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Path: ...!feeds.phibee-telecom.net!weretis.net!feeder8.news.weretis.net!eternal-september.org!feeder3.eternal-september.org!news.eternal-september.org!.POSTED!not-for-mail From: AMuzi <am@yellowjersey.org> Newsgroups: rec.bicycles.tech Subject: Re: Extensive article on Rivendell and Grant Petersen Date: Wed, 25 Sep 2024 10:52:18 -0500 Organization: Yellow Jersey, Ltd. Lines: 195 Message-ID: <vd1bjk$3nokv$4@dont-email.me> References: <vct3ic$2tr2a$1@dont-email.me> <sls4fj914qnt9is0crvsd4dpli978v8ebt@4ax.com> <vcukup$37v5r$5@dont-email.me> <jvl5fjt14puvrscsra3jrjj2lgr22qhhdq@4ax.com> <vcuvih$39ji0$4@dont-email.me> <oq26fjpl0hc62vq4jpe50htdoavd26mcgu@4ax.com> <vcvr4o$3hhf0$1@dont-email.me> <pnQIO.1160654$grz1.912786@fx03.ams4> <msl7fjljviv2kgo3p13hsffga55kjdpsfp@4ax.com> <Q0SIO.2217267$kpic.1696407@fx15.ams4> <hvv7fjt8cvlaq62uknoriusuvdmgr5a6i4@4ax.com> <fnVIO.806338$qP12.292583@fx02.ams4> <5fa8fjpqcnhi1e661moanf8bqtpc3jrlq6@4ax.com> MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 8bit Injection-Date: Wed, 25 Sep 2024 17:52:21 +0200 (CEST) Injection-Info: dont-email.me; posting-host="b591b7a6b3d8bc0020ed64baf626e671"; logging-data="3924639"; mail-complaints-to="abuse@eternal-september.org"; posting-account="U2FsdGVkX19jdXB4c5K2wdPHv7mB40Ej" User-Agent: Mozilla Thunderbird Cancel-Lock: sha1:QBk9odG3z225FLTqIkH3elXRks8= In-Reply-To: <5fa8fjpqcnhi1e661moanf8bqtpc3jrlq6@4ax.com> Content-Language: en-US Bytes: 10489 On 9/25/2024 10:20 AM, Catrike Ryder wrote: > On Wed, 25 Sep 2024 14:46:35 GMT, Roger Merriman <roger@sarlet.com> > wrote: > >> Catrike Ryder <Soloman@old.bikers.org> wrote: >>> On Wed, 25 Sep 2024 10:57:52 GMT, Roger Merriman <roger@sarlet.com> >>> wrote: >>> >>>> Catrike Ryder <Soloman@old.bikers.org> wrote: >>>>> On Wed, 25 Sep 2024 09:05:25 GMT, Roger Merriman <roger@sarlet.com> >>>>> wrote: >>>>> >>>>>> Frank Krygowski <frkrygow@sbcglobal.net> wrote: >>>>>>> On 9/24/2024 3:17 PM, Catrike Ryder wrote: >>>>>>>> On Tue, 24 Sep 2024 14:14:41 -0400, Frank Krygowski >>>>>>>> <frkrygow@sbcglobal.net> wrote: >>>>>>>> >>>>>>>>> You might do well to read some of the archives of this group. There have >>>>>>>>> always been people posting opinions that were factually wrong, and there >>>>>>>>> have always been people pointing out those mistakes. As I've noted >>>>>>>>> earlier, having mistakes pointed out is a necessary part of the process >>>>>>>>> of education. >>>>>>>> >>>>>>>> That's fine of the person being corrected understands that the >>>>>>>> corrector is qualified to do so and is truly interested in making >>>>>>>> things better. In my opinion, you fall far short of both those >>>>>>>> standards. >>>>>>> >>>>>>> Your opinion on that matter is worthless. You don't have anywhere near >>>>>>> the background needed to judge technical proficiency. Professional >>>>>>> Engineering licensing boards of two different states have disagreed with >>>>>>> you, not to mention those conferring my engineering degrees and those >>>>>>> institutions for whom I've worked. >>>>>>> >>>>>>>>> There are many examples of ideas that were posted frequently, and noted >>>>>>>>> as wrong. Most of them seldom pop up any more - and not only, I think, >>>>>>>>> just because there are fewer posts. I think people actually learned things. >>>>>>>>> >>>>>>>>> Examples of mistaken claims? Chains wear by stretching the metal. Old >>>>>>>>> frames get "soft." Increasing spoke tension makes a wheel more rigid. >>>>>>>>> Tying and soldering spokes makes a wheel stronger. Headsets fail by true >>>>>>>>> brinelling due to impact loads. Hanging a bike by the front wheel makes >>>>>>>>> the spokes stretch... and many more. >>>>>>>>> >>>>>>>>> BTW, what was that stopping distance from 20 mph again? ;-) >>>>>>>> >>>>>>>> 20 MPH would be maybe 9/10 feet if I didn't concern myself with >>>>>>>> slamming the chain rings into the ground or doing a face plant on the >>>>>>>> ground in front of the bike. 30 MPH would be a little further. Two >>>>>>>> front brakes work better than one, especially when the rider's weight >>>>>>>> is already more over the front wheels before he applies the brakes. >>>>>>> >>>>>>> Right, good one. There is no way you can stop your tricycle in 10 feet >>>>>>> from 20 miles per hour. That would require a deceleration of 43 ft/s^2 >>>>>>> or 1.34 times the acceleration of gravity. IOW you'd need tires with a >>>>>>> static coefficient of friction at least 1.34, plus absolutely perfect >>>>>>> application of both brakes so that both wheels were at the absolute >>>>>>> limit of traction but not skidding. And you'd have to be in a "nose >>>>>>> wheelie" all the while, with your rear tire up in the air so every bit >>>>>>> of your weight was on the front wheels. It's essentially impossible. >>>>>>> >>>>>>> For 9 feet, your acceleration would have to be nearly 48 ft/s^2, and >>>>>>> besides