cactusjack
September 21st, 2010, 08:42 PM
This one is kind of long, but if you feel like giving it a read, please vote in the attached poll. Unless someone points me to an existing product, I am thinking of trying to make a prototype or two for testing.
I've been struggling to find an ideal solution to comfortably achieve fine throttle and brake control. My comfort problem may be exacerbated by a torn collateral ligament in my thumb that I never got fixed, as a result of which my throttle thumb kills after a couple of laps. But even assuming a functioning thumb, I think there is a serious compromise between the two functions with current technology.
I have a Euro throttle and use the biggest cam available, which is 56mm in diameter and achieves a full throttle opening in 54.6 degrees of rotation. If I grip my bar comfortably, I am not able to open the throttle all the way without really tweaking my wrist. If I rotate my hand forward to increase my range of rotation, then the transition from throttle to brake becomes awkward and forces me to also rotate my brake lever forward/down to match the forward rotation of my wrist when off-throttle. And even then, the whole situation just feels awkward, and the brake lever needs to be pretty low in order for the angles to work out. So either my wrist/thumb hurts at open throttle or my throttle-to-brake transition is not as smooth as it could be.
I've been making it work; my point is that it's not an ideal situation. But a couple of times, late in particularly tiring race weekends, I've caught myself not opening all the way every time.
The ideal throttle rotation would be something like 45 degrees, which comes out to a 68 mm cam at the throttle tube. But I wouldn't want to increase the cam diameter much from the 56 mm I am using now, because the throttle would become way too touchy. And that's on a 600. On a liter bike, even the 56 mm may be too touchy.
Thing is, the touchiness is really only an issue in the beginning of the rotation. As the throttle is opened more, the control can become more granular / less precise -- it's the initial application of the throttle, when the bike is still leaned way over and the traction balance very precarious, that requires the most precision.
So why not design a throttle cam that has an elliptical rather than circular cross section? Provide a more forgiving profile in the first several degrees of rotation, then progress towards a steeper profile as the throttle opening increases. Frankly, I could even use a slightly mellower profile than the 56 mm in the beginning -- for argument's sake, let's say start at a fixed 52 mm for 10 degrees, start gently ramping up over the next 10 degrees, and increase the slope more aggressively for the final 25 degrees. The precise break points for the transitions would have to be tweaked, but I like having three profiles to reflect the three kinds of throttle application: (1) throttle on / setting throttle; (2) feeding progressively more throttle on exit; and (3) opening throttle all the way (the last one can be quite steep, especially on a 600, because at this point, nothing much should happen...on liter bikes wheelies remain a possibility, I imagine).
I no longer possess the trigonometric or calculus chops to figure out the required diameter at maximum rotation or the two distinct rates of change in diameter, but I guess the details can be figured out if the idea is sound.
There is a company that makes a progressive throttle out there, but their product is meant to mellow out initial throttle application and increase the diameter from there only enough to achieve a stock throttle rotation from closed to open. They also make a quick throttle kit, but that one is not progressive and is the rough equivalent of the Euro throttle I currently use.
For roadracers, I think a combination of the two would be ideal.
So the question is: if something like this existed, would you be interested in trying it out?
And if I'm missing something obvious that either already exists or that makes this a stupid idea, please feel free to let me know.
Frankly, write down anything you like. Share your frustration if you have experienced the same thing as me, or share your method of making it all work out smoothly if you've found one.
I've been struggling to find an ideal solution to comfortably achieve fine throttle and brake control. My comfort problem may be exacerbated by a torn collateral ligament in my thumb that I never got fixed, as a result of which my throttle thumb kills after a couple of laps. But even assuming a functioning thumb, I think there is a serious compromise between the two functions with current technology.
I have a Euro throttle and use the biggest cam available, which is 56mm in diameter and achieves a full throttle opening in 54.6 degrees of rotation. If I grip my bar comfortably, I am not able to open the throttle all the way without really tweaking my wrist. If I rotate my hand forward to increase my range of rotation, then the transition from throttle to brake becomes awkward and forces me to also rotate my brake lever forward/down to match the forward rotation of my wrist when off-throttle. And even then, the whole situation just feels awkward, and the brake lever needs to be pretty low in order for the angles to work out. So either my wrist/thumb hurts at open throttle or my throttle-to-brake transition is not as smooth as it could be.
I've been making it work; my point is that it's not an ideal situation. But a couple of times, late in particularly tiring race weekends, I've caught myself not opening all the way every time.
The ideal throttle rotation would be something like 45 degrees, which comes out to a 68 mm cam at the throttle tube. But I wouldn't want to increase the cam diameter much from the 56 mm I am using now, because the throttle would become way too touchy. And that's on a 600. On a liter bike, even the 56 mm may be too touchy.
Thing is, the touchiness is really only an issue in the beginning of the rotation. As the throttle is opened more, the control can become more granular / less precise -- it's the initial application of the throttle, when the bike is still leaned way over and the traction balance very precarious, that requires the most precision.
So why not design a throttle cam that has an elliptical rather than circular cross section? Provide a more forgiving profile in the first several degrees of rotation, then progress towards a steeper profile as the throttle opening increases. Frankly, I could even use a slightly mellower profile than the 56 mm in the beginning -- for argument's sake, let's say start at a fixed 52 mm for 10 degrees, start gently ramping up over the next 10 degrees, and increase the slope more aggressively for the final 25 degrees. The precise break points for the transitions would have to be tweaked, but I like having three profiles to reflect the three kinds of throttle application: (1) throttle on / setting throttle; (2) feeding progressively more throttle on exit; and (3) opening throttle all the way (the last one can be quite steep, especially on a 600, because at this point, nothing much should happen...on liter bikes wheelies remain a possibility, I imagine).
I no longer possess the trigonometric or calculus chops to figure out the required diameter at maximum rotation or the two distinct rates of change in diameter, but I guess the details can be figured out if the idea is sound.
There is a company that makes a progressive throttle out there, but their product is meant to mellow out initial throttle application and increase the diameter from there only enough to achieve a stock throttle rotation from closed to open. They also make a quick throttle kit, but that one is not progressive and is the rough equivalent of the Euro throttle I currently use.
For roadracers, I think a combination of the two would be ideal.
So the question is: if something like this existed, would you be interested in trying it out?
And if I'm missing something obvious that either already exists or that makes this a stupid idea, please feel free to let me know.
Frankly, write down anything you like. Share your frustration if you have experienced the same thing as me, or share your method of making it all work out smoothly if you've found one.