Modern Vespa

I have been testing GTS300 (and my own) stopping capabilities. Training for the eventual need for a panic stop. Yesterday whilst heading to work I saw a light turn yellow in front of me that I would have normally driven through versus trying to stop. The intersection doesn't have traffic coming from the right and the traffic coming from the left has to cross a long distance to get to the far lane I was in. Additionally there were no cars close behind me. So with the light coming on fast and me traveling 50mph, I decided to hit the brakes hard to see if I could make the stop by the white line.

Just as I was thinking that yes, I was going to make it, I felt my rear tire start to slide out to the right and had to lay off the brakes to keep the bike up. Ended up stopping a few feet past the white line, embarrassingly rolling back behind the white line as other cars were coming to a stop behind me.

Lesson learned? Well, I thought the speed and distance were safe for the stop attempt, but if I was actually trying to stop from hitting something real, I would have either gone down or rammed right into it.

I'm a fairly new rider (1 year) and hadn't yet felt the rear wheel slide out like that while hard braking. Anyone else prone to testing their panic stopping and experience similar sensations?

If there's nobody around, then yes I do tend to test such situations out. Mainly because I'm new to riding on the roads and that's how I make myself comfortable with the machine.

Sliding the back wheel I'm ok with now, fairly happy with it. Haven't tried a stoppie yet

Mainly because we're going to Jamaica week after next and I don't want to go in plaster

I slow down hard when getting home. Its not a stop but it would help in a

accident I think. Maybe I should hit a parking lot and try a few myself.

Paul

This thread had loads of good tips from people.

You probably already know this, but it bears repeating.

Use both front and rear brakes. The front brakes account for about 70% of the stopping, so if you use only your rear brake, you're only getting about 30% efficiency.

The key to not locking up the front brake is apply steady pressure to the brakes until you feel the weight transfer to the front forks. Once you feel that, you can squeeze a lot more. The real key is feeling the weight transfer. Once you feel that, the chances of locking the front wheel decrease significantly.

Did you take the MSF course? If so, remember what they said about what to do when you lock the rear wheel? Hint: Keep it locked. When the rear locks and starts to drift off center from the front and then regains traction while the wheels are pointed two different directions, a high side situation can be induced... very much not a good thing.

Nice post you made in that thread. This comment applies to what I experienced:

Skids happen if you apply too much brake to one wheel. If you find the rear brake skidding then don't panic - just release the brake for that wheel. If the front wheel skids then it's very very easy to fall off unless you release the brakes instantly. If either case if you end up skidding then you know you were riding too fast or too close to other traffic.

Definitely felt the rear skid and released the brake. I released both brakes and then reapplied to finish my stop.

I always start with light brake before hitting both hard and I always use both brakes at the same time when stopping, so I think I did everything right. I was maybe just too close to make the stop safely. It was definitely a good learning experience for me.

Please see previous post about NOT releasing the rear brake if you lock it up. The problem the poster describes is called a high-side (described below by an MSF instructor).

The high-side, by contrast, results from a loss of traction by the rear wheel, followed by recovery of traction. For street riders, as opposed to racers, it generally arises in a maximum braking situation. In such a situation, when you want all the braking you can get, it's easy to exceed the maximum, that is, to slide one or the other of the tires. What do you do? If the front tire slides, you release the front brake. Quickly! Quite intuitive. But if the rear tire slides, you should stay on the brake and slide it to a stop, contrary to one's instincts.

High-sides hurt. A lot. Fortunately have never had the issue on the street, however back in the day on the track... I can tell you for certain that landing on your head and watching your bike go tumbling by is NOT a good experience.

Or landing on your butt like one of the MotoGP racers did at Donington Park last Sunday.

I've found the GTS250ie braking impressive after practice. For what it is worth I never practice in live traffic. Locking wheels, front, back or both are potentially disastrous without knowing what to do. I've practiced rear brake slides a few times and I've determined it's better for me to learn to brake without sliding.

The one time I went down on the road began with a rear wheel slide. But that was in snow...

I find ongoing technical enlightenment about a lot of riding issues on Dan Bateman's Musings of an Intrepid Commuter blog. He is a Team Oregon Motorcycle Training Program trainer and is exposed to more stuff that I will ever be able to try. A recent post dealt with front wheel skids:

FRONT WHEEL SKIDS AND THINGS I REALLY DON'T WANT TO DO AGAIN. He is a humorous writer and has some excellent technique advice.

Snow? You're crazy. Thanks for the link. This guy is very funny.

Snow is what separates Vespa riders from Crazy Vespa riders. I've done some. You can see those rides in my WINTER RIDING section.

Snow is sort of an acquired taste...

Snow is that really cold white stuff, right? Not much of that around these parts. We mostly just deal with pea soup fog in the winters.

I follow your blog regularly, Steve. I enjoy it greatly. Especially the newer posts about the Bonneville. Much lust for the Bonneville here.

40-0 is pretty quick when the car infront has suddenly stopped

Just last week I went from 30 to 0 in 25 feet on the GTS.

I had a BMW X5 decide to be courteous in front of me and out of nowhere stopped to let traffic into the flow from a street with a stop sign.....

