I like the ride of them, but the flat record is
> pretty bad for me. For me it's been glass.
>
> On Tuesday, April 17, 2012 12:55:06 PM UTC-7, Mojo wrote:
> Prompted by this thread I changed out the Rolly Poly/Ruffy Tuffy front/rear
> combo on my road bike wheels to the pair of (what I have considered to be
> special event) Grand Bois Cerf 28mm tires. I rode them for 25 mountainy miles
> yesterday and enjoyed their feel immensely. Today I got a front goathead
> flat. This is the 3rd flat I have had on these tires in about a dozen rides.
> This is by far the worst flat record of any tire I have used, ever. I
> understand I cannot say this will be the flat record for me in the future or
> for you in your environment, but my faith in the tire is shaken and it
> affects the enjoyment of my ride. I am putting more effort into scanning the
> road or trying to stay off the dirtier portions of the road instead of
> enjoying the view or thinking my deep thoughts. {~;
> .
> When I got home I fixed the flat, pulled the GB Cerfs and replaced them with
> the RP/RT combo. As I was changing them, I weighed them on my Park digital
> spring scale. To the nearest ounce, the Cerf was 10oz, Rolly Poly 11oz, Ruffy
> Tuffy 13oz, Jack Brown Green 33mm was 12-13oz. All of these tires are made by
> Panasonic. Now I believe Jan Heine's rollout tire comparisons are valid. But
> for me to flat every second or third ride is just not worth the lower rolling
> resistance or an ounce or two of rotating weight.
>
>
>
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