Changing crank length and primary gear reduction on Rohloff/Gates equipped 2021 Homage GT with Class-1 CX Gen-4 motor.

JimAndArrow said:
I feel like the gearing on the Rohloff Load is already low enough for me given that it starts with the 55, in 1st I’m going slow enough to be borderline balance constrained with the dog up front, and my cadence is lower than yours, but very curious to hear the results!
Click to expand...

And yes, as show in the spreadsheet clips in my first posting, the Rohloff equipped Load models come stock with 55/19 (2.89) versus the 60/19 (3.16) gearing on the Homage and DeLite models equipped with a Rohloff hub.
So your Load's stock gearing is already 8.3% lower than my stock gearing (or 9.5% depending upon how you calculate it).
That much difference would be noticeable.
 
JimAndArrow said:
On my Load 75 the right lever is the rear brake, not the front brake which is what that lever is on a motorcycle or scooter. Or were you wondering if R&M deliver them with right/front in the EU? If so, that would suggest maybe they have the right cable and/or hose lengths and we could just buy them pre-cut from R&M to swap… I actually did the same thing as you on my last bike build, had them swap levers, which is apparently not a common request though I find that surprising.
Click to expand...

Back in the days of externally routed metal cables to actuate the brakes, it was quite easy for me to flip the actuation on my own.
And per Stefan Mikes, the UK and Australian bikes are the only ones which come from the factory with the brakes set up the "Correct" way round to match motorcycles and scooters.

I have no complaints about how much better the hydraulic disk brakes work on modern bicycles, but they are definitely more involved to bleed properly, and internal routing complicates things even further.
So, I am leaving the task of swapping the hose to the shop this time around.
 
Project update:
After a couple of missed calls, my LBS finally managed to get my bike hooked up to the R&M computer through the interwebs and downloaded the software updates into my bike which is required for the Bosch drive system to recognize the new primary belt drive ratio.
The charge to do the R&M remote update was only $45.
I consider that quite reasonable.

It took me another week after they finished the bike to be back in town so that I could pick it up.
And right now Milwaukee is locked in the deep-freeze, so have not been able to do more than ride it around inside the shop, but it seems to work properly now.
No error messages, no loss of assist, normal shifting.

And it now has a much lower overall gearing, which I am sure will be great when I take it off road down in the desert southwest next month.
My most used gear range is also now above the 7th/8th gear split, so the Rohloff will shift better and be in the most efficient range most of the time.

I am very happy that R&M agreed to accommodate my request to change the gearing ratio of the belt drive.
I will keep you informed about the long-term results.


In other news:
The cost of running a new brake line to the rear wheel was quite a bit more, since they ended up needed to drop the motor to get the hydraulic hose routed through the frame.

But I am happy to have paid for the work so that I now have my front brake lever on the right side, which is the same configuration as motorcycles, which I have done with all of my previous bicycles to prevent confusion when going from motorcycle to bicycle.


I will report back with a more thorough report of the effect of the changed gearing as I put some more miles on the new setup.

Bottom Line:
R&M was cool about supporting the change to my belt drive gear ratio, but it might take a bit of time for your LBS to get the appointment set up to do the remote transfer of the required software changes.

YMMV
 
Hey BMWzenRider,

First thank you for your original post as I was thinking I may want to change the sprocket on my Homage when it comes if it didn't give me enough hill climbing ability. I was thinking about dropping from the 60 tooth down to the 55 or 50. I was also thinking that the Bosch engine (Speed version) wouldn't care, I would just have to get the right belt size. Well your post cleared that up. A software change IS necessary and you brought up the idea of changing the pinion in tandem with the front sprocket. After reading through the posts I have a few follow up questions:

First, is the new setup still working fine for you? And anything you would think to do different if you did it again?

Second, I was confused a bit by the second section of your chart (The Belt Drive Models part). I currently have a Nevo3 which has the Vario hub and 55/24 gearing. In looking at the section under the "Roloff Gear and Ratio" section (the one with the numbers 1-14) it looks like the numbers are the same as for the upper table. So the numbers in the lower chart don't look like Vario numbers since I know Vario has less of a gearing spread. The Vario is 0.5 to 1.9 which if I am reading the upper chart correctly would correspond to the numbers directly below the 1 to 14 numbers (0.279 to 1.467). I was thinking I could see what my Nevo3 with the Vario was and compare it to the Homage with the Roloff that is on order by looking at the lower chart. So I guess I need to ask what the figures in the lower table mean. If I am correct on reading the upper chart, it looks like the Vario lowest setting (0.5) would be just above the stock Homage Roloff's 3rd gear? (2.29 x .5 = 1.145 compared to Roloff 3rd gear, 1.137)

Third, I was wondering if it seemed R&M reprograming your bike with the software update was something that was an exception for you or did it seem like they would do it routinely for anyone making the gear changes?

