"Emergency Stoppies" thread in "Staying Alive"
So I've been practicing emergency stops on my new Yamaha WR250X and have scared myself and annoyed the onlooker I didn't know I had.... I ...

So I've been practicing emergency stops on my new Yamaha WR250X and have scared myself and annoyed the onlooker I didn't know I had....

I never had any real problem with e-stops on my old Honda XR125L. The rear drum brake made it almost impossible to lock the back wheel, and if I did manage to lock the front about the worst thing that'd happen would be a chirp from the tyre as I released and re-applied the brake.

The WR is a bit different. My first attempts were plagued by locking the back wheel since I'd developed a heavy right foot on the XR, and my stopping distances weren't anything like as good as I felt they should be. So, less rear, more front. My next attempt saw the forks dive so savagely I thought I was going over the bars, and when I backed off a bit there was a sharp bounce from the rear that had my feet off the pegs. My next couple of attempts were similar, although I managed to keep my feet on the pegs.

Cue the unexpected observer who'd been watching all this from his front garden further down the road: I got asked to take my stunt riding elsewhere, and when I protested I was practicing emergency stops I had it pointed out that my back wheel had been going in the air....

So why the stoppies? I could take the XR right to the point of locking the front wheel, but I'm thinking the WR would flip if I tried that. Is my technique at fault? I'm being as smooth as I can, but the rear tends to lift as I progressively brake harder. Is it down to the suspension set up, and if so could some adjustment lessen the tendency? Or is it just down to the basic design of the bike?

Whether a bike stoppies or locks the front is down to a couple of things, the most obvious being the amount of grip you're getting from the front tyre and the surface! If the tyre can cope with a stoppie, it's delivering a fair amount of grip!

The second point is down to the CoG of the bike / rider. In short, if the CoG is relatively far forward and high, it'll stoppie, if it's further to the rear and low the bike will "push" the front. My old FZ750 was almost impossible to stoppie without sitting on the tank, but the Hornet does it no problem.

The fact you are pulling a stoppie tells you that's it for the brakes, you're on the limit - there's nothing left!!

The fork dive is down to the style of bike - if you'd picked a supersports machine, the fork dive would have been much less in distance and slower to plunge due to stronger damping.

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"Force has no place where there is need of skill" Herodotus 450BC

It's partly down to the design of the bike I think. Sometimes on my commute I see motard riders messing about sticking the back wheel in the air and they really aren't braking that hard.

You can try adjusting the suspension - increasing compression damping will slow down the rate the forks compress. You could also try upping the preload to reduce the amount of fork travel.

If you get a lot of dive from the front end, I think that'll make it more likely for the back end to lift.

Are you actually stopping fairly quickly or does the back lift under meduim hard braking?

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CBA TBH

Good point about adjustment - seems the WR has fully adjustable forks, although you're unlikely to tune all the dive out given the intended purpose of the bike.

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Sponsor Page XMAS OFFERS Blog Website Courses Riding Tips Shop
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The dull copyright bit - feel free to nick it for personal use. If you want to reprint it for your club, I'd like a mention as author. Otherwise hands-off. Full terms
"Force has no place where there is need of skill" Herodotus 450BC

Agreed, I doubt there will be any chance if dialling all the dive out. Even if you could, the front end would be totally out of balance with the back end I reckon.

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CBA TBH

Take comfort from the fact that accidents are more often the result of a failure to apply enough braking force than too much, IIRC. At least you're not suffering from that problem. Just don't do it on a bend

It does sound as though you may be snatching at the front brake rather than squeezing it - the word "savagely" may be the key. My Tiger dives with the best of them but never so violently my feet come off the footrests.

I've never had people chase me away for stunt riding though.

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Ian.

I've had people leave me behind for boring riding . . .

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Argue with me: http://the-ride-info.blogspot.com/

Sorry I didn't reply before, but dead computer + week on Microsoft .Net course (where's the vomiting smilie when you need it) = new Apple Mac Pro so I'm only just back on-line.

It felt like the back end of the bike was going way in the air but, thanks to the one family member who's not acutely anti-bike, I now know it wasn't more than 3"-4". The forks have 10" of travel and I was going through about 7" so I'm not bottoming them. Even so, upping the compression damping looks like it'd be worth a try if I can keep the front and rear balanced.

It is a tall bike (seat height measured at about 92cm) and Yamaha have done the mass centralisation thing - despite the spec saying it's heavier than the XR it feels much lighter and easier to manage - so I'm guessing it's as Spin and Quickshift said.

Plus I was definitely going faster on these stops than I'd done before on the XR - probably nearer 40 than 30; I have to keep an eye on the speedo in the 30's and 40's... - and the front brake is powerful so I have to be careful to apply it smoothly.

Practicing at low speeds has helped and shown me that I can stop quickly, but the bike does seem somewhat prone to lifting the back wheel.

Just as long as I don't end up doing this...

"Go where you look", eh?

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Argue with me: http://the-ride-info.blogspot.com/

that makes me feel dizzy seeing it repeat over and over...wonder what it did for him!

He should have looked left, right or even up as he left the seat

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CBA TBH

I read a website just on the other day that categorically states bikes can't flip on the brakes. Should send 'em the link!

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The dull copyright bit - feel free to nick it for personal use. If you want to reprint it for your club, I'd like a mention as author. Otherwise hands-off. Full terms
"Force has no place where there is need of skill" Herodotus 450BC

With that solid black visor, yeah, probably...

no-one has mentioned keeping your weight as far back as possible, this will help if you're doing unwanted stoppies.

You're probably not applying the brakes noticeably too 'savagely', or with long-travel front suspension you'd be locking the front before it got any weight on it. Remember this surfeit of grip may change in the wet though [or on oil, gravel, overbanding....]
But if you're doing stoppies, you may want to reconsider bothering with the back brake during e-stops - or maybe only for the very first bit [to get weight onto teh front faster] then let it off. Braking effect of rear tyres [even sticky ones] on air is negligible ; and locking it is unhelpful, and that - or diverting attention to 'how much back can I apply without locking it' - is diverting valuable attention from the real games in town, which are
-how much front can I apply without either locking it or going over the top
-when/if I should change between emergency braking and steering instead

well done for practicing e-stops. I think I'd be immoderate with the curmudgeonly old git ...

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Rubber Side Down
TFDodo
VFR750, CBR400
We've seen it all - Bonfires of trust, flashfloods of pain...

"you only get away with it
... until you don't"