Kontact

Skidding tires don't necessarily stop faster than brakes. This is part of the reason for anti-lock brakes.

Ironfish653

The ‘no’ is more in how the bicycle itself is reacting during the brake application.
There is a ‘compression’ of the front, and an unweighting of the rear, but on a rigid road bike, you may not realize how close you are to a skid or lockup because the bike doesn’t really telegraph what’s going on.
instead of a motorcycle, we’ll compare and full-suspension MTB to a fully rigid road bike. The CG and mass distribution are more similar, but the MTB will also exhibit the dive and squat behavior under braking that tells you how much extra load you’re putting on a particular tire and how fast the limit is approaching. On an MTB though, you also have the added advantage of being able to use the rider’s body mass to move significantly counter those forces than on a moto.
On a rigid road bike, these things are still happening, but the only “suspension “ is the flex of the tire sidewalls. Without that feedback, bad braking habits or less than optimal technique is “fine” right up until a skid or lockup.

wolfchild

ABS brakes doesn't mean shorter stopping distance, they just allow better steering and control....On snow and ice covered roads ABS brakes will cause the wheels to lock up.

Kontact

And therefore a skidding 28c tire will stop quicker than at maximum brake pressure below lock up?


Under normal circumstances car tires don't skid on dry pavement. When it is slippery, antilock brakes keep the lock ups short so the wheels don't hydroplane - which would increase stopping distances compared to the brakes working. Bikes have little contact patch and behave a bit more like wet pavement comparably.

https://www.icbc.com/partners/driver...nts/ts274w.pdf

tomato coupe

Okay, but I didn't make any mention of brake application, so maybe you meant to direct your explanations to another person?

big john

He means a skidding tire will contribute to deceleration more than a tire which isn't being braked at all.

Kontact

I kind of doubt that's what he meant.

big john

Well, it is what he wrote. Maybe he will come back and let you know.

Eric F 

I understand that, but that’s not what I said. A skidding rear tire will contribute to deceleration more than not using the rear brake at all.

It’s exactly what I meant.

Kontact

I see. Since you need a brake to skid, why skid the tire at all instead of modulating the brake?

Ironfish653

Quite possibly. I may be answering a question that is composite of other posts as I've come and gone through this thread today.
I was trying to stay within brake application, since the OP question is if bikes really need a rear brake.
As we saw in the How You Ride A Bike thread, the perception of feedback and control inputs is a whole kettle of dynamic variables, that proved very hard to pin down any sort of consensus; so I chose to try to keep it to the minimum of conditions an operations within the scope of the OP

rsbob 

If bike companies could get away with selling bikes with only a front brake, they probably would. Legal concerns no doubt preclude that.

Next question please.

terrymorse 

I know many people think that braking in a turn risks sliding the front wheel, but you would have to grab a huge amount of brake to actually slide out on hard, dry pavement.

You can draw a force vector diagram to convince yourself, as the braking force and the centrifugal force are perpendicular.

Eric F 

Your reading comprehension sucks…or you’re being intentionally adversarial.

Please review the context of the post I was responding to regarding rear brake use in an emergency stop.

50PlusCycling

Not superfluous, I can tell you this as a longtime motorcyclist. Rear brakes are quite effective, and allow you to use less of the front brake. We all know (or should know) what happens when you grab too much front brake. I have a nice lump on a collarbone to remind me.

PeteHski

Yeah, you can get away with a lot on dry pavement when you are nowhere near the limit of either braking or lateral grip - i.e. nearly all of the time. It's usually in the wet that it all goes wrong for those who overstep the mark.

The force vector diagram you refer to is known in motorsport as the "traction circle" i.e. a vector plot of the combined longitudinal and lateral grip available from the tyre. In reality it's more like an ellipse, but the principle is clear i.e. If you are braking there is less lateral grip available from the tyre and vice-versa.

Kontact

No, I was just wondering in what situation anyone would ever choose or want a skid. It never seems necessary or useful.

prj71

I'm riding along at 22 mph. All of sudden a car runs the stop sign and pulls out in front of me or a deer in the field next to me decides to jump out in front of me.

Both have happened to me. Typical human reaction is to grab both brakes real hard in those situations...then you skid. Not unheard of or uncommon.

Kontact

And feeling the onset of the skid, and not being a bot (like some forum members), you release some of the pressure and modulate the brake as you've learned from riding a bike over time.

prj71

Doesn't work like that when said objects are literally less than 50 ft in front of you.

Kontact

It worked when I had the incident I described in this thread. Otherwise I would have crashed.

beng1

Rear brakes are important in some situations. If you are going very fast downhill and trying to slow, then the rear brake will have a lot to contribute because the deceleration is not high compared to someone coming to a complete stop abruptly. If you look at the brakes on passenger automobiles and motorcycles, the front brake is always much larger than the rear brake, because braking transfers all of the weight to the front wheels and they have more grip the harder the deceleration, while the rear wheel has less grip because of weight transfer. So if the operator of a bicycle or motorcycle or any vehicle with separate controls knows these facts, then they can use their brakes front and rear to maximum effect.

Going down some very steep hills on a MTB, I drop behind the seat and put my butt right over the rear tire of course, and this lets me use both brakes and stay slower and safer than the braking power of just one wheel can. And if I am going down steep grades, or just stopping on the level from a high speed that is not a panic situation, then I can use both brakes with ease and save wear and tear on the front pads.

Disc brakes put far, far more strain on spokes and wheels than rim-brakes do, as all the force of braking has to travel through the spokes to the rim and tire, so the wheels have to be in top condition with the spokes at a high tension so they do not have to endure cyclic loading and unloading as much as they would if their tension was not up to snuff.

Us older riders grew up in the 70s and earlier riding bikes with nothing but a rear coaster brake, and we would delight in seeing who could make the longest skid mark with the rear wheel, and we became expert at stopping by skidding and controlling the skid, it was fun. The coaster, like the disc, also put a terrific strain on the spokes, but we had thick spokes and steel rims and tires of thick rubber, so we never had problems. My current road bike has nothing but a coaster, and using some common sense I have had no trouble in city traffic or down steep descents and have not locked the rear wheel up once even on wet roads. One of my next projects will hopefully be riding a fixie with no brakes at all in city traffic and down hills as riders had to do in the 19th century as a bit of historical research, and as a lot of people still do. So if safe riding can be had with coaster or no brakes, then having any disc or rim brake at all should be sufficient for riders with common sense.

If you are often getting into panic-stop situations, which is about the only riding scenario where the rear brake will cause the rear wheel to slide from lack of braking experience, then it is time to think about your riding style and why you are always getting into trouble.

Nyah

After the mishap I had yesterday, I was thinking the same method. Because I put my focus on the front brake, when I had little time to react (stopped-car in front of me), I went OTB. I need to focus on applying the rear brake first and follow-up with the front.

Eric F 

On a road bike, probably not. I never implied that anyone would/should intentionally skid the rear tire in an emergency stop, but it happens sometimes, even with experienced/skilled riders. If it starts skidding (the exact words I used before), it's still more effective at slowing the bike - in combination with the front brake - than using the front brake alone. You directly doubted that I meant this, but it's exactly what I meant from the start.

Steel Charlie

As a right handed ex-motorcycle racer it always seemed intuitive to have the front brake on the right lever. Setting up the bicycles the same way was a no brainer. I use and recommend right lever to the front brake to right handed anybody.
JMO of course. YMMV