Lastly, since I will never be able to ride all the different gearing options, I was wondering how much you would feel the difference between say 60/19 stock set up and say the 55/22 setup (The one that seems the most attractive for me to consider). I know this is something that may be considered subjective but I would hate to go too radical or make a change that wouldn't result in any noticeable difference. So any thoughts would be appreciated.

In closing, just wanted to thank you again for all this information. A buddy of mine and I were talking and wondering if making a sprocket change was doable. I did a quick google search and here is all the information and more. It was like this was written for me :)
 
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This is a very interesting thread. I'm 62 and have much the same issues. These changes are very interesting and after reading and digesting over and over I feel I would also be a candidate for the same programing and gear changes. Is this a one up thing or can I get the same programming? I appreciate all the testing and politics you have done and i don't want to tag on tour efforts but I don't have the energy to go through what you did.
 
BMWzenRider said:
Just for fun {and because I LOVE playing with spreadsheets and gathering data!} I updated my spreadsheet to include some lower primary gear ratio options.
Here is the result:

View attachment 108967
Click to expand...
Ah, man, this is outstanding!

I was just searching for the tooth counts so I could calculate the overall ratios myself, and here it all is lol. Thanks very much for this!
I wanted to compare the overall ratios of this bike to my present one, a Priority Current with the Shimano 5-speed hub (which I love, by the way). Just in case anyone cares, 1st gear on the Current (1.393) is about 4.5 on this Homage, and 5th gear on the Current (3.664) is just a shade over 12th gear. So, I would get about 3.5 lower gears, and 2 higher gears. Which is good (for me).

Pedaling at 28mph on my Current in top gear is too bloody fast (for me) at about 94rpm, and on the Homage/Delite, I calculated about 74rpm (much better!).

Thanks again for your lovely spreadsheets!

-James-
 
Update for anyone interested. I have a HS Homage (Class 3 engine) with the Rohloff hub and decided to try to make some gear changes. R&M only has one other bike with a different gear ratio on the Class 3. The Load 60 has a slightly lower gear ratio as it has a 55/19. The first thing I had my LBS do was reach out to R&M and see if they would reprogram that software package into my bike if I made that switch. R&M turned down the request. Not sure if they just no longer willing to do that or US laws are different and they just don't do it in the US.

So I figure lets plow ahead and see if the conversion from the 60/19 to the 55/19 is close enough that the software doesn't throw a fit. Here we ran into the first problem. I had thought that the stock belt would work. It did not (was too big). The next smaller size belt was too small so the LBS tried using a 22 in the back to make the stock belt work. I was dubious and figured the change would be to much for the software. Much to my surprise it all worked. The end result is that I got the gear ration (55/22) I would have chosen if all options were on the table. I have put 100 miles on the new set up and all is running smoothly.

Seems maybe the Class 3 engine is less sensitive to gear changes than the Class 1? Just a guess but anyway it seems to be working fine for me. So if you have the Class 3 and are thinking of giving this a shot it seems to work. I will post back if suddenly it all stops working. Keeping my fingers crossed as I love the new ratio and the new hill climbing gears I now have. I feel like I now have an SUV with Jeep gears. :)

Thanks again BMWzenRider for the info in this thread, which gave me the courage and knowledge to give this a try.
 
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BMWzenRider said:
In other news:
The cost of running a new brake line to the rear wheel was quite a bit more, since they ended up needed to drop the motor to get the hydraulic hose routed through the frame.

But I am happy to have paid for the work so that I now have my front brake lever on the right side, which is the same configuration as motorcycles, which I have done with all of my previous bicycles to prevent confusion when going from motorcycle to bicycle.
Click to expand...


BMWzenRider said:
I am confused; whenever I have done this I just swapped the brake lever assemblies whilst keeping them attached to the hydraulic lines. I have always found them to be intentionally reversible.
Click to expand...
 
What a great analysis of gear ratios and cadence. I have a Charger4 Vario, bought 3 months ago. I found that the gearing was much too high. The Charger4 comes with a 55 tooth "sprocket" and a 24 tooth rear "cog"; giving a ratio of 2.29 to 1. Worked up a spreadsheet, and determined a 46 tooth "sprocket" would give me a ration of 1.92 to 1. Ran this by my local bike shop and they would be willing to make the change if R&M would approve. R&M gave them the OK and the swap was done by the shop.