absolutely perfect braking reflexes, you'd need tires with a >>>>>>> static coefficient of friction at least 1.48. >>>>>>> >>>>>>> And 30 mph would be _much_ farther, not "a little." The velocity term >>>>>>> gets squared in the relevant calculation, much as it does when >>>>>>> calculating kinetic energy. >>>>>>> >>>>>>> I'm sure you don't know what a lot of that means. But what you're >>>>>>> claiming is practically impossible. Feel free to prove me wrong by doing >>>>>>> what you claim and posting video evidence. >>>>>>> >>>>>>> >>>>>> Even if he means without thinking time >>>>> >>>>> Yes, I know I'm going to stop and my fingers are already on the brake >>>>> levers. >>>>> >>>>>> 20mph is 6 meters or 20ft for a car, >>>>>> which almost certainly can out brake the trike. >>>>> >>>>> I doubt that. >>>>> >>>>>> If a planned braking action on the MTB probably could reduce that a touch >>>>>> as it has huge amounts of grip and braking force, and frame allows one to >>>>>> get behind the rear wheel. >>>>>> >>>>>> Other bikes at best would equal, the old commute bike as it has weight to >>>>>> the rear is surprisingly effective at emergency stops or just using the >>>>>> rear brake hard, but even that will during a emergency start to lock the >>>>>> rear. >>>>>> >>>>>> Neither of the road/gravel bikes would do well at emergency stops as your >>>>>> in the wrong position ie far too forward. >>>>>> >>>>>> Roger Merriman >>>>>> >>>>> >>>>> A few weeks ago, after posting about braking, I tested the Catrike's >>>>> brakes at 15 MPH. I stopped at about 6 feet, keeping the chain rings >>>>> off the ground. >>>> >>>> That?s really hard to see how, you?ve mentioned that the trike pitches >>>> which suggests that its weight is quite forward. >>> >>> Indeed it does pitch forward. It's easy to lift the rear tire off the >>> road, however, the center of gravity of me on the Catrike compared to >>> someone on a two wheeler is much lower. LIfting the rear wheel of the >>> ground still requires a lot of braking force. >> >> Lifting the rear wheel on the MTB in position ie off the rear wheel Is not >> easy at all, if it’s more of emergency brake the rear wheel might lock if >> I’m not in position in position your not lifting the rear wheel on flat >> ground. >> >> Even my gravel bike tipping forward isn’t particularly an issue if I can >> get in position and if not it’s more likely to lock the rear than lift it. >> >> My old commute bike with a lot of rear weight even on an emergency stop >> your not going to lift it at worse it will lock. >> >> The weight being low isn’t the issue it’s the weight forward/rear and that >> your weight is static. >>> >>>> Note that cable disks are by some margin less powerful than hydraulic >>>> systems, ie even a fairly modest cheap twin pot is going to be many times >>>> more powerful, let alone 4 pots and so on. >>> >>> I really don't understand the issue of more powerful brakes. I changed >>> my Avid bb7s from long pull to short pull and I still have to back the >>> calipers off so as to not lock up the brakes at high speeds. The >>> brakes are perfectly capable of slamming the chain rings into the >>> ground and pitching 205 lb me out on my face. I've heard of people who >>> have had that experience. One on a Catrike 700 with an even lower >>> center of gravity than my Expedition. >> >> That’s all to do with the CatTrike Geometry ie it’s weight forward so it’s >> limited by its pitching, that doesn’t make the cable disks powerful just >> that the geometry limits the trikes braking, I have had bikes with cable >> disks a few different models in fact, powerful they are not, about the same >> as rim brake bike. >>> >>>> I run Magic Mary?s at 2.40 they are soft and gummy tires and on tarmac they >>>> are effectively glued to it! Even with that 6ft at 15MPH seems ambitious! >>> >>> I use road tires, of course. 40MM at 70/80 psi. I suspect my tires are >>> glued to the road better than your knobby MTB tires. >> >> Not a chance, Marathons are designed for touring and commuting get many >> thousands of miles out of those, compounded with higher pressures, my >> Gravel bike with similar sized tires but half the pressure and more volume >> and softer rubber and so on. Is likely to be a better at this. >> >> Let alone the MTB with soft sticky rubber much more volume 700*64 is a lot >> of air a frame that allows one to get off the back its geometry etc, ie I >> can if break to the limits of the tires for that reason. >> >> Your limited clearly by the trikes geometry, where as upright bikes >> particularly slacker geometry MTB are able to utilise not just more >> powerful brakes but brakes with absolutely enormous amounts of power, see >> my posts few months back with the DH brakes. >>> >>>>> -- >>>>> C'est bon >>>>> Soloman >>>>> >>>> Roger Merriman >>>> >>> ========== REMAINDER OF ARTICLE TRUNCATED ==========