Hot on the heels of the last post, here we go again, with the next little problem to work on. It looks like the bad wrist isn’t going to recover much more now without an operation, and Dog knows when that’ll happen. So I’ve been pondering how to reduce the load (torque) my poor old wrist feels at the twist grip.
It seems to me there are two ways to do this ….. firstly, increase the diameter of the twist grip to get more leverage, the second is to replace the cam at the throttle body to do the same job (more on this later) – or maybe a combination of the two! So let’s look at the first option.
The Aprilia heated grips (with replacement Ariete grip rubbers) are 32.8mm diameter and probably the cheapest and easiest way to increase this would be to simply fit a set of Grip Puppies. But the fact is the Aprilia heated grips are quite poor when it comes to output. The 13Ω elements are really only any good for chilly Spring, Summer and Autumn mornings and certainly don’t do much on a freezing Winters day in the UK. So I started to hunt around for a better heated grip with
more power. In the end I opted for a set of Oxford Products Premium Adventure grips (OF690).
These grips are approx. 35mm diameter, so that’s one box ticked, and they have heater elements averaging approx. 7Ω …… that’s almost half the resistance and will mean twice the output. The grips are 132mm long and can be trimmed if necessary down to 122mm, so fit shouldn’t be an issue.
The heat adjustment is in five steps (30%, 40%, 50%, 75% and 100%) using PWM (Pulse Wave Modulation). In other words, a microcontroller turns the power on for a certain percentage of the 1.3 second cycle ….. so 75% output means the grips are on for approx. 0.975 seconds, then turned off for 0.325 seconds – total 1.3 seconds – then the cycle repeats itself. Now this is all well and good but they really missed the mark to my mind. Microcontrollers are great little gadgets and can be programmed for all sorts of things and as far as these grips go, they only scratched the surface. First off, when you turn off the grips they turn back on at the default 30% or 100% if you hold the button down – NEVER at the last setting you may have been using*. Secondly, a rapid warm up would have been nice, say 100% for 2 minutes at start-up, then back 
to your last used setting ….. but none of this is programmed in on the OF690.
In fact isn’t it about time grips came with temperature sensors in-built? Think about it ….. set the desired heat and ride along happy as larry with toasty fingers on a bitter winters day. Stop for a minute and take your hand off the grip and it now cools rapidly – the cooling temp sensor feeds back to the controller, which now ramps up the output to try and restore the grip temp back to that desired. You then plonk your size 10 winter mitt back on the well heated grip, and now the grip is insulated the system reduces power to maintain the temperature. And it goes without saying that both grips should do this independently!
Anyway I digress, the whole point is that the new grips will give me a welcome increase in diameter, even then I have the option to add Grip Puppies over the top but I think this might be overkill! But who knows ……
Next post I’ll look at the pro’s and con’s of changing the cam at the throttle body to achieve a reduced torque at the twist-grip.
*This function along with 9 heat settings instead of 5 is available on the Hotgrips Advanced Adventure UK SPECIFIC (EL690UK). Why didn’t I buy these? Simply because I got the OF690 set for £30 cheaper! 😀