So we're back to #1 - light tires & tubes. Followed by #2 - light rims & spokes.
No one else want to chime in on friction? How much slip does say, a semi-knobby tire like the Cazadero allow compared to the RH & is that noticeable when accelerating? Inboard brakes are a thing of beauty & danger, I believe the Lotus 72 F1 car may have been the 1st to implement. The problem has been the load on the half shaft which, according to the inquest, the associated failure of that was the cause of Rindt's fatal crash in that car. On Wednesday, April 7, 2021 at 3:07:59 PM UTC-5 ascpgh wrote: > The comparison to motor vehicle unsprung weight may parallel bicyclists' > focus on wheel and tire weight but available horsepower of even weak > engines makes all but the most competitive motor vehicles seem sloppy with > their unsprung, wheel and tire weights comparatively. > > You on your bike won't make enough horsepower to overcome much weight > increases by anything distant from the hub. The greatest improvement to > angular acceleration (increasing a wheels rotating speed) will be at the > greatest distance from the axle; tires/tubes. Smaller changes in weight net > larger feelings of better response at that distant component, tubes come in > second, rim choice third. Spokes are next and the hubs may be eclipsed by > having lighter pedals. Light wheels, on the unsprung weight topic, do seem > to ride nicer because they don't require such impact to move up and down > over surface irregularities. Heavy rimmed wheels cancel benefits of light > tires in my very subjective experiments. > > Total weight of a bike can affect what you've felt as a difference between > your two bikes but the fastest way to improve the ride of a bike to me is a > wheel made of a light rim/spokes and a light tire. I ruined the young woman > we mentor by loaning her my Rambouillet's PJW-made wheels for a long ride. > Velocity Synergy rims with 36°, straight gauge spokes, XT hubs and RH > Stampede Pass ELs and light tubes. She is having me work up a price for a > set of responsibly lighter wheels with a dyno hub front as a result. > > Some strategies in automotive design to reduce unsprung weight are > elegant. The Alfa Romeo Giulia GT 1600 Junior De Dion rear suspension > removed the brake disc from the unsprung weight by putting them on the > other ends of the half shafts, on either side of the differential. that > carried on in their designs for decades. > > Andy Cheatham > Pittsburgh > > > On Wednesday, April 7, 2021 at 11:41:15 AM UTC-4 philipr...@gmail.com > wrote: > >> Car & motorcycle racers talk about unsprung weight, in other words the >> weight of the components that the suspension system does not act upon >> (rims, tires, brake calipers etc.). Keeping this number to a minimum is >> critical to building a competitive vehicle as this directly effects >> acceleration & braking performance and cannot be manipulated by suspension >> design. This is consistent with Newton's 2nd law which states that >> Acceleration = Mass/Force. >> >> To my mind, in hard tail/front bicycle design the tire & tube are that >> suspended component, everything after them is "sprung" by the sidewall >> stiffness & tire pressure (in racing design, tires parameters take priority >> over the rest of the unsprung parts too) so as Patrick Moore says, they are >> the most critical part of the acceleration equation (not the only by any >> means, but the foundation). >> >> Ignoring the friction component for now and looking at the numbers, a >> Rene Hearse tire set is 1/2 pound lighter than the Cazaderos (125 grams per >> wheel). This doesn't sound like too significant difference on a 30lb bike >> EXCEPT as above, this is unsprung weight which most significantly affects >> acceleration. Put friction back into the equation (the coefficient of that >> between the tire and the pavement is your grip) and consider a tires >> viscosity (how sticky it is), deformability (how much the sidewalls absorb >> your energy input versus transmitting it directly to the road) and >> hysteresis (the speed at which the deformation of the tire returns to it's >> normal shape after deformation) and I think you have most of your answer in >> tire science? The Rene Hearse is lighter, most likely less susceptible to >> deformation, has faster hysteresis and a tread pattern that offers more >> grip. >> >> As a