Joe Remi

You adjusted the cable to get the braking you want so all good as far as the question you wanted answered. But I will repeat from my earlier post that the rear locking up sooner isn't what you want, it wouldn't have prevented your toss over the bars. The best situation is full braking with no lockup..in your scenario the front is probably the one that locked and over you went. Sometimes this happens!

Kontact

Well, that's why they have the two thickness washers I mentioned - to account for varying width mounts. I had thought you said that the mounts were the same front and rear.

Andrew R Stewart 

..

FBinNY 

IMO - this thread is a good example of what happens when you ask the wrong question. Instead of stating at the outset that you went OTB, you assumed that unmatched brake action was the cause, and asked about that without saying why.

So naturally you got answers related to matching brakes, including mine saying it didn't matter. So, I repeat that there's no safety issue there as originally asked.

However, now I can say that there is a safety issue, but it's not the brakes. It's your incorrect assumption that your OTB event was caused by a mechanical issue that's causing a safety issue, by keeping you from listening to good advice like that from BK that you should focus on your braking technique.

I know you're convinced, and though I could spend time trying to explain how to brake effectively, I know you won't listen because you're locked in by your assumptions. So, I suggest you reevaluate your assumptions by considering the following:

1- Knowing (I hope) that the front brake acts independently of the rear, how, EXACTLY, would any changes to the rear brake reduces the chances of an OTB because of excess front brake force?

2- What are the considerations that determine when and how one would have an OTB? ie. body position, downslope, etc?

3- What is the difference between stopping the bike vs. stopping the rider? Or more specifically, how do you stop the rider in an emergency stop.

4- Why is it that bicycles have had 2 independent (usually unmatched) brakes for well over a century, and nobody has ever cared? Do you believe that that so many people could be so ignorant and uncaring about such a safety issue? Have you thought about how simple it would be to alter the balance between front and rear braking, and given that wondered why nobody ever bothered?

So, it's your bike and your safety, and I now leave you to deal with it as you see fit.

sweeks

I didn't see this mentioned earlier: when the brakes are applied, the center of gravity of the bike-and-rider system moves forward. If the center of gravity moves ahead of the front tire's contact patch, the bike can flip over (forward).
Good technique for hard braking involves the rider straightening the arms and moving the body rearward off the saddle. This keeps the center of gravity behind the point where the bike will flip. On a downhill at high speed it's a good idea to be prepared for this maneuver. You may be able to find images of mountain bike racers on steep downhill stretches with their bodies so far back that they are literally resting their stomachs on the saddle. Now, this level of re-positioning is probably not necessary in most street riding, but a lesser shift *can* be practiced under controlled conditions. Once you have the technique in your skill set, you will be more comfortable with emergency stopping, even on descents.

Joe Remi

I'm new to this particular section but not to Bike Forums and I'm a little surprised at the tone of some comments. Yes the OP could probably use some practice with braking, it's not a talent on the bicycle that's acquired overnight. I'm not sure being condescending with advice is going to get them there.

FBinNY 

First, a thank you to Sweeks for the detailed explanation of good brake technique.

I had originally planned on going that route, but changed course because of the OP's passing on the advice to practice braking and insisting that it was a mechanical problem. It's been my experience that when people stubbornly cling to wrong theories they don't let go easily, which is necessary as a prelude to considering alternate theories. I've also learned that people are most likely to change be open to changing their preconceptions when they "discover" new info for themselves.

So, I tried to make the OP think about things for himself, and was hoping that my third question would lead him the the answer that Sweeks posted, or at least open him up to considering it.

As it's said, you can lead a horse to water...... but, getting it to drink sometimes takes a bit of attitude.

Darth Lefty 

I don't think mismatched braking force is the same thing as mismatched bite point which is what the first post was about. I liked my brakes to bite early as possible so I followed the normal procedure to get them both to bite as early as possible without rubbing the rim.

My last few bikes have had middling hydraulic brakes and they all bite the same unless something is wrong because that is how they work.

Funny thing about left/right. I had my bikes set up backward to match my motorcycle when I was single, but with a family and a fleet and no motorcycle I leave them all set up regular

oldbobcat

You could cut your front cable and housing to match the length of the rear cable. Just loop the excess a couple of times and attach it to the fork with a couple of zip-ties.

Joe Remi

One reason I like a later or "softer" bite on the rear is I have a steep, short drop into my neighborhood that I like to do a little drag-braking on. I come sailing around to the right and down at a decent clip, grab both brakes to get 'er slowed up, then mostly release the front and pull pretty hard on the rear lever to keep things slow and stable as I near the bottom.

