Help! Need advice. Which new gear ratio on R&M Charger GX?

Tbone

Member
Approaching 7k km on my Charger GX and it'll be two years old this spring. Couldn't be more happy with this über-expensive two-wheeled car replacement that I use as a commuter, chore vehicle and... chick-magnet ;-). After last inspection (October 2018) my e-bike mechanic suggested I renew my drive chain. He said the derailleur doesn't need replacement but the chain and gears do. (Really???) Although a little unexpected, as I thought I could take the drive-chain to at least 10k km--and I probably still can--I want to start considering the issue.

Note: Even when off-road, especially on extreme uphill terrain, like what I experienced last year in Croatia, I was never able to fully use the the high gears--the uphill gears; those are the "high" ones, right? It's always felt like the bike, even with its high-torque CX motor, can't fully use those high gears in extreme situations--well, at least I can't use them. I realise this may have something to do with my size and weight and stamina, but even the monster CX motor has its limitations. Which means there are simply some terrains I've learned to avoid or, when I approach them, just get off and push (or use the walk function of the motor). Which also means, maybe I don't need those gears.

Would love to hear anyones thoughts on the following:

- Is it worth it to just go down to 8 or 9 gears?
- Has anyone changed their gear ratios? My Charger GX has 11 gears. For 95% of use, I've only found 8 gears useful, which means...
- Should I change the front sprocket (smaller, larger)? My riding ratio for street/off-road is about 60/40 (maybe 70/30).
- Will such a gear change negatively effect battery life?
- Which brand of gears/chain/derailleur would you recommend?
- Here's a real wild-card question: can I convert it to a Rohloff with belt?

Thanks for any advice or tips.

-Tom (aka tbone)
 

David Berry

Well-Known Member
Tom …
  • If your mechanic suggests that your chain needs replacement, accept the advice. Chains are cheap – especially after 7000 km!
  • If you keep using a 'stretched' chain, you will most likely damage your cassette – now that's not cheap!
  • Hill-climbing gears (the large sprockets on your cassette) are low gears.
  • If you don't expect to use the lowest gears, don't change to a 9-speed cassette; change to an 11-speed with a closer range; for example, a new 11-32 instead of the supplied 11-42. Apart from losing your unused ultra-low gears, you will benefit from having the gears that you do use every day more closely spaced which will allow you to get just the right pedalling cadence.
  • Fitting a larger front sprocket (chainwheel) will make all gears 'higher'. This would rid you of the ultra-low gearing without necessitating changing your 11-42 cassette. Worth seeking advice.
  • Rohloff E-14: not possible.
  • Rohloff with belt drive: most unlikely, but ask just the same.
  • Rohloff with conventional chain and chain tensioner: worth considering (meaning seek expert help!) providing you can get a straight chain line.
… David
 
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Tbone

Member
Thanks David! Sounds like great advice.

I think my cassette is already the one you describe. It's definitely got 11 speeds in it. The low gears (thanks for the terminology correction, btw!) are much farther apart than the 8 higher gears.
Will be seeking more advice from mechanic soon.

-Tom
 

Alaskan

Well-Known Member
@David Berry gave you very good, experienced and knowledgeable advice. The good news is that, if you can install a Rohloff with belt drive (the most expensive and the very best option), the E-14 electronic shifter for the Rohoff, has recently been made available as an aftermarket upgrade. Once I became accustomed to riding with a Rohloff, I was hooked. Riding my other bike with a traditional derailleur now feels primitive and awkward. I am in the process of 2018 Riese & Muller Homage Rohloff to the E14 shifter.

As to just replacing the cassette with new gears to go with the new chain; If I understand you correctly, you never use your lowest (largest ring in the back) gears. If that is the case, replacing your cassette with an 11-32 tooth might work just fine. You will lose some hill climbing ability. I assume you either live in a place without any steep hills or you are in very good condition, are of leaner build or all three.

