Cycling UK Forum

When I had a MTB with v brakes I was using the front much more than the rear. I would replace the front pads 3/1 rear.

Redvee wrote:When I had a MTB with v brakes I was using the front much more than the rear. I would replace the front pads 3/1 rear.

Taking into account that a lot that extra rim and pad wear would be because of the amount of crud the front wheel is throwing back. At least that's my experience, despite using the front more than the back.

My experience on my bike - Rigida Chrina rims, Campag Chorus brakes and blocks - the brakes wear at the same rate (as do the rims).

This is because I use both brakes.

I use both brakes because I keep forgetting which is front and which is back!

meic wrote:If you use both brakes then not as much weight is thrown forward as if you just use the front brake. This more equal distribution is much better for your control of the bike.
This is much more obvious when you have suspension.

I'm trying to understand this. If the bike is rigid, then your weight it thrown forward almost purely due to deceleration, thus is doesn't matter if you've used front or rear brakes (for the same level of deceleration). What else have I missed that means that less weight it thrown forward when using your rear brake?

I can understand that if you have suspension then the movement of forks and rear triangles will alter the geometry of the bike so might change the weight distribution.

As ever I dont know the theory which this observation supports.

I start with the observed effect not a theory.

I can venture a theory but it may be wrong.

Using the front brake you develop a turning moment about the front axle which is lifting the rear of the bike.
Using the rear brake you develop a turning moment about the rear wheel which is pushing the front of the bike down.

When using the rear brake you are keeping more force down on the rear wheel.
If using both brakes you can (within limits) balance the amount of weight on each wheel.

Definitely 50/50 for me, purely because too much front wheel braking can be dangerous on all but the most perfectly dry tarmac.

Just throwing the front anchor on can cause a serious off, much more severe than just a rear end wash out or skid, try it and come back and tell me I'm wrong, probably in 6 months when you've been released from Hopspital though .

Mick F wrote:Emergency stops need BOTH brakes despite what Sheldon Brown reckons. Do your own experiment. I did, and proved him wrong.

All you proved is that either your front brake is not a very good one, or that you are (justifiably) scared of using its full power for fear of going over the bars.

Sheldon is correct to say that it is possible to stop quicker using just the front brake than it is using both brakes, provided that your brake is a decent one. Mark a is correct to say that the front/rear weight distribution changes are purely an effect of rate of deceleration, not of which brake is being used. Maximum deceleration occurs when the weight on the rear wheel is zero, at which point it is not providing any braking force. Conversely, if the rear brake is doing anything, the rate of deceleration is less than the maximum.

Whether Sheldon is correct to recommend routine use of the front brake only is another matter. I'd reckon not - you are probably more likely to get hurt doing so than you are an a not quite fast enough emergency stop.
I'd recommend using the back brake as an indicator in an emergency stop - squeeze it very gently, haul on the front brake until the rear wheel locks, then let go of the rear brake and pray.

andrew_s wrote:Sheldon is correct to say that it is possible to stop quicker using just the front brake than it is using both brakes, provided that your brake is a decent one.

How?

Sorry, but I entirely disagree.

I know, coz I proved it, and it makes sense, that the front brake is best to stop. I cannot disagree with that. The front brake is possibly as much as ten times more powerful.

BUT the rear brake plays its part in stopping the bike.

In an emergency stop situation, if you apply both brakes, you will stop quicker. Yes, the rear will lift and you may do a header, but only if you're not competent and/or you're sitting too far forward and too high.

When you brake suddenly, you can be caught out. If you know what you're doing, you will shift your weight back against your arms at the same time as braking and put more weight at the back. There's no point in doing an ES and flying off into what you're trying to avoid! Stay on the bike, brake as hard as you can on BOTH brakes even though the rear brake only provides minimal braking. Every little helps.

PS:
Do your own experiment. Don't take my word, or SB's word for it.

It's worth (re-)reading http://sheldonbrown.com/brakturn.html in detail.

I've never had to do a real emergency stop. When practising I have noted the tendency that SB mentions for the rear to fishtail if the rear brake is on. Nevertheless, I stop more quickly than when it is off.

I suppose this is because the rear brake is effective during the brief time before the front brake grips fully and the rear wheel starts to rise.

The fishtail doesn't worry me. Depending on the emergency, I might be better letting the bike slide away from me and falling to my side, than staying on the bike and hitting the emergency head first.

In real life, I sometimes need to make fairly sharp stops. For these, I use both brakes.

snibgo wrote:I've never had to do a real emergency stop. When practising I have noted the tendency that SB mentions for the rear to fishtail if the rear brake is on. Nevertheless, I stop more quickly than when it is off.

You stop more quickly with both brakes because without the fishtailing that tells you you are getting close to going over the front, your natural caution means that you squeeze the front brake less hard.
Overcoming caution and learning how hard you can brake without doing a faceplant is just a matter of practice. If you do practice, you get to play silly games like this stoppie on youtube (note that you have to ease up on the brake to stop the back wheel continuing to come up, so a stoppie is not a particularly quick way of stopping)

Despite Sheldon's advice, I too use a bit of back brake in an emergency stop. However I don't kid myself that I'm stopping as quickly as is possible - I just accept that I don't have the skill to stop quicker, and that I don't have the nerve to acquire that skill.

If you've used the rear brake, someone else who was better at it could have stopped quicker.

Shifting your weight back is a red herring. You can shift your weight just as well using the front brake only as with the back. It allows you to use the front brake more for a quicker stop, but doesn't mean you get any extra benefit from the back brake unless you reach the limit of the front brake's power or the front tyre traction.

Still don't quite agree.

Please don't say one brake or the other brake. Use both brakes - but with skill.

Only one brake cannot be better than both.

Plain physics.

Prove it.
I did.
Why don't your prove it like I did?

Read my posts on the subject, and CJ's response.

If anyone doesn't agree, put their experiment where their mouth is.

Mick F wrote:Plain physics.

Well, it's not plain physics, because plain physics tells you that at the point of maximum braking where the rear wheel is just off the ground, then the front brake alone is doing all the work.

However, [img]complicated[/img] physics and real-world experience seems to show that both brakes are better. Maybe it's because there are other physics effects which are working along with the front brake's stopping power, maybe it's because in reality people just don't use the front brake to its theoretical maximum because of the fear of flipping over the bars.

Given the choice between theory and experiment, experiment is the way to go every time. Until someone else does a "better" (whatever that might entail) experiment which shows something else.

mark a. wrote:Well, it's not plain physics, because plain physics tells you that at the point of maximum braking where the rear wheel is just off the ground, then the front brake alone is doing all the work.

Nope.
Maximum braking is when BOTH brakes are working.

The mere fact that a bike/human geometry throws the weight so far forward that the back wheel lifts is besides the point.

Before the back wheel lifts, there is a finite point before it lifts that it gives maximum braking force. If by skill, the rider can make that lifting moment take longer to affect the lifting, the back brake has even more effect.

Please try your own experiments - on a quiet dry road with a slight downward slope. Start off at the exact same point and brake at a particular point further on. Apply brakes: rear only, front only, both. Apply them as hard as you can.

Take some chalk the mark the road where you stop, and a tape measure to measure the relative distances.

I'm actually agreeing with you, Mick, but I think that the phrase "plain physics" makes it sound too trivial and simplistic.

I haven't done the calculations to see whether the optimal deceleration occurs before the rear wheel lifts or not, but it's possible. I haven't done my own experiments yet, but yours work and I'll choose those results over "plain physics" any day.