Braking Advice ...

cedar404

Returned to cycling recently on a Focus MTB, but as i found I spend little time on mountains I sold it to a work colleague and got a Focus Cyclo-cross bike (Mares Comp 2010).

Went out for the first time today, conditions not great but was determined to go out for a cycle. It rained for about the first 90 minutes quite consistently and then the sun came out. Near the end of my cycle I was coming down a small country lane (wet, strewn with leaves and a bit muddy in places) with about a 10% gradient, sharp corner to the right, braking from the drops at not that fast a speed when I suddenly realised the back wheel had totally locked up and I was now sliding sideways across the road smack into a hedge !

Fortunately I escaped with just cuts to my hands. Had a nice chat with a farmer who wandered up the road to see me, he reckoned I was the latest in a long line of cyclists to misjudge the corner and end up in the hedge.

My question is what did I do wrong here ? I'm a pretty nervy downhiller so I was not going that fast, going from disc brakes to the v brakes on the new bike did i simply misjudge the stopping power and have now learnt my lesson ? Any tips on how to corner on downhills without sliding out ?


Cheers.

cedar404

Aha, so I am reading on Sheldon Brown that I probably fishtailed, would this have happened if the road had been dry ?

Aggieboy

Were you braking 'in' the corner? It's best to take your speed off, in a straight line, before entering the corner. Otherwise your momentum is taking you, in this case, towards the hedge (as you found out ). Hope you're OK.

cedar404

To be honest just at the moment I was thinking about leaning in to the corner I realised everything was going sideways (literally), next couple of seconds I don't remember and then i was underneath my bike thinking why am i in a hedge by the side of the road

John.T

All heavy braking should be done before the corner if possible and using the front brake most. On dry surfaces you will hardly need to use the rear at all as there is not much weight on the rear tyre due to weight transfer from the front braking. In less good surfaces you should use both brakes but still the front one most. It is a question of finding the levels of adhesion but you have just found one limit the hard way. It is better to 'push the envelope' gently until you know the limits. If your bike is using cross tyres you have probably the worst setup for greasy tarmac. Slicks are much better. MTB tyres put more rubber down but the tread is not stable. Cross tyres do not put much rubber down but the tread will move about under braking.

andrew_s

You were using too much back brake.
You can brake harder using just the front brake than you can using both brakes.
Sheldon was an advocate of using the front brake only, so you learnt how to brake as hard as possible.

If you are just riding along on a flat road, about 1/3 of your weight is on the front wheel, and 2/3 is on the back wheel. If you are going downhill, you'll have more on the front and less on the back. If you are going uphill, you'll have less on the front and more on the back.

As you brake, weight is transferred from the back of the bike to the front. The limit on how hard you can brake is determined by the point as which you have no weight at all on the back wheel. If you try to brake harder, you do a face plant over the front of the bike as the back wheel comes up in the air. Fairly obviously, at this point you are doing no braking with the back brake at all.
If you are using the back brake, before all of the weight has gone to the front the back wheel will start to skid. Once it's skidding, it will go sideways just as easily as forwards. The front of the bike is still slowing down, so the back wheel will try to overtake the front and you get the back of the bike moving sideways.

If I'm interested in braking hard, I do almost all my braking with the front brake, with just a gentle touch on the back brake. Then as soon as the back wheel starts to skid, I let go of the back brake and stop squeezing the front brake harder.

That's all on clean and dry surfaces, where it's impossible to skid the front wheel as the back wheel lifts first. If the road is greasy or sandy, then you won't be able to brake so hard, and due caution is in order.

the_village_idiot

i dunno anything about bikes but.....

its no different from driving a car- which i do dabble in:

You over steered into the corner- as someone has said- as you brake you shift weight forwards- giving the front more traction- and the rear less- so you locked it up

Much like in cars- do most of your braking in a straight line.

You can do it around a corner- but if your asking the wheels to give some of their traction to turning- you cant expect them to brake to their full capacity at the same time. If you do brake- apply most of it to the front wheel (which has more traction)

markos1963

In the dry you should be able to split your braking force 75-25 front to rear, in the wet split it 50-50, to do this on a downhill section push your weight rearwards and shift backwards on the saddle, this will move the weight distribution backwards and help to stop the back wheel locking up. As others have said get the braking done in a straight line and freewheel through the bend.

oldwelshman

In wet, shift backwards on saddle and change braking from a 75 25 to 50 50 split, hmm a bit complex this especially going down a 10% grade.
Just practise it becomes natural but I use hardly any back brake and in wet it is easy to lock the back wheel but not too difficault to handle, lock the front and your fooked

roger_merriman

get to feel the slipping point, ie the point at which the tire starts to slide.

with practice should be able to feather the brakes and adjust the power of the brakes.

the_village_idiot

markos1963 wrote:

In the dry you should be able to split your braking force 75-25 front to rear, in the wet split it 50-50, to do this on a downhill section push your weight rearwards and shift backwards on the saddle, this will move the weight distribution backwards and help to stop the back wheel locking up. As others have said get the braking done in a straight line and freewheel through the bend.

interesting.....

please explain why you would try to change the brake byast in the wet over the dry?

obviously the absolute traction levels are less in the wet- but surly the relationship between the two is the same?

