Theoretical top speed

[Philip]

I made a quick theoretical speed calculator for our bikes. Just input the tire diameter (inches) and the mph for each sprocket combination will be computed.

Alta Redshift Sprocket Calculator

View attachment 4093

Cool! A very handy reference. Could you please post this in Resources?

The SM needs a second table though because it has only a 24" tire.

 

[C5tor]

Cool! A very handy reference. Could you please post this in Resources?

The SM needs a second table though because it has only a 24" tire.

It is a spreadsheet, so you can change the tire size by opening it in Excel or Google Sheets, etc. Just type in a new tire size in the diameter field.

 

[Dmagg]

This was a good top speed run in a stock 2019 exr. I think the spreadsheet given on this thread estimates 71 mph. The guy in the video was cruising at 76. When I first saw the video it seemed like the bike was electrically limited in the way it stopped accelerating once it reached 76 (which is why I made the post to begin with), but I agree that the gear ratios can explain it

 

[TCMB371]

I had the spreadsheet calculating for 13000rpm motor speed. Oops. At 14000rpm the EXR calculates to just about 76mph with stock gearing.

 

[Caryder]

2019 EXR, 15/48 sprockets, Shinko 705 tire... today GPS said 89 mph. Definitely RPM/speed limited and not aero limited. Three attempts, 88/88/89 (last one was down hill just to confirm it wasn’t aero limited). Also... It gets to top speed fairly quick.

 

[TCMB371]

Sounds about right for 13000rpms, assuming you're running a 120/80 R18 Shinko 705 (25.56" diameter). When set to 13000 rpms, the calculator shows 88.3mph. So your rear tire is probably a tiny bit larger diameter than 25.56".

 

[Caryder]

Sounds about right for 13000rpms, assuming you're running a 120/80 R18 Shinko 705 (25.56" diameter). When set to 13000 rpms, the calculator shows 88.3mph. So your rear tire is probably a tiny bit larger diameter than 25.56".

I assume the run I did yesterday is logged. I know that log files download when multitool is connected, but can you target a specific file date range to download? I'm curious what the actual motor RPM was.

 

[C5tor]

Speaking of log files, is there a way to turn off the log file download feature while in multitool? (Yes I know they don’t download while you are on the right-most tabs.). It just seems to take a lot of cycles downloading, when all I wanted to do is look at some current data.

 

[TCMB371]

I assume the run I did yesterday is logged. I know that log files download when multitool is connected, but can you target a specific file date range to download? I'm curious what the actual motor RPM was.

Multitool looks at the logs stored on your bike (most recent first) and checks if the computer has it already. If not, it downloads it. If so, it skips to the next one and checks again. As of now you can't target it.

The software dev team likely configured it this way so that field techs could retrieve log files of the session a test rider just finished. IE, they tried to simplify/automate the process for the "less computer savy" field techs in a sense.

 

[TCMB371]

Speaking of log files, is there a way to turn off the log file download feature while in multitool? (Yes I know they don’t download while you are on the right-most tabs.). It just seems to take a lot of cycles downloading, when all I wanted to do is look at some current data.

You don't have to let the log file download finish. Often times the download can be ignored if you don't really care about the logs.

 

[datadog]

Dealership techs did not have the ability to see logs, so there wasn't a need to simplify much. The data files are quite simple by nature. In the field, there were three employees that could view data. Engineering could view if they needed to.

Every time you turn the key off, a log file is terminated. Turn it back on, new file starts. Multitool is also clever enough to realize the last complete log file it has downloaded locally, so if you disconnect MT it will start where it last finished. Charging is logged as well as moving time.

 

[Caryder]

Ok, so reading through the responses, if I connect multitool it will download the most recent log file from yesterday’s ride first. I just wanted to confirm the motor tops out @ 13 or 14k RPM. The speed calculator spreadsheet matches 13k RPM too close to be a coincidence, but I thought the motor spun up to 14k.

 

[TCMB371]

The motor is rated for 14000 rpm but i have not seen my bikes spin up past 13000rpm. I've found that the MX/MXR and EX/EXR are limited to 13000rpms in all maps. The SM I got to play around with for a little while was limited to around 11000rpm in Map 1-3 and 12000rpm in Map 4.

 

[Caryder]

The motor is rated for 14000 rpm but i have not seen my bikes spin up past 13000rpm. I've found that the MX/MXR and EX/EXR are limited to 13000rpms in all maps. The SM I got to play around with for a little while was limited to around 11000rpm in Map 1-3 and 12000rpm in Map 4.

Ahh, that explains it. Thanks.

 

[Mark911]

Wow, I’d expect at least 100mph with some gearing changes. As Brian mentioned, we hit 95mph (in the 1/4 mile!) with the Grom and it’s the same weight at the Alta (although a somewhat less frontal area).

 

[Caryder]

Wow, I’d expect at least 100mph with some gearing changes. As Brian mentioned, we hit 95mph (in the 1/4 mile!) with the Grom and it’s the same weight at the Alta (although a somewhat less frontal area).

I agree, at least 100. My EXR has no problems hitting 88 in a short distance. I bet the little Grom chassis has a lower drag coefficient, and it’s direct drive (right?) eliminating the extra drag of the gearbox. I’d like to see the Alta motor in a go kart. Pretty sure it would rock.

 

[Mark911]

Here you go . . . . .

 

[F451]

View attachment 4200

Neck snapping torque, nice! I want one, Lol.

 

[Caryder]

View attachment 4200

Any links to stats or video on that? I assume it would have to be on par or better than any 125 shifter or TAG kart.

 

[Mark911]

Any links to stats or video on that? I assume it would have to be on par or better than any 125 shifter or TAG kart.

It's pretty fast considering the weight . . . . not sure if it's faster than a shifter as I haven't really opened it up yet (still doing shakedown work). I've got to get it handling properly first as the higher CG needs to be compensated for with track and stiffness adjustments and that takes track time.