Wobbling at 15 to 25mph

SPRIDDLER · Post by **SPRIDDLER** » Wed Mar 23, 2005 11:01 am

Sorry, me again.
Between about 15 and 25mph there is a pronounced, nay severe, wobbling at the handlebars. In a straight line (at 15 to 25mph) it's just a nusiance, but cornering round a tight bend it's decidedly scary. The bike runs wide and the 'bars get into quite a serious wobble. It's usually too late to (front) brake, and grip disappears as we drift into the gravel and debris at the edge or even the middle of the road.
Even light front braking increases the wobble. It's also hair-raising to take one hand off the 'bars at these speeds to signal. There's no trace of any slackness in the front fork legs, headstock, wheel bearings or rear fork, (and there's certainly none in the fundamental orifice). Tyre pressures are 18 front, 20 rear (solo, 11 stone).The rear tyre is a Taiwanese(?) Safety Mileage type pattern, quite old, and some cracking in the sidewall although it MOT'd OK. Front is a new Dunlop or Avon usual front type ribbed (can't remember which).
Any ideas?

pwaltham · Post by **pwaltham** » Wed Mar 23, 2005 2:16 pm

Neville
I could be wrong, no doubt others will let you know, but a few possibilities:
1. Rim not true
2. Is the new front tyre seated correctly, is the tube trapped
3. Could the wheel do with balancing

This could be a starting point at little or no cost
Good luck
Peter

bjork · Post by **bjork** » Wed Mar 23, 2005 9:20 pm

As you say the front tyre is new, I would go with Peters suggestion of checking that first. It is not totally unknown also for the tube to be fitted twisted! Plays havoc with your balancing beleive me! Another cause could be steering head bearings too tight perhaps? Have you had the bike long? Has this just started to happen?

lawrence · Post by **lawrence** » Wed Mar 23, 2005 9:37 pm

Have you got your piece of string out and checked the wheel alignment Neville? Easy to do. If the wheels aren't true it plays havoc with the handling.

Lawrence [}:)]

itma · Post by **itma** » Wed Mar 23, 2005 10:59 pm

is this wobble what used to be called a tank slapper? ie side to side motion? if so it is usually attributable to over tight head race bearings,
daft question ...are all your frame bolts tight?
was the wobble there before you went?
if so ain`t there an article for the potty here?..."wobbling awound fwance"
do you normally ride wobbly bikes? would you like to buy this set of stablilisers?[:D][:D]

SPRIDDLER · Post by **SPRIDDLER** » Thu Mar 24, 2005 11:47 am

Yes Ken, the wobble's been there all the time. I bought this P & J, last Oct (I last rode 35 yrs ago when I had a Greeves Hawkstone and a M20 with flatbed chair to transport it to meetings). I've only used the G3LS for 20 mile runs at weekends in daylight during this winter. Yes, I nearly had a slapper one night when I was snugged up at an auberge and the waiter, Roland Butter, recommended the services of one, Sabena Pleasure.
Steve, Peter, I'll check the tyre and tube seating - the wobble certainly seems to originate at the front wheel, although I realise that it would be felt at the 'bars anyway, even if it was caused by other faults- i.e. Vin de Pays. As for wheel alignment Lawrence, I tied a piece of string between the wheels as you suggested, and it certainly did play havoc with the handling for 20 or 30 yards until it snapped.
I must say the French seemed to be intrigued by this bearded 'Silver Rocker' - especially when I fell over on the quay at Fecamp and couldn't get out from underneath. Stabilisers might indeed help Ken.
Got the squits in Barfleur - dodgy mussels perhaps (is that too much information?), and amused the assistants in a busy Pharmacie with my attempt to explain the symptoms. I had much difficult swallowing the prescribed huge blue capsule. My, how Madame laughed. Anyway, for all the good it did I might just as well have shoved the "suppositoire de medication" up my xxxx. (Useful technical tip).
Murky blowthrough, mes amis, for all the suggestions.

itma · Post by **itma** » Thu Mar 24, 2005 6:18 pm

could i have the address of the slapper please?

MikeM. · Post by **MikeM.** » Fri Mar 25, 2005 3:44 pm

Afternoon Neville,
I use an Avon ribbed on the front of my Twingle and have noticed on fitting new tyres over the past few years there tends to be a bit of front end wobble for the first 50 to 100 miles then the wobble disappears. I also run the front on 21psi and the rear (a Dunlop K70) on 24psi. Avon changed their tread pattern a few years ago and up to this time I never had any front end problems.
You may therefore find that the problem may go with the more miles you cover.
MikeM.

SPRIDDLER · Post by **SPRIDDLER** » Sat Mar 26, 2005 7:12 pm

Thanks Michael - I like your suggestion to do lots of miles.
I've had a proper look at the tyres and it's an Avon Speedmaster on the front and a Yokohama 93-Y rear. I've done about 250 miles over yesterday and today and the wobble may be diminishing, so I'll be patient. I'll try upping the pressures a tad too. I assume you are not, say, 23 stone? Repair lines along the road, tarmac joins and roadside ripples etc tend to cause quite a substantial wandering. So too if I have to ride along the white lines painted down the middle of the road (like when filtering down the outside of queuing traffic) - but I believe that's normal. Can be a bit scary though when I'm being pulled around as if 'The Force' is in control! (Dr Who tonight - yippee). Neville

Rohan B. · Post by **Rohan B.** » Sat Mar 26, 2005 11:41 pm

Tyre pressures have appeared as a mention before I got to post - but those quoted pressures could go up 5 to 10 psi and still be on the safe side ? 18 psi in the front of a modern tyre is almost on the low side of being flat ? Wouldn't brake very well either ?

Having said that, I've noticed that ribbed tyres in general tend to track and/or squirm over irregularities in the road. I've noticed that switching to some of these dual-purpose tyres (on other machinery)(Pirelli or Metzler)(21" front rims required...) has cured this completely...

hopethishelps,
Rohan.