09-09-2020, 07:08 AM
(This post was last modified: 09-17-2020, 07:55 AM by Jan Oelbrandt.)
(09-08-2020, 03:54 PM)Ed_R Wrote: I'm too addicted to my enviolo (NuVinci) hubs to want to build one and don't really like derailleur gears.
Quote:The Nuvinci CVT hubs are great. With modified 3D prints of the BigBox and the servo horn, the Shift4Me would work with them too. This is needed to house the two-cable setup of the Nuvinci.
Slightly over shift and then drop back, not sure for how long or by how much.
Quote:As Visitor007 pointed out correctly, it is already there. The CorrectAmount parameter does an over-shift of a pre-set amount PWM when moving to a larger derailleur sprocket, and this amount divided by 4 when moving to a smaller sprocket. This turned out to be great working for 9-speed derailleurs, PWM correction of 100. You can see that in action in this close-up video. It could be (haven't tried it) that this amount has to decreased for cassettes with more gears (typically 11-speed these days) and increased for older cassettes like 5- or 6-gears. In the Hubgear version of the code, you'll see it is only set to 4 (almost nothing).
Time the shifts to happen at the dead spot of the pedal stroke. <...>
Would love to know if it could remove the need to ease off the power when shifting.
Quote:That's a great idea. However: from what I suspect, the servo like the recommended ones wouldn't be fast enough to do so. For example: if you're doing 60 rpm, and let's sat the dead spot is 36 degrees (pedal round 12 o'clock), that makes for 0,1 second time for the servo to pull the cable and the chain to slide onto the next sprocket. Not enough, I'm guessing.
On hubgears it could work...
But what I would do to try it out, is to install two (at a different angle positioned) reed sensors, so the measurement of the cadence is more precise. That way, one could very accurately define the time where the dead spot occurs, so that shifting can be done at that exact moment. The installation of 2 sensors is something I considered during developement, but I decided against because with 1, cadence sensing is good enough and setup is a lot easier (for example, there's only one bar of a bike frame that's near the left pedal to install a sensor. So you'd need a bracket of some kind to install a second sensor)