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Why is there a spring in my front v-brake, but not in the rear?

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Why is there a spring in my front v-brake, but not in the rear?

Old 09-23-20, 05:48 PM
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crankholio
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Why is there a spring in my front v-brake, but not in the rear?

The fittings at the tops of the front and rear noodles are different. The rear has a smaller fitting. The front has a larger fitting with a spring down in the barrel. Anyone know the reason for this?
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Old 09-23-20, 06:28 PM
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Originally Posted by crankholio View Post
The fittings at the tops of the front and rear noodles are different. The rear has a smaller fitting. The front has a larger fitting with a spring down in the barrel. Anyone know the reason for this?
You have a failed attempt by Shimano to make an antilock brake system. The spring is meant to keep the front wheel from ‘locking’ (it can’t but that’s a different discussion). It doesn’t work and makes the front brake spongy. It would be better to just replace it with a regular noodle.
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Old 09-23-20, 06:33 PM
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Originally Posted by cyccommute View Post
You have a failed attempt by Shimano to make an antilock brake system. The spring is meant to keep the front wheel from ‘locking’ (it can’t but that’s a different discussion). It doesn’t work and makes the front brake spongy. It would be better to just replace it with a regular noodle.
Ah, good to know. I searched Google and couldn't find a single example of a noodle spring. Thought I was going crazy.
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Old 09-25-20, 05:35 AM
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Many OEMs called them "power modulators" and marketed them as a feature. They're somewhat common on front linear pull brakes, especially on hybrid bikes and bikes marketed towards the recreational riding crowd.
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Old 09-25-20, 06:34 AM
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My wife's Trek came with one of these. I had never seen one and was a bit mystified why the brake felt spongy. Now, I'm mystified why anyone thought this was a good idea.
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Old 09-25-20, 07:28 AM
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Originally Posted by Moe Zhoost View Post
My wife's Trek came with one of these. I had never seen one and was a bit mystified why the brake felt spongy. Now, I'm mystified why anyone thought this was a good idea.
Former bike shop employee here: I once had a customer return a bike because it was "dangerous." She was an unskilled rider and took her v-brakes equipped hybrid down a hill, stood up, and grabbed a handful of front brake in a panic. Went over the bar and was seriously injured.

The spring is to stop people like that from killing themselves. It takes a while lot more effort to lock up the brake and OTB. [edit: I am not saying that it's effective, but that's the intent.]

Last edited by mack_turtle; 09-25-20 at 12:28 PM.
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Old 09-25-20, 09:02 AM
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Originally Posted by mack_turtle View Post
Former bike shop employee here: I once had a customer return a bike because it was "dangerous." She was an unskilled rider and took her v-brakes equipped hybrid down a hill, stood up, and grabbed a handful of front brake in a panic. Went over the bar and was seriously injured.

The spring is to stop people like that from killing themselves. It takes a while lot more effort to lock up the brake and OTB.
What you describe wouldn’t have been helped by a tiny little spring that makes the brakes slightly less effective. The spring isn’t strong enough to stop the brake from compressing it completely. If anything, the “ABS” noodle inspires a confidence that it shouldn’t.
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Old 09-25-20, 09:17 AM
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Originally Posted by cyccommute View Post
What you describe wouldn’t have been helped by a tiny little spring that makes the brakes slightly less effective. The spring isn’t strong enough to stop the brake from compressing it completely. If anything, the “ABS” noodle inspires a confidence that it shouldn’t.
after test-riding dozens of bikes with those springs, I can say with 100% confidence that the spring adds some modulation into a system that is otherwise on/off only. some modulation, but not a lot. it's not enough to prevent a really stubborn person from flying OTB, but it helps. a person with an ounce of sense would feel the warning from that spring mechanism and probably back off the brakes before that. it's supposed to be the bike manufacturer's liability safeguard. it's minimally effective, but it's better than nothing when you put grandma on a bike she points her bike at a hill with no idea what she's doing.
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Old 09-25-20, 09:48 AM
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Originally Posted by mack_turtle View Post
after test-riding dozens of bikes with those springs, I can say with 100% confidence that the spring adds some modulation into a system that is otherwise on/off only. some modulation, but not a lot. it's not enough to prevent a really stubborn person from flying OTB, but it helps. a person with an ounce of sense would feel the warning from that spring mechanism and probably back off the brakes before that. it's supposed to be the bike manufacturer's liability safeguard. it's minimally effective, but it's better than nothing when you put grandma on a bike she points her bike at a hill with no idea what she's doing.
Linear brakes aren’t “otherwise on/off only”. I’ve owned many sets of them. I’ve installed them on many bikes for people with less experience than I have and never found anyone who had problems with modulating them. I’ve even seen 5 year olds master them without any instructions. 99% of them are of such poor quality that getting the rear wheel to lock is next to impossible. I have Motolites on one of my bikes which is of a higher quality than any other linear brake I’ve ever used and it’s not “on/off”. Blaming the brakes for a crash is about equivalent to the “just riding along” excuse.

