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let's talk about brakes

Old 04-03-09, 02:39 PM
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let's talk about brakes

Give your opinions, observations, tips, whatever.

I'll start rambling...

Single pivot sidepulls are simple. Well made SPSP's stop very well and give good control for modulating the braking force, making them well suited to racing and other fast riding. They are easy to adjust and keep their adjustment longer than any other type of brake. The only tricky thing is centering them, but once you manage that, the rest is easy.

I think it's a shame that when Campagnolo brakes became popular, other brands switched the "pull" side from the right to the left. This favors left-handed mechanics. I like to hold the brake closed with my left hand and operate the cable bolt with my right hand.

SPSP's seem poorly suited to heavily loaded bikes, as they require more hand force than center pull.

I can't for the life of me figure out why Mafac centerpull brakes work better than Weinmann centerpull brakes. They're a ***** to adjust, but I like them. Is it because of stiffer alloy in the calipers? And now you can tell that I was a mechanic back in the 70's and 80's, mentioning this old stuff.

I always lusted after cantilever brakes. Again, why do they stop so well? Is it because the bosses are brazed on and therefore stiff and the calipers are also short and therefore stiff? Someone gave me a cheap Univega hybrid bike, and I plan to fix it up. Not sure what I'll do with it. It has cantilever brakes and 700C tires. I could call it a cyclocross bike, but it has upright handlebars.

What's the deal with dual pivot side pull brakes? Are they better in some way than single pivots? I have a pair on my new bike, a generic fixed gear bike I got CHEAP at Nashbar. No opinion on them yet. They seem adequate but not impressive. I realize I should not compare these cheap brakes with high end brakes of the same design.

What's the deal with disc brakes? What breakthrough enabled them to emerge recently? Lightweight hydraulics?
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Old 04-03-09, 05:18 PM
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It seems to me that my inexpensive long-reach Tektro dual pivots kick the crap out of the old single pivots that came on my '80s era Nishiki. Granted, I also upgraded to inexpensive Tektro aero levers at the same time, and I know that they have a different pull ratio.

The braking performance is not only related to the stiffness of the mounting point, but also the stiffness of whatever that mounting point is attached too. Newer bikes have much thinner tubing in the chainstays and forks than older bikes. The modulus doesn't change however, assuming that you're using steel, so there is going to be more flexure in a thinner walled steel tube than a thicker steel tube. It seems to me that cantilever brakes were on older bikes with thicker tubing walls and so had that mechanical advantage over the newer linear pull cantilever brakes (after all, V-brakes are cantilevers too).
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Old 04-03-09, 05:18 PM
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Recently someone posted a photo of an old (70's maybe) Schwinn cruiser with fairly crude (by todays standards) disk brake setup. Everything old is new again, hey?

The technology for disk brakes has been around for some time in cars and motorcycles but my feeling is their introduction into cycling coincides with the development of suspension technology. It's not until recently that we've had the shocks to handle terrain that requires more powerful breaking than cantis or Vs can provide.

That said, I use mechanical disks on my rigid winter commuter which rarely sees much of a decline. I like the dependable braking in ALL conditions (from sloppy, muddy, salty roads to temperatures so low regular pads get hard and brittle), as well as long pad and rim life.
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Old 04-03-09, 05:41 PM
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I've ridden rather extensively with single pivot sidepulls, including good ones like Ultegra and Dia Compe, and was very satisfied with them. They were easy to modulate and did stop the bike as quickly as traction and tip-over allowed. The down side was the high lever effort on long down hills and the tricky centering.

Then I got Ultegra, and later Dura Ace, dual pivot sidepulls. A HUGE improvement. Lever effort was much lower for a given braking force so my hands didn't get as tired on long winding downhills (of which I've got plenty) , modulation was just as good and centering them was a snap. I've also used cheapie dual pivots like Tektros and Shimano RSX and even they are far better than the best single pivots. I see absolutely no negatives to them and a lot of pluses.
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Old 04-03-09, 06:16 PM
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Originally Posted by noglider View Post
What's the deal with dual pivot side pull brakes? Are they better in some way than single pivots?
My personal experience had been that dual pivot caliper brakes stay centered much better.
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Old 04-03-09, 06:21 PM
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Dual-pivots have more mechanical advantage than single-pivots. However, that means you need to set them up closer to the rim in order for the lever to not bottom out so it takes less of a wobble in the rim to start rubbing the brake. Dual-pivots are probably less effective than single-pivots with the QR open (say if you broke a spoke and were limping home).

