Tank Slapper or Head Shake on Supermotos

[EEEliminator]

General question for those on motards/supermotos regarding head shake.

I was reading up on hypermotards and there were several discussions about issues with headshake at high speeds on rough roads. I know hypers aren't true supermotos, but they have "similar" geometry and more travel than a sport bike. My understanding is that these bikes should do better on rougher roads than say a sport bike. I've yet to experience any real head shake on my current bike at any speed on any road conditions, I'm not riding at the limit on the street either... I know these style bikes aren't set up for high speeds either. I have experienced this on my previous bike an 80s Japanese standard.

Reason I'm asking is I'm interested in switching to a motard style bike from by CBR. Looking mainly at the larger CC bikes KTM 690 or Ducati given that I'd like to be able to some trips that may require sometime on the highways. I'm expecting that some of the local roads that are a bit rougher should be more fun on something like this.

 

[xgambit]

its not headshake if the front wheel is off the ground

 

[Gary856]

I thought you could get headshake on any bike hitting a bump the wrong way under hard acceleration - the front end looses contact with the ground and comes down wrong.

IIRCC one of the instructors at my Total Control class said he was on his DRZsm, from a dirt shoulder he went WOT, and got into a nasty headshake as his crossed over the edge of the road onto pavement at a shallow angle. He put a leg down and saved it, but got a terribly bruised knee from it and had to go to the hospital to get the fluid/blood drained from the knee. He had a steering damper on that bike but it was disconnected (due to not working right) when that happened...

 

[EEEliminator]

I thought you could get headshake on any bike hitting a bump the wrong way under hard acceleration - the front end looses contact with the ground and comes down wrong.

IIRCC one of the instructors at my Total Control class said he was on his DRZsm, from a dirt shoulder he went WOT, and got into a nasty headshake as his crossed over the edge of the road onto pavement at a shallow angle. He put a leg down and saved it, but got a terribly bruised knee from it and had to go to the hospital to get the fluid/blood drained from the knee. He had a steering damper on that bike but it was disconnected (due to not working right) when that happened...

I'm concerned with the suspension getting unsettled due to bumps in the road rather than coming off of a wheelie. On my older bike if I was really light on the bars and gave it a quick left-right I would get a pretty bad shake. In turn on bumpy roads or crossing uneven pavement like you mention above it would get sketchy too. I attributed this to the older worn suspension, bearings, etc...

My current bike isn't perfect but it's pretty solid in these situations. From what I've read a damper doesn't fix the situation(just reading on the Ducati forums). Just trying to figure out if this is potentially an issue with the type of bike or the particular bike.

 

[Junkie]

some 'tards will headshake just riding along on the freeway. it's the geometry.

 

[kingmoochr]

Bumpy road... SM>Sprotbile any day (with properly set up suspension, for ANY bike).

High (read...California) freeway speed on grooved cement with sketchy tires = wandering bike.

I have a Husky 630 that I've had to 90mph, it is only sketchy on aforementioned roads. Even still, it isn't headshake. The "loose" steering might be unnerving for pussy Ducati owners who are scared any time their bike doesn't feel like a viedogame (I recently sold my 996) but if these bikes had a chronic problem, it would be readily documented. For me, SM>*, I'm not going back.

 

[stoppie]

My ktm 525exc converted motard gets a little shaky from time to time but never out of control , just keep riding and ignore it , it will never tankslap but will shake its head at you once in a while when riding hard on bumpy uneven surfaces, no big deal.

Now the hypers and sportbikes may be a different story got a serious tankslapper on a cbr 929 years ago which bruised both my wrists and knees, thought I was gonna die, but didn't obviously.

No need for a steering damper on the KTM that I have but the 929 without a steering damper was asking for trouble.

 

[the grinch]

I have a Scotts stearing damper on my DRZ, it still has some head shake at about 80 and above. If I turn the damper up it goes away of course. At top speed it will still head shake even with the damper full hard, it is fun when you forget to turn the damper back down after you slow down to take a turn.

On a side note:

It also likes to head shake when I am standing on the seat while steering through the twisties. I figure that center of gravity must affect a bike's tendency to head shake.

Also, it is a converted enduro, I'm not sure if there is a geometry difference between a stock DRZ motard and an enduro model with 17 inch wheels.

 

[Caddywumpus]

Hahahahaha hypermotard is not a true motard.

 

[russ69]

Given the right conditions just about every bike will shake it's head. Even a MotoGP bike.

 

[Lovedoc]

I have a Scotts stearing damper on my DRZ, it still has some head shake at about 80 and above. If I turn the damper up it goes away of course. At top speed it will still head shake even with the damper full hard, it is fun when you forget to turn the damper back down after you slow down to take a turn.

On a side note:

It also likes to head shake when I am standing on the seat while steering through the twisties. I figure that center of gravity must affect a bike's tendency to head shake.

Also, it is a converted enduro, I'm not sure if there is a geometry difference between a stock DRZ motard and an enduro model with 17 inch wheels.

