Locking up the front wheel . . .
 

I'm new at ridin, so I have lots of questions. I read on the Sheldon site that the front brake gives you more stopping power, since it bears more of wieght, so I've been trying to make sure I get used to using the front brake lots.

But the thing is, I can use the back brake to lock up the rear wheel, but I can't seem to get the front wheel to lock up. Should I be able to lock up the front wheel, or are my brakes slipping, do you think?

(I don't know, maybe it has something to do with the front suspension absorbing a lot of the forward momentum so . . . um . . .well, that's as far as my physics will take me. :) )

if you get your front wheel to lock using the front brake, your rear end would be lifted up...

road bike brake just doesn't have the stopping power as of mtb vbrake...

No....

You do not want the front to lock. Plus it's harder for reason of weight load.

See, under any kind of deceleration on a bike, the bike slows down, but, your mass attempts to move forward...this is why your rear wheels skids, even though most of your weight is right on top of it...the bike slows down, but your are still trying to move forward...this transfers the weight in front of your rear wheel, causing slight leverage in the front of your bike, which reduces load on the back wheel...so now sinc there is less load, there is less force needed to lock it up.

now for your front wheel, it sees that extra force, so it takes more to lock it...but since its up front...the harder you brake, the higher it's load. This is why you should use the front brake primarily. Now...you can decelerate too fast, and that ends up with you over the handlebars, eating ground. You have to factor your weight distribution and angle of decent when braking, since boh of those affect your maximum rate of decelaration before going over the bars.

My trick is to apply hte brake softly for a few feet, then start clamping down harder and harder while still pedaling until i feel the pedal load ease up...this means i'm reaching hte point where my back wheel is lifting, so i need to stop adding pressure until i get proper feedback again.

A suspension helps give you a bit better feedback, gague it on how far your front end is dipping...usually i can tell by handlebar feel as well due to my suspension that i am getting near the max point for my safe braking. The dip varies bike to bike, so use the pedal method for a while to assist in figuring out how much dip is proper.

You don't want to lock up your front wheel. If you're ever successful in locking up your front wheel, you are going to do a forward flip.

Actually, why all this fixation on stopping? Most people are trying to figure out how to make their bicycle go faster.

I'm a bit paranoid about locking up the front since the time I accidentally did it on a slippery bridge and went face-first into the pavement. (Not for the first time, either...) Nevertheless, I did lock up both front and back wheels in April doing an emergency stop for a stoplight that tried to fool me, and managed to keep it upright and balanced to a full stop. Very cool. :D

Don't be tempted to rely on using the front brake too hard. Hit some sand or a rock and you'll be eating pavement and tooth chips for dinner. Since these things are a matter of habit you don't want to start developing bad habits, or they'll bite you hard when you find yourself in an emergency situation. Rear brake first, then start soft on the front.

bkr

I like to practice locking my front wheel, in a flat sandy spot. This lets me get the feel for when lock up is imminent and helps in controlling at the point of lock up. On pavement it is also fun to ride out a stoppie with the back wheel about a foot off the ground, good practice as well.

im sure this has all been said:

-caliper brakes simply do not have the power to lock up the front wheels
-you dont want to flip
-locked wheel = pass friction point = longer stop = NO CONTROL

for maximum braking i grab the fronts and modulate the rear

I use the front brake on just about any kind of surface, downhill, bends, outside camber, sand on the road. The trick is in your modulation. You can get very fine control of the brake, and ease off at the slightest loss of traction. Recovering from a front wheel slide is something that takes experience, but its quite do-able.
On one club ride, all the experienced riders negotiated sand on a downhill corner, including a couple on a tandem with a child on a tow-along. A newbie rider on a full sus MTB was the only one to wipeout.

I find that locking the wheels is more down to surface conditions than the power of the brake. In particular I've managed some fun two wheel skids on wet cobbles on a 15+% hill where even the slightest pressure locks the wheels, keep staying upright and you're fine. It's worth noting that the coefficient of sliding friction is (always) less than the coefficient of static friction so skids stop you slower.