Dual-pivots are also easier to keep centered but I've never had any issues with centering my single-pivots (I have both types).

Last edited by Gonzo Bob; 04-03-09 at 06:24 PM.
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Old 04-03-09, 06:23 PM
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Originally Posted by noglider View Post
I think it's a shame that when Campagnolo brakes became popular, other brands switched the "pull" side from the right to the left. This favors left-handed mechanics. I like to hold the brake closed with my left hand and operate the cable bolt with my right hand.
Maybe I'm too young since I don't remember brakes ever being the other way, but I always figured the pull side was on the left so that the front brake cable could curve smoothly from the left brake lever to the right side of the bike and also for the rear could curve comfortably from the right lever to the left side of the bike. Trivial, but I always make up reasons for things I don't know the reason to.


Originally Posted by Retro Grouch View Post
My personal experience had been that dual pivot caliper brakes stay centered much better.
Same here.
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Old 04-03-09, 06:32 PM
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I've heard from a few people that modern "aero" style road brake levers (the kind where the housing runs out the side and under the tape) perform better than the old style. Why is this? Different amounts of pull?
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Old 04-03-09, 09:03 PM
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I believe they have a higher mechanical advantage, i.e. for each inch that the pull the lever they actually pull less cable than the older style but with more force. At least with the Tektros that I have and love (same as Cane Creek SCR-5) the hood and lever are also a lot more comfy than my old non-aero's.
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Old 04-03-09, 09:38 PM
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Originally Posted by silver_ghost View Post
I've heard from a few people that modern "aero" style road brake levers (the kind where the housing runs out the side and under the tape) perform better than the old style. Why is this? Different amounts of pull?
Yes, the leverage ratio was changed in the levers and you end up putting a larger amount of hand-movement into a shorter cable-pull. This increases leverage. To calculate overall mechanical-advantage of a lever+caliper combo, you can use the following formulae:

LeverLeverage = (distance from hand to pivot) / (distance from cable-pull to pivot)
CaliperLeverage = (distance from cable-clamp to pivot) / (distance from pad to pivot)

OverallLeverage = LeverLeverage * CaliperLeverage

So dual-pivots increase leverage by decreasing the distance between the pad and pivot. Same thing with modern aero-levers. The overall effect is a larger lever-throw is squeezed into a shorter pad-movement. Kinda like a crow-bar where the long-lever side harnesses a lot of hand-movement into a tiny movement at the prying end.

In the final results though, it's your front-tyre's traction that ultimately determines maximum braking-G. Wide low-pressure tyres with lots of contact surface area with soft rubber-compound gives you A LOT of braking traction. The fastest stopping bike I had as a converted MTB with fat sticky 26x2.0" slicks.
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Old 04-03-09, 10:18 PM
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Just as a bit of history - or trivia - a somewhat eccentric but brilliant bike shop owner named John Mackie in Toronto in the '70s created a side-pull brake with one fixed pad. Think about it: tolerances are so close on a properly set up pair of brakes that the articulated brake pad simply pushed the wheel into the fixed brake pad. Lteral travel would have been only a few mm. Stopping was intantaneous. in fact, that's why the system reportedly never took off. The brakes worked too well. I rode one of the prototypes at the time and stopping power was incredible. Like nothing I've ever experienced since.
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Old 04-04-09, 02:51 AM
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When I got my first "good" bike, it was carbon with Ultegra dual-pivot sidepulls. The brakes were noticeably better than the SPSP 105's on my old steel Trek. Later I got an slightly newer old alum Trek with Dura-Ace SPSP. Those brakes are awesome! Not sure which is better the new Ultegra's (dual) or the old Dura-Ace (single).

