Brake technique

Bicycle related chatter & discussion
User avatar
marc2131
Posts: 1120
Joined: 03 Jul 2011, 13:14
Location: Ashbury
Contact:

Postby marc2131 » 05 Jul 2012, 09:21

Been reading up a bit on this and have not come up with a definitive answer.
I know CNSW has trained some DHBC riders, was braking technique discussed and/or taught?

User avatar
weiyun
Posts: 4173
Joined: 17 Nov 2006, 22:32
Location: Birchgrove
Contact:

Postby weiyun » 05 Jul 2012, 11:26

Sheldon Brown has written up 99% of what one needs to know about this subject.
http://sheldonbrown.com/brakturn.html

Bookmark his site, there's a wealth of cycling related information there. Well worth spending a few nights exploring.

User avatar
geoffs
Posts: 239
Joined: 20 Nov 2006, 12:07
Location: Ashbury

Postby geoffs » 05 Jul 2012, 14:26

Well nearly everything
Stuart H I think gives a better description of what the effect is of using the brakes which is as follows:
Using the front brake while turning will cause the bike to understeer or tend to go wide. This is a bad thing.
Using the rear brake will cause oversteer or cause the bike to turn sharper (up to a point where the rear tire skids)
At the motorbike training course they teach that you should only use your front brake when you are upright and going in a straight line. In other words as soon as you start to lean into a corner stop using the front brake

User avatar
weiyun
Posts: 4173
Joined: 17 Nov 2006, 22:32
Location: Birchgrove
Contact:

Postby weiyun » 05 Jul 2012, 14:52

Like driving a car, ideally one shouldn't be using the brake whilst in a turn. Brake before the turn.

User avatar
Stuart
Posts: 2568
Joined: 11 Mar 2008, 10:43
Location: Dulwich Hill

Postby Stuart » 06 Jul 2012, 14:32

The rear brake can be used to get a bike turned faster on entry and even once in the corner, just be careful you don't give it too much or the back end will slide and you may get highsided ....

User avatar
Toff
Posts: 1215
Joined: 20 Sep 2007, 14:34
Location: Stanmore

Postby Toff » 06 Jul 2012, 14:36

I remember reading an article where Greg Lemond stated that his technique for high speed cornering was to brake with both calipers before leaning into the bend, but then leaving his hand on the rear brake lever through the turn, to scrub off the last bit of speed while turning. This got him through corners just as safely as other riders, but faster, since he could enter the corner at a higher speed.

User avatar
mikesbytes
Posts: 6991
Joined: 13 Nov 2006, 13:48
Location: Tempe
Contact:

Postby mikesbytes » 06 Jul 2012, 21:46

If you want to learn about some advanced braking/corning techniques, then talk to me.

timyone
Posts: 4380
Joined: 22 Nov 2006, 20:29

Postby timyone » 08 Jul 2012, 12:43

Yeah, I personally would stick exclusively to what ever it is that Mike does.

On motor bikes they teach you to press lightly, then squeeze down for emergency and sudden breaking, not just to smash them down, as it skids, so it is two motions, I haven't had this required often on the push bike though.

User avatar
Karzie
Posts: 709
Joined: 03 Nov 2008, 17:14

Postby Karzie » 11 Jul 2012, 11:45

In my humble opinion, the most important thing is to constantly and mindfully practice braking with a dominant left hand. I think the Europeans have got it right by having the front brake in the left hand.

User avatar
weiyun
Posts: 4173
Joined: 17 Nov 2006, 22:32
Location: Birchgrove
Contact:

Postby weiyun » 11 Jul 2012, 14:13

Starting to touch on the subject of brake modulation? Going further, the hardwares matter too. The difference b/n different qualities of brake calipers/pad/rim can be highly significant.

User avatar
Karzie
Posts: 709
Joined: 03 Nov 2008, 17:14

Postby Karzie » 11 Jul 2012, 18:34

Very true Weiyun, the technology is so much better these days as well. That said, of the five or six non-collision accidents (bicycle and motorcycle) I've seen in the last couple of years, every one of them (IMHO) was because the rider hit the front brake first while the wheel was turned. There's no recovery.

User avatar
weiyun
Posts: 4173
Joined: 17 Nov 2006, 22:32
Location: Birchgrove
Contact:

Postby weiyun » 12 Jul 2012, 10:05

I think Sheldon has explained that whilst the front is the primary brake on the bike, there are still plenty of uses for the rear. Hence I agree with you that those fixie riders with only the front caliper or without any are just plain illogical if they care to ride under all conditions.

Richard
Posts: 266
Joined: 06 Sep 2009, 21:04
Location: Ashfield

Postby Richard » 12 Jul 2012, 11:48

An interesting tip given to me by a XC motocross racer / mtb rider

If you are coming into a corner and you want to scrub speed and not have the rear lock up is to put the rear brake on and pedal against it.

It sounds really counter-intuitive but it really seems to works. The rear then grabs the road. This is not really suitable for tight corners where you might touch the inside pedal on the ground.

I sometimes use this when descending in the Alpine Classic. You have to be in a high enough gear that you can still pedal in relation to the speed you are going.

Try it. Dont ask me why but it works.

User avatar
weiyun
Posts: 4173
Joined: 17 Nov 2006, 22:32
Location: Birchgrove
Contact:

Postby weiyun » 12 Jul 2012, 14:19

That makes sense from basic physics point of view.

patn
Posts: 247
Joined: 07 Jun 2010, 15:47

Postby patn » 13 Jul 2012, 11:02

i can't think of the reason why that would work-can you explain? keeping the torque very high while turning has some effect on handing? interesting, but i don't follow...