People don’t go over the bars because of the brakes all that often and, if they do, the reason is usually less the fault of the brake than the technique. Standing up and braking on a downhill like your customer describes isn’t the fault of the brake and no little spring would have done much to have done much to prevent her from going over the bars.
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Old 09-25-20, 10:01 AM
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Originally Posted by cyccommute View Post
People don’t go over the bars because of the brakes all that often and, if they do, the reason is usually less the fault of the brake than the technique. Standing up and braking on a downhill like your customer describes isn’t the fault of the brake and no little spring would have done much to have done much to prevent her from going over the bars.
I agree with you 100% on this. If I recall correctly, this was on an Electra Townie too, which is a big old barge of a bike and very difficult to crash like that. Like I said, the spring is a bike manufacturer's attempt at "liability insurance" for people who are really stubborn and foolish with their bikes. you can't make people not crash their bikes, but it's a good idea to try to make it more difficult to do so.
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Old 09-25-20, 10:33 AM
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Originally Posted by mack_turtle View Post
after test-riding dozens of bikes with those springs, I can say with 100% confidence that the spring adds some modulation into a system that is otherwise on/off only. some modulation, but not a lot. it's not enough to prevent a really stubborn person from flying OTB, but it helps. a person with an ounce of sense would feel the warning from that spring mechanism and probably back off the brakes before that. it's supposed to be the bike manufacturer's liability safeguard. it's minimally effective, but it's better than nothing when you put grandma on a bike she points her bike at a hill with no idea what she's doing.
Linear pull brakes have plenty of modulation unless they are set up very poorly...which is always possible.
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Old 09-25-20, 10:36 AM
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for people who are used to crappy brakes who grab the lever with four fingers instead of one or two, v-brakes are too much. unfortunately, bike manufacturers have to design for the least common denominator of clueless new riders, which is why they equip these bikes with "gear indicator windows," QR levers that are "easier to use," and little springs in the brake noodles.

aren't people apparently concerned with "catapulting disc brakes"?
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Old 09-25-20, 10:49 AM
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Originally Posted by mack_turtle View Post
I agree with you 100% on this. If I recall correctly, this was on an Electra Townie too, which is a big old barge of a bike and very difficult to crash like that. Like I said, the spring is a bike manufacturer's attempt at "liability insurance" for people who are really stubborn and foolish with their bikes. you can't make people not crash their bikes, but it's a good idea to try to make it more difficult to do so.
I think you are dealing with a JRA situation. Without doing the calculations, I would say that a Townie would be next to impossible to do an endo...with any kind of brake and in any rider configuration. The Townie is longer and has a lower center of gravity than a regular bike which makes it next to impossible to lift the rear wheel and send the rider over the bars. It’s more like a tandem or recumbent that a tradition double diamond frame. I’d suspect that you could even skid the front wheel ...something that is impossible with a regular bike...before the rider would go over the bars. I have no doubt that the woman crashed and probably ended up on the ground with the bike somewhere behind her but she never went “over the bars”. She just DFOed* and thought the brakes were to blame.

Originally Posted by mack_turtle View Post
for people who are used to crappy brakes who grab the lever with four fingers instead of one or two, v-brakes are too much. unfortunately, bike manufacturers have to design for the least common denominator of clueless new riders, which is why they equip these bikes with "gear indicator windows," QR levers that are "easier to use," and little springs in the brake noodles.

aren't people apparently concerned with "catapulting disc brakes"?
We’ve had linear brakes for about a quarter century now. They really aren’t that much of a problem nor would grabbing brakes with four fingers instead of 2 cause that much of a problem. I suspect that a lot of people blame brakes for crashes because that’s the thing they remember doing last. Actual “going over the bars because of the brakes” is a very rare event that happens under very specific conditions. A lot of things that bike manufacturers do is a response to a small number of problems.

