dkri
Posts:95
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| 08/02/2014 09:13 PM |
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Can't tell you yet. That story is going to run on the other VN shortly.
Sorry. |
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| formerly dkri |
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Dale
Posts:1767
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| 08/02/2014 09:59 PM |
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Cool! That will be interesting to read
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Ride On
Posts:537
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| 11/08/2014 07:17 AM |
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I was thinking about disc brakes and the peleton again last night.
Say you are in a group traveling at 40 ft/sec ( 25 mph = 37 ft/sec ) and you can stop in 20 ft ( avg stoping distance of a bike traveling at 25 mph is 24 ft ) you will stop in 2 sec. Assuming a constant deceleration rate you will be slowing down at 2 ft/sec.
Ok so I'm behind you by 1/2 ft and we are bothe traveling at the 40 ft/sec. All is good. You spot something and hit the brakes. Because you are decelerating at 2 ft/sec I close that 1/2ft gap in .25 sec. If I now hit my brakes and decelerate at the same rate as you all will be good when we both stop. My front wheel will be right up on your back wheel but not to bad.
Now we both get disc brakes. Things are better we both now can stop from the 40 ft/sec in 15 ft instead of 20 ft. Great. Ok not so great. Your and mine deceleration rate is now 2.7 ft/sec. Remember that 1/2 ft gap I had behind you ? I now close that gap in .185 sec not .25 sec. My reaction time from when I see you slow to when I apply my brakes has just shrunk
Given that human reaction times are some where between .18 to .5 sec with the avg right around .25 sec I'm most likely going to run into the back of you because you are declerating at a faster rate and my distance behind you didn't cahnge. .065 sec doesn't sound like much but in terms of reaction times it is pretty big.
So disc brakes are great when you are on your own. Stopping sooner / faster is great. In a group if I slow down to fast it decrease the reaction time for the guy behind me which could results in something not so good for the both of us. |
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jmdirt
Posts:775
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| 11/08/2014 01:45 PM |
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| Ride On, there was an interview with Tyler F. and he said the same thing without the math so the pros are thinking about it. He, and others, have said that either everyone in the platoon uses discs or no one uses discs. |
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jacques_anquetil
Posts:245
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| 11/08/2014 07:52 PM |
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breaking at two speeds.
imagine a wet criterium with sharp, downhill corners. it's gonna be utter pandemonium as slippery-carbon rim-brake'd riders pile into the back of the panic-grabby disc-brake'd racers.
isn't the UCI suggesting that the 2015 Paris Roubaix be run as a disc brake-only test event? |
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Orange Crush
Posts:4499
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| 11/08/2014 09:04 PM |
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The governing body was originally shooting for 2015, but Campagnolo’s slow movement toward discs and SRAM’s recent recall moved that optimistic timeline back. Even 2016 may be overly optimistic. “If the answers aren’t here today, I don’t think the UCI is a year or two away,” Meyer said.
The UCI, and in particular its new technology officer Dimitris Katsanis, has made it clear that it believes that a wholesale swap is the safest route, when the technology is ready.
http://velonews.competitor.com/2014/08/bikes-and-tech/stopping-progress-debate-hydraulic-disc-brakes-pro-peloton_340905 |
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Ride On
Posts:537
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| 11/08/2014 09:04 PM |
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I guess I explained it wrong.
You close on the rider in front of you faster because he is decelerating quicker because of the disc brakes he has. It maters not what brakes I have if I never get a chance to apply them |
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Orange Crush
Posts:4499
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| 11/08/2014 09:30 PM |
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You explained it well; I got it. But I don't think it matters
1. You could make that argument for any speed sport, F1, moto etc. 2. You can only brake so hard with skinny tires and can already lock up standard brakes 3. This could not be any worse than braking on carbon rims.
I'm only cynical on this cause a problem was created (braking on carbon rims) that subsequently had to be "solved". Money + money equals more money to be made. |
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Ride On
Posts:537
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| 11/09/2014 06:01 AM |
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This also does bring up the issue with non pro bike races. Sure the UCI can get all the riders to change at once, but what about you and I in our local races. Some guys change over others don't. I will less safe if I'm lined up with 20 guys on disc brake bikes and 20 guys on rim brakes. None of us are safer. Local races should ban them until everyone changes. NEVER.
