fishtailing under rear braking

[Euan Uzami]

On my road bike, whenever i put the rear brake on fairly hard but not as hard as the front, and after I put the front on, the rear end always seems to slide out and fishtail around. Obviously it probably looks quite cool to passers by as it probably looks like a bit of a stunt and that i intended to do it or if not that it happened 'cos i was going quite fast, but it could be a bit dangerous!
So is there a knack to not doing it?
i've got michelin pro2 tyres on there at the minute, but it used to do it on last pair of tyres I had on aswell so it's not that.

[Biggsy]

There are things you could try, including a single-pivot caliper instead of a dual-pivot, but really the best answer is simply not to pull that lever so hard.  Rely more on your front brake whenever you can.  You don't have to use the rear brake at all in most situations on the road to brake quickly and safely.

If concerened about going over the bars, it's deceleration that makes the bike tip up, and it starts to happen before the front wheel locks up.  Don't grab the lever too quickly, brace against the bars, shift your weight back, release the front brake if the rear wheel does lift and re-apply when it comes back down, and you should be OK.

For those slippery situations where it would be dangerous to use the front brake so much or at all, ideally you should be going slowly enough in the first place for a rear skid not to be too disasterous.

[Ian H]

If you brake hard enough you will lose traction.

[andrew_s]

Putting the front brake on slows you down faster, and as weight is transferred to the front wheel by the deceleration you end up with not enough weight on the back wheel to stop it locking up. Once it's locked up, it will skid sideways just as easily as forwards, hence the fishtailing.
The answer is to use the rear brake less as you pull on the front brake. If you are braking as hard as possible, the rear wheel is on the verge of coming off the ground and you get no braking from it at all.
What I do is to apply the brake brake very gently indeed, and take the rear wheel starting to skid as an indication that I can't brake any harder on the front brake without risking going over the front of the bike.

[iakobski]

The easy answer is don't use the back brake. It's completely and utterly useless for slowing you down anyway (if your front brake is working). You add nothing whatsoever by using both brakes.

There are only three uses for the back brake:

1. light braking in a corner to oversteer as described on another thread.
2. alternate front/rear braking on long descents to prevent overheating the rim
3. if the front brake fails.

I can't remember the last time I used the back brake, the blocks are like new and the bike has done 30,000 km.

[Che]

The easy answer is don't use the back brake. It's completely and utterly useless for slowing you down anyway (if your front brake is working). You add nothing whatsoever by using both brakes.

There are only three uses for the back brake:

1. light braking in a corner to oversteer as described on another thread.
2. alternate front/rear braking on long descents to prevent overheating the rim
3. if the front brake fails.

I can't remember the last time I used the back brake, the blocks are like new and the bike has done 30,000 km.

4. (and as hinted at above) braking in conditions where skidding is likely, as a front-wheel skid will floor you, while a rear-wheel skid, as you've observed will generally not.

[andygates]

And stick your arse back off your saddle, to move your weight back.

[Jacomus]

And take your weight on the pedals not the bars.

[tiermat]

The easy answer is don't use the back brake. It's completely and utterly useless for slowing you down anyway (if your front brake is working). You add nothing whatsoever by using both brakes.

There are only three uses for the back brake:

1. light braking in a corner to oversteer as described on another thread.
2. alternate front/rear braking on long descents to prevent overheating the rim
3. if the front brake fails.

I can't remember the last time I used the back brake, the blocks are like new and the bike has done 30,000 km.

4. (and as hinted at above) braking in conditions where skidding is likely, as a front-wheel skid will floor you, while a rear-wheel skid, as you've observed will generally not.

5. If you have a front tyre blow out/puncture, trying to slow yourself by using the the front brake would be at best stupid, at worst suicidal....

I only use the back on long descents, as previously mentioned, and tend to go through front brake pads like no tomorrow, but I am only on my second set of rears after 2 1/2 years and nearly 4.5K miles.

[Biggsy]

Moving your weight back and putting it through the saddle or pedals will make the rear wheel less likely to lift, but will make the front tyre more likely to slip.

Particularly, without the normal weight on the front, the front tyre will effectively be over-inflated and more prone to bouncing up and loosing traction after it hits a bump.

