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Originally Posted by FastJake
(Post 14396943)
I think the point was that on the newer dual-pivot brakes, even the rather cheap ones work very well. Compared to the old single-pivot sidepulls where you had get pretty high end stuff to get acceptable performance (a noteable exception being the Shimano SLR single-pivot calipers, before they switched to dual pivot.)
We can argue about this till we're blue in the face, it's just my opinion based on my experiences...except for the braking distances being equal, that's not an opinion it's fact. You can only stop as fast as the tires will grip the surface, thus if the rims, pads, tires, air pressure, road conditions, bike weight, and (160 pound) rider weight are the same, all brakes regardless of design will stop the bikes in the same distance. Once the rider weight or carrying weight goes over 200 pounds the advantage may slightly lean toward cantilevers (and especially disk but let's not use that example) due to less caliper movement. Some, if not most of the Shimano SLR design was copied from Dia Comp who also made Suntour. Also Shimano had a slightly better version of the SLR 105 version they slapped the Dura Ace 7402 name on it that used thicker calipers for less flex, ball bearing movement, and a lighter spring. But again, if all things being equal you can only stop as fast as the tires will allow. |
Originally Posted by rekmeyata
(Post 14397012)
Since I've never rode on the cheapest sidepulls ever made, I would have to disagree. I've used mid to high end side pulls and mid end (Athena) center pulls. Like I said earlier if all conditions are equal they will all stop a bike just as quick. The thing I like about side pulls like I said before is their ability to modulate better.
We can argue about this till we're blue in the face, it's just my opinion based on my experiences...except for the braking distances being equal, that's not an opinion it's fact. You can only stop as fast as the tires will grip the surface, thus if the rims, pads, tires, air pressure, road conditions, bike weight, and (160 pound) rider weight are the same, all brakes regardless of design will stop the bikes in the same distance. Once the rider weight or carrying weight goes over 200 pounds the advantage may slightly lean toward cantilevers (and especially disk but let's not use that example) due to less caliper movement. Some, if not most of the Shimano SLR design was copied from Dia Comp who also made Suntour. Also Shimano had a slightly better version of the SLR 105 version they slapped the Dura Ace 7402 name on it that used thicker calipers for less flex, ball bearing movement, and a lighter spring. But again, if all things being equal you can only stop as fast as the tires will allow. may vary considerably. Power assisted brakes have pretty much become standard in the automotive industry for just that reason. |
Originally Posted by anixi
(Post 14396541)
So Dave, if you were given the choice between RX100 duals and Dura Ace singles, you would pick the RX100s? That's basically the decision I have to make.
If you want a trick setup, the use the excellent Dura-Ace 7403 dual pivot on the front, and a 7402 on the back. I was running this way years before Campagnolo came up their 'differential' system. You don't need the sheer stopping power on the back, and extra pad clearance on the rear rim is a good thing when you are humping on the pedals. And the single pivot is somewhat lighter. |
Originally Posted by Dave Mayer
(Post 14397148)
I have RX100's dual pivots (both long and short reach) and Dura-Ace 7400 and 7402 single pivots. The 7402's are the best single-pivot brakes ever made. Longer arms which result in more leverage, light springs and a trick ball-bearing assembly between the arms that results in a smooth action. Nevertheless, all of the Dura-Ace units are in a box. The RX100 short-reach brakes are fitted on my main bike. That's my answer.
If you want a trick setup, the use the excellent Dura-Ace 7403 dual pivot on the front, and a 7402 on the back. I was running this way years before Campagnolo came up their 'differential' system. You don't need the sheer stopping power on the back, and extra pad clearance on the rear rim is a good thing when you are humping on the pedals. And the single pivot is somewhat lighter. |
Originally Posted by Burton
(Post 14397139)
I'm guessing 'better' is a relative thing. While theoretical stopping distances may be identical - braking effort
may vary considerably. Power assisted brakes have pretty much become standard in the automotive industry for just that reason. |
Originally Posted by rekmeyata
(Post 14400562)
Incorrect. Non power assist brakes on a car took a lot of foot power to get the brakes to grab hard, a lot of women and some men could not apply the brakes hard enough in a panic stop to brake fast enough. However, once the adhesion limits of the tires were reached it didn't matter if you had non power or power brakes. You don't have that problem with single vs dual pivot brakes. If you can't squeeze a properly working single pivot brake lever then your too weak to be riding a bike. If a 7 year old girl can squeeze cheap poorly working single pivot brakes on a Walmart bike then anyone without a handicap can squeeze good ones and do so effortlessly.
