I ordered a pair of Slipnot chains several weeks ago from Justin at www.slipnottraction.com and was really impressed at their performance. I had some difficulty getting the 3.8″ chains for a 85 mm rim to fit on my 4.0 VeeRubber Mission. Justin just mailed me a new set of the larger chains with a prepaid postal envelope to return the old chains in. I ended up using the 4.0 for 80mm rims which fit on my 4.0 Missions with 50mm rims if I deflated the tire first but not on 80mm rims. In general I’d say you should order chains that are one rim size larger than what you are trying to mount so they are not too tight. ie if you have a 50 mm rim get the chains for the 80mm rims. If you have 80mm rims buy the chains for the 100mm rims.
The chains are much easier to mount with the tire off the bike. I found that letting some air out was key in getting it to fit right. It takes about 5 minutes for each tire to put them on and less to take them off. They work great on plowed roads with hard packed snow and ice on them. I felt totally safe cruising along at 25 mph which I would never do without chains or metal studded tires. Braking is awesome on them and they do help the front tire track properly and not slide out on the turns. They are a reasonable solution for daily commuting in the snow that you can take off when the weather gets better. You can also buy both chains for less than the price of one studded fatbike tire. There are chains for almost every size tire here, but be aware that you must have 1/4 inch of clearance around the ENTIRE tire (including V brakes if you have them).
In the deep powder these chains really shine. Working like a giant paddle the rear chain just about doubles my traction and it’s really fun to get the tire up to speed then drop down on the seat and feel the bike shoot forward. Without chains I’m often stuck in eternal burnout land when the snow gets over 8 inches deep.
The only disadvantages I’ve found with the chains is the added weight (about three pounds together) and the fact that it’s much easier to dig yourself in if the back tire starts spinning. Without chains the tires will spin but end up moving very little snow. With chains the tires spin and they dig down to the ground. In a foot of powder you quickly get dug in too deep to move. That being said it’s easy to lift the bike out of the rut and then get the tire up to speed and ride off again. The front chain helps the front tire washout in turns less than without chains, but still not as much as I would like. I’m thinking of modding the chains and adding a section of chain in the middle of tread that circles the tire to keep it from sliding sideways when you turn.
My biggest fear was the chains wearing into the very expensive fat bike tires. So far I haven’t seen any signs of this happening, although I’ll know more after a couple hundred more hours of riding. The chains are made from high quality materials and I recommend that you order the $5 repair kit when you buy the chains as it comes with extra lengths of chains and extra turnbuckles in case your chains are a little short (mine were).
Justin responds best to phone calls 970.903.6185 and has more sizes of chains than what are listed on the website. If you are in doubt about what you need then call him and find out what his best guess is.
If you’re too cheap to buy chains you can make some ghetto ones yourself for about $15 worth of stuff at your local hardware store. Instructions on doing that are here.