User avatar
marc2131
Posts: 1120
Joined: 03 Jul 2011, 13:14
Location: Ashbury
Contact:

Postby marc2131 » 13 Jul 2012, 11:09


Richard
Posts: 266
Joined: 06 Sep 2009, 21:04
Location: Ashfield

Postby Richard » 13 Jul 2012, 11:20

Applying the rear brake and pedalling against it is not really for during cornering but rather a great way to scrub speed before and sometime at the entry into of a sweeper on a descent without locking up the back or relying on the front for the vast majority of the braking especially when the road surface is less than ideal.

Again I am not sure of the physics behind it but it seems to work wonders if you are coming up to corner when you are at the limit (actually over the limit) and you need to scrub speed and still be in control. I am not suggesting that the front is not used but it complements the front braking a shed-load.

Try it. It sounds mad but works. It kept me on the road side of the ARMCO barriers coming down Mt Hotham in January. I had a bit more ballast around the waist this year and the brakes had to work overtime!

I'll leave to the DHBC brains trust to explain it technically.

User avatar
weiyun
Posts: 4173
Joined: 17 Nov 2006, 22:32
Location: Birchgrove
Contact:

Postby weiyun » 13 Jul 2012, 12:53


Richard
Posts: 266
Joined: 06 Sep 2009, 21:04
Location: Ashfield

Postby Richard » 13 Jul 2012, 13:02

Interesting explanation.

The key advantage to me is traction while still white knuckle braking for dear life

Its like your rear end is actually gripping the road.

mmmm - sorry that sounds like a dog with worms scraping its rear end down the road

shrubb face
Posts: 1010
Joined: 09 Sep 2008, 01:43
Location: Marrickville

Postby shrubb face » 13 Jul 2012, 14:25

Weiyun's physics is broadly right, but it doesnt really answer the question of what benefit it might provide. Given that the wheel is a closed energy system, once the wheel locks up, ie the static friction force between the tyre and the ground is exceeded by the force generated by the wheel torque, you only have two options in order to stop the skidding, either decrease the wheel torque (letting off the brakes or pedalling) or changing the dynamic friction coefficient (moving to a less slippery surface). Now assuming that we want to keep slowing down (otherwise why else would be braking?) our options for reducing the backwards wheel torque is to modulate the brakes (let them off a bit) or pedal whilst braking just as hard to induce a forward torque. Whilst both have the same overall effect on the system, it would be my opinion that you have better control/modulation of your brakes at lower braking forces, rather than pedalling and having to put the brakes on harder.

On the motorbike the benefit of using the back brake whilst cornering is different because unlike a bike wheel which has a free wheel, a motorbike (or a fixed gear bike for that matter) has engine braking effecting the process, inducing another force in the system. But that’s another matter all together.

User avatar
Toff
Posts: 1215
Joined: 20 Sep 2007, 14:34
Location: Stanmore

Postby Toff » 13 Jul 2012, 14:59

Nice one Shrubb. I was half way through typing a whinge about the ineffeciencies of pedalling while braking, which in my opinion is good for heating up your rims, but not much else. I was up to the point where I was comparing co-efficients of dynamic versus static friction, but your answer is simpler and considerably more succinct too.

I will add a couple of comments though...

- If a rider is unaware of the braking effort required to initiate a back wheel skid, I can see how pedalling can provide a safety margin for the rider, which may prevent excessive braking from locking up the rear wheel.

- Whilst it's pretty clear that pedalling while braking is a poor substitute for learning how to modulate your brakes properly, who really cares about this technique, or even if it causes you to avoid locking up the rear wheel anyway? Most of the braking is done by the front brake, and anyone who is braking at the limit of the bike's capabilities will have the rear wheel off the ground anyway. There won't be any friction, (static, or dynamic), since the rear tyre won't be in contact with the road.

So, if you want to scrub off excessive speed, and your back wheel is still in contact with the ground, you're probably not braking hard enough with the front brake.

Richard
Posts: 266
Joined: 06 Sep 2009, 21:04
Location: Ashfield

Postby Richard » 13 Jul 2012, 15:11

Time for the DHBC Mythbusters to do some field testing

Richard
Posts: 266
Joined: 06 Sep 2009, 21:04
Location: Ashfield

Postby Richard » 13 Jul 2012, 17:44

Toff et al.

All points taken and valid.

T'was just a tip passed on from another but when I had a go it apparently seemed to do something positive for reasons unknown.

User avatar
mikesbytes
Posts: 6991
Joined: 13 Nov 2006, 13:48
Location: Tempe
Contact:

Postby mikesbytes » 13 Jul 2012, 18:51

Perhaps some could get some feel with light peddling, but I'd be more interested in where I position the weight

User avatar
Toff
Posts: 1215
Joined: 20 Sep 2007, 14:34
Location: Stanmore

Postby Toff » 13 Jul 2012, 22:16

If you are descending, you should push your arse to the back of the seat, so you have more weight over the rear wheel. If you are cornering, you should weight the pedal on the outside, as if you are standing on this leg, almost unweighting the saddle. Clearly you can't pedal whilst weighting just one leg this way, so makes some of the discussion above irrelevant...


Return to “Conversation”

Who is online

Users browsing this forum: Google [Bot], MSN [Bot] and 1 guest