Bafang to Rohloff belt drive question.

If a 60T sprocket does not fit, we can look at 19/55 (see below). For that @Ravi Kempaiah needs to confirm how much range there is at the rear axle to move the wheel forward or backward.

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The 2.75 ratio is certainly better, but is it doable? With all the very low gears on the Rohloff and an available 1500watts I dont think climbing that hill will be an issue…it wont be a fast climb but will be doable.

Ravi, what do your engineers say about the 55/20, 55/19 or 60/20 options?
 
Cybersnow said:
Ravi and I had a informative phone call. While Ravi was adamant about increasing cadence, at 78 years old I am not sure I will ever be able to maintain a cadence of 75 for hours at a time. I guess I have to accept that I am now an old fart and that my marathon days are over. I guess that leaves me with a few choices. The first being buying another bike or trying to convert the existing one so I can enjoy it. After not riding for about a year I know that picking up the cadence will help. Rather than spending the money on another bike I have decided to adjust a few things on this bike. I don’t have the skills or tools to modify the belt system and the two tiny bike shops in my little town have declined on working on a belt system, so the bike gets transported to Boise Idaho on Thursday. I will have them contact Zen Sales and explore if it is possible to adjust the 2.5 ratio closer to 3.0. If that is not possible then I wonder if it would make sense to replace the Rohloff with a standard 11 speed gear set.
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As you can see you are in good hands so don't throw the baby out with the bath water just yet.
1... I think some front/rear sprocket changes should be doable.
2... You're just getting back in the game after a long while and you may be able to get your cadence up a little once you get back in a groove. I'm running 2.5 and manage 18 mph rather easily even with my chicken legs. Though I agree the 2.5 is too bias towards the lower gears.
3... Everything is a compromise and now that I've had the Rohloff a while.. I don't know if I'd ever want a derailleur again.
4... I'd definitely use the bike bit and see what milage you get. You may be able to increase assistance enough to achieve the speed you want while still getting a workout and getting home with battery to spare.
 
Jeremy McCreary said:
With 60/20 external gearing, all of those speeds would increase by 20%, but I'd worry about the effect on the 35% climb the OP faces on every ride from home.
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Going from 22/55 to 20/60 basically shifts the lower gear by a little over one gear.

So unless he has to use gear one today with 22/55 he shouldn't miss it when going to 20/60
 
scrambler said:
Untighten the wheel, move forward to take the belt of the sproket, remove wheel, open the rear triangle, slide the belt out through the opening.
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Ah yes, just found a photo. If the belt's that easy to change, inadequate wiggle room on rear wheel position might not be a deal killer.
 
Cybersnow said:
This web site has some very knowledgeable and very helpful members. I am totally impressed. I think by changing the rear sprocket and riding on a regular basis this bike will certainly work out.
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One way or another, hope you get this bike tweaked to your needs.

I've been drooling over the Photon Ultra since it was announced. Will have to see how battery range works out, but the stock 19-101 gear-inches would be perfect for my cadence, hilly terrain, and determination to pedal at low assist whenever possible. The salt and sand here have not been kind to my chain drivetrains, and I'd be proud to have a bike with an engineering marvel like the Rohloff onboard.

Good luck, and keep us posted!
 
Jeremy McCreary said:
Ah yes, just found a photo. If the belt's that easy to change, inadequate wiggle room on rear wheel position might not be a deal killer.
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Well the issue is that Gates does not make belt for every number of teeth, so you always have to check the chainstay for the closest available belt, and see if the bike can accommodate the small change in chainstay...
 
One thing also to consider... Your ability is your ability.. as is mine.
And again though the 2.5 is too bias toward the lower gears.. by increasing the gear ratio you also will be making it harder to pedal in any particular gear and thus may require more assistance. I know gear 11 is the sweetspot on the Rohloff so making changes to make it your go to makes sense.. but 11 will feel tougher to pedal in than it does now. Spinning gears at higher rpm always feels easier so I try to stay in the gear that's spinning with just enough resistance to exercise. I measure my rides in time smiling not speed or distance.
All the calculations are very helpful.. but in the end the main variable is our input.
I too want to go with a higher gear ratio but with the thought of making the lower gears more usable.
All this said I say use it a bit as something new often can feel wrong until you find your (and it's) groove. After all it's summer time, prime ride time.
 
With the stock 55/22 gearing, the OP would have to pedal at a sustainable 78 RPM to cruise at 16 mph in 11th gear. That's a long way from his preferred 60 RPM. He's clearly an experienced cyclist, so we have to take that 60 RPM seriously.

How much cadence can he expect to gain with realistic training? I went from a tight 75-85 range to 80-90 in a year and 2,000 mi of casual hilly low-assist riding after 20+ years away. That 5 RPM bump brought me back to the cadence of my youth with no further gains in the 8 months since. I'd need serious training to get much higher, and I'm not about to spoil my fun with that.

