What causes a tank slapper
Discussion
What causes a tank slapper? Manufacturers' bloody-minded insistence on sticking with tele forks...
www.tonyfoale.com/Articles/Steer/STEER.htm
www.tonyfoale.com/Articles/Steer/STEER.htm
bmw114 said:
I have my ideas about what causes a tank slapper and how to deal with it but explaining whats happening is a bit like explaining the off-side rule.
So have you had one?
What did you do about it?
Has anybody lost control doing one?
How do you make sure it does happen again?
Had a Slapper or two in my time
Never had one so bad to crash from it and not had one on the Ducati, I think a relaxed grip helps.
This guy lost control doing one:
www.randtclub.com/Video/cedwards/tankslapper_tt99.mpeg
Presume you mean make sure it doesn't happen again?
Steering dampers are supposed to help as does a relaxed grip on the bars, also try not to cross the centre white line/catseyes whilst banked over.
Yes, many a wiggle that I would just ride through. maybe a little back brake, maybe ease the throttle off or on, depends on circumstances.
Only one real lock to lock that springs to mind. The end knuckles of two fingers remind me daily because teh fingers won't straighten after being squashed against the tank when the locktops broke.
60-70mph, straight line, country lane, steady throttle. Sunken patch of road, not a pothole, just a depression, sends a twitch through the bars. Hit a second one whilst slightly out of line. I remember hearing the screen break as I hit it (though I'm not sure if it was from in front or behind). Then being ahead of the bike on my back. Then the bike passing me. Rolling a bit and bashing my head a few times. Watching my bike head into the verge and back out on the road coming to a rest on the tarmac as I slid to a stop.
My right ankle hurt with barely a mark on my boot. The carbon armour on my gloves likely saved my tips being blown off Sheene-style. My back muscles hurt from the wrenching. The bike survived quite well.
High on the repair list was a Hperpro steering damper that has probably stopped a few similar incidents.
Only one real lock to lock that springs to mind. The end knuckles of two fingers remind me daily because teh fingers won't straighten after being squashed against the tank when the locktops broke.
60-70mph, straight line, country lane, steady throttle. Sunken patch of road, not a pothole, just a depression, sends a twitch through the bars. Hit a second one whilst slightly out of line. I remember hearing the screen break as I hit it (though I'm not sure if it was from in front or behind). Then being ahead of the bike on my back. Then the bike passing me. Rolling a bit and bashing my head a few times. Watching my bike head into the verge and back out on the road coming to a rest on the tarmac as I slid to a stop.
My right ankle hurt with barely a mark on my boot. The carbon armour on my gloves likely saved my tips being blown off Sheene-style. My back muscles hurt from the wrenching. The bike survived quite well.
High on the repair list was a Hperpro steering damper that has probably stopped a few similar incidents.
EDIT to add that the below is just what I was told by some bloke once, so it could be totally incorrect.
Basically they happen when one side of the tyre experiences a road condition (cats eye, white line) that gives it more grip than the other side, or sends a jolt through that side of the tyre. This sends the bars a-twitching. I've had loads on the 7R, just from being hard on the throttle and clipping lines etc. Also, when I got the bike the rear shock was wound totally solid so there was no rear suspension movement!
I generally just ride through them, once you've noticed them they've sorted themselves out. A few times though they've lasted a bit longer, so i've had to ease off the gas a bit. Once it sorts itself out, straight back on the power!
>> Edited by Mad Dave on Friday 14th October 09:36
Basically they happen when one side of the tyre experiences a road condition (cats eye, white line) that gives it more grip than the other side, or sends a jolt through that side of the tyre. This sends the bars a-twitching. I've had loads on the 7R, just from being hard on the throttle and clipping lines etc. Also, when I got the bike the rear shock was wound totally solid so there was no rear suspension movement!
I generally just ride through them, once you've noticed them they've sorted themselves out. A few times though they've lasted a bit longer, so i've had to ease off the gas a bit. Once it sorts itself out, straight back on the power!
>> Edited by Mad Dave on Friday 14th October 09:36
I replaced the std suzook thingy with a nice ohlins steering damper and it is superb. I only seem to get small minor 'tank slappers' when accelerating smartly (officer!) in 2nd and 3rd. The front is going very light at this point and it is the changing up a gear which seems to kick it off. I normally run on position 5 for the road (of 18 odd) and wind it up 5 to 7 clicks for trackdays. I never get a 'tank slapper' on neutral or off throttle.
I did use to get bad ones at 110-120 (ie flat out) on my W-reg GSX750 in the early to mid eighties however that was probably caused by a 19" front avon roadrunner with a bad wear pattern (remember those? you could put them on the front or back depending on the tyre direction
). Stopped doing it when I replaced with a metzeler ME33 front and 99 rear combo! Those were the days!
I believe the correct technique is to relax, lean forward and DON'T throttle off whatever you do. You're supposed to gently accelerate your way out, but that's not always possible if a corners looming. Braking increases the load on the forks and makes matters worse.
Tried it a few times as I had one of the early Blades and they were a bit prone to it
Tried it a few times as I had one of the early Blades and they were a bit prone to it
gRsf12 said:
60-70mph, straight line, country lane, steady throttle. Sunken patch of road, not a pothole, just a depression, sends a twitch through the bars. Hit a second one whilst slightly out of line. I remember hearing the screen break as I hit it (though I'm not sure if it was from in front or behind). Then being ahead of the bike on my back. Then the bike passing me. Rolling a bit and bashing my head a few times. Watching my bike head into the verge and back out on the road coming to a rest on the tarmac as I slid to a stop.
That is a frighteningly descriptive paragraph!
Glad you're OK.
I always thought that it was extreme steering head angle along with bumps + steering input.
On the track, I've only ever had really bad ones after running onto rumble strips when exiting corners a little wider than planned. You occasionally get them when flicking quickly from left to right and the suspension tops out as you go past vertical.
On the road on my K1 GSXR600, the worst ones have been on really bumpy b roads where I've known that it's really bumpy, but muscle the bike around anyway rather than being gentle with the bike and allowing it to flow around on it's suspension beneath me. To get rid of them, I've relaxed my bar input and backed off slightly. It's always worked in the past. Oh, and if you have a proper one you should remember to pump the brakes a little since the pads get pushed back in the calipers.
On the track, I've only ever had really bad ones after running onto rumble strips when exiting corners a little wider than planned. You occasionally get them when flicking quickly from left to right and the suspension tops out as you go past vertical.
On the road on my K1 GSXR600, the worst ones have been on really bumpy b roads where I've known that it's really bumpy, but muscle the bike around anyway rather than being gentle with the bike and allowing it to flow around on it's suspension beneath me. To get rid of them, I've relaxed my bar input and backed off slightly. It's always worked in the past. Oh, and if you have a proper one you should remember to pump the brakes a little since the pads get pushed back in the calipers.
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