For motorbikes the rule of thumb for ideal braking with no skidding is 2/3 front and 1/3 rear braking power which I reckon is what I use mostly on a proper bike as well. On a motorbike this can be achieved nicely with twin front discs and a single rear (or a single disc and a drum) but for bicycle rim brakes it's easier just to pull harder with one hand than to fiddle with setting the leverage. For cycle disc brakes you could use a larger front disc than rear (or front disc and rear rim) to achieve the same effect.

thats funny im worried about being able to hit 40mph on a bike. ill stop when i hit an uphill ;)

In traffic or in an emergency where you just can't swerve away, stopping quickly, safely, and correctly can save your life.

Hitting 40 mph isn't too hard if you have a long down hill. Just don't pedal, that'll ruin your aero position. Just get real lean and coast.

exactly,

I've had many near hit instances..one time i was flying down a hard hill, and i see something in the edge of the trail...couldnt swerve it due to the narrow trail, so i slammed the brakes...I gtopped withint a few feet of this passed out drunk (possibly homeless, too dark to tell). Could have killed him if I hit him going 30. So it's not always jsut your life that proper braking can save.

Man, if I get going that fast I will be screamin like a baby! On a bike that would feel like warp 2!

I think what makes the front brake feel a little awkward to me is the front suspension. I never had a bike with suspension before, and it's weird to me how it mushes down in a quick stop (not that I have had many of these).

Don't ever want to lock a front wheel. You will flip the bike. Eack bike handles differently. On my old Raleigh Grand Prix the rear would just start to lift as got close to lockup. My Trek is far different. The rear wheel will lift with only moderate braking on the front. On my recumbent I've never had to go to wheel lock but my guess is that locking the front will result in loss of stering, a skid and wreck. A rear wheel skid could be just as bad although possibly recoverable if you got off the brakes quick enough.

'bent Brian

If you ride a road bike, and the front caliper won't lock up at all, I'm guessing you either have worn-out pads, steel rims, or the brake cables need to be tightened.

I locked my front caliper the other day, when a pedestrian made an unexpected turn into my path. The rear lifted about a foot off the ground before I came to a complete stop. Fortunately the impact was minimal, and neither of us fell or were hurt. We both appologized profusely.

And as far as Sheldon's recommendation for only needing the front brake, I have to respectfully disagree. The rear brake is very useful for slowing down on long descents, additional stopping power on wet roads (rear-wheel skid is much more forgiving than front wheel skid), and using it reduces wear and tear on the front pads and rim. Fixed-gear bikes may not need them because pedaling slower should provide some rear wheel braking, but they do serve a purpose on a bike with a freewheel.

I find it funny how many "don't lock front brakes" there are. Its excellent practice to find the front balance point (especially for mtb) and when you get good there are some fun tricks you can do. I am still looking for a set of brakes where I can be seated with weight back and lock the front to lift the rear up for a seated nose manual :)

Some well set up Avid Mechs. :)

you have a "Bighit Comp 2002, Kona Roast 2002 and specialized BMX"... not sure if youre aware that its very very difficult to lock up the front brakes on a road bike... i would say impossible if not for very special circumstances

I was wondering about a MTB (diamonback outlook). I just had the bike tuned, and now the front brake seems to have a little more stopping power to it. I don't actually know what the mechanic did. Tomorrow I'll have to try out locking up the front wheel again.
The whole reason I brought this up was, that I was under the impression that if I couldn't lock up the wheel, then the brakes must not have enough stopping power and that they needed to be readjusted.

yeah, you don't want to lock up anything, because that's when you're losing traction (the reason why cars have ABS). and i don't know about the idea of the caliper not being able to lock a front wheel. i've done some mean endos (a couple intentional) on my 80s road bike with the original calipers and pads.

Vs and Cantis should definately be able to lock the front.. if they cant then they are maladjusted

actually they should grab hard, very hard, but not lock up. I have an outlook as well, and what should happen is the fork should drop signifcantly, and you feel the back tire lose some traction at most. Anything more is not really a good thing unless you are all about tricks...and really, the outlook is not the best choice to be doing stunts on...it's a light duty trail bike, not a freestyle BMXer. In all truth, I felt the level f urban irding i gave my outlook was a bit much...given it still rides fine, but I know i've hit the limits of it a few times, and I'm not even some super fit competiton type...just a fat guy with decent leg power :p

Yeah Catatonic, that describes what happens with the front fork on mine. What do you mean you "hit the limits a few times"? You mean you went up and down stairs a lot?