The OP sounds like a stronger cyclist than I am at about the same age, so maybe he can add more than 5 RPM with realistic training. But going from 60 to a sustainable 78 RPM sounds pretty implausible. He told us flat out that even 70 RPM is unsustainable now in 11th gear at 16 mph.
 
A couple of things, first I did find a bike shop that has experience in gates belts and rohloff axles. i did do a 20 mile ride averaging about 17+ mph on the flats in gear 14. I am not sure that moving that speed down around gear 11 is going to make it any harder to pedal, but it will allow me a couple of gears to go faster if I have the strength to pedal. Like Jeremy said, I can hope to get my long ride average up a bit but am old enough not to shoot for the unachievable. My legs are still pretty strong from lifting and carrying heavy objects and living in the mountains means every walk is a combination of uphill and down hill. But fast I am not!
 
Cybersnow said:
A couple of things, first I did find a bike shop that has experience in gates belts and rohloff axles. i did do a 20 mile ride averaging about 17+ mph on the flats in gear 14. I am not sure that moving that speed down around gear 11 is going to make it any harder to pedal, but it will allow me a couple of gears to go faster if I have the strength to pedal. Like Jeremy said, I can hope to get my long ride average up a bit but am old enough not to shoot for the unachievable. My legs are still pretty strong from lifting and carrying heavy objects and living in the mountains means every walk is a combination of uphill and down hill. But fast I am not!
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If your shop can fit the 19t rear without changing the belt or front sprocket, that would seem a good next move. You can enjoy the benefits while your cadence comes up. At 67 RPM, 55/19 will give you 15.9 mph in #11.
 
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After a few conversations with Zen and Ravi, they were kind enough to offer swapping a 19 tooth sprocket for my 22 tooth. One of the questions that came up from the bike shop was whether the bike has a tensioning adjustment. The individual that called me back is the expert on that part of the bike and explained how easy it is to make the adjustments. Apparently I will not need a different belt. I am now waiting for the part to arrive and then will take it to the shop in Boise. Thanks everyone for your help.
 
I'm not suggesting that you don't make some changes to the bike.. just that you ride a bit longer to better understand what it is you have.
A couple of observations...
You haven't riden in a year. I become petrified after not riding 3-4 weeks in the winter when it's too cold. 🤣 So give yourself a little bit of a chance. After the winter it takes me about a month and a couple of hundred miles to shake off the cobwebs.
You said that you can do 60 - 70 rpm right now. Getting up to 70 - 80 may or may not be achievable but with less than a 100mi after 1 year...how can you know?
You know your body best so listen to it. But doctors do recommend less pressure on our joints especially as we age so if you can achieve the desired speed with rpm I think it may be better for you in the long run.
Coming from a BBS which has a much different power delivery curve may be part of the issue. Especially if you never tuned the BBS which is very aggressive out of the hole and much better at maintaining cadence being a cadence-sensing only controller.
What PAS are you using now?
What current /watt output do you see on the display at your desired speed?
Initially I found the stock Ultra tuning adequate but sluggish out of the hole and more demanding on me than the BBS. It took me about 1000 mi to get used to it and understand what tweaks I wanted to tune on the Ultra.

Jeremy McCreary said:
With the stock 55/22 gearing, the OP would have to pedal at a sustainable 78 RPM to cruise at 16 mph in 11th gear. That's a long way from his preferred 60 RPM. He's clearly an experienced cyclist, so we have to take that 60 RPM seriously.

How much cadence can he expect to gain with realistic training? I went from a tight 75-85 range to 80-90 in a year and 2,000 mi of casual hilly low-assist riding after 20+ years away. That 5 RPM bump brought me back to the cadence of my youth with no further gains in the 8 months since. I'd need serious training to get much higher, and I'm not about to spoil my fun with that.
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I think the 80 - 90 range is the high average for the novice cyclist so going above that is a ceiling on most of us without some serious training and a time machine. I think working up to 75 is within the average humans capabilities where 95 is starting to push boundaries.
Jeremy McCreary said:
The OP sounds like a stronger cyclist than I am at about the same age, so maybe he can add more than 5 RPM with realistic training.
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He actually sounds stronger than I so that's why I think he can, I think he can...
Jeremy McCreary said:
But going from 60 to a sustainable 78 RPM sounds pretty implausible. He told us flat out that even 70 RPM is unsustainable now in 11th gear at 16 mph.
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That's why we have ebikes

In the end the 2.5 ratio isn't ideal unless your doing a lot of steep climbing.. but it is joint friendly for us ol' timers so I wouldn't run too far from it until you've had some more saddle time. Getting g11 to your sweetspot is desirable so I understand where you are coming from.
 
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I think the hardest part is going from a road bike averaging 22 mph and weighing about 20lbs to an E bike weighing close to 80lbs. But I will make a few changes that are more bike fit related and keep on riding. I can always go back to a 22 if needed.
 
Cybersnow said:
I think the hardest part is going from a road bike averaging 22 mph and weighing about 20lbs to an E bike weighing close to 80lbs. But I will make a few changes that are more bike fit related and keep on riding. I can always go back to a 22 if needed.
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I say ride both of them.
 
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