Your example of the 7 year old and cheap single pivot brakes sorta fits because the biggest complaint is that the brakes don't work well ... because they require more effort than the usual child can produce. (Except I can't remember the last time I saw anything other than stamped V-brakes on kids bikes but maybe thats just me.) In case you've forgotten - cars trucks and motorcycles all used to be exclusively a man's domain before power steering, power assisted brakes and hydraulic clutches. It was all about level of effort - I think that was the point. |
Originally Posted by Dave Mayer
(Post 14397148)
If you want a trick setup, the use [a] dual pivot on the front, and a [nice single pivot] on the back. I was running this way years before Campagnolo came up their 'differential' system. You don't need the sheer stopping power on the back, and extra pad clearance on the rear rim is a good thing when you are humping on the pedals. And the single pivot is somewhat lighter.
Originally Posted by anixi
(Post 14397415)
I might get rid of the 600 DP in the rear, overkill.
Those hardcore SP BB SLRs were a mighty fine brake, and basically the same thing with a different finish all the way down to RX100, IIRC. But not good enough for the front, IMO.
Originally Posted by rekmeyata
(Post 14400562)
Incorrect. Non power assist brakes on a car took a lot of foot power to get the brakes to grab hard, a lot of women and some men could not apply the brakes hard enough in a panic stop to brake fast enough. However, once the adhesion limits of the tires were reached it didn't matter if you had non power or power brakes. You don't have that problem with single vs dual pivot brakes. If you can't squeeze a properly working single pivot brake lever then your too weak to be riding a bike. If a 7 year old girl can squeeze cheap poorly working single pivot brakes on a Walmart bike then anyone without a handicap can squeeze good ones and do so effortlessly.
Even using the aforementioned BB SLRs, I've never locked the front above like 5km/h with a SP, and I have a pretty decent strength to weight ratio, thanks very much. The first time I used a DP in a hurry, I went straight over the bars. The second time, I effortlessly kept the back wheel in the air for like 6m, something I'd consider only just possible with a nice SP. It's absolutely night and day. Maybe you're used to having nicer pads and/or much lighter wheels than I've ever used, or maybe you're just trolling. |
Originally Posted by Burton
(Post 14400702)
LOL - incorrect? You just took a lot more words to say exactly the same thing!
Your example of the 7 year old and cheap single pivot brakes sorta fits because the biggest complaint is that the brakes don't work well ... because they require more effort than the usual child can produce. (Except I can't remember the last time I saw anything other than stamped V-brakes on kids bikes but maybe thats just me.) In case you've forgotten - cars trucks and motorcycles all used to be exclusively a man's domain before power steering, power assisted brakes and hydraulic clutches. It was all about level of effort - I think that was the point. And most of us on this forum are not riding on cheap single pivot Walmart style brakes, and those cheap Walmart single pivot brakes cost Walmart probably $5 to have on their bikes! Those Walmart brakes are a far far cry from even low end Shimano single pivot brakes they use to make. My example of a 7 year old was to show that even with cheap stiff crappy single pivot brakes they can activate the brakes with no problem, so how is it an adult would complain about nice smooth single pivots. I haven't forgotten that cars were a man thing back ages ago. but again the contrast of the level of effort on using older cars brakes is not even closely, or remotely related to the effort needed to apply the brakes using single pivots. I use to have a car with manual brakes! You can't tell me that using manual foot brakes are the same level of effort, or even close to the same level of effort as single pivot brakes!! You need to go drive one! All this you said in your first sentence was a very feeble attempt to make it look like I was saying the same thing. I wasn't even remotely saying the same thing as you tried to make it sound like I was. |
FWIW, I have RX100 brakes (I think short-reach) with Kool-Stop pads, and the braking power is more than adequate. :thumb:
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Originally Posted by rekmeyata
(Post 14400562)
If you can't squeeze a properly working single pivot brake lever then your too weak to be riding a bike. If a 7 year old girl can squeeze cheap poorly working single pivot brakes on a Walmart bike then anyone without a handicap can squeeze good ones and do so effortlessly.
Walmart sidepulls? Forget about it. Those stamped steel pieces of crap can barely be made to slow the bike at all, much less stop it. |
Originally Posted by FastJake
(Post 14403937)
You obviously haven't used many lower-mid end SP calipers. Many (cheap Dia-Compe models come to mind) from the 80s were so flexy and offered such poor performance that they could never be made to lift the rear wheel.