I also bought some new Nashbar dual-pivot brakes. Not nearly as good as the Ultegra's or Dura-Ace, but better than the old Campi SPSP brakes they replaced.

Btw, I recently replaced the SPSP 105's on my Trek with some Campi dual-pivots and they the Campi's are much better.

Conclusion: old Dura-Ace SPSP brakes are great. New Ultegra and Campi dual-pivot are great.

PS: love the Mafac Racer centerpulls on my '75 Peugeot (even though they're a b!tch to adjust).

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Old 04-04-09, 03:52 AM
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Originally Posted by sunburst View Post
When I got my first "good" bike, it was carbon with Ultegra dual-pivot sidepulls. The brakes were noticeably better than the SPSP 105's on my old steel Trek. Later I got an slightly newer old alum Trek with Dura-Ace SPSP. Those brakes are awesome! Not sure which is better the new Ultegra's (dual) or the old Dura-Ace (single).

I also bought some new Nashbar dual-pivot brakes. Not nearly as good as the Ultegra's or Dura-Ace, but better than the old Campi SPSP brakes they replaced.

Btw, I recently replaced the SPSP 105's on my Trek with some Campi dual-pivots and they the Campi's are much better.

Conclusion: old Dura-Ace SPSP brakes are great. New Ultegra and Campi dual-pivot are great.

PS: love the Mafac Racer centerpulls on my '75 Peugeot (even though they're a b!tch to adjust).
Your experiences give us no information on performance differences between brake types unless you controlled for different brake pads. Put Nashbar crap pads in ultegra calipers and see what happens.
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Old 04-04-09, 04:30 AM
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The Nashbar DPs are rebadged Tektros. And the stock pads are said to be junk. Replacing them brings back the advantage of DPs. Koolstops are the ones to get.

Brake performance is basically about stiffness of the alloys utilized and the leverage of the arms.
The old Dura Ace SPSP were robustly stiff and an had slightly longer caliper arms for better leverage.
In contrast, a pair of the infamous Dia Compe AGC's with their short arms had no meaningful braking.

I also loved my Mafac Racers, too bad I gave them away when I 'upgraded' to Suntour Superbe sidepulls. I noticed no significant difference in braking.
I still have a pair of Mafac 2000 awaiting the proper bike to be installed on.

As for discs, downhill racing, and muddy conditions mandated their introduction. I think in the future, rim brakes will give way to discs across all mid to high end bikes, that's road and mountain. It will be marketed as superior....but what it really offers is higher profit margins and reduced inventories by centering on one design. Pursuing that ultimate all carbon rim will also necessitate discs.
Rim brakes will be relegated to cheap xmart type bikes.
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Old 04-04-09, 08:11 AM
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Originally Posted by Gonzo Bob View Post
Dual-pivots are probably less effective than single-pivots with the QR open (say if you broke a spoke and were limping home).
That's not my experience. On Shimano dp brakes with the qr on the calipers, leaving the qr open makes the lever come closer to the bars but braking power remains the same. On Campy dp brakes with the qr in the lever, leaving it open makes the reach to the lever greater but has no effect on braking power.

Originally Posted by Gonzo Bob View Post
Dual-pivots are also easier to keep centered but I've never had any issues with centering my single-pivots (I have both types).
Dual pivots can be recentered by hand while single pivots usually require a thin wrench on the center bolt. Either is easy to center in your shop. DP's have a big advantage on the road if you bump the caliper with the wheel off while changing a flat.
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Old 04-04-09, 08:56 AM
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Originally Posted by noglider View Post
I think it's a shame that when Campagnolo brakes became popular, other brands switched the "pull" side from the right to the left. This favors left-handed mechanics. I like to hold the brake closed with my left hand and operate the cable bolt with my right hand.
Just an aside, but I still have my old 'third hand' brake tool, which worked well for holding the brakes closed, making the left/right side irrelevant. It's just a spring steel wire, chrome-plated I think, shaped to fit over the nuts on the two brake shoes and squeeze them together. Part of it is shaped into a handle for both convenience and leverage. I don't know if such things are still available today, or what they'd cost, but it was cheap thirty years ago.
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Old 04-04-09, 09:11 AM
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I just checked Park Tool's web site and, to my surprise, none of their third hand tools are listed. I have about three different designs hanging on my tool rack but haven't used any of the lately.

