high speed wobble..

[blade023]

Here's something that I've not experienced before, especially on the fazer; while riding along the dual carriegeway this evening on the way home I found that my handlebars were extremely light (under constant speed) and I could easily start the front end wobbling quite distressingly. Scared the bejeezus out of me!

So some background; had a bit of a knock the other day* which meant I had to go out and buy a nice new set of renthal bars (slightly wider) and new bar end mirrors. I was doing no more than 15mph, probably closer to 5mph at the time (after braking, but I honestly don't think I had enough time to stop. Read; should probably have been further back**)

The bars I replaced were off (I believe) a Yam diversion, and the new ones I got are much lighter.

And now the question; what exactly should I be looking at to remedy this front end lightness and tendancy to wobble? (induced mostly by me I think.) I was thinking of bar end weights as I have none on right now nor did I before, but the renthals are much lighter bars.

I'm going to phone around to get booked in at a local workshop so they can have a look over the front end to make sure all is good, but I'd like a bit of advice on what I might look for myself. I'm reasonably competent with mechanical things, but I haven't done any work on the front end before aside from taking the wheel off and changing discs and pads.

* In case anyone is interested, some dozy bird in a car in front of me decided to slam the anchors on. Going downhill. I hear squealing tyres, see brake lights and go for my brakes while thinking "I'm not gonna stop in time, I'm not gonna sto...." then after about a 40cm front wheel skid my front wheel hits the back of her, my balls hit the tank and the bike hits the deck. Queue me lying in the foetal position with 2 women (1 from the car bahind) asking me questions about am I ok and ambulances and such, and me trying to explain (in between gasps) that I'm trying to coax my balls out of my abdomen.

** This is a point that's been raised by my bro; he says my following distance is too far and that I should close the gap more to stop people squeezing into it or pulling out of junctions. I prefer a larger gap between me and the vehicle in front as it gives more time to react. In theory.
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Current: VFR800 2008 13.7k and rising rapidly!
Sorn: 2003 FZS1000 30k(ish) looking to sell.

[TUG]

Lighter bars, no bar end weights to counter the vibrations, there could also be other reasons such as a bent fork leg or damaged yoke, when I picked up my ER5 the front end had a shocking wobble if I let go of the bars (I actually nearly shit) which I put down to binding front brake and possible incorrect tire pressures combined with shitty renthal bars, no end weights and headstock bearings that had long gone.

After I sorted the brake and the headstock bearings it didn't really do it again but I only rode it once and that was for less than a mile. The wobble is caused by something fighting against the bikes steering so you should probably check the bearings (headstock and front wheel bearings) To check the bearings, get a trolley jack with a bit of wood on your headers with the bike on a center stand or paddock stand and lift it with about 5cm of clearance from the floor. The reason for this is so you can feel for any notches in the steering, use light pressure on the bars and you will feel a notch straight away. If it seems fine, go to the front of the bike and carefully pull the front towards you by the fork legs and push them back, there should be no play here at all, if there is then your headstock bearings need to be tightened up.

To check the wheel bearings, turn the bars to full lock and then move the wheel with your hands holding it firmly so it doesn't rotate check for play like you did with the headstock bearings but ensure the steering stays in place, the rim shouldn't move at all without turning the bars even 0.05mm, there should be no play at all.

If you get play from either of these then that's a starting point but given you just stated you smashed into the back of a stationary car my concern would be making sure the forks are straight and the yokes and that the impact didn't damage the bearings.
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Haz ER-5, innit!

[gavbriggs]

* I prefer, when possible, to choose an escape route to the sides of the obstruction.
** I usually always have an escape path in mind as I ride. Sometimes it's not possible but f you constantly look for one chances are you will find one if needed.
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Recent bikes: Varadero 125 - Mod 2 3/2/14 - Bandit 1200 SK4