note, another 1/3rd or so of a pound can also be saved in switching >> to lightweight tubes (which are also susceptible to all the same parameters >> as the tires). >> >> Now this sounds like a lot of semantics, bicycles are light and the >> forces involved (our legs) are weak compared to ICE technology. But it's >> exactly because those forces are so weak that small gains in tire >> performance become significant. Your tires are actually fairly closely >> matched, quality brands, if you move into the word of low end Kendas or >> similar, the savings can be in the 2 to 4lb range for a set! >> >> Bear in mind, I'm merely a dilettante at this, the physicists amongst you >> may well be correcting me on the above. But the theory can be tested at >> least in perception by swapping the tires & tubes between your bikes? >> >> >> >> >> On Wednesday, April 7, 2021 at 9:08:14 AM UTC-5 Patrick Moore wrote: >> >>> Also, the Cazaderos have small knobs; this will certainly affect rolling >>> resistance. >>> >>> On Wed, Apr 7, 2021 at 8:06 AM Patrick Moore <bert...@gmail.com> wrote: >>> >>>> I've used all sorts of wheel sizes and weights, from just shy of 20" to >>>> just over 30", and tires ranging from 175 grams to over 900 grams. IME, >>>> wheel diameter and tire weight affect the ride far less than tire quality >>>> (supple, light casing) except on hills, when at least in the extreme -- in >>>> my case, 800 gram rim and 800 gram tire + 200-250 gram tube; the rim and >>>> the tire were the "lite" models! -- you certainly can feel a difference >>>> climbing over a sub 175 gram tire, 360 gram rim, and 70 gram tube, >>>> especially if the overall wheel diameters differ by about 5". >>>> >>>> One of my "plane-y-est" bikes is that Matthews dirt road bike with 700C >>>> X 60 tires. Granted that the wheels are quite light for their size (29 >>>> 1/2" >>>> tall, 60 mm wide, Velocity Blunt SSs, Big Ones), but the bike just feels >>>> easier to pedal in a given gear in given conditions; at least as good as >>>> my >>>> bikes with much lighter wheels. On the flats. Climbing, the light-wheel >>>> bikes feel faster. >>>> >>>> All that said, good quality light wheels and especially top quality >>>> tires really do affect the pleasure of the ride. >>>> >>>> On Wed, Apr 7, 2021 at 6:58 AM Adam <adam....@gmail.com> wrote: >>>> >>>>> Hi all, hoping to get some thoughts on the role of wheels in >>>>> acceleration and climbing. >>>>> >>>>> I recently picked up my first Riv (Hillborne) and am running Dyads and >>>>> Barlow Pass tires. Among other things, I'm amazed at the difference in >>>>> acceleration, speed, and particularly climbing vs my other bike, which is >>>>> a >>>>> pretty heavy Salsa Marrakesh with stock wheels (WTB sx19 and Shimano m475 >>>>> hubs) and Cazaderos. >>>>> >>>>> I'm not necessarily jumping to replace the Marrakesh's wheels ATM, but >>>>> I am curious whether anyone has thoughts on whether or not that's likely >>>>> the difference I'm feeling in acceleration and speed? >>>>> >>>>> There's definitely a substantial weight difference between the two >>>>> builds, but I've loaded up the Sam a few times and it's still way >>>>> quicker. >>>>> I'd just swap the wheels, but the Marrakesh's are disc. >>>>> >>>>> thoughts? >>>>> >>>>> -- >>>>> You received this message because you are subscribed to the Google >>>>> Groups "RBW Owners Bunch" group. >>>>> To unsubscribe from this group and stop receiving emails from it, send >>>>> an email to rbw-owners-bun...@googlegroups.com. >>>>> To view this discussion on the web visit >>>>> https://groups.google.com/d/msgid/rbw-owners-bunch/215efd40-085a-4216-83b3-f8ae46aea0e7n%40googlegroups.com >>>>> >>>>> <https://groups.google.com/d/msgid/rbw-owners-bunch/215efd40-085a-4216-83b3-f8ae46aea0e7n%40googlegroups.com?utm_medium=email&utm_source=footer> >>>>> . >>>>> >>>> >>>> >>>> -- >>>> >>>> ----------------------------------------------------------------------- >>>> Patrick Moore >>>> Alburquerque, Nuevo Mexico, Etats Unis d'Amerique, Orbis Terrarum >>>> >>>> >>> >>> -- >>> >>> ----------------------------------------------------------------------- >>> Patrick Moore >>> Alburquerque, Nuevo Mexico, Etats Unis d'Amerique, Orbis Terrarum >>> >>> -- You received this message because you are subscribed to the Google Groups "RBW Owners Bunch" group. 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