If anything in the wet i would expect you to place more braking force on the front? this means the rear has less braking responsibility- and more traction responsibility. this is good because loosing the rear is prob harder to control than loosing the front?

Perhaps lean back- giving the rear more weight, and therefore traction. However- still use the front brake say 60%- meaning that the rear is used for 40% braking- and so has lots of traction left for cornering

markos1963

the_village_idiot wrote:

markos1963 wrote:

In the dry you should be able to split your braking force 75-25 front to rear, in the wet split it 50-50, to do this on a downhill section push your weight rearwards and shift backwards on the saddle, this will move the weight distribution backwards and help to stop the back wheel locking up. As others have said get the braking done in a straight line and freewheel through the bend.

interesting.....

please explain why you would try to change the brake byast in the wet over the dry?

obviously the absolute traction levels are less in the wet- but surly the relationship between the two is the same?

If anything in the wet i would expect you to place more braking force on the front? this means the rear has less braking responsibility- and more traction responsibility. this is good because loosing the rear is prob harder to control than loosing the front?

Perhaps lean back- giving the rear more weight, and therefore traction. However- still use the front brake say 60%- meaning that the rear is used for 40% braking- and so has lots of traction left for cornering

Actually braking and traction are the same thing, grip. You need to be in control of both wheels weather braking,steering or accelerating. In the dry you can get away with putting more pressure on the front during braking as you have more grip, the weight transfer forwards during braking acutally increasing grip. In the wet you have uncertain levels of adhesion and so you need to achieve the same amount of braking but using both wheels, if you lose the front under braking you will undoubtedly fall off, you have more chance of recovery if the rear breaks away, ideally you don't want that either so the need to balance your braking is needed. Hope thats clearer than it looks! This principle I have transfered from 30 years of motorcycling and it worked pretty good for that and so far its working on bicycles for me.

cedar404

Thanks for the words of wisdom guys. I managed to get out on Sunday for a while in the raging winds, the roads were dry so braking was much easier.

I think the main thing I have to overcome is coming from a MTB with disc brakes to my new bike, and working out as I go along what sort of braking distances are realistic + when to brake, oh and not brake in the corner !

Hornetto

It is really interesting to hear all the stuff about using the front brake. From childhood I was always told not to use the front brake at all because it is likely to send you over the handlebars. To this day I do most of my braking with the rear (with the occasional touch on the front to take extra speed off when already applying the rear), most likely because of the advice I was given as a child.

Was what I was told when I was young bad advice, and have I unwittingly been doing it wrong all these years as a result??? :shock:

211dave112

you say that you are a nervy descender, that's prob part of the problem, when you're nervous you're more likely to grab at that brakes and over do it a little bit. when you're relaxed it's easier to think things through in your head and do everything that bit smoother.

Rockhopper

I never actually use the rear brake on my Ducati, becasue of the two massive disks up front its not really needed (plus the rears don't work very well anyhow) and if i'm braking nice and hard i can lift the rear wheel off the floor so not much point trying to use the brake!

On push bikes some people say use more rear in the wet, this is not a bad idea becasue if it does lock up its easier to save a rear end skid than a front end one.

Mister W

Hornetto wrote:

It is really interesting to hear all the stuff about using the front brake. From childhood I was always told not to use the front brake at all because it is likely to send you over the handlebars. To this day I do most of my braking with the rear (with the occasional touch on the front to take extra speed off when already applying the rear), most likely because of the advice I was given as a child.

Was what I was told when I was young bad advice, and have I unwittingly been doing it wrong all these years as a result??? :shock:

It's a myth... unless you hit something it's very difficult to go over the handlebars. When on two wheels you should use more front brake than rear. As you brake your weight shifts forward over the front wheel, giving you more traction on the front wheel and less on the rear. That means it's easier to lock up the rear when braking, which means it's better to use the front brake.

Ask any motorcyclist or look at the braking system of any motorcycle. They all have better brakes on the front than the rear because you use the front brake much more.