For those 36" riders out there, tire selection has just gotted smaller. According to Unicycles.com, (supplier of Wheels TA tires and Airfoil rims,) the new batch of Coker 36" button tread tires will not fit the Airfoil rims.
That left me with two options, resign myself to using heavier Coker rims for my build project, or make my own tires. After a not very hard descision, I started cutting up a TA. The tool required for major tire modification is a motor sport heated tire groover. These are commonly used in both street and offroad racing to alter treads to specific conditions. The tools can be widely aquired from motorbike dealers everywhere, I found that they were about $80 US.
Altering the tire with the knife is actually very easy, provided one is a bit handy. The biggest problem is setting the depth of the cutting blade. This, of course, is to prevent cutting into the actual casing of the tire. I found that between 2-3 mm of depth was all that we could get. At this point picking the design of the tread is the next step. We chose forward facing chevrons on either side, with horizontal cuts in the middle. This should give us a fast rolling tire with plenty of traction for the hardpack conditions we have here. I removed about 4 oz, or 1/4 lb of total rubber from the tire. This is by no means an insignificant sum, especially with the mass coming from the farthest rotating mass from the axle.
It took me about one full hour to groove one tire. The will of course vary on your skill level and tread pattern. I am so far very pleased with the results as they seem to work very well.
It had the nice effect of lightening the tire, but it was mostly for traction. I have not yet ridden it, as I’m waiting for the frame. Near as I can figure, the TA is about 300 gm’s lighter than the Coker to begin with. With this additional 100 gm weight loss, that puts it at about a pound lighter. The tread should be pretty grippy offroad though.
Cool. That’s exactly what I was planning to do but haven’t got round to it yet. Where did you get the cutter from? The heated tyre groovers I’ve seen are all enormous and wouldn’t go shallow enough - I was going to try it with a lino cutter heated in a gas flame.
Rob
EDIT: just seen your post about weight - I thought the Coker tyre was lighter than the TA…?
Pretty easy. Lots of other places sell these as well. It’s really the first groover I seriously looked at, I kind of bought it on an impulse without talking to anyone who had used one, but it worked really well. I couldn’t be happier.
I have seen mostly weights around 2000 gms for the Coker. The Ta’s I’ve gotte have all been around 1700. I could be mistaken, but I remember seeing the Coker weights several times on this sight. The weights for the TA’s were on an accurate gm scale.
I just googled “motorcycle tire groover.” I knew of the larger ones for ATV/Truck purposes, but I knew that smaller ones existed from watching Moto GP racing. They had a thing on once about prepping rain racing slicks. I’ve kind of kept it in the back of my mind until the need arose. Perfect application for this though, I can’t imagine doing it any other way.
They also make tyre cuttters for kart tyres, like this one (expsensive i know) that might do the job. I also thought that the TA was heavier than the coker tyre incidently.
Have you got that wheel built with a bike hub? the axle has nuts on each end.
Some cotterless axles are like that, with a thread poking out that has a nut on the end to hold the crank, rather than a hollow threaded axle that takes bolts. I think the Suzue unicycle hubs are that style.
Wow! I’ve been wishing for a knobby 36er tyre (although I’m starting to wonder if I really ought to use a smaller, fatter tyre during the rainy season).
Would it be possible to see a pic from a slightly different angle so we can see how deep the cuts are?
Cuts are limited to about 3-4 mm deep. Any more than this, and you reach down to the casing of th tire. Since the tires are 4 ply, I am not worried about cutting down to the cords, only cutting through them.
Edit: Here’s a more aggressive version we cut up as well.
That’s looking really good. I’ve been having a go at this for a few days, but without any fancy tools. I’ve used a craft knife (the kind with snapable blades to resharpen) as they are sharp and thin and available. It is taking forever though - a couple of hours to do about 1/4 of the tyre!
I’m going for more of a hybrid tyre - leaving the centre three lines smooth and just taking chunks out of the side lines (most of my riding is on road, this modding is mainly just for fun).
What could happen if the threads of the tyre are cut through? - I’ve hit quite a few in my cuttng.
Ben lent me his siping tool to mod the Wheel TA tire on my Nimbus. I cut grooves across the tire every 15mm. It took me an hour and a half, because it was my first experience cutting a tire with a siping tool. The next one should go a lot faster.
This is stinky, smoky work, so I utilized my welding vent to clear the smoke out of my basement workshop. It worked pretty well. This is definitely outside work, if you don’t have proper ventilation inside.
I took the newly-cut tire out for a road ride, and it felt fine…no perceptible drag compared to a new Wheel TA tire. I haven’t played in the dirt with it, yet. I expect that it will give me a little extra traction when the going gets wet or loose. In addition, I shaved off a little rotating mass, learned how to use a new tool, and had fun creating a unique, albiet basic, tread.
I’ve just finished my own modding. I wanted to maintain the silky road smoothness, and loose some weight too, so I was going for cutting out quite a lot.
I used a craft knife, and it took ages - about 10 hours of work. It would have been faster if I realised that the knife wasn’t fully sharp, and when I swapped to a new blade it cut very well.
This amount of rubber removal has shed 140g from my tyre (I kept the cuttings to weigh after).
A bit off the subject, but what were the TAs originally designed for? I can’t beleive there’s a tire out there just for a Unicycle, so there must have been an original application?
It’s quite exciting that these developments in 36ering are happening now. Those treads look rather like they could be more suitable for offroad than (for instance) the Coker tyre, although I’ve never ridden that.
I like off-roading my 36er with 150mm cranks; would like to try 170mm cranks and see how rough the terrain I can ride is.
I’m still hopeful that somebody might do further investigation into tread-ifying the TA tyre and maybe be able to offer it as a service. I don’t really have the tools, space or time to do it myself, but an offroad 36er could be cool nonetheless.