This whole idea that disc brakes will make group riding safer just is so stupid. Great idea for me by myself , terrible idea for bike racing in a group. |
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longslowdistance
Posts:2881
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| 11/09/2014 10:05 AM |
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Just chewing the fat here, but an argument for more powerful brakes is that some accidents would never happen if everyone had them. A problem such as an unexpected suddenly appearing road hazard could be avoided by everyone.
If you want to ban something, ban carbon rims. |
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Ride On
Posts:537
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| 11/09/2014 11:08 AM |
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| Just hammering home the point, if you are by yourself more powerful brakes should help you stop sonner. More powerful brakes in a group increases your deceleration rate which in turn decreases the reaction time of the rider behind you from rear ending you. In theory it can lead to MORE crashes not less. |
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Oldfart
Posts:511
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| 11/09/2014 11:46 AM |
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| Silly argument. Racing in a peloton we all ride way way too close. Follow that close on the highway in your car where we all have good brakes and see what happens. Don't care what kind of brakes anyone has, when rider you are following 30 cm back hammers on his brakes you're hitting him. This happens now. |
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Master50
Posts:340
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| 11/09/2014 05:10 PM |
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Posted By Ride On on 11/09/2014 11:08 AM
Just hammering home the point, if you are by yourself more powerful brakes should help you stop sonner. More powerful brakes in a group increases your deceleration rate which in turn decreases the reaction time of the rider behind you from rear ending you. In theory it can lead to MORE crashes not less.
Just to pile on this idea. I agree that in a pack the emergency grab a handful will result in crashes now. I don't see disks changing anything here. it is for the fast decent on a wet Carbon rim and a guy on a disk brake bike. The carbon wheel and rim brake guy starts braking a week sooner and slows in an interminably long time. the disk brake guy passes him before the corner Brakes hard and late and drops the other guy every corner. they can adjust instantly just like we could with cantilevers, V brakes, U brakes and disk brakes all intermixed on MTB rides.
Disk brakes for the road are not about ultimate stopping power but predictability and modulation are big benefits of disks that rim brakes do not deliver. Sure aluminum rims are pretty good when wet but disks are still a lot better. |
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Ride On
Posts:537
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| 11/10/2014 06:45 AM |
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Posted By Andy Eunson on 11/09/2014 11:46 AM
Silly argument. Racing in a peloton we all ride way way too close. Follow that close on the highway in your car where we all have good brakes and see what happens. Don't care what kind of brakes anyone has, when rider you are following 30 cm back hammers on his brakes you're hitting him. This happens now.
Yes and disc brakes make this worse. Safe follow distance is directly related to deceleration rate ( quality of the brakes ) . The faster you decelerate the less reaction time I get to apply my brakes. Give us both crappy brakes and I can follow much closer behind you since you can not slow down quickly ( neither can I ) but we are a connected system. It is a very flawed conclusion that better brakes makes us riding together safer. |
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Master50
Posts:340
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| 11/10/2014 10:07 AM |
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Posted By Ride On on 11/10/2014 06:45 AM
Posted By Andy Eunson on 11/09/2014 11:46 AM
Silly argument. Racing in a peloton we all ride way way too close. Follow that close on the highway in your car where we all have good brakes and see what happens. Don't care what kind of brakes anyone has, when rider you are following 30 cm back hammers on his brakes you're hitting him. This happens now.
Yes and disc brakes make this worse. Safe follow distance is directly related to deceleration rate ( quality of the brakes ) . The faster you decelerate the less reaction time I get to apply my brakes. Give us both crappy brakes and I can follow much closer behind you since you can not slow down quickly ( neither can I ) but we are a connected system. It is a very flawed conclusion that better brakes makes us riding together safer.
This is already a problem. mix 20 types of carbon an aluminum brake tracks under rim brakes I recall a new set of wheels I had never used wet yet. A race in the rain coming to a fast corner and I am the only one not slowing down. Thankfully my guy to the left saw that he was going to hit me if he tried to corner so we both went straight through and u turned to chase back on. I appreciate the disparity between different wheels and combinations. A wholesale change would equalize all the braking but as it is there is a huge disparity between the wheels in use now I don't think your concern is a show stopper. If anything disks would reduce this disparity a lot.
Standardization is what I think will be the biggest deal. all wheels fit all frames and all use the same retention method whether thru axles or what ever. |
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