Rider down - am I really that cr*p...?

Originally Posted by andreis

When releasing too much the wheel would would start spinning again. And by spinning I mean that the engine is spinning the wheel again, not that the wheel would start to spin because of the forward motion of bike + friction.

Tha above assumes that the throttle is open such that the engine speed is greater than the road speed. The only way the wheel will "spin up" is if the engine revs are high.

When braking in general, on the road, you should virtually always have the throttle closed, which will make the engine want to return to idle, not increase in speed. This causes enginge braking, and whilst not really needed, can be extremely helpful... I'll come to why in a second.

If the force applied to any brake disc is sufficient to lock the wheel up, releasing the brakes removes that force from the equation. Given I've already said that the throttle should be closed (in almost all situations), the wheel will start rotating again, but solely because of friction with the road surface. It won't spin up in this situation, because the engine is still busy trying to idle, not accelerate.

Now, engine braking... if you do lock up the rear wheel by accident, the rear is going to want to "fishtail" - as in, the back of the bike will want to move sideways if you lean over at all. To prevent this, releasing the brakes will allow the wheel to grip, and due to the fact the SV is a V-twin engine, engine braking will mean there is still some brake force applied (from the engine, not the brake pads) whilst the brakes are released, thus allowing you to slow down marginally quicker. Of course, engine braking doesn't really apply in the case of a locked front wheel.

With a locked rear wheel, the bike is pretty easy to control, even the wheel remains locked (just don't be expecting to stop any time soon!). With a locked front wheel, there's a very big risk of "low siding." Low sides like this happen because the front wheel isn't gripping the tarmac due to it being locked (anyone that's ridden on snow/ice will know the feeling). To prevent a low side like this, your only option is to release the brake. You obviously don't need to worry about the front wheel spinning up, as there's no driving force on it other than the road itself. If you still want to stop quickly, then you'll have to re-apply the brakes.

In fact, the UK bike test has an emergency stop test included. If you lock the rear tyre up, that's OK. But if you lock the tyre & do not release the brakes then subsequently re-apply them, you fail that element of the test.

I've personally locked both tyres (individually and a couple of times both at the same time!!), and the above has kept me safe with no major drama.

Originally Posted by andreis

Anyway, the best way is to never lock up

Very true, although I'd still advise anyone to practice locking the tyres, just so that they know what to do in the event of accidentally locking them during an emergency brake.

[ophic]

The problem is the fishtailing that Baph mentions. A locked rear can fishtail too far to one side, and it does this very quickly if the bike is at all leant over. If the brake is released at this point, the rear suddenly gains traction and starts turning again - only its now pointing significantly in the wrong direction. The whole bike snatches violently back into line and this can cause a highside if severe enough. Some people do teach that if you lock the rear, you keep it locked, to avoid this exact situation. It means that if you're at all leant over, you will lowside instead of highside.

Originally Posted by petevtwin650

Better vision, so you weren't surprised by the vehicle maybe?

Very good point - its all about road positioning for the best view to enable good forward observations - prevention better than cure

[Mr Speirs]

Originally Posted by Jamiebridges123

I just stopped caring if I die or not, if I fall off or not.

Trust me, if you are getting on your bike with that attitude you should stop riding. That's the attitude I had (apart from the die bit) before my accident and you have no idea just how stupid, naive and over confident I felt. An attitude like that allows you to ride beyond your means and if your lucky you don't hit anybody and you survive to learn your lesson.

Originally Posted by petevtwin650

Better vision, so you weren't surprised by the vehicle maybe?

Originally Posted by ArtyLady

Very good point - its all about road positioning for the best view to enable good forward observations - prevention better than cure

I agree. It seems that it was your poor positioning that is the root cause, only compounded by your grabbing the brakes. Had you been in the best position and speed you may not have needed to touch the brakes at all. Get some advanced training, you don't have to agree with all the stuff presented to you, but a good observer should be able to help you.

Of course everyone makes mistakes, it's more important to learn from these so as to not repeat them. Learning from others mistakes has to be less painful and cheaper.

[Biker Biggles]

Abs ???????

My last two offs have been down to locking the front wheel because I was too aggressive on the front brake.

Chalk it off as experience. You live and learn. Practice progressive braking, I'm going to when I get back on a road bike. 2 and a half years of riding and I still can't ride properly

Originally Posted by Mr Speirs

Trust me, if you are getting on your bike with that attitude you should stop riding. That's the attitude I had (apart from the die bit) before my accident and you have no idea just how stupid, naive and over confident I felt. An attitude like that allows you to ride beyond your means and if your lucky you don't hit anybody and you survive to learn your lesson.

I don't ride like a numpty. I simply don't worry about dieing because that causes you to panic. I had a severe off a while back and since then my riding has changed for the better. But if you worry about dieing you start making panic decisions which often cause you to crash.

Originally Posted by ophic

The problem is the fishtailing that Baph mentions. A locked rear can fishtail too far to one side, and it does this very quickly if the bike is at all leant over. If the brake is released at this point, the rear suddenly gains traction and starts turning again - only its now pointing significantly in the wrong direction. The whole bike snatches violently back into line and this can cause a highside if severe enough. Some people do teach that if you lock the rear, you keep it locked, to avoid this exact situation. It means that if you're at all leant over, you will lowside instead of highside.

All very true, but for the most part, the theory of teaching to keep the rear locked if it does lock is very outdated.

As I stated, do that on a UK bike test, and you get a major fault for it.

A couple of years ago, I had an incident where the bike seriously fishtailed. I was riding beyond my ability, and simply not thinking about what I was doing.

Esentially, I was going over the speed limit, and came around a corner to find a line of stationary traffic in a queue at roadworks traffic lights. This was a single carriageway road, and as I hit the brakes, the bike was still leant over. The front brake made the bike want to stand up, so I leant over even more to avoid on coming traffic. That made the rear step out to the right. So I released the rear brake, and re-applied. The bike then "snapped" back exactly as described above (only without the high-side - you have to be VERY far out for a bike to hish-side like this!), and I locked the rear up again & the bike stepped out to the left.

As this point, the stationary bus ahead of me was approaching fast. Probably an estimated collision speed of 50mph.

The only option I had available, was to release all brakes, and put the bike down the side of traffic, between those queuing and those on-coming. This allowed the bike to settle, so then I could get back on the brakes - in a straight line, and stop before the red light.

That day taught me a serious lesson in my riding ability. I'd seen the roadworks that morning & not given them a consideration at all on the way home. It could of all been avoided with a little forethought.

[ophic]

Originally Posted by Baph

All very true, but for the most part, the theory of teaching to keep the rear locked if it does lock is very outdated.

Didn't say I agreed with it there must be a point of no return there somewhere though.

Originally Posted by Baph

you have to be VERY far out for a bike to hish-side like this!

actually you don't - you just need to be at quite a high speed - and probably some other combination of lean angle, front brake... i dunno. But I've seen it happen on a track much more easily than you would expect - rear only veering out by a few degrees. I think I flipped my 125 this way but i've got no real idea as it was all a bit frantic.