Andy_K 

I've been using them for about 3000 miles, changed the pads about 500 miles ago.

Camilo

I think you're over-stating this. What you've probably read and heard is that the rear brake doesn't give nearly a much stopping power as the front. But to say it doesn't add to it is just wrong. A lot of people, because of misguided fear of going over the handle bars, use only the rear brake (my wife and daughter two examples). They stop just fine.

I guess I'm just wondering if you have a brake adjustment issue. My wife is 5-1, late 50s very small weak hands and uses Tiagra STI's with rim brakes no problem. But of course, she's also small in stature so that's a big difference from your situation and probably changes it totally.

But if it were me, I'd have the entire braking system checked out before putting both levers on the front brake and having the rear brake be an after thought.

Seattle Forrest

Open the quick release on your rear brake, and go for a ride, to learn whether you believe this or not.

ThermionicScott 

I don't know anything about those brake levers, but is there any way to modify/adjust the travel on them? Seems like there are shims you can add to *some* levers that allow them to "start" closer to the closed position, which may help you get more leverage on them. I've got little hands too, so when setting up drop bars, I have to be careful that I can still reach the brake levers when in the drops.

- Scott

Andy_K 

I actually did that accidentally last week (had the wheel off for maintenance just before leaving in the morning). I didn't notice until I got to work and saw it while locking up to the rack. Apparently, I don't use my rear brake very often.

Andy_K 

At the risk of committing heresy, let me quote from the Holy Scriptures:

and again

and finally,

I had also drawn the same conclusion from reading Bicycling Science, and looking it up I find something suspiciously close to the first verse I quoted above,

However, on re-reading I find that the author here is only arguing against the sufficiency of the rear brake alone and goes on to talk about weight distribution in a manner similar to what cyccommute said and mentions that tandems and recumbents don't have the same limitations related to rear wheel lift as other bikes.


Yes, everyone seems to be wondering that. I think it's funny, but I guess I brought it on myself.

My "problem" is/was largely a theoretical one. Since I never get to the point where my rear wheel is lifting off the ground, I reasoned that I must not be achieving maximum possible stopping power. I actually have pretty good stopping power, but it seemed like it should be theoretically possible to increase it.

FWIW, I'm guessing that I have significantly more weight planted over my rear wheel than your wife does, and at any given speed I probably have close to twice as much momentum. Maybe it's not even my weak hands that are at fault. It might be the size of my gut.

cyccommute 

Sheldon Brown's (and many others') interpretation is what is wrong. It's a trick of the math...look at the Bicycling Science reference...that when the braking force of the rear wheel goes to zero and the rider is about to go into pitch over when you reach the maximum possible deceleration that a bike can develop. It's not when the rear wheel is just about to lift. It's not when the rear wheel skids. Maximum deceleration occurs at that very instant before disaster. I don't know of too many people who are always stopping in a nose wheelie balanced at the point of no return.

In mountain biking, the maxim is that if your rear wheel is skidding, let up on the front brake. This puts the rear wheel back in contact with the ground and prevents you from going over the bars. Of course, the rider would already be pushed back and down on the bike.

Steely Dan

sheldon certainly knew A LOT about bikes, but he was not infallible. i highly doubt his statitic that ALL "skilled cyclists" use only their front brake 95% of the time. there's a crapload of subjectivity that goes into a statement that bold.

i easily consider myself a skilled cyclist and when i apply the brakes on any of my bikes, i usually apply braking power to both the front and rear wheels. when i need to panic stop, i move myself off the back end of my saddle to put more weight over the rear wheel to increase stopping power of the rear brake, while also taking my front brake to the limit of safety, ie. brake hard up front, but not enough to be thrown over the bars.

on my featherweight road bike, i also like to slam my front brake super hard right at the very end of the braking process to lock up the front wheel and lift the back wheel off the ground a couple of inches for dramatic flair. the maneuver is a little dicey if you're riding clipless and you don't have good clipping out reflexes

Andy_K 

Worse than that, Bicycling Science is only saying that is the maximum possible braking force for a given weight distribution.

I actually started studying that section because I was certain that Sheldon was wrong and wanted to understand it. I looked at the BScience "90%" statement and saw from the equations that the remaining ~10% would disappear as braking force increased to the tipping point. I guess I gave up too soon. I should have kept thinking.

Andy_K 

Oh, but there's so much post-modern angst and doubt down that line of thought. If Sheldon was sometimes wrong, what can I ever believe? I think I'll deny it instead.

Sixty Fiver

I own quite a number of bicycles that do not have a rear brake and can generate enough stopping power to lift the rear wheel with all my weight thrown back and my stopping distance is about half of those who are only using a rear brake and skidding. I am able to pull off a nearly 1g stop while those using a rear brake can only manage a .5g stop.

This is physics.

This is not to say that a rear brake or a mean to control the speed of the rear wheel is not essential as there are some circumstances where using the rear brake is preferable to using the front... wet and icy roads or loose gravel is a place where you want to be light on the front brake to prevent the front wheel from skidding as if this happens it is usually all over.