[Jacomus]

Moving your weight back and putting it through the saddle or pedals will make the rear wheel less likely to lift, but will make the front tyre more likely to slip.

Particularly, without the normal weight on the front, the front tyre will effectively be over-inflated and more prone to bouncing up and loosing traction after it hits a bump.

Which is why you should run your front tyre inflated to whatever pressure lets it deflect the same as the rear, which is generally about 1.5bar less on a roadbike, 1bar less on a mtb.

Taking your weight on the pedals under braking does not stop the increase in effective weight on the front tyre as you brake, the frame still transmits it.

Using your legs, which have very little to do with steering, to resist the weight of your body attempting to keep moving forwards, allows a lighter touch on the bars, which increases your control over the front wheel, and decreases the effect that bumps and ripples have on your steering.

[Biggsy]

Which is why you should run your front tyre inflated to whatever pressure lets it deflect the same as the rear, which is generally about 1.5bar less on a roadbike, 1bar less on a mtb.

The difference in air pressure you would normally use is only enough to equalise the deflection when your weight is distributed normally.  Shift your weight back further than normal and the front tyre will be over-inflated then.

If you have the front tyre soft enough to be properly inflated when your weight is well back (further than normal), it will be chronically under-inflated for normal riding.

Some weight is transmitted by the frame to the front wheel when you put it on the pedals, but more weight goes to the the front wheel when you put it on the bars.

In some situations, it is dangerous to reduce the weight that goes on the front.

[Chris N]

There are only three uses for the back brake:

1. light braking in a corner to oversteer as described on another thread.
2. alternate front/rear braking on long descents to prevent overheating the rim
3. if the front brake fails.

4. (and as hinted at above) braking in conditions where skidding is likely, as a front-wheel skid will floor you, while a rear-wheel skid, as you've observed will generally not.

5. If you have a front tyre blow out/puncture, trying to slow yourself by using the the front brake would be at best stupid, at worst suicidal....

6. When signalling to turn right (if your back brake is operated by the LH lever).

I use mine rather a lot - especially when riding fixed.

[Jacomus]

Which is why you should run your front tyre inflated to whatever pressure lets it deflect the same as the rear, which is generally about 1.5bar less on a roadbike, 1bar less on a mtb.

The difference in air pressure you would normally use is only enough to equalise the deflection when your weight is distributed normally.  Shift your weight back further than normal and the front tyre will be over-inflated then.

If you have the front tyre soft enough to be properly inflated when your weight is well back (further than normal), it will be chronically under-inflated for normal riding.

Some weight is transmitted by the frame to the front wheel when you put it on the pedals, but more weight goes to the the front wheel when you put it on the bars.

In some situations, it is dangerous to reduce the weight that goes on the front.

Yebbut how much can you change your centre of mass by hoiking back in the saddle (unless practicing mtb/dh stylee bum over the rear wheel - which isn't easy with a saddle at the correct height).

Couple of inches back?

Putting your weight through the bars or though the pedals cannot change how much you weigh, or where it affects the bike - the front wheel.

It can feel as if more weight goes onto the front wheel, because you are using your relatively weak arms to support your body, not your incredibly strong cyclists legs. The adverse effect on how the front wheel tracks also seems to support this idea, though that is a misinterpretation of causality - the steering goes heavy and hard to move because you are keeping yourself on the bike with the same muscles as you are trying to steer with, not because all your weight is going through the front wheel.

Just to make sure we haven't crossed wires, when I said taking your weight through the pedals, I didn't mean get back in the saddle, I mean cocking the pedals to horizontal and supporting your weight through your legs, without really changing your body position backwards.

Weighting the bars as you brake is more dangerous than weighting the pedals - because if you lock the front wheel, with your weight on the bars, the front will disappear from underneath you, pushed away by your own weight. With weight on the pedals, you have a *small* chance of catching the bike, as your weight isn't being borne by the steering.

BTW, I am fully prepared to accept I'm wrong if someone can wade in with some facts n figures to disprove me.

[Ian H]

BTW, I am fully prepared to accept I'm wrong if someone can wade in with some facts n figures to disprove me.

