From: wardman@gandalf.ca (Russel Wardman)
Subject: Re: winter riding - was MX racing questions 
Organization: Gandalf Data Ltd.
Date: Thu, 20 Aug 1992 12:30:16 GMT


>	If someone is interested I could supply the names and addresses
>	of some companies that make/sell studded tires here in Sweden.
>	I don't have the addresses here at work, but as I remember,
>	both Trelleborg (excellent) and Cheng Shin (poor (they say))
>	produce studded tires from factory. Other companies just put 
>	together the tires and studs you want (as they do for the
>	professional MX'ers and Enduro-types), and they should be able
>	to recommend you the best combination of tires and studs for 
>	your needs!

I understand that one of the tire companys is offerring a similar type
of tire here now, and due to its commercial availability, the CMA
(canadian motorcycle association) is considering a adding a class
just for these.

>>Over here we use special screws which resemble sheet metal screws
>>and are 1.25 to 2.0 inches long (sorry about mixing metric and imperial)
>>but only the slotted hexagonal head of the screw protrudes from the tire.  
>>Up to three street tires with their sidewalls removed are inserted in the
>>tire before studding.

>	How do you mean, is it the head of the screw that grabs the ice?
>	Isn't that a bit blunt? And how about wear?
 
Thats correct, the head protrudes. Compared with spike tires they are
blunt but they do stick reasonably well. I've never had the chance to try
oval dirt tracking, but based on watching them, I would say that our ice 
tires give us slightly more traction than they have. You still get into 
that crossed-up slide, but not quite as much, and even when your crossed
up, if your on the gas when back tire finds a rut, you have enough 
traction to wheelie.  


>>The bikes are lowered down and some of the guys steepen the steering angle.
>>I expect the geometry changes are similar to those George C. made to his
>>CR500RR for road racing.

>	Why is that? If you wanna go fast, why not use a street-bike?
>	I read an article last year about som guys here in Sweden that 
>	equipped their GSX750R's and GSX1100's with studded MX-tires.
>	The reporter wrote something about "the experience got slightly
>	hairy when the studs started touching the lower steering-head and
>	the insides of the front mudguard due to the centrifugal forces
>	in the tire at 200 km/h (appr 120 mph)... It appears that they
>	started out with Enduro-bikes, but wanted more speed.

Since the ovals are relatively short (200 to 300 metres max. cicumference)
and the
corners are tight radius (I'd guess 25 metres) the combination of 0 to
100KMH acceleration and light weight handleability (quite important when 
your sliding in the corners and having to contend with ruts) would 
be difficult to match in a street bike. I have seen a Harley Davidson
Woods Rotax 600 dirt tracker win races though. The open class races  
are restricted to 600 cc's , but I don't think more cc's would help
anyways. It is also much more convenient to use a MX'r since their swing 
arms are already wide enough to accept a knobby tire. If I had money to
burn, I might try turning a TZ250 into an ice racer, but....
 

>	I always wanted to visit Canada, but it is quite far away,
>	and I can't go there on my bike, studs or no studs...

Since the ice is still quite a ways off , I think I will concentrate
on getting my bike ready for this weekends Calabogie ride. Calabogie 
is a hilly area about 1 hour from here with endless trails, fire roads
and power line runs. Ton-o-fun! 
>>Russell Wardman 

>>>Anders Johansson, Telia Research, Sundsvall, Sweden.

Russell Wardman
-- 
**         Russell Wardman         **      Gandalf Data Limited        **
**        Hardware Designer        **     Nepean, Ontario Canada       **
**    Network Components Group     **          613-723-6500            **
**  (rwardman@hobbit.gandalf.ca)   **                                  **
Newsgroups: rec.motorcycles.dirt