Your front brake is the primary and provides nearly all the stopping power, the rear brake should be able to lock up the rear wheel but is best used as a speed modulator... I rarely use my rear brake when I am riding on nice roads in decent weather but do use it when I am riding in inclement weather and in the winter to prevent front wheel skids.

A great deal of how well you stop is technique... this is something I have practised to the point where it has become reflex and my daughters have learned the same in that they use their front brakes to near exclusion unless the road conditions warrant rear braking.

cyccommute 

Yes, it is physics. But I've not seen anyone here suggest using only the rear brake. The 0.5g deceleration number I posted is for a normal rider sitting in a normal position using both brakes or even using only the front brake. If you are using only the rear brake, the deceleration is, of course, going to be lower. You don't approach 1g of deceleration until you shift the center of gravity back and down.

I would also suggest that Andy_K work on his braking technique rather than try to add more brakes to the bike. You really don't want to skid the front wheel, Andy. A locked up front wheel is a recipe for disaster. The best place to learn braking technique...and bike handling skills in general...is on a mountain bike off-road. If you can handle a bike in the bad conditions you experience on dirt, think of how much easier good conditions will be.

Seattle Forrest

I use both brakes when I want to stop. I know that most of my stopping power comes from the front, but I'll take what little the rear can give me, too.

AndreyT

What the Sheldon Brown's web site is saying about front wheel braking is absolutely correct, if overly theoretical. For any specific rider position (shifted backwards from the saddle or not) the braking force generated by the front wheel alone at its ideal maximum braking force point (as described below) will always be greater than the sum of front and rear braking forces at any other (non-ideal) point. (Assuming, of course, that the wheel-to-road traction is sufficient to achieve that braking force).

For each given rider position, maximum braking force is achieved with front wheel braking only. And it is achieved when the the rear wheel bears 0% of the bike weight, i.e. at that exact point when the rear wheel makes that "infinitely light" contact with the ground. Of course, in this configuration the rear wheel has no traction at all. I.e. its is either about to lift from the ground (if pushed forward/up) or it is about to skid (if pushed sideways). In such situation there's no difference whatsoever between the root reason for these two scenarios.

The only issue with this sort of front wheel braking is that is only possible under the ideal braking force, continuously maintained by the front wheel brakes. Applying excessive force will ultimately result in front flip (or at least front wheel stand), while applying insufficient force will keep some weight (and traction) on the back wheel, taking it away from the front wheel. No cyclist is ever able to maintain this force perfectly and continuously. An experienced cyclist will be able to stay very very close to the ideal by observing the feedback from the bike and adjusting the braking force accordingly.

This inevitably will result in short periods (or long periods, depending on how good the cyclist is) when the rear wheel receives some portion of the bike weight. For this reason it might make sense to apply rear brakes as well, to "pick up" those portions of traction that from time to time "escape" to the rear wheel. Or it might not, since it can lead to rear wheel lock up.

no1mad 

Wow, between all of the techno-gibberish, I think I may have figured out my affinity for flat bars and wide tires- I brake like a mtb'er! Dunno if it's all those years as a kid using a coaster brake or maybe it was that one time I did a fairly good Superman dismount...

MadMan2k

I just try to coast almost to a stop when I know I'm going to stop, and try to avoid going too fast for conditions and look out for hazards so I can get ready for them in time. That way I don't worry too much about my minimum stopping distance, I just make sure my brakes will stop me pretty quickly on flat ground and hold my speed or stop me completely on almost any hill around here.

bud16415

I didn’t know how Fred it is but I added a second front brake lever from a mtn bike to the tops of my drop bars. I added it to the left side so I can only pull one at a time but could have just as easily added it tothe right if I felt I didn’t have the hand strength to really set the brake. I didn’t do it with a cross lever you normally see I ran two cables and stacked two cable supports under the stem nut removing a spacer. I mainly wanted a brake lever on the top as I like my STI levers really low in the drops where I ride most of the time. The mtn lever works really to take off some speed or to hold the bike against a hill while standing. It also is useful for me when transitioning from the tops or hoods to the drops while braking. If I ever break a front cable I know I have backup now. I don’t worry about looking Fred do what works for you.



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bud16415

After reading the whole thread again and also the Sheldon Brown’s take on this again. I thought back to my first dislike of my STI drop bar setup. I ended up removing the tape after experimenting for a few months with different stem heights and bar angles and nothing seemed to be optimal for my hands. I found the hoods a comfortable riding location with the bars lifted and that made the drops awkward. I found I liked the drops when nearly level as a riding position and liked them even more when I set the stem higher than the excepted norm. I started moving the STI’s around on the bar looking for a location I could shift and brake from both places and my hands are average size to slightly small and I never found a compromise position where I felt in control 100%. As I liked the drops the best I lowered them down to where I had exceptional control in the drops both stopping and shifting. The other advantage to that location for me I kind of knew or felt but this thread made it clear to me and that is when stopping fast Like the OP I’m a bigger guy and I have more inertia to stop moving. Thus more brake effort it also means that Newton law applies and a body in motion stays in motion unless acted on by an outside force. I’m not attached to the bike so that reaction proportioned between my weight and the weight of the bike has to be acted on thru my arm strength. What better position can I be in than solidly in the drop position with my center of gravity lowered and my arms reacting the force rather than my arms acting as pole-vaulting poles to lift my body forward and upward. The notion of a front wheel stand stopping I think is flawed as its assuming the rider attached to the bike and not moving as an independent body and the G force of deceleration due to body position causing a partly weightless or in the case of an end over total weightless condition of the rider. The heavier rider is at a disadvantage in terms of moving mass but has an advantage in tractive effort for braking if he keeps his weight aligned such that it is applied thru the bike to the tire road interface. Sheldon points out that most end overs are a case of the rider leaving the bike first and then the bike following. I believe this to be the case also and what may be flawing the math.