The back locked and slid out the front dug in.

The back then lifted off the ground (a 'brakey' ) and swung around, when it came down I was flung out the left side.

Be careful how far you push it.

I didn't hit the X5, in retrospect I wish I had.

I know I'm going to blow any karma I might have on this but I feel your MSF instructor is wrong on this point and I think your instincts are correct. If you continue to slide the rear then you've lost all braking from that tyre and you've also lost all ability to steer. In short you're barely in control of the bike. If the rider doesn't crash then they'll certainly be afraid of ever using the rear brake to it's full again.

If you just gently release the rear brake the moment you feel it start to skid and then just gently re-apply the pressure then you keep control of the bike and have more braking available to you.

The best way to practise is to ride at about 10mph on grass (gravel/sand etc) then apply JUST the rear brake to make the rear wheel slide. The moment you feel it slide just let off the pressure and re-apply. Repeat until you feel fully in control of the slide. What you learn is directly relevant on the road.

If you have ABS then this is done automatically for you. It certainly doesn't intentionally lock up any wheels for your benefit.

If you find yourself sliding your wheels quite often then you're simply riding too close to the vehicle in front or just simply riding too fast for the conditions.

When I was taught braking at the limit, I was told that if the rear locks up, you gently and slowly release it and then gradually apply again. For a front brake lock up, quickly release it.

Total agreement from me. Thumbs Up.

I concur, this apply- release- reapply does work when the back wheel steps out on an emergency stop. Well, it has worked for me.

It is also the current advice given by instructors for an emergency stop here.

Alright, first I think I did everything right.
Then the high-side folks tell me I was lucky I was hurtled over the handle bars.
Now it sounds like I did everything right again.



I certainly did lighten the brake and reapply as soon as I felt the rear skid start. I had my speed down to about 10MPH when the rear started to slide. I was really clamping down on the brake to try and make the stop on the mark. The "instinctual" reaction seemed to do just what mike_bike_kite describes in his grass practice.

A few points...
1. I took my MSF almost 20 years ago. I am sure that some of the instruction points have changed since then.

2. Depending on how far out of line with the front wheel the rear is and your rate of travel, a high side has a good chance of occurring with the release/reapply technique. It's just physics, no way around it.

3. I really need to re-take the experienced rider course again (been 15 years) if they ever offer it again here in SD.

4. Practicing these situations is never a bad thing. Learning how your bike performs under various circumstances is knowledge that can save your life.

5. I haven't practiced emergency stops in a while because with my two main rides the techniques are entirely different. The Harley has ABS so release/reapply is actually a bad thing and there is no such thing as rapid deceleration with a P200 unless you run into something

True, but we are taught release/reapply should always be used when braking in a straight line (as one should be). If the front wheel, an immediate complete release, if the back, lay off the brake until the back just starts to rotate again.

If the back has slid round for any reason, then what happens next or should be done about it depends on a large number of factors, e.g. speed, road surface and condition, available space etc.

Definitely but that's why a forum can be so useful. Allowing the rear wheel slide so far would only come from poor training. If the rider can sense that the rear is skidding (it's not hard!) then they just need to let off the rear brake to allow the rear wheel to gain traction before re-applying the brake again. You don't need fast reactions, you just need to know what to do. It's not hard and is very easy to practise safely as mentioned above. Actually your Harley's ABS is releasing and re-applying the brake for you many times a second. That's why you don't have to do this yourself.

if your rear wheel is too far sideways releasing it slow or fast will high side you. I guess the trick is not to let it get too far over but if you throw it into a hard stop and the rear steps out quickly, on a poor surface, it might be best to ride the slide, by letting the front wheel stay ahead, playing the front brake, till it is slow enough to release rear,straighten, reapply both.
usually all this happens so fast that you are reacting and inventing as you are going along best avoid the whole thing I say

Quite. Observation and anticipation are the keys.

I make a point to always remember the MSF admonition about releasing brakes in a real-wheel lockup but...

Does it apply to CVT-based transmissions, as we have on modern scooters? If the rear wheel locks on a motorcycle and you release the brake, the bike is still in gear and I'd expect bad things to happen. With a CVT transmission, is that still the case?

Never tried it and don't plan to; just trying to figure out the physics in my head. Then again, it may have nothing at all do to with the transmission and I'm just confused.

On a geared m/c you'd have the clutch pulled in. That's not the problem - the problem expressed earlier (which I refute) is that a rear wheel (without drive note) that gains traction will inevitably cause a high-side.

I call bollocks.

It might - but in more experienced hands it probably wouldn't.

Per OP...if you are going to practice emergency braking then I would suggest an area where you can do if safely. Start off slow 10 mph and work your way up. This addresses the practice of sudden / emergency stops.

To minimize putting yourself in an awkward position (increasing the likely hood of locking up)...precaution is key. This will not eliminate the potential of having to deal with an sudden / emergency stop however it may just give you better odds.

Perhaps the best practice I apply is to keep a definite "cushion" between vehicle in front of me and modulating when coming to a potential or real stop. I will modulate the front and and rear brake (modulating) and when coming to a complete stop using both brakes.