Too much brake on the front can get hairy at the bottom juncture to flat road, too much rear can skid and send me off course.

wheelreason

And drill the tires, sand the rims, and pound a 1 1/8" stem onto the 1 1/4" steerer, it all works better together as a set...

I got from the original post that it was operator error and not the brakes that were an issue. See folks fly over the bars when they get their brakes adjusted "properly" when they had been running them with hardly any stopping from the get go, it's a thing.

Schweinhund

What he's saying applies to this. the washers he's talking about space the pads either closer to the arm and a bit further from the rim, or further from the arm and closer to the rim. you just need to remove the pads from the arms and swap sides with the washer sets.

FBinNY 

Sorry, but you're missing the point.

While he originally described it as related to shoe to rim distance, or possibly delayed engagement, he's now making it clear that his issue is the geometry yields lower leverage in the rear (compared to the front).

He's correct on that point.

However, he's wrong to believe it matters. Bikes have typically had poorer leverage on rear brakes about as long as they had two brakes. Some have argued that it's intentional, to better proportion brake force (like in cars) but it's actually an inadvertent consequence of fork and seat stay geometry.

In any case, the OP has to make the shift from obsessing about meaningless brake design non-issues and focus on learning how to make short stops safely.

Kontact

This is not correct. If rearranging the pad washers causes the geometric relationship between the rim, pivot and cable angle to be the same, the leverage is the same.

FBinNY 

What EXACTLY is not correct in my post.

Andrew R Stewart 

I was one of the posters who mentioned rider error but note that I did after giving the OP good advise and a link to a site with far more info and even diagrams. Like Francis mentions this was only after the OP seemed to not catch on to all the advice and description attempts before. Even still I don't think any of us, who mentioned the rider's responsibility, did so in an attack manor. No personal digs just simple unbiased language. Andy

ralphs

Maybe pick up an old brake modulator...These were supposed to prevent stoppies.

Kontact

That there is sime sort if built in mechanical disadvantage to his rear brake. Regardless of initial locations, the front and rear can be set up to offer the same leverage.

FBinNY 

Sorry no.

I never said "inherent", simply acknowledged that the OP's brake and issue were as described. Nor did I discuss whether or not it could be "fixed", since I didn't and don't consider it an problem.

In any case, this is simply a case of you being you, and posting for the sake of "proving" that someone else is somehow wrong, or to start a pointless argument.

That's why I generally avoid responding to your "corrections"


FWIW just for grins, I'd love to see how you'd adjust the geometry of a V-brake to materially increase the leverage.

Joe Remi

Or use old Campagnolo single-pivot calipers. Magazine testers used to complain that they couldn't lock a wheel and Campy would tell them they weren't supposed to, they're "speed reducers" 🤷😂

Andrew R Stewart 

This point, racers need speed control more than stopping power, is lost on many. Andy

oldbobcat

You got it.

Kontact

By setting the pad spacing up to put the cable as close to 90 degree to the lever arm when the pad is in contact with the rim. That puts the pad force directly into the rim rater than acting at an away from or toward the hub.

FBinNY 

I said MATERIALLY, which it would have to be in this context.

Given the geometry of V-brakes, the near vertical rms in a typical setup, and the typical sweep between 11 & 1 o'clock, I argue that the maximum possible change in leverage is very MARGINAL, and therefore not relevant.

However, there's no point in arguing. The knowledgeable readers here can draw their own conclusions, others can try for themselves.

FBinNY 

I agree, but you do what you can.

The reality is that the front brake alone is the issue, with the rear being at most a marginal player.

Unfortunately. There's no practical fix.

50 years ago the CPSC devoted significant energy to the issue,* and ultimately concluded that, given the variables, preventing headers could only be achieved at significant loss of normal and emergency braking power.

Shimano later tried with their brake limiter that was mentioned earlier on, but the results only verified the CPSC's conclusions.

So, while absolute prevention isn't practical, practicing hard stops does imprint what's needed on our brains and addresses the issue very effectively. Every experienced rider has had to make emergency stops, and yet managed (for the most part) to avoid the dreaded header.

So, despite your claim otherwise, practice does make (nearly) perfect. That's why musicians do it, why the FAA puts pilots through simulators, why divers, the military, police, and just about anyone who may face predictable emergencies drills on a regular basis.

Simply put, in an emergency, you rely 100% on your training.

After 50+ years and well over 200k miles, I still periodically do hard stop drills, especially on an unfamiliar bike.

So, it's your bike and your choice and feel free to tinker with the brakes, but DO NOT reject the notion of emergency stop practice.

---------

* back then helmets were not in use, and the traumatic results of headers, especially in children, was one of the highest a reas of concern.