I do know that going into the deep drop location is a position I’m better suited body wise to coast in than ride in, also provides me the best control and it does exactly as mentioned it forces my CG back in the saddle putting more weight over the rear wheel reacting the lever effect. It gets me more straight armed into the blocking my forward travel in relation to the bike and has me more aero in the process assuming I want to go fast down the hill.

With my STI’s lowered I know I have easily twice the stopping power in my hands just due to ergonomics and shifting is also greatly improved as is handling. What the down side was is I didn’t have anything on the top and no hoods. That’s when I added the mtn brake and I later added a homemade stoker hood made from some old school ten speed brake parts. This setup is 90% of the way there for me and I don’t see myself going back to the compromise location of the hoods. I do wish there was something invented that hasn’t been and as far as I know isn’t on the market. If anyone has seen stoker hoods used on tandem bikes they have a fake lever built into them. I have never ridden a tandem and know little of the usage of the lever. But for me the perfect system would be a stoker hood setup where that little lever could be set up like a cross brake. Seeing as how I’m the only person that would buy such a thing I don’t see anyone making one and I might have to build my own.

Here is my Fred setup as it is today.



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cyccommute 

This is, again, a misinterpretation of the physics. The maximum deceleration that can possibly be attained is when the normal force on the rear wheel is zero and when the rider is at the highest possible angle above the front hub. The trick of the math is that this is all that you can get and you can't get no more. Go past this point and you aren't braking...you are falling. In practice, this is not a situation that you want to be in, even in a panic stop. The edge of that balance point is too fine and the ability to go past the point of no return is too easy to use it as a regular tool.

On the other hand, up to the point where the rear wheel leaves the ground (not a skid because the rear wheel is still in contact with the ground), the amount of deceleration that the rear wheel provides isn't zero. On the other hand, when the rear wheel leaves the ground, the amount of lever force is moot anyway so applying the rear brake goes from having an effect, i.e. doing some good, to having no effect but also having no detriment.

This is sensible and basically states what happens in the real world. You might be able to brake ideally in an ideal world but the world is seldom ideal.

Bottom line: Unless you do a nose wheelie all the time use both brakes.

Ridefreemc

Agree 100%. I have both the BB7s and Shimano XTR hydraulic (different bikes of course) and they are quite different. The BB7s are fine, but they don't stop close to as well as the XTRs. I like the BB7s for the bike they are on, but it takes a significant amount of effort to come close to, and not actually get to, what I can do with the hydraulic system.

Kojak

Honestly, only a true bike geek would even notice. I wouldn't do something like that to one of my race/road bikes but on a commuter it's worth a try.

As for my experience, I use my rear brake with some frequency, and my technique involves ass (barely) on the saddle, weight shifted way back.

Kojak

As for hydraulic brakes, I'd only be leery if one had long steep descents on their route. I've read several articles about people who have adapted MTB hydraulic brakes to road bikes and have run into trouble with brake fade. Not something you want to deal with when you're flying down a hill.

https://plus.url.google.com/url?sa=z&...4A1Wxhv4fJLHMY.

jeffpoulin

Just curious, for those who are doing 1g braking with rim brakes, do you get excessive wear of the rims and/or pads? Or is the wear the same as 0.5g braking that takes twice as long?

cyccommute 

The distance needed to stop is inversely proportional to the g force. Thus, if you are decelerating at 0.5g, it takes twice the distance to stop as at 1g deceleration. The amount of time that you have the brakes on is longer in the lower g deceleration so the wear on the system is actually worse than in the harder deceleration case. Given that friction is probably higher in the higher deceleration case, it would be hard to say if the amount of wear is higher, lower or a wash, however. I don't notice excessive wear in rims or pads on my bikes but then I'm not always doing panic stop style braking.

bud16415

Stopping is a factor of friction. Friction produces heat. Heat in almost all cases causes excessive wear. Heat is dissipated by surface area, air flow and time. In the extreme case of coasting to a stop wear would be zero wear. As the time shortens it is logical to assume wear will go up.

If the goal is to race the longer you go fast the quicker you stop the faster you will complete a course of mixed stopping and going. If your goal is to save resources and be safe I would say anticipation combined with slow stopping would best do the job. I have read on long downhill’s the method to best manage controlled speed and heat would be to alternate front and rear brakes. That also sounds right to me.

Just my opinion and I could be wrong.