Measuring Loaded Rim Height - Unassisted?

On Apr 19, 7:33*pm, Dan O wrote:
On Apr 19, 9:40 am, "(PeteCresswell)" wrote:

I going to try getting serious about the 15% rule: where a tire is
supposed to roll best when inflated so that the rim height is 15% less
than when unloaded.

Does anybody have a slick way to do this unassisted? * Seems like a
rather fine measurement to me.

Go to the butcher and have him cut you enough meat to equal your own
weight. *Stuff a pair of your pants and shirt to make a meat scarecrow
and put it on the bike. *Hold the bike with one hand to keep it from
tipping and measure with the other.

beef, pork,or goat ?

On Apr 20, 12:28*am, "(PeteCresswell)" wrote:
Per thirty-six:

wassup, no cornflakes today? * just tie a rule to a spoke with the end
touching the ground with the bike unweighted and read at the edge of
the rim. *Get on bike in normal riding position and get off bike and
the rule will have slid up but the friction from the tyre wall will
have stopped it sliding back down. *Read the rule again at the edge of
the rim. * Alternatively use tubulars. *You'll only worry about how
long you should leave the rim clouting the road when you get punctured.

Nice!..

I went into it thinking I was going to have to get around the parallax
error and the expected small distances.

But I just went and *did* it and parallax error seems tb moot.

To wit: I measured 40/35 at 70 PSI (5 more PSI than the tire is actually
rated for). * *5/40 = 12.5%...... 5/35 = 14.3%....

Backed off to 65 PSI, got 42/34....== 20%

Mildly puzzled when I connected the pump the second time and the
pressure read more like 60 - not long after airing it up to 70... but
I'm rationalizing that as being due to air loss pressurizing the pump's
hose.

Allowing for measurement error (especially PSI error) *and the fact that
the tire is going to lose air anyhow and I'm not going tb all that
compulsive about filling it before every ride... *I think I'll just air
it up 70 whenever I think about it and call it a wrap.

Maybe some day when I've been drinking too much coffee, I'll try a
series of measurements using different pump pressures and see if one
consistently falls closer to the magical 15%
--
Pete Cresswell

forget the cornflakes and the coffee, they're dumbing you down. Try
a cup of cocoa, tamarind or dates, and buttered spinach for your
breakfast.

On Sat, 20 Apr 2013 06:54:59 -0700, raamman wrote:

On Apr 19, 7:33Â*pm, Dan O wrote:
On Apr 19, 9:40 am, "(PeteCresswell)" wrote:

I going to try getting serious about the 15% rule: where a tire is
supposed to roll best when inflated so that the rim height is 15%
less than when unloaded.

Does anybody have a slick way to do this unassisted? Â* Seems like a
rather fine measurement to me.

Go to the butcher and have him cut you enough meat to equal your own
weight. Â*Stuff a pair of your pants and shirt to make a meat scarecrow
and put it on the bike. Â*Hold the bike with one hand to keep it from
tipping and measure with the other.

beef, pork,or goat ?

You'll need peanut powder and chilli dressing for the goat prior to
barbecueing which may be tricky.
--
davethedave

yeah I wuz over to HD buying a dowel. HD security didnah wanna sell me a Ryobi device ahnounsing over the PA it was not stocked...but I know the crud in HD so I looked and LO ! there's a wall of these device including a stack of $14 devices and $39 devices giving time temp and bp