That is why *everyone* is always disappointed after installing new tires, whether they are LRR or not - the MPG will *always* go down, even if the spec'ed rolling resistance of the new tires is lower than the previous tires. Because by the time that the tires are worn they are so much thinner and stiffer that the actual losses are lower than the newer (thicker, more flexible) tires. I noticed the same when replacing my 2002 Prius OE tires with the also LRR Sumitomo HTR 200 tires - even while I always pump them to 45+ PSI, the MPG went down considerably (several MPG) from around 50 to around 47 and only after they started to age did the MPG go back up again. (What also helps is that a worn tire is *smaller* so the miles are indicating high, leading to a larger error in artificially increasing MPG, so the only real measurement is in the pump data which I unfortunately do not have). Also, the torque to accelerate the car will reduce a little bit with smaller tires, but this is unlikely to have a significant impact.
Cor van de Water Chief Scientist Proxim Wireless Corporation http://www.proxim.com Email: cwa...@proxim.com Private: http://www.cvandewater.info Skype: cor_van_de_water Tel: +1 408 383 7626 -----Original Message----- From: EV [mailto:ev-boun...@lists.evdl.org] On Behalf Of Michael Ross via EV Sent: Monday, November 10, 2014 1:48 PM To: Lee Hart; Electric Vehicle Discussion List Subject: Re: [EVDL] Range vs Speed 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 find a LRR MC tire. >> > > I wonder why motorcycle tires are so much worse. Bicycle tires are > obviously very good. What is different about motorcycle tires. Is there > some fundamental reason for the higher rolling resistance, or is it just > that the manufacturers don't bother (and customers don't care)? > -- > A designer knows he has achieved perfection not when there is > nothing left to add, but when there is nothing left to take away. > -- Antoine de Saint Exupery > -- > Lee Hart's EV projects are at http://www.sunrise-ev.com/LeesEVs.htm > _______________________________________________ > UNSUBSCRIBE: http://www.evdl.org/help/index.html#usub > http://lists.evdl.org/listinfo.cgi/ev-evdl.org > For EV drag racing discussion, please use NEDRA (http://groups.yahoo.com/ > group/NEDRA) > > -- Put this question to yourself: should I use everyone else to attain happiness, or should I help others gain happiness? *Dalai Lama * Tell me what it is you plan to do With your one wild and precious life? Mary Oliver, "The summer day." To invent, you need a good imagination and a pile of junk. Thomas A. Edison <http://www.brainyquote.com/quotes/quotes/t/thomasaed125362.html> A public-opinion poll is no substitute for thought. *Warren Buffet* Michael E. Ross (919) 550-2430 Land (919) 576-0824 <https://www.google.com/voice/b/0?pli=1#phones> Google Phone (919) 631-1451 Cell (919) 513-0418 Desk michael.e.r...@gmail.com <michael.e.r...@gmail.com> -------------- next part -------------- An HTML attachment was scrubbed... URL: <http://lists.evdl.org/private.cgi/ev-evdl.org/attachments/20141110/88d1 8b9b/attachment.htm> _______________________________________________ UNSUBSCRIBE: http://www.evdl.org/help/index.html#usub http://lists.evdl.org/listinfo.cgi/ev-evdl.org For EV drag racing discussion, please use NEDRA (http://groups.yahoo.com/group/NEDRA) _______________________________________________ UNSUBSCRIBE: http://www.evdl.org/help/index.html#usub http://lists.evdl.org/listinfo.cgi/ev-evdl.org For EV drag racing discussion, please use NEDRA (http://groups.yahoo.com/group/NEDRA)
