Bit of a mini tank slapper

[AndyL]

Ok, I meant to post this as soon as I got back from Mallory but as I got soaked to the skin I couldn’t be arsed. Now I’ve dried out I thought it’s… ‘time to ask an expert’.

So, there I was, cruising back from Mallory (whilst it was still sunny – just east of Leicester) and took a detour through some lovely twisties near to Tilton and Houghton-on-the-Hill. The bike went round the corners as well as my bulk would allow and coped with all that was thrown at it.

However, as I entered the village of Tilton I I eased off the throttle and obeyed the speed limit… and as I was on the road on my own I took the opportunity for a bit of a stretch. As my hand was off the throttle the speed dropped and then I got a hell of a shake from the front end… a real wobble and the handlebars juddered badly. At first I thought I had hit a pothole, but when I was on a clear bit of road I did the same thing again with exactly the same result.

So at about 40mph with hands off no problems, but as the speed dropped down to 20 – 25mph I got this violet shuddering from the front end. I tried it on an incline, on a straight and level bit of road, on a smooth surface and on a rough surface… all with the same result.

Now, do you think this phenomenon was caused by my camping gear being on the back and acting a bit like a sail or have I got more fundamental problems?

The frame is straight, the forks are straight and not leaking and the tyres are brand new. Had the rain let up since last weekend I would have got the old girl out and tried to replicate without my extra load to see if that was the case. Hopefully tomorrow the sun will come out so I can go and try it out, but in advance I was hoping for some initial thoughts in case it is something more serious that I ought to be looking out for?

It didn’t happen on the way to Mallory, but that may be because I didn’t take my hands off the bars at any point. With even just the slightest hand contact with the bars the bike won’t shake… only when my hands are completely clear.

What do you think?

Andy

[Anonymous]

Not sure what causes it… but my 900F used to do that. I don’t believe it would be your load. My guess would be wheel alignment. Have
you checked your rear and front tyre run in line?

SteveG

[GrahamR]

My 900F2B used to do the same until I adjusted the steering head bearings. Also I think the wrong tyre pressures can have the same effect.

[AndyL]

Wheel alignment was out by the merest of fractions. Re-did it and the tank slapper stops.

Thanks Steve.

[Author]

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