Park does still list their BT-2 Cable Stretcher (aka 4th hand tool) and that will also keep the calipers in the right position while you tighten the anchor bolt.
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Old 04-04-09, 09:21 AM
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yes hillrider , for some reason park tools have stop making their third hand tools. i too have the same three designs hanging on my rack . i guess it a sign of the time. the newer bikes don't need them?
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Old 04-04-09, 11:56 AM
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There was always a cheap alternative to the 3rd hand tool....a spare toe strap.

You can also use one of those Quick Grip clamps as a substitute for a 3rd hand tool.
They are under $5 and the rubber end pads won't scratch the aluminum.

I still have my 3rd hand tool. Some guys don't know what it is when I take it out.
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Old 04-04-09, 12:18 PM
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Park stopped making their Third Hand tool - BT-1 - a few years ago. I should have bought-up a bunch of 'em. As for their Fourth Hand, it doesn't have a lock on it. So it's really a Third Hand. I bought the Pedros, which does lock in position. Cheaper material, but it as a "Fourth Hand."

If you want a Fourth Hand that doesn't lock, forget the Park one. Get the Hozan. Much better design in my opinion.
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Old 04-04-09, 12:28 PM
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Originally Posted by Pepper Grinder View Post
Your experiences give us no information on performance differences between brake types unless you controlled for different brake pads. Put Nashbar crap pads in ultegra calipers and see what happens.
Stock Ultegra pads (at least the ones that came with my 6500 series brakes) aren't that good. They are good to start off, but then the wheel gets coated with pad and the brakes stop working well. I run Salmon cool stops now and I am much much happier. Ultegra DPSP FTMFW!

EDIT- Someone should mention that disc brakes are awesome, right up to the point that you warp a rotor, then they are horrid. Not to knock them, but you have to take the good with the bad.
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Old 04-04-09, 12:44 PM
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Originally Posted by Tabor View Post
EDIT- Someone should mention that disc brakes are awesome, right up to the point that you warp a rotor, then they are horrid. Not to knock them, but you have to take the good with the bad.
You can true and replace rotors easily. Rims...not so much.
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Old 04-04-09, 12:50 PM
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Originally Posted by Wordbiker View Post
You can true and replace rotors easily. Rims...not so much.
I would like to respectfully disagree here. Getting a rotor as true as new after warping it will be next to impossible given how it has to be done by overbending. Truing a rim can be easily and precisely accomplished by simply turning the spoke nipples.

I agree on replacement of course which is why my new commuter has a front disc.
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Old 04-04-09, 01:36 PM
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There's a better way to center a SPSP, which is to adjust the relative spring tension. Usually, the best way to do that is to put a wrench handle (the wrong end of the wrench) on top of the spring that's too strong and bang on it with a hammer. In fact, this is far more reliable than centering it at the pivot bolt.

The advantages of SPSP brakes:

- brake pads never need readjustment
- work as well when loose as when tight, which is useful when your wheel is out of true.

DPSP's (dual pivot sidepulls) have neither of these advantages.

Another rambling: I think cantilevers are the most elegant brake.
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Old 04-04-09, 02:51 PM
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Originally Posted by joejack951 View Post
I would like to respectfully disagree here. Getting a rotor as true as new after warping it will be next to impossible given how it has to be done by overbending.
Not only that, you'd only be curing the symptoms of the problem. Whatever condition existed causing the rotor to warp will still be present and will certainly warp the new "trued" rotor, or even a new replacement rotor. Find the real problem first and fix it. Most likely it's a caliper alignment issue, especially on disc-brakes that have one fixed side.
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