ice riding....speed runs

[Moto Squid]

I've finally studded up my bike (02 cr 125) and tested it out....what a blast!!! Problem is 5th gear WFO is ~72mph and I get there in about 500 feet, thats way too soon and it wants to go much faster. Do you think a 125 could pull a 13/40 sprocket ratio (13/52 currently) Mathematically 13/40 calculates to almost 90mph @ ~12,900 rpm.

I'm looking for a 40 tooth, or there about, sprocket for a 520 chain. All I need is for it to be solid or have 6 spokes. Then I can drill new holes and turn the center larger....any suggestions as to what bike might have such a sprocket?? Everything I've got is for a wider streetbike chain :(

Thanks

 

[WoodsRider]

I have a 40-tooth rear from an XR250L if you're interested.

 

[CRPilot]

You could try a 15/52 combo first, it equates to a 13/46 and would be easier to find. But, a 125 with 13/42 would probably accelerate like a Harley.
I run 15/49 on a 250 and it works well -pulls strong right to the over rev, but I rarely need 5th gear.

BTW - where are you riding? We ice ride just about every weekend just west the Milwaukee area.

 

[pyromaniac]

Love to see some of you are riding on lakes. Are you riding factory tires or are you making your own cause maybe i can improve my tires with some of your ideas.

 

[UKcr125rider]

Be carefull if you fit the 15 toother. You may have to remove the chain guide and sprocket guard to give the bigger sprocket enough clearance. This leaves your cases vulnerable to damage if your chain should clip it because of a derailment or somethin like that. Be wary of removing that important guide!!

 

[FritoBandito]

We started ice riding last year. I was wondering what other riders use for tires? I am using 5/8 Kold Kutters on the Michelin MX tires with a old innertube for a liner and a 3 inch wide peice of carpet also in the tire to stop any screws from giving me a flat. I have seen that Kenda makes a 19 inch tire for ice screws, but is unavailable from all the places I have looked at. Are there other tires that work , or do MX tires work just as well as anything else? I'm just fishing for some info to give me an edge on the guys I ride with, so anything you can tell me will be appreciated.

 

[pyromaniac]

Originally posted by FritoBandito
I am using 5/8 Kold Kutters on the Michelin MX tires with a old innertube for a liner and a 3 inch wide peice of carpet also in the tire to stop any screws from giving me a flat.

My next icetire im gonna try something like sheet metal screws, little modified. They are almost 5/8(if thats 16mm) long and pretty thick like 5mm. When trying to pull them out they seem to sit rockhard but the forces they are exposed for is just incredible. How thick are your kold kutters and do they stay in the tire even if not riding pure ice?

 

[CRPilot]

Check the link below for a picture of my tires. I'm using the Kenda rear and a Dunlop 490 on the front. The front is using 1.5" Kold Kutters with 2 liners. (cut and trimmed 21" street bike tire) The rear uses 1" Kold Kutters with one liner. You can't beat the set up for ice riding, but if you start getting into deep snow they will start to push a bit. I built these, but the stud pattern is based on Fredette's set up.

http://photos.yahoo.com/bc/jmbeckman/lst?&.dir=/Bikes+and+Riding&.src=ph&.begin=17&.view=t&.order=&.done=http%3a//photos.yahoo.com/bc/jmbeckman/lst%3f%26.dir=/Bikes%2band%2bRiding%26.src=ph%26.view=t

 

[WoodsRider]

I have the same tires as CRPilot. They are Fredette-built tires that use 1" Kold Kutters and street-bike tires for liners. Mine were built for circle-track not TT since the outer left knobs do not have screws installed.

I also built a front tire for off-road riding through snow. I used a 752 copy with an old dual-sport tire as a liner. I fastened one 3/4" ice screw into each knob. The one thing I've found about using liners is there is very little room for a tube in the front. This year I'm experimenting with a 24" bicycle tube in the front.

 

[IrishEKU]

Woods, have you tried running a Urethane foam or foam inserts instead of a tube?

 

[WoodsRider]

Irish - There's not enough room for a foam insert. The liner takes up a huge amount of room thus the reason for using a bicycle tube. Additionally I don't like the "feel" of foam inserts.

