Very interesting. So, upshot, at least per Mitch's experience: if you have sufficiently wide tires, the discs, at least hydraulics, can stop easier -- and "better" in this sense -- on road bikes with aluminum rims by requiring less concentration and "technique" in hard slowdowns at high speed. I wonder at which tire width this becomes significant? Probably at not much under 40 mm?
On Mon, Jul 3, 2017 at 8:58 PM, Mitch Harris <mitch.har...@gmail.com> wrote: > > > Right, you hope they're not comparing discs to rim-braking on carbon brake > tracks where rim-braking is not at it's best. > I've noticed I do brake later into steep high speed road turns on my disc > road bike, turns that require coming down from 50 mph to 20pmh on my canyon > descents, but the biggest difference in late braking is with wider tires. > When I compare are tires (41mm Baby Shoe Pass EL) with brazed-on Raids on > A23 rims vs. TRP Hy/Rds 160 rotors with Modolo levers on Pacenti TL28 rims, > I brake somewhat later with discs. But I noticed braking much later into > these high speed turns on my most recent canyon descents on 47-48 Switch > Back Hill EL tires. I'm guessing I'd also brake later on rim brakes with > SBH tires too--they fit on my bike with Raids but not under the fenders so > I may have to remove fenders to try it sometime. > > In general I don't see a lot of difference in braking quality or power in > these two road set-ups, rim vs. disc, except that the same amount of > braking requires somewhat less hand effort with discs. Both seem to do > really well with high speed descending on pavement with heavy braking for > tight switchbacks. Hand effort seems really good to me with the Raids too, > much less hand effort than required with the regular old single pivot > Record brakes I'm used to. But hand effort is still noticeably less with > discs. > > But the big difference in late braking for me has been with increasing > tire width. This surprises me because I was doing these same 50mph to 20mph > turns on 25mm tires with no complaints before I started riding fatter tires > on the road. I'd hear descending was faster on fat tires and I would think > maybe that's just for riders who aren't fast descenders. But I think the > difference is there because I brake noticeably laters on 42mm tires > compared to 25mm and then on 48mm tires the late braking is really > noticeable. I think the reason for the late braking is probably two things > (?): there is more grip with the larger contact patch, but also wider tires > soak up more road irregularity and surface roughness through the turn and > on narrower tires I feel like I need to get speed down a little earlier in > preparation so I can manage that roughness leaned over while with the wider > tires I'm more ok leaning the bike over and trusting the tires to handle > more of that roughness than narrow tires can on their own. > > The late braking difference in lower hand effort seems to come from the > fact that I notice I use progressive stages of hand effort when I scrub a > lot of speed (50 down to 20). BTW, all of this braking I do on descents is > from the hoods. On rim brake Raids, I squeeze and lose a lot of speed, but > then there is a harder squeeze I have to ramp up to with more hand strength > to get down to the safe 20mph to go through the sharp sweeper turn. Some > people might do this all with one progressively firmer squeeze but for me > it does feel like two separate squeeze--one big firm one then a really hard > one. On disc Hy/Rds I don't require that second stage of harder. One stage > of firm hand pressure on Hy/Rds takes me all the way down to 20mph. This > simpler process lets me brake later I think, or at least that seems one > likely explanation, all else being equal. (The old school Record single > pivots handle the same 50mph down to 20mph turns just fine but it takes > noticeably more hand pressure than the Raids.) > > --Mitch > > -- > 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-bunch+unsubscr...@googlegroups.com. > To post to this group, send email to rbw-owners-bunch@googlegroups.com. > Visit this group at https://groups.google.com/group/rbw-owners-bunch. > For more options, visit https://groups.google.com/d/optout. > -- *30% Supply and Demand discount, listmembers only, on all resume, LinkedIn, and writing services, until Demand equals Supply! And there's more! 10% kickback for any referral resulting in fully paid, list-price contract. And still more! I am offering services in trade for a road bike, or frame and parts, that are period compatible with my AM hub, circa 1937 to 1961. See my website for what I do and what I charge; email for details.* Resumes, LinkedIn profiles, bios, and letters that get interviews. By-the-hour resume and LinkedIn coaching. Other professional writing services. http://www.resumespecialties.com/ www.linkedin.com/in/patrickmooreresumespec/ Patrick Moore Alburquerque, Nouvelle Mexique, Vereinigte Staaten ************************************************************************** ************** -- 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-bunch+unsubscr...@googlegroups.com. To post to this group, send email to rbw-owners-bunch@googlegroups.com. Visit this group at https://groups.google.com/group/rbw-owners-bunch. For more options, visit https://groups.google.com/d/optout.
