General 15:50 Gear Ratio on EXR

[VINSANITY]

I have been playing with gear ratios on my EXR.

I ride quite a bit on the street and sometimes single track and MX tracks.

I put 15:50 gears on and the bike seems to conserve battery better when street riding due to lower motor RPM.

I thought off road power would be sacrificed but actually I find almost do difference and on longer fast straits I think it’s an improvement.

Wondering if I should try 48 or even 46 rear just to see what happens.

 

[fsfs]

I have been playing with gear ratios on my EXR.

I ride quite a bit on the street and sometimes single track and MX tracks.

I put 15:50 gears on and the bike seems to conserve battery better when street riding due to lower motor RPM.

I thought off road power would be sacrificed but actually I find almost do difference and on longer fast straits I think it’s an improvement.

Wondering if I should try 48 or even 46 rear just to see what happens.

This is all from memory so I may be 500 to 1000 rpm off. At about 7000 rpm the voltage generated by the motor equals the battery voltage. To go above 7000 rpm the inverter starts to weaken the field (caused by the magnets on the rotor). At about 13k rpm 70 amps RMS is required just for field weakening -- this causes considerable losses. These losses probably aren't so bad to about 10k rpm; above 10k they start to get pretty significant.

 

[VINSANITY]

That’s really interesting and helps in understanding how the power system functions.

Any idea on how to tell what the Alta motor RPM actually is during operation / actual riding.

 

[TCMB371]

That’s really interesting and helps in understanding how the power system functions.

Any idea on how to tell what the Alta motor RPM actually is during operation / actual riding.

your bike logs data points like RPM every time the key is turned on. You just need to download it off the bike via Multitool.

 

[Judaslefourbe]

You just need to download it off the bike via Multitool.

Got a few weeks?

 

[fsfs]

That’s really interesting and helps in understanding how the power system functions.

Any idea on how to tell what the Alta motor RPM actually is during operation / actual riding.

I think the motor to counter shaft gear ratio is 3.53
The speedometer assumes default sprocket count and tire size, so you can calculate the relationship between the shown speed and the motor RPM.

 

[Matt]

If you can get multiple functioning on a cellphone with a Bluetooth module plugged into the data port you could have real time RPM displayed on the phone via the dashboard as well as a variety of other information.

 

[fsfs]

If you can get multiple functioning on a cellphone with a Bluetooth module plugged into the data port you could have real time RPM displayed on the phone via the dashboard as well as a variety of other information.

The data port is CAN or something else? Can you pick up 12V or 5V from the same connector?

 

[Matt]

The data port is CAN or something else? Can you pick up 12V or 5V from the same connector?

It is CAN. I don't remember the pin schematic off the top of my head. I think it is somewhere on this forum. Even if you couldn't use the connector for a power supply you could just have a small battery powering the Bluetooth module. Would be a bit annoying but it's possible. The other thing with this idea is you would want to make sure there is no way water can get into the acm housing so it's a bit risky of a project for that reason.

 

[Rashid510]

The data port is CAN or something else? Can you pick up 12V or 5V from the same connector?

The ACM is reporting CAN. There is a 9V battery which keeps the ACM powered on for CAN TX/RX.

 

[Matt]

I tried to get Ubuntu running on my phone a while ago but without rooting the phone I couldn't find another way to make it work and I don't have a spare phone so I didn't want to root it. I am also not a software or electronics guru so. Even with just a cabled option so your phone is always plugged in it could work which is what I was trying to facilitate. I wanted to see some areas of my ride I could improve efficiency on for the 24hr race.

 

[fsfs]

It is CAN. I don't remember the pin schematic off the top of my head. I think it is somewhere on this forum. Even if you couldn't use the connector for a power supply you could just have a small battery powering the Bluetooth module. Would be a bit annoying but it's possible. The other thing with this idea is you would want to make sure there is no way water can get into the acm housing so it's a bit risky of a project for that reason.

ESP32 would do the job nicely. Could be a neat project for someone who has the time to do it.

 

[fsfs]

I tried to get Ubuntu running on my phone a while ago but without rooting the phone I couldn't find another way to make it work and I don't have a spare phone so I didn't want to root it. I am also not a software or electronics guru so. Even with just a cabled option so your phone is always plugged in it could work which is what I was trying to facilitate. I wanted to see some areas of my ride I could improve efficiency on for the 24hr race.

