I've fitted a nice new Avon Roadrider - AM26 - 100/90V19... It's a beautiful thing..!!
(http://www.wheelhousetyres.co.uk/media/catalog/product/cache/1/image/9df78eab33525d08d6e5fb8d27136e95/i/m/image_885.jpg)
When I bought the bike, it had a Metzeler Lazer - ME33 - 100/90V19... It was OK while it lasted, but tended to track over road seams and white lines, especially as it approached it's wear limit...
(http://www.apex-powersports.com//images/Products/110-6032.jpg)
When I came to balance the wheel/tyre, I removed 110 grammes of adhesive wheel weights off it first (that is NOT a typo BTW - there was almost 4 ounces of lead stuck to that wheel..!!) After that, with new wheel bearings fitted and the discks all cleaned/painted up, it appears that the wheel doesn't need any weights on it at all... I couldn't get the wheel to stop in the same place twice when spinning it on v-blocks... I dare say the proof will be in the pudding... :-\
So... As I've been playing about with the forks, brakes, etc... After fitting the front wheel it was time to refit the front mudguard... It doesn't... Fit that is... The new tyre is wider than the inside of the guard...!!! >:( >:(
After measuring all the new parts I've fitted and three different 100/90 19 tyres, I found:
The Avon roadrider is 104mm at its widest point (fitted to the Hesketh Astralite)
An Avon Venom is 100mm at its widest point (fitted to a cast alloy Yamaha Wheel)
A Pirelli Night-Dragon is 103mm at its widest point (unfitted).
The Metzeler was recycled weeks ago, so I can't measure that now...
The Hesketh mudguard appears to be made of GRP with a wall thickness of about 5mm (avg). Taking as many measurements as possible, it appears that the narrowest part of the guard is 100mm (ish) which is why the Roadrider is too wide for it...
I'm planning on "relieving" material from the inside at its narrowest point... The mounting points between the forks are 2mm wider than the widest point of the guard, so it will be slightly spread when secured in place, but it's still going to be a tight fit...
Has anyone else had similar problems..? I have checked the recommended tyre fitment on the hesketh and 100/90 19 is correct (110/90 18 on the pre-production models, apparently).
Jeff
Hi Jeff,
I have just fitted the exact same tyre to the front of my Angry Chicken along with it's matched item on the rear and it appears to fit fine. It is a little tighter that you would expect and I had to double take it's proximity to the front guard when I was fitting it but at it's closest point there appears to be maybe 3mm clearance between tyre and guard!
However, up to now I have not been able to rotate the wheel as it is clamped in the bike lift so as soon as it's finally free I'll double check.
Very Strange! :-\
Pete
Hi Pete;
Are you measuring at the sides or between the top of the tyre and the underside?
Jeff
Hi Jeff,
I'm measuring at the sides as that is where it appears to have the least clearance. In the centre of the tyre there appears to be plenty of room.
Pete.
I just found Avon Motorcycle Tyres "Tires 101" document... (http://www.avonmoto.com/download/Tires101forConsumers.pdf) Online...
The 2nd/3rd paragraphs on Pg 1 say it all... With the tolerences they're allowed, the 100/90V19 Roadrider could be anywhere betweem 95 - 105mm, so the 104mm mine measures is simply near the top of the allowable range...
Any, obviously, my front mudguard is near the bottom of the allowable range of widths... Typical..!!
Not for long though... The tyre is staying..!!
Jeff
The Avons are a wide tyre.
I have helped adjust front mudguards at rallies when owners have noticed them rubbing.
The up and down adjustment on the mudguard slots usually enable you to get a clearance.
I think Tig's red bike was one that I helped adjust.
Never had the Avons myself but ridden a couple of Hesketh with them on and they feel good.
Pirellis are a good grippy tyre as well and not so wide as the Avon.
But I found them a bit soft for the weight of the Hesketh when touring and they wear quickly in the middle of the rear tyre and the edges of the front tyre.
I currently use Michelins and find they give excellent life touring - double the mileage of the Pirellis.
They keep their shape very well.
Dave H
I've been diverted away from the mudguard issue because I've had to get my new wheel spacer modified (-0.5mm on the shoulder), but this will be addressed... The GRP appears to be unusually thick on my guard, even for a Hesketh panel..!! If I take 2mm out of each side, it'll clear easily and still be 3mmm thick, so I think this is the way to go...
I couldn't adjust the height so that the tyre didn't rub unless the guard was in danger of acting as a front air brake...
It'll all come out right in the end... :)
Jeff
Sorted...
Pic: Big H with front end completely reassembled... (http://iloapp.empressmcc.org.uk/data/_gallery/public/11/139258939759221900_resized.jpg)
I used a medium grade sanding disc on my angle grinder to "relieve" the two internal bulges... Using a pair of calipers to gauge how much material had been removed... It was remarkably easy to sand only the required areas because they intrude into the curve of the guard so much... It was also interesting to not how the hand-layed GRP has so many bumps and undulations... Mine has two lovely smooth bits now... ;D
I took off about 2mm each side...
When refitting the guard I used an old trick - tape a length of fuel pipe along the centreline of the tyre tread, then lower the guard into place until it touches the pipe right along its length... I made sure the pipe was less than half of the circumference of the tyre, so that I could use the section without the fuel line to check for proper clearance... It's fine now...
Jeff