On my DRZ-S model, the high speed shake goes away completely if I hold the bars in the lightest possible grip. Don't need a damper.

 

[codger]

My KTM 450 used to shake its head on acceleration exiting corners it looked scary to others but I just stayed on the gas and it straightened right out. i got used to it and it wasnt an issue. it shook worse than any of my other dual sports did especially when riding on the dot knobbies prior to installing the Sm wheelset. I never had it shake on me with the SM wheels.

 

[fast4d]

you can remove most of the head shake at high speeds with suspension changes. my zrx had serious headshake if I got WOT at 60mph in a straight line. I just got new springs and reb on the fork and it was mismatched to the stock rear setting.

KTMs have 2 offsets you can choose on their triple clamps.

 

[rrrdbw]

Some say 690 SMC doesnt need a damper. I find that ridden on rough roads like Mines/Mt Hamilton/Santa Cruz goat trails hauling ass the GRP damper I have on, has saved me from many a tank slappers and jolts from fucked up pavement while leaned over. Its peace of mine
I've ridden it without damper speed over 100pmh with no headshake at all. Might have to put a little more weight on front tire to prevent the shakes like coming over turn 10 I think @ Thunderhill.

I also have a street legal 450 EXC i converted to SM that used to get shaky and squirrly on the tight twisties cause I wasnt riding it SM style I rode it more sportbike style which doesnt work tooo well with dirt bike suspension. I added GRP damper and road it SM style now it is solid on any corner.
Definitely need to have your suspension set up , if your suspension isnt set up properly all the steering damper and fancy shit you put on isnt going to help you feel confident on the bike.

 

[kingmoochr]

It would appear I'm seeing a trend in here... converted "supermotos" WITHOUT their suspension redone seem to have problems (which makes sense since they're dirt bikes, not street bikes) where properly done supermotos, or factory bikes seem fine. Funny how that works.

I also have a street legal 450 EXC i converted to SM that used to get shaky and squirrly on the tight twisties cause I wasnt riding it SM style I rode it more sportbike style which doesnt work tooo well with dirt bike suspension. I added GRP damper and road it SM style now it is solid on any corner.
Definitely need to have your suspension set up , if your suspension isnt set up properly all the steering damper and fancy shit you put on isnt going to help you feel confident on the bike.

This

 

[louemc]

Given the right conditions just about every bike will shake it's head. Even a MotoGP bike.

That's the truth of it....This subject goes bat shit crazy with opinions based on limited experience that is patched together from pieces of elements that involve a dizzy number of different ways they get put together.

There is only one answer for me...Put the freakin Scotts Damper on, and enjoy what it does for you everyday, all the time. There is no debate on whether it is needed or not.

Let the ones that don't think they need it...not have it... that's their life...they are free to live their life...lots of bikers do lame shit...buy the cheapest tires they can, go helmetless in states that allow them to, etc. But...Ya can do better.

 

[JPK]

Headshake can be caused by many things. On the V-Strom, it can be caused by the unfortunate combination of:

- high speed (anything north of 80ish)
- any sort of load on the rear in a top case or side cases
- a front fairing that starts to act as a wing, lifting the front at speed.

Add to that any sort of pavement irregularity, and things go pear-shaped in a hurry. Any time I had the side bags full on my Wee it would definitely feel looser, and when coupled with speed or wind or bad pavement it would get unsettling. I never experienced a full-on tankslapper on it, but a few folks on Stromtrooper.com have. I now run a Scotts damper, and it has made a HUGE difference (along with a fork brace) on the bike.

 

[EEEliminator]

That's the truth of it....This subject goes bat shit crazy with opinions based on limited experience that is patched together from pieces of elements that involve a dizzy number of different ways they get put together.

There is only one answer for me...Put the freakin Scotts Damper on, and enjoy what it does for you everyday, all the time. There is no debate on whether it is needed or not.

Let the ones that don't think they need it...not have it... that's their life...they are free to live their life...lots of bikers do lame shit...buy the cheapest tires they can, go helmetless in states that allow them to, etc. But...Ya can do better.

I agree with what your saying there are so many variables. From the responses it does look like head shake is not an uncommon occurrence in riding a motard especially at a speed. They're not designed for high speed so it makes sense, it's just the nature of the bike. I guess they're meant to be ridden a little looser and that's what makes them fun to ride.

I need to figure out if I want something for tight twisty roads and around town riding vs something that can handle extended periods of time on the highway and long sweeping turns. Given the degrading road quality on many roads and lack of interest in triple digit speeds makes a motard intriguing.

 

[louemc]

^^^ A Motard should be intriguing, they are serious bikes.
They also come in many forms/sizes, so..there is some deciding work, that has to be done, to pick what's best for your riding use. (and your personality)

We have never had it so good as we have it..right now.

 

[Map8]

I need to figure out if I want something for tight twisty roads and around town riding vs something that can handle extended periods of time on the highway and long sweeping turns. Given the degrading road quality on many roads and lack of interest in triple digit speeds makes a motard intriguing.

Own at least two bikes.