The Consumer Product Safety Commision, by the way, doesn’t like lawyer lips. They don’t require them and think that they are not a good solution.

*”Done Falled Over”
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Old 09-25-20, 10:57 AM
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Originally Posted by cyccommute View Post
I think you are dealing with a JRA situation. Without doing the calculations, I would say that a Townie would be next to impossible to do an endo...with any kind of brake and in any rider configuration. The Townie is longer and has a lower center of gravity than a regular bike which makes it next to impossible to lift the rear wheel and send the rider over the bars. It’s more like a tandem or recumbent that a tradition double diamond frame. I’d suspect that you could even skid the front wheel ...something that is impossible with a regular bike...before the rider would go over the bars. I have no doubt that the woman crashed and probably ended up on the ground with the bike somewhere behind her but she never went “over the bars”. She just DFOed* and thought the brakes were to blame.

*”Done Falled Over”
long story and it happened several years ago, but we saw photos of it and she brought in the x-rays of her busted skull. we were afraid she was going to sue the store, but she didn't. hard to believe, but she OTBed a Townie. regardless of how it went down, you're right—nothing could have been done about such a bizarre, freak accident, but bike manufacturers try to mitigate those liability risks with goofy solutions like springs inside brake noodles.
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Old 09-25-20, 10:58 AM
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mack_turtle The thing about the disc brake ejecting a wheel is that the problem can develop over time and repeated stopping, which can cause micro-movements of the axle in the dropouts and eventually loosen the QR. The (erroneous) thinking behind Direct-pull brake 'power modulators' is that the possibility of the front brake sending you arse-over-teakettle is potentially built in to properly functioning brakes from day 1.

The solution is probably education - shops should be informing clients when they pick up their new bikes that a ham-fistful of front brake could be hazardous, and that they should be practicing using the front brakes to be proficient before attempting speed runs down a mountainside. In the early days of V brakes I tried to make each customer aware that the new style of brakes is likely much more than to what they were accustomed.
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Old 09-25-20, 12:24 PM
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Originally Posted by mack_turtle View Post
Former bike shop employee here: I once had a customer return a bike because it was "dangerous." She was an unskilled rider and took her v-brakes equipped hybrid down a hill, stood up, and grabbed a handful of front brake in a panic. Went over the bar and was seriously injured.

The spring is to stop people like that from killing themselves. It takes a while lot more effort to lock up the brake and OTB.
Yeah, I get the intent, but deliberately making the brake less effective because they're concerned about their liability exposure is a questionable strategy. Better off fitting the bikes with rear brakes only.

I'd expect that your customer would have gone over the bar even with this device. Standing up and panic braking is a skill that few will ever master.
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Old 09-25-20, 12:27 PM
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Originally Posted by Moe Zhoost View Post
Yeah, I get the intent, but deliberately making the brake less effective because they're concerned about their liability exposure is a questionable strategy. Better off fitting the bikes with rear brakes only.

I'd expect that your customer would have gone over the bar even with this device. Standing up and panic braking is a skill that few will ever master.
I'm pretty sure that bike did have a device like that. that's my point: it's an attempt at mitigating a risk that can only really be resolved through natural selection. bike companies can throw up their hands and say "we tried" with this. bike shops can't be responsible for reminding new riders to not be stupid.
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Old 09-25-20, 12:36 PM
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Originally Posted by mack_turtle View Post
bike shops can't be responsible for reminding new riders to not be stupid.
Just wondering - do bike shops have customers sign some sort of liability waiver when delivering a new bike? Maybe it's in fine print on the receipt.

YouTube would not be as entertaining if people stopped being stupid.
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Old 09-25-20, 12:43 PM
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I didn't sell enough bikes to remember the specifics—I was in the shop more than the sales floor—but I recall making a customer sign something about wearing a helmet, obeying road rules, not riding in the dark without lights, etc. no one read it, they just signed it. i was all totally common sense stuff anyway.
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Old 09-25-20, 01:42 PM
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All Bikes came from the manufacturer with an 'owners manual', which included lawyerly words about the risks of cycling being your own, but had very little value otherwise. This owners manual sometimes got passed to the client at the point of sale and sometimes not.

Occasionally people we forgot to give them to would storm back in a few days later and demand they be given the owners manual, as if we kept it from them for some nefarious purpose or were selling them on the black market.
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