Zen Photon Ultra - limited version (Bafang Ultra, Rohloff Speed hub, Gates belt drive)

[Gionnirocket]

I have some question on the different settings available on the Bafang M620 motor. I have built a number of e bikes using the bafang conversion kits in 750 W and 1000W versions. How difficult is it to convert from the Road version to the Off Road version? Besides the difference in available power is there any other difference like speed? I know the kits allowed you to go in at the display and enter a code that allowed certain changes like top speed to be entered (last bike build was over 5 years ago and that might have changed).

I believe it's a toggle of the display buttons also know as ECO/SPORT.
I changed my display to the 860C which allows for 9 PAS as used on the 750W conversion motors.
Never liked the 5 eco/5 sport option.

 

[Cybersnow]

I recently ordered the Photon Ultra and will receive it mid May. I am pretty excited about the bike’s setup but know little about the actual details. How did you go about changing the display? Did you order directly from Bafang or from a distributor? I rebuilt the 1000W motor once on the BBS01 (i think that is what it was) and found all the parts from a distributor, but no longer remember where.

I am asking again if anyone knows the details/changes between the Rpad version of the Photon Ultra vs the Off Road version?

 

[Cybersnow]

I found a pretty detailed explanation of how to reprogram the motor, but to be honest I would probably screw it up even if it appears to be simple. Two questions I still have are; the difference between the Road and Off Road version.? The model of the Rohloff hub on the Ultra and if there is a different one on the Off Road version?

 

[Gionnirocket]

I found a pretty detailed explanation of how to reprogram the motor, but to be honest I would probably screw it up even if it appears to be simple. Two questions I still have are; the difference between the Road and Off Road version.? The model of the Rohloff hub on the Ultra and if there is a different one on the Off Road version?

The hubs are all geared the same... The end result can be adjusted by using different chainrings and rear sprokets. Rohloff suggests not going above 2.5x rear to front.

Where are you reading Road / Off Road?
If it's as I think... It's in the programming of the PAS settings as mentioned earlier. The Road (or Eco) are typically slightly less aggressive than Off Road(Sport). But if you get into the programming, you can set them as desired.
Once you have the bike.. if you tell us what you'd like to adjust there are many here that can help.

There's some useful information here once you weed through the superfluous and the vainglorious narrative.... though I don't agree with all of the implementation advised.

Ultra Tuning: Master Thread -- Start Here!

If you're starting out to tune, or re-tune, your Bafang Ultra G620/M510 motor, you've come to the right place. There's a lot to setting up an Ultra to ride the way you want, but if you take it a step at a time it won't be as daunting. You don't have to do them all at once - I actually recommend...

forums.electricbikereview.com

 

[Cybersnow]

First, thanks for the great reference on how to tune the m620! I ask because the new Ultras offer either a Road or Off Road version and other than 750w vs 1000w, and the accompanying change in torque, there is little data on what else changes. I did order the Ultra in the Road version, but many of my friends up in Idaho ride off road versions from other companies.

 

[Gionnirocket]

First, thanks for the great reference on how to tune the m620! I ask because the new Ultras offer either a Road or Off Road version and other than 750w vs 1000w, and the accompanying change in torque, there is little data on what else changes. I did order the Ultra in the Road version, but many of my friends up in Idaho ride off road versions from other companies.

Ahh ok....
So you are referring to the difference in total rated wattage of 750w or 1000w. From what I understand there is no difference other than firmware limiting the 750w version.
Have you asked this question directly to Zen?

 

[Cybersnow]

Yes I have. I missed a call from them last night. I posted this here as I know that they often read and reply to this forum. I also read on the Rohloff website that there are various versions of the hub, some of which can take about 120 Nm and others that can take up to 220 something. If the hub provided is rated at 120 Nm it is clearly not a good idea to go to off road with this hub. Just trying to get a feel for my limitations. Maybe overthinking it…but typical for this engineer .

 

[Gionnirocket]

I'm confused.... as I read it the hub variations are to fit different frames, axles and braking set ups.. But the hub is basically one. Now maybe those factors may change rated torque, but I don't believe so.... but then again I didn't research too much beyond the version I received which is the A12 @ 130 Nm

Technical Data - Rohloff AG

www.rohloff.de

 

[Ravi Kempaiah]

Yes I have. I missed a call from them last night. I posted this here as I know that they often read and reply to this forum. I also read on the Rohloff website that there are various versions of the hub, some of which can take about 120 Nm and others that can take up to 220 something. If the hub provided is rated at 120 Nm it is clearly not a good idea to go to off road with this hub. Just trying to get a feel for my limitations. Maybe overthinking it…but typical for this engineer .

Hi,
I just returned to Canada from an extended trip to Asia. I am just catching up on all emails.
Re: Rohloff variations, please take a look here - https://www.rohloff.de/en/products/speedhub/speedhub-variations

Basically, the hub internals are the same, and they are all rated for 130Nm, but the hub is able to handle much more. This is why companies like Optibike are using the same Rohloff hub on their flagship models like R22, which is rated for 190Nm of torque.
Optibike R22 - https://optibike.com/r22/
Based on our experience working with Rohloff, here is what we recommend.