Walmart sidepulls? Forget about it. Those stamped steel pieces of crap can barely be made to slow the bike at all, much less stop it. Yes, it may take quite a lot of hand force to squeeze the levers hard enough, but you will be able to get to the adhesion-limits of the front-tyre with crappy brakes. Now, how long those brakes stay in that optimal adjustment is another question altogether of durability, but that's not performance. I've got early 1990's 105 single-pivote sidepulls on my race bike. Actually replaced the dual-pivot DA calipers that came on the bike to save 1/4 lb. Same thing with ditching the STI levers for regular aero levers and downtube shifters. Have no problems lifting the rear or sliding the front. It's a matter of mechanical ability in troubleshooting and fine-tuning the system. |
Originally Posted by rekmeyata
(Post 14402709)
No I did not say the same thing, I contrasted manual car brakes with bicycle single pivot brakes and their not even closely similar in difficulty of operation.
BTW - the Ferrari F40 didn't have power-steering or power-brakes and it's really not that difficult to maneuver. Well... above 3mph in a parking-lot. |
Mechanical logic supports the dual pivot brakes. IMHO single pivots come from the camp of the gram police.
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Mechanical logic supports the dual pivot brakes. IMHO single pivots come from the camp of the gram police.
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Originally Posted by FastJake
(Post 14403937)
You obviously haven't used many lower-mid end SP calipers. Many (cheap Dia-Compe models come to mind) from the 80s were so flexy and offered such poor performance that they could never be made to lift the rear wheel.
Walmart sidepulls? Forget about it. Those stamped steel pieces of crap can barely be made to slow the bike at all, much less stop it. However, all my kids had cheap Walmart bikes with those cheap flexy single pivot brakes and they did stop the bikes, if they couldn't stop the bikes as you said Walmart would have been in serious liability problems. True they are crappy brakes but will stop when called upon. |
Originally Posted by DannoXYZ
(Post 14404244)
I think you are. You're both talking about the amount of brake-lever or brake-pedal needed to get to the adhesion limits of the tyres. With single-pivot calipers and cars without vac-assisted power-brakes, it does require more muscle. Adding dual-pivot calipers and power-brakes will get you the same braking-distances, but will require less force.
BTW - the Ferrari F40 didn't have power-steering or power-brakes and it's really not that difficult to maneuver. Well... above 3mph in a parking-lot. All you guys must be wimps. I can't believe you all think it takes a super human to stop a bike using single pivots, this is just lunacy. |
Danno and rekmeyata, before you guys continue swinging your dicks in people's faces, what with our inferior skillz and wimpy hands, why don't you guys tells us about brake pads and riding conditions and stuff.
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Originally Posted by rekmeyata
(Post 14405631)
But the "muscle" required to squeeze the lever of a single vs a dual is very little, it's not like trying to squeeze one of those V hand exerciser devices! And you also agreed with me! yes you did. when you replied about the limits of adhesion on the tire; but you were wrong when you said it takes quite a lot of hand force...this is obvious from a person who has never used good quality single pivot brakes.
All you guys must be wimps. I can't believe you all think it takes a super human to stop a bike using single pivots, this is just lunacy. |
Originally Posted by anixi
(Post 14394870)
This is interesting. I have a shimano 600 dual pivot on the rear of my Pug, but, I also have single pivot Dura Ace that I could use. Could it be that the DA single would do as good or better job than the 600 dual, and add less weight to the bike?
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Originally Posted by Retro Grouch
(Post 14406186)
You should have seen the ration of rag that I took when I suggested that V-brake levers will work with cantys or calipers. I don't know how many pounds of force it takes to operate a bicycle brake but I don't think that it's very much. If it takes 5 lbs with a canty lever that would make it 10 lbs with a V-brake lever. That's double but it's still not very much.
And single pull brakes probably take less then 6 pounds of force to activate. So your pounds of force thing got me to thinking, how could I test the pounds of force to activate my levers. Then it occurred to me I have a fish weigh scale...fine, it's not very scientifically accurate but it's all I have. I took the scale hook and hooked it at the end of the levers and pulled each lever until the levers were at full depression The two cantilevers I have took the most, as I thought, the DiaComp took 8 pounds and the Shimano took 6. The single pivot brakes took between 4 to 6 pounds of pull tested on 3 different brands (two Shimanos, one medium and one highend; one highend Suntour, and one medium DiaComp). The dual pivot Athena brake took 4 pounds...exactly the same as the Suntour Superbe!! By the way the DiaComps (one cantilever and one single pivot) took more pressure to activate then the Shimano cantilever or single pivot, with the exception of the Superbe which was made by DiaComp. Also I'm sure cables, and adjustment factors are variables which I could not eliminate. If I tested the same thing again except this time just till the brakes touched the rims the activation force was obviously far less coming in between 3 to 1.5 pounds...again, the 1.5 pounds was on both the Superbe and the Athena. I also tried one the old kids single pivot Walmart bike brakes and it took 9 pounds, the most of any brake which figures. Now please note, I did allude to this in the above paragraph, a small fish scale is not very scientific, but it gets the point across. My daughter, when she was 8 and weighed 40 pounds use to be able to activate her Walmart bike brakes with no problems and even get the brakes to lock up the tires! Imagine that! And she was not some superwoman, today she only weighs 95 pounds and she's 23 years old and has no problems activating her cantilever brakes...but she probably has massive Popeye type forearms from using her Walmart bike. Now in the words of the famous Kimmo, I'm done waving my dick around about this. Not sure what Kimmo wants to know about riding conditions. I know some of my pads are Campy, Shimano, DiaComp, and Superbe, others don't have brand names, but I doubt if either Campy, Shimano, DiaComp or Suntour make their own pads, so it's anybody's guess as to who made them. |
Fish scales, no matter how accurate or inaccurate, are only good for measuring static weights. The braking force required to stop a vehicle varies directly with its weight and speed, and the proportion isn't linear - its exponential. It shouldn't take a genius to figure out that the speeds attained by a seven year old wouldn't approach that of an adult, nor would the weight, nor would the braking forces. Its pretty easy to stop a spinning wheel on a bike in a stand using any brake. Thats absolutely no indication of what to expect in the street with a rider.
