Just thought that I would chuck in a few cents worth here, cos I have been around tyrewarmers for a while now [having previously owned tyrewarmers.co.nz] so thought it my business to find out how the different ones are put together etc.
The CAPit warmers made in Italy are probably the industry leaders at this time. Their single temperature product has technology, as has been identified herein already, that does not use an inbuilt switch as all other single temp products do. They do adjustable temperature products with a controller, as do other brands. CapIt are all over MotoGP and make a great product. The key though, is that their useage is different to that of the switched products, as KG has pointed out. Without the switch, it is possible for the element to keep heating and go over its design temperature, given certain conditions. So, the warmers are not designed to be left on all day. This of course is typical of European racing where you have a smaller number of longer sessions, rather than our short sessions all day long. So there, you heat the tyres for the time required and that is that. Whereas here, we have one set to last all day, and multiple days when it comes to that.
The 'Holroyd' warmers made in the UK under the RaceTec and Tyrewarmers.co.nz brands are a much less sophisticated warmer, but a product that works extremely well. The key to the CapIt and Holroyd warmers is the amount of heating element that is in them, and the insulation. In a RaceTec warmer there will be something like 15 to 20m of sheilded element. CapIt is similar. This means that the heat density per unit area in these products is lower than the cheaper Chinese warmers which if you are lucky will have 5-8m of unsheilded element. This means that the propensity for those latter products to overheat locally and burn the warmer and then the tyre is much higher. I have seen new chinese warmers burn holes into brand new tyres, fucking everything! All of the other common brands that are on the market are made in China, probably in the same factory, HotHoops, MotoGP, Sumomoto etc etc. In all my years of looking at warmers, which I do cos I am a bit neardy that way, I have never seen a 'higher level' brand for want of a better term, burn holes in tyres.
The insulation outboard of the element means that less energy is input into the warmer because less of it is being used to heat the cold air around the outside of the warmer.
The orientation of the element in the RaceTec product, circumfirential, is also, I believe, a better design, offering more even heating of the tyre surface. CapIt use the wave design, but as I said, use a lot of element, so the heat coverage is also very good.
The RaceTec product uses a simple bimetallic switch that opens the circuit at a given temperature. With some effort this can be changed for a different temperature range. I have lower temperature switches [for 70 deg C which was apparently preferred for the Pirelli tyres] and replacement 80 deg C switches. Of course the switches can fail over time, but they are replacable and thankfully almost always seem to fail open circuit, which is good. But this means that you can, in theory at least, leave them on indefinitely and they will maintain the correct temperature, within reason of course. The over/under temperature is 5deg at best. But one trick is that if you put the join [where the switch is near] under the mudguard, it will get hotter there than the lowest part of the warmer. So it is best to put the join at the lowest part of the wheel so as to get better temperature all round.
There are other technologies that have been used. A great product was from California where the guy imbedded the element into a cast sheet of high temperature silicone rubber and then made a covering and more insulation around that. These were the best warmers I have seen, but sadly he gave all his money away in sponsorship and inventory and went bust, taking all the jigs and IP with him. They were really good warmers. I'm sure there were a few of those still around.
Another was from Germany where they used element printed onto high temperature plastic sheet [poly carb or something I assume, sort of like roasting bag polymer] and forming that into a warmer that always had a curved shape. This offered superior heating, but it came with a fuck off huge and heavy control box with a torroidal converter in it. Nowadays, and then too really, that control would be done with a small switch mode power supply. They also had diabolical male plugs that just got hammered!! Germans eh? Go figure. I wonder if there are still any of them around?
The ChickenHawk brand from the USA are also a good product, but they have not been all that keen on making a 240V product cos they make plenty for the 110V markets. They can do it, no problem, just not so keen, at least that was their story back in the day. Colt warmers were made in Australia, not sure if they are still around. They were a great product.
So anyway, the upshot is that like most things, you get what you pay for. OK, so $320 landed for Chinese warmers with a control box is all well and good, but I would not put those warmers any where near my pair of $400, $500, $600 pair of tyres having seen the damage they can do, and sadly, when they fail, they tend to do it in closed circuit!
Oh and incidentally, as this is where this thread started, the use of an InfraRed thermometer to measure tyre temperature is highly fraught. They are typically not calibratated to correctly measure the diffuse blackbody radiation that eminates from a hot tyre. The only reliable method is a contact thermocouple type thermometer such as used by tyre technicians at MotoGP/WSBK. IR thermostats only used there to look at heat of header pipes and track temperatures [roughly as they use the contact type for that too].
My few cents worth.
"Life is what happens to you while you're busy making other plans." John Ono Lennon.
"If you have never stared off into the distance then your life is a shame." Counting Crows
"The girls were in tight dresses, just like sweets in cellophane" Joe Jackson
Originally Posted by malcy25
Got both Holroyds and Capits, neither of which are temp adjustable. Both have some form of temp control process going on as I see them going on and off at various times. Have to admit, the adjustability of a flasher set would just be one more variable that I'd end ignoring! They seem to work at a level that brings they tyres to a nice "brie cheese" setting....and I'm always early out the garage so I lose a bit of temp. so on the high side good for me. Plus as some less than charitable souls would say, the tyres would come back cooler than I started from my riding!
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