There are few real facts and figures in cycling and an awful lot of spurious ones.

If you watch good descenders, they get into a racing position — bum back on the saddle, elbows bent, back horizontal. They don't jerk the bike about; rather they flow smoothly round corners. Watching them is generally more informative than listening to their theories.

[Biggsy]

On the road, there is only a slight chance of recovery in a corner once front tyre has started to slip sideways.  You are more likely to start slipping sideways if the front wheel is loaded too lightly.  The priority should be to prevent any slipping in the first place.

The point that needs checking is whether the front wheel is loaded less heavily when you put less weight through your hands.

Since the pedals are further back, I would have though that weight on them is distributed more evenly to both wheels than it is when putting more weight on the bars.

EDIT: I realise you have to lean further forwards to increase load on front wheel.

I do accept that you won't shift tooooo much weight back on a road bike purely by sitting further back in the saddle.

EDIT: Actually I'm not sure I do accept that because there are times when even that might be enough reduce front traction enough to make the tyre slip.

[Biggsy]

There are few real facts and figures in cycling and an awful lot of spurious ones.

If you watch good descenders, they get into a racing position — bum back on the saddle, elbows bent, back horizontal. They don't jerk the bike about; rather they flow smoothly round corners. Watching them is generally more informative than listening to their theories.

Yes, but also you have to think about your own experiences and use theory to help you work out what was going on and how you could do better.  Copying a racing cyclist won't help me when I'm not riding the same bike in the same way.

Pro racers use long low handlebar stems, so actually a fair amount of their weight goes on the front wheel even when they appear to be leaning back.  With a bit more of an upright position, I'm concerned that sometimes there won't be enough weight going on the front.  I'm wondering if that caused my last crash.

[Jacomus]

Remember that this is the braking thread, not the cornering thread.

Weighing the bars as part of cornering is just as important as keeping your weight off the bars whilst braking is.

[Ian H]

Remember that this is the braking thread, not the cornering thread.

I think I'm going round the bend. Confused at least.

[Biggsy]

Remember that this is the braking thread, not the cornering thread.

Fair point.  Subjects this big get confusing.

Weighing the bars as part of cornering is just as important as keeping your weight off the bars whilst braking is.

One aspect is the same, though.  Whether cornering or braking, the tyre is more likely to start skidding when it is less heavily loaded.  But I agree that a skid is more dangerous when there is more weight on the wheel.  All this could apply to either wheel.

So, although there are times when you should shift one way or the other, I think it's a good compromise between preventing a skid and making a skid more bearable, normally, to balance your weight between the two wheels, for braking as well as cornering.

[Che]

... a skid is more dangerous when there is more weight on the wheel.

Trying to decide if I buy that or not. I think that it's pretty much the case that if you have a front wheel skid under any circumstances (only happened to me once, and that was on diesel), you're going down fast and hard, no matter what.

[Biggsy]

Trying to decide if I buy that or not. I think that it's pretty much the case that if you have a front wheel skid under any circumstances (only happened to me once, and that was on diesel), you're going down fast and hard, no matter what.

I think you might go down even harder if there was more weight on the wheel, and it is possible to recover from a front-wheel skid if you're going in a straight line.

But I know it doesn't take much of a fall to get a nasty injury.

[andygates]

I've never recovered from a front-wheel skid.  Bam! Sack of potatoes, every time.  I *usually* recover from back-wheel skids.

[Euan Uzami]

ok
I'm getting the impression that the general consensus is weight back helps, albeit how much it helps and in what way may be debatable.
so  thanks for the informative suggestions.

... You don't have to use the rear brake at all in most situations on the road to brake quickly and safely.

if i hadn't have done in this situation i would have been embedded in the rear end of a renault clio. 

[teethgrinder]

I've never recovered from a front-wheel skid.  Bam! Sack of potatoes, every time.  I *usually* recover from back-wheel skids.

I have.
It's extremely rare for me to get a front wheel skid. It wasn't servere and I was going in a straight line  (until I started to skid) and hit a wet drain cover. I've had others I've recovered from too. but I don't really know what I did. I just sort of went with it. Probably a lot of luck involved too.