 

[IrishEKU]

Woods, thats why I mentioned the Urethane, it sprays in and sets up solid. Alot of components I worked on in the military came packaged in the stuff. I understand the "feel" of it though, it must be similar to riding a couple of bricks.

 

[CRPilot]

Woodsrider: Kinda of funny, but with two liners in the front I don't need a tube. The tire is so stiff already. I went to check the air pressure after about 20 laps, and found zero (valve was frozen). I pumped it up to 35psi and ran again. I couldn't tell the differance. The pressure from the liners plus the rim lock were good enough to prevent the from spinning.

 

[WoodsRider]

Irish - How would you remove the tire from the rim?
Ice tires are expensive to build or buy and last many seasons, so cutting them off is not an option.

CRPilot - What tire pressure do you normally run? Do you vary the pressure based on the outside temperature (hardness of the ice) or just stick to one pressure?

 

[IrishEKU]

Woods, the way I understood it many moons ago was that they would have an extra tire set up and spray the foam into an unmounted tire that was lined with a thin film of grease or cooking spray. Once it had set up they would pull out the doughnut and cut it into sections and then install while mounting the tire. I never really understood the lenghthy and time consuming process but I knew a few that would swear by it.
Others that had more $$$ than brains would have a second set of rims set up and foam sprayed in through the valve stem and just swap out once the ice set up. I don't know how many times they replaced the tires but it did invove cutting the tire off and new stems. As for the tread locks I don't recall if they used them or not. I am guessing they did, because if it is the same flavor as the suff I came in contact with it won't bond to metal at all.

 

[CRPilot]

Woodsrider:

I typically run 35psi regardless of outside temp. My theory is you want the tire as stiff as possible so that there is zero flex in the tire itself. That way when the studs bite the ice they do not flex and loose grip. The more the studs flex in the tire, the less grip you have. The flexing of the tire(read: knobbies) is what will eventually loosen the stud or begin to rip the knob off the carcass. You should get longer life out of the tire with less flex.

To adjust for ice conditions I will adjust the compression adjusters. Softer ice ususally gives better traction (consistent) as the studs sink into the ice farther thus I will stiffen the compresion. With harder ice I will soften the compresion slightly. Theory is with harder ice the studs don't sink in as much and by reducing compression, you will untimately reduce peak the force on the ice and prevent the tire from breaking loose. You can also use this to dial in the amount of slide when backing it into corners.

 

[WoodsRider]

CRPilot - Thanks for the info!

Irish - Seems like a lot of work. Changing tubes isn't bad and I don't mind changing tires.

 

[IrishEKU]

True, probably why I was busy ice fishing and riding snow mobiles. Keep us posted on how the bicycle tube works out.

 

[Moto Squid]

CrPilot...We go riding on the Sheboygan River near Kiel (it opens into a bay area and is sweet!) and also on Lake Ellen. Actually on Saturday I'm going to the radar run at the Sheboygan Marsh

What I've done is take a 47T sprocket from a XT250 turned the center to fit my hub and redrilled the holes. I won't have the 14T front until next week so that stinks. Once I try that out that combo I'll decide if I want to custom make another sprocket, probably more like a 43 or 44T would be realistic

As for tire I just took my worn dunlop 739 rear and put some old one on the front. I used a total of about 1200 7/16" gold digger studs...about 900 were on the rear

 

[MuN]

There is something Iceracing-info from Finland
http://www.iceroadracing.com/english.html

MuN

 

[pyromaniac]

Motosquid do you have any pictures on your tires? Man 1200 of that kind of studs isnt that very, very costy. Also pretty heavy isnt it?

The goal i have is to create a tire that have good performance on ice and on the MX track. Last long enought and should be easy to make and dont take too long time to restud. Last but not least, as cheap as possible!

I havent yet been able to to have all those things in one tire. And i dont think your tires have all those things. Sure have good traction on ice but how long do they last on the MX-track? Also over $100 buck is too much for me unless it last very very long time. Right now i have just made a new rear tire that i hope will give enought traction on the lake to make it fun and on the MX-track and last long enought. It only costs like $5 and will take probably just 30 minutes to restud so if i have a good traction for maybe 10 hours on the MX track i will be happy.