Is there some sort of published protocol or does it need to be reverse engineered? It would be much easier to just pipe CAN to WiFi or bluetooth and do the processing on the phone.

 

[Rashid510]

Is there some sort of published protocol or does it need to be reverse engineered? It would be much easier to just pipe CAN to WiFi or bluetooth and do the processing on the phone.

Awhile ago there was a thought to use a USB-C to USB-A dongle to connect to the CAN transceiver and then to a phone. You can try a Zigbee or a Pi as well...

 

[Matt]

Is there some sort of published protocol or does it need to be reverse engineered? It would be much easier to just pipe CAN to WiFi or bluetooth and do the processing on the phone.

Like I mentioned I am not a software guru ha but I was trying to get the multi tool software running on my phone. I bought the proper dongles to go from canbus to usb-C and in order to get multiple on my phone I needed a different operating system that the software can speak with happily. I was trying to get Ubuntu installed as the operating system so that I could download multitool software and then try and connect to the bike via the dongle I made. Just couldn't get the software running on my phone is the main issue. I think you could with relative ease have a Bluetooth module sending the can signal to your phone and then have your phone process that information in multitool but I am not sure if multitool would need to be modified to accept a Bluetooth signal vs looking for the CAN connection.

 

[fsfs]

Awhile ago there was a thought to use a USB-C to USB-A dongle to connect to the CAN transceiver and then to a phone. You can try a Zigbee or a Pi as well...

I have played around with a non-rooted phone running Termux. I got it to use a USB serial device (normally /dev/ttyACM0) under linux, but it didn't show up as such device. I hade to use libusb to get it to work. Also, it doesn't work on every phone. IMO, that route is painful. It is much easier to slap a CAN transceiver on an ESP32 and just pipe the data over WiFi.

Edit: something like this -- The CAN32—an ESP32-Based CAN Bus Board

 

[Matt]

I have played around with a non-rooted phone running Termux. I got it to use a USB serial device (normally /dev/ttyACM0) under linux, but it didn't show up as such device. I hade to use libusb to get it to work. Also, it doesn't work on every phone. IMO, that route is painful. It is much easier to slap a CAN transceiver on an ESP32 and just pipe the data over WiFi.

Edit: something like this -- The CAN32—an ESP32-Based CAN Bus Board

Would this mean we would have to build a program to interpret/display the data we are after that runs on our phone? Is the Alta always outputting this data through the CAN or does there have to be a positive connection with multitool to engage the ACM? Sorry if I am asking dumb questions

 

[fsfs]

Would this mean we would have to build a program to interpret/display the data we are after that runs on our phone? Is the Alta always outputting this data through the CAN or does there have to be a positive connection with multitool to engage the ACM? Sorry if I am asking dumb questions

They are not stupid questions. I do not have an Alta so I cannot check. Perhaps the bike spits data out on CAN regardless if multitool is connected or not. If somebody connects a CAN dongle to it and there is a bunch of traffic on the bus then the bike is probably spitting out the data and multitool is just listening. Someone with an Alta and CAN dongle needs to try (or maybe somebody already knows).

Edit: what is multitool written in? If some interpreted language like python then the source is available so it is possible to duplicate it in the ESP32.

 

[VINSANITY]

I put a 48T rear sprocket with a 15T front on an EXR and it improves range for street riding and still works really well for trail riding and MX tracks - I am thinking the stock EXR 13:53 gearing was totally unnecessary for mortals - maybe Josh Hill needs the power but for me it still wheelies without even thinking and handles off road trails in sandy conditions almost the same as stick gearing.

I’m going to try a 46T rear sprocket to see what the limit is.

It seems if you can keep motor RPM lower battery range improves.

 

[Johnny Depp]

I put a 48T rear sprocket with a 15T front on an EXR and it improves range for street riding and still works really well for trail riding and MX tracks - I am thinking the stock EXR 13:53 gearing was totally unnecessary for mortals - maybe Josh Hill needs the power but for me it still wheelies without even thinking and handles off road trails in sandy conditions almost the same as stick gearing.

I’m going to try a 46T rear sprocket to see what the limit is.

It seems if you can keep motor RPM lower battery range improves.

I have always thought this to be true. When you have all that instant torque from zero rpms.... Gear it to the moon and see what happens. I strongly suspect lap times and holeshots will continue to improve, as well as less power usage.