The improvement is very noticable. The mechanic who did the work and test rode the bike said that the new ratio makes the bike much more usable throughout the range of the Enviolo 380 hub. The cadence at all usable speeds; 0-20 mph is in the middle of my preferred range of 70-90 rpm. The change required a new belt. To the best of my knowledge no programming change was needed.

Excellent post BMWzenRider, thank you!
 
Hi @BMWzenRider and others that are smarter than me.....

I was hoping you might be able to provide some expertise here.

I had my SuperCharger 2 serviced today and I specifically asked them to check if the Enviolo was still in full "overdrive" as my SC2 is a high speed and my cadence to maintain 40kph is too high for my liking.

I was hoping for the quick fix here that the bike was no longer in overdrive and I'd gain some resistance to go faster - sadly, not, In top "gear" it's still spinning 90rpm or so at 35kph meaning to push up to full boost of 45kph I'm 105rpm + which is a bit silly.

I logged into "My Bike" on the R&M website and see I have a 55/24T combo on the chainring/pinion and looking physically at the bike there is no room for a larger chainring so I'm wondering if I could put a smaller pinion on the rear.

I looked at https://www.gatescarbondrive.com/products/rear-sprockets?product_line=CDX and there are options from 19T through 23T and when I go to https://www.gatescarbondrive.com/Apps/DriveCalculator/index.html it let's me calculate things...

55/24T = 2.292 gear ratio
55/19T = 2.895 gear ratio

I'd obviously need to change belt length to adjust - the calculator does show the belt teeth, but it's listing by gear, and an enviolo is variable resistance so not sure how to choose which belt length I'd need.

ANY help really would be appreciated.

Now that I've ruled out the enviolo overdrive situation, my only option is to change the rear pinion size I believe.

Many thanks in advance,
Sam
 
santacruzdave said:
Hi Sam,
When I was researching gear ratios, I ran into a spec sheet for the Enviolo hub on my Charger4. You might find it helpful in answering the "how many teeth" question for the rear hub. Looks like 20 to 28 tooth sprockets are supported. Here is the link:


Good luck!
Click to expand...
Thanks @santacruzdave !

I note it says minimum sprocket ratio for a Bosch Gen 2 (I have a Gen 4 I think) is 0.8 … not sure what that ratio is … to the chainring? I’ll drop them an email and see if they have any recommendations

Thanks for sharing
Sam
 
sammcneill said:
Hi @BMWzenRider and others that are smarter than me.....

I was hoping you might be able to provide some expertise here.

I had my SuperCharger 2 serviced today and I specifically asked them to check if the Enviolo was still in full "overdrive" as my SC2 is a high speed and my cadence to maintain 40kph is too high for my liking.

I was hoping for the quick fix here that the bike was no longer in overdrive and I'd gain some resistance to go faster - sadly, not, In top "gear" it's still spinning 90rpm or so at 35kph meaning to push up to full boost of 45kph I'm 105rpm + which is a bit silly.

I logged into "My Bike" on the R&M website and see I have a 55/24T combo on the chainring/pinion and looking physically at the bike there is no room for a larger chainring so I'm wondering if I could put a smaller pinion on the rear.

I looked at https://www.gatescarbondrive.com/products/rear-sprockets?product_line=CDX and there are options from 19T through 23T and when I go to https://www.gatescarbondrive.com/Apps/DriveCalculator/index.html it let's me calculate things...

55/24T = 2.292 gear ratio
55/19T = 2.895 gear ratio

I'd obviously need to change belt length to adjust - the calculator does show the belt teeth, but it's listing by gear, and an enviolo is variable resistance so not sure how to choose which belt length I'd need.

ANY help really would be appreciated.

Now that I've ruled out the enviolo overdrive situation, my only option is to change the rear pinion size I believe.

Many thanks in advance,
Sam
Click to expand...
So an update to this:

Enviolo confirmed there is no Gates pinion/sprocket compatible below 22T so the biggest benefit I get is from a 24T to 22T… so a marginal increase (and they doubted whether this would support nice cadence at 45kph)

R&M on the other hand wanted absolutely nothing to do with it and repeatedly pushed me back to the dealer who could only decide if this was possible and that the dealer needs to take all the risk…. I pointed out I don’t intend to make the change myself and would get the dealer to do it, I just wanted guidance from R&M if this would improve things … flatly refused to discuss that.

🤷‍♂️

Quite disappointed in this post sales approach from R&M to be honest - surely not hard for them to provide guidance on something as simple as this ….
 
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