CVT and offroad driving conditions

[coachgeo]

Im curious about how a CVT would be used in conditions that WANT to increase wheel speed but you don't want it too. Mud for example

how do you gear down on purpose to use your torque to climb things for example?

[albertaphil]

Coach, I think the easy answer to your question is that with a CVT, your throttle becomes the POWER lever. Period. The driver must stop thinking about engine rpm and power output separately. So, if you're in the mud and you don't want your wheel(s) to spin, you back off on the throttle until the spin stops. When you want power, you add throttle, and your rpm will do whatever it wants to produce the power needed to move the wheel as fast as you ask it to. If that kind of power needs high rpm, then that is what happens.

As for gearing down to use torque...we think that way because we are accustomed to being stuck in a gear, and we want to be in the right gear at the right time, with the engine producing the right amount of power in a controlled way to do what we want. With the CVT, you have any and every gear available to you at all times. To climb the hypothetical hill you mentioned, it will take the same amount of POWER regardless of what rpm our engine is running at, but with a gear transmission, we try to place our engine in the right rpm range to make power in a way that is easy for us to control. The only way to "gear down" your CVT is to add throttle until your wheel is going the speed you want. That being the case, a speedometer that is geared to the rear wheel of a CVT bike would be much more useful in offroad conditions than the standard front-wheel-drive speedo.

I think that the confusion when thinking about this setup happens because with gear transmissions, the gear ratio is what it is. A CVT, must be set up to match the engine's power, rpm, and torque, to produce the right kind of driveability. What would be really cool is a CVT that could be adjusted on the go for the type of driving you're doing. I'm sure the CVT's in cars now are like that, but to change the setup of your Comet, for instance, you must pull the clutch apart to add pucks (weights) or springs. The secondary pulley must also be tuned to the engine, and to the primary pulley.

Most new quads come with CVT transmissions. If you're used to jamming gears, you might not like it. But it is really nice to just add throttle and go whatever speed is appropriate, and let the engine rpm look after itself. It might be worth finding someone with a CVT quad and take it for drive to understand what I'm saying. Hope this helps.

Cheers,
Phil

[smokyjoe]

The strictly-offroad 2WD ROKON bikes switched to a CVT back in the early 70's, they weren't very well received I think for the reason you mentioned. The Rokon used an ancient design Albion 3 speed manual with a centrifugal clutch, when Rokon couldn't get the Albion any more they switched production to the CVT for a few years 'till they came up with a crashbox of their own. I have a little Honda with a CVT, I love it, just twist 'n go. I've driven the Rokon with the CVT and offroad once you are used to the different feel it's a charm. I think it works just as well as shifting, just takes gettin' used to, and that's all.

[IgorVigor]

I have found that its quite hard to keep the back wheel(s) spinning on a CVT equipped bike/quad...its possible, but no where near as easy as a manual box...

As others have said, the CVT is almost permanently adjusting the gear ratio to suit the currrent situation so if the back wheel starts spinning they quite often will just alter the ratio to regain control...

if for some reason it does keep spinning, just get more weight onto the back wheel(s) by leaning back, or bouncing/rocking backwards and forwards onto the wheel...

I personally prefer a manual box, but a CVT is my second choice (don't like auto's that change to preset gears )...
It just takes a bit to get used to...mostly that the engine stays at the same RPM even though your slowing down...