Tire pressure is an important consideration. I have a theory that says that
the tire pressure should be slightly less than the pressure that it takes to
deform the surface the tire is rolling over since it takes more energy to
deform most surfaces than to deform the tire.
Some think that by increasing tire pressure that I reduce traction due to less
surface area on the road. Well, in some situation maybe yes, but no. The
coefficient of friction between two give materials is a constant. In a low
tire pressure situation there is greater surface area in contact with the road
at a lower pressure. In a high tire pressure situation there is less surface
area in contact with the road but at a higher pressure. I've not done that
analysis but I believe that the amount of force it takes to break traction is
basically the same for both situations.
I run 115 psi in my road bike tires, 43 psi in my car tires, 7psi in my
electric ATV tires, 25 to 45 psi in my mountain bike tires and 4 to 15 psi in
my fatbike tires. My theory seems to hold true when riding the road bike from
asphalt to the lawn compared to doing the same on the fatbike. Oh, and both
have great traction in both environments. Even when backpacking with my hard
soled hiking shoes, walking on the harder part of the trail takes less effort
than walking on the soft part of the trail.
On Nov 11, 2014, at 4:07 PM, via EV ev@lists.evdl.org wrote:
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Today's Topics:
1. Re: Range vs Speed (Michael Ross via EV)
2. Re: Range vs Speed (Cor van de Water via EV)
3. Re: New EV trike pickup. (jerry freedomev via EV)
4. Battery future vid very good (jerry freedomev via EV)
5. EVLN and other posts ... (brucedp via EV)
--
Message: 1
Date: Mon, 10 Nov 2014 16:48:21 -0500
From: Michael Ross via EV ev@lists.evdl.org
To: Lee Hart leeah...@earthlink.net,Electric Vehicle Discussion
List ev@lists.evdl.org
Subject: Re: [EVDL] Range vs Speed
Message-ID:
cannqeo+qtbmtvdqce2qb8uc9fz--ewyb5j0t9k-kzwf7oon...@mail.gmail.com
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On a road bike (more efficient than thick tired MTB) bicycle tires are very
thin. There is some heat generated in the rubber itself from weighting and
de-weighting and side loads. The molecules are literally sliding across
each other, unwinding and winding back up. Heat results. The fabric
carcass also has some flexing and sliding around. Heat results.
Because the bike is human powered weight is measured out in grams instead
of kilos or pounds. In particular the rotating bits have inertia to
overcome spinning up - light tires make the bike noticeable more
responsive.
Pumping the tires up hard reduces the flexing and decreases rolling
resistance. But designing them with less thickness is always better for
efficiency. Harder compounds where there is less internal flow helps too.
If you could run a tire 1/8 inch thick you would get much better efficiency
from it.
On Mon, Nov 10, 2014 at 1:56 PM, Lee Hart via EV ev@lists.evdl.org wrote:
jerry freedomev via EV wrote:
Hi Lee and All, I'm using some early Mazda Miata front hubs, brakes
that has retraction V shaped springs that with just a couple tiny
holes drilled in the pad for the wire spring end to fit, could fit
many disc brakes that don't have them stock. Likely able to do it
with just removing the tire.
That's a great idea. I'll have to look into that. My LeCar EV always has
dragging brakes. Like many, they depend on the roll-back of the rubber
piston seals as their spring to pull back just a tiny bit. Then the
calipers are supposed to be floating on pins, so that the slight runout of
the rotor and play in the wheel bearing are enough to push the pads away
from the rotor.
It doesn't work. The o-ring pullback is too little, the pad is just loose
between the piston and rotor (and tends to lay against the spinning rotor),
and the floating pins always rust up and won't move.
On Tire LRR common car tires are bad but MC tires are 2x's worse I
found on my Streamliner MC low CG chassis !! I'll have to find
better before doing the EV Streamliner, maybe even adapting LRR car
tires if I can't