1. Do not shift under load. Easing off on pedals and changing gears at 6'clock or 12' clock position ensures the gear hub pawls are not damaged. For detailed understanding of the gear shifts, please take a look at the video when you have 15 mins.
   
   
   
   
2. Regular maintenance - an oil change every 6 months would help, and do not overfill when performing this maintenance.
   
   
3. If you want to run high power, use gear 11, which can handle much higher torque as the 11th gear is direct drive 1:1. As such, it is the most efficient in the box and also the one that generates the least wear on the hub internals. So ideally, it is the one you want to be in the most.
   

 

[Cybersnow]

Thanks Ravi!
This answers my questions on the Rohloff hub! Do you have any information on the gearing of the belt drive? I am not sure what the equivalent to sprockets are on a belt..cogs? What is at the motor vs at the hub?

 

[Ravi Kempaiah]

Thanks Ravi!
This answers my questions on the Rohloff hub! Do you have any information on the gearing of the belt drive? I am not sure what the equivalent to sprockets are on a belt..cogs? What is at the motor vs at the hub?

Hi John,
The front ring is 55T, and the rear cog is 22 T.
If needed we can change the rear cog to 20T.
The 22T will last a bit more than 20T because of the larger surface area associated with more cogs.

 

[Jeremy McCreary]

Hi John,
The front ring is 55T, and the rear cog is 22 T.
If needed we can change the rear cog to 20T.
The 22T will last a bit more than 20T because of the larger surface area associated with more cogs.

Any idea what the bike's effective gearing range is in gear-inches?

 

[Cybersnow]

Ravi,
Using your numbers, I wanted to get an idea of the cadence needed to go about 16mph in various gears. Thanks, the gearing is very similar to the bikes we have been riding. I did not factor in any pedal assist from the motors and am very happy with my findings. Oh, is a 20 tooth cog pretty available?

Thank you very much.

Jeremy, Sorry I did not do that computation. I started at the Rohloff gear of 11 which is a 1.0 gear at the rear 22 tooth cog.

 

[Ravi Kempaiah]

Any idea what the bike's effective gearing range is in gear-inches?

This might be useful:

Graphical Gear Calculator for Bicycles

The bicycle gear calculator displays graphically the gearing of derailleur gears and gear hubs. It can be used to compare different setups to find the optimal gearing for all kinds of bicycles.

www.rohloff.de

 

[Cybersnow]

Very interesting, i could have save a bit of work. Thanks!!

 

[Jeremy McCreary]

Ravi,
Using your numbers, I wanted to get an idea of the cadence needed to go about 16mph in various gears. Thanks, the gearing is very similar to the bikes we have been riding. I did not factor in any pedal assist from the motors and am very happy with my findings. Oh, is a 20 tooth cog pretty available?

Thank you very much.

Jeremy, Sorry I did not do that computation. I started at the Rohloff gear of 11 which is a 1.0 gear at the rear 22 tooth cog.

Maybe @Ravi Kempaiah will weigh in.

The bike's external gear ratio is 55/22 = 2 .5. We know now that the Rohloff's gear 11 of 14 has an internal ratio of 1:1. Final drive from crank to wheel is then 2.5:1. If D is effective wheel diameter in inches, then gear-inches for gear 11 would be 2.5 * D. For D = 27.5 in, that would come to 69 gear-inches — which is closest to gear 8 of 10 on my current bike.

More interested in the final gear-inches for the bike's lowest and highest gears. For that, we'd need to know the bike's D and the Rohloff's lowest and highest internal ratios — which I have yet to find.

 

[Gionnirocket]

Maybe @Ravi Kempaiah will weigh in.

The bike's external gear ratio is 55/22 = 2 .5. We know now that the Rohloff's gear 11 of 14 has an internal ratio of 1:1. Final drive from crank to wheel is then 2.5:1. If D is effective wheel diameter in inches, then gear-inches for gear 11 would be 2.5 * D. For D = 27.5 in, that would come to 69 gear-inches — which is closest to gear 8 of 10 on my current bike.

More interested in the final gear-inches for the bike's lowest and highest gears. For that, we'd need to know the bike's D and the Rohloff's lowest and highest internal ratios — which I have yet to find.

This might help.
Example for 650b.



Here's for other diameter wheels.

Crankset - Rohloff AG

www.rohloff.de

 

[Cybersnow]

The data for each gear is on the Rohloff website. I only used 11-14.

 

[Jeremy McCreary]

The data for each gear is on the Rohloff website. I only used 11-14.

Not so easy to find, but I eventually dug up this technical page on their E-14 Speedhub.

The internal ratios for gears 1 and 14 are 0.279 and 1.467, resp. With the Ultra's external ratio of 2.5 and an assumed 27.5 inch wheel diameter, that gives 19 and 101 gear-inches, resp.

Very promising for pedaling my terrain at low assist.

 

[Cybersnow]

I had totally forgotten about gear inches and focused on a comparison of cadences required to attain 16mph. That is the speed we typically try to maintain on trips longer than 20 miles (over relatively flat or gently rolling hills). I was very pleased to find that the Ultra was very comparable to my unpowered gravel bike. I only looked at 11-14. After looking at the lower gears I was convinced that with the bike programmed in the Road mode I would have no issues climbing some of the steeper grades, in fact I dont expect to ever get below gear 4 or 5.