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Originally Posted by Kimmo
(Post 14406135)
Danno and rekmeyata, before you guys continue swinging your dicks in people's faces, what with our inferior skillz and wimpy hands, why don't you guys tells us about brake pads and riding conditions and stuff.
- original 105 pads - 600 Ultegra pads - DA pads - Matthausers (original KoolStops with finned holders) - KoolStop salmon - currently unknown Weinmann black pads Most riding done with Mavic MA-40 rims or MA-2. Racing done on Arc En Ciel, Mavic GL280, Sun M19a, M19a-II or Saavedra Turbo260 rims. Never had any issues with going from 60mph to 20mph on downhills with a single-finger squeeze on the levers. rekmeyata, note that I didn't say how much more lever-force is required between single versus dual-pivot levers. It just said that it does require more force. Personally, I don't like too much leverage as it makes modulation at the limit of adhesion more difficult. The difference between howling the front tyre and sliding is featherweight. I think the major factor clouding the single versus dual-pivot discussions is testing controls. Most people will replace the levers and replace/overhaul their cables when changing out single to dual-pivot brakes. If you had old-style straight-pull levers with exposed cables, these have less leverage than aero-levers with hidden cables. Just changing the levers alone while retaining the same crusty cables and single-pivot calipers will result in a 1.2-1.3x increase in leverage. Then add in new teflon-lined housing when you changed to dual-pivots will again add another variable to the mix. The final result may be you get a 2.0x increase in squeeze-force at the rims for a given squeeze-force at the levers. But it's not all due to the dual-pivot calipers. I'd surmize it's more of 1.25x with the lever change, 1.3x with new cables and maybe 1.25x with dual-pivot calipers. So fairly even contributions at each stage gives 1.25*1.3*1.25 = ~2x double the clamping force. Of course this won't change actual braking-distances much as that's limited by the adhesion limit of the front-tyre. |
Originally Posted by DannoXYZ
(Post 14409271)
rekmeyata, note that I didn't way how much more lever-force is required between single versus dual-pivot levers. It just said that it does require more force. Personally, I don't like too much leverage as it makes modulation at the limit of adhesion more difficult. The difference between howling the front tyre and sliding is featherweight.
. I'm sure if I put teflon cables on my 85 Schwinn Cantiliver DiaComp brake system and take off the factory original cables, those DiaComps would perform better...how much better? I don't have a clue, the original cables are still good and using the brakes with more hand pressure doesn't bother me. This hand pressure thing goes deeper then just brakes, people today complain about having to squeeze a Polar bottle! I think nothing of squeezing a Polar bottle, just as I think nothing of squeezing single pivot or cantilever brakes vs dual pivots. Call me weird, but it just doesn't bother me even in the least bit. |
My 105 single-pivot sidepulls brake as well as any rim brakes I've used without much effort. The tight clearance required by dual-pivot sidepulls (due to higher mechanical advantage) is annoying. Caliper stiffness (regardless of caiper mechanism) seems to have a much larger effect than the small increase in mechanical advantage with dual-pivots; the beefy 105s work much better than flexy old lower-end Dia-Compes or cheaper modern dual-pivots.
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I think I've seen modern dual-pivot brake sets with actually a center-pivot rear brake sold in the set.....I assume to either reduce braking force on the wheel which is most likely to skid, or simply because it's cheaper to make a center pivot brake.
I've never noticed a real difference in power between these brake styles -- all can be aadjusted just fine to me. The levers make a much larger difference IME. |
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