My question is: are you able to keep pedaling and not spin out going down hill or would you like to have higher gears to be able keep pushing at higher speed and go faster? If that is the case changing out the chain sprocket at the crank is very easy. Adding two teeth would make all your gear ratios higher, i.e. higher for speed but not as low for hill climbing. I have a Cube Touring Hybrid with a Bosch CX motor and an 11 speed Shimano with 11-42 teeth and a 15 tooth front sprocket. As it is out of warranty I installed a speed delimiter that gives it electric assist without limit. I could not spin the crank fast enough to keep pushing the bike over about 22 mph It now has a nineteen tooth front sprocket which allows me to keep pedaling going down hill at 30 mph. In order to recapture some of the hill climbing ability (I live on a steep hill), I changed out the cassette for an 11-46 tooth model. The Cube is a relatively light bike. With the higher torque of the CX and the extended gear range it has become my "hot rod bike", significantly more zippy and nimble than my regular ride. It also serves as a guest bike for visiting friends who want to experience the fun of e-biking with me. By the way S-ram is now offering a 12 speed with a 10-50 tooth cassette for a 500% range, still not quite the 526% range of a Rohloff but darn close.

Keep in mind that the Bosch motor drive has a gear ratio of 2.5/1 so adding one tooth in the front is the equivalent of adding 2.5 teeth
 

Tbone

Member
Update!

I guess I should have also said that my Charger GX is limited to 25km/h. I rarely bother trying to pedal above that speed on account the bike is just too heavy. I use the Bosh settings thus:

Turbo = when I'm hungover or having that lazy day
eMTB = off-road
Tour = don't use it anymore since eMTB upgrade
Eco = I use this mode most now when riding my common route of 30-35km per day.

-T
 

Alaskan

Well-Known Member
;If you have any interest in moving at a faster pace, the Bikespeed RS produced in Germany allows assistance at higher speeds with all ride data remaining accurate. Given that you have had the bike two years, the Bosch warranty has expired so voiding the warranty is no longer an issue. With the Bosch CX motor you have more than enough power to move the bike at higher speeds. I am 68, weigh 210 lbs and my R&M Homage with all the gear is close to another 75 lbs. I can easily sustain 24 mph on flat ground with no wind for at least an hour without interruption. The nice thing about Riese & Muller bikes is that they are so well built and engineered they are designed to be safe at those speeds. I find that, traveling through town in traffic, that I am much safer going close to the same speed as the surrounding automobiles.

I am not trying to talk you into anything here just letting you know about a very viable option if it has any appeal to you.

In any event, adding a Rohloff with a belt drive would be a very substantial and satisfying upgrade to your already excellent bike. The only impediments I can think of would either be cost or feasibility.
 

Tbone

Member
@Alaskan, thanks for the info. I'm jealous of your speed freedom. Also jealous of your weight! (Which means I'm a bit more than 210lbs. But just a bit!) I live in Germany in a rather urban environment and I want to take full advantage of bike lanes. 25kmh is the speed limit here. I think that's about 15-18mph. Anything above that requires insurance and licensing and ... you can't use bike-lanes. Which means you have to drive with the cars in their lanes. No thanks. I'm starting to love the bike lanes here and the faces on car drivers as I pass them while driving through the city.

The Rohloff thing is just a second thought. Will most likely stick with a derailleur for now.
 

tompat

Active Member
The good news is that, if you can install a Rohloff with belt drive (the most expensive and the very best option), the E-14 electronic shifter for the Rohoff, has recently been made available as an aftermarket upgrade.
Where can this be bought? I have not seen it in online shops but then I didn't dig too deep either..
 

Alaskan

Well-Known Member
In the USA the Rohloff service and parts distributer is Cycle Monkey in Richmond California. Riese & Muller has to approve E14 compatibility with their particular model and the work must be done by an authorized dealer. To my knowledge the E14 shifter is not being sold direct to the cyclist but rather through the installing shop. Cycle Monkey provides tech support to the dealer.

https://www.cyclemonkey.com/blog/tech-talk-retrofit-your-e-bike-rohloff-e-14-electronic-shifting
 

Chris Nolte

Well-Known Member
Yes, this is correct and I have been reaching out to brands and Bosch to see what retrofits would be possible from a support side as the brand would need to provide the motor software or request it from Bosch. As a dealer we don’t have the ability to modify the software only minor things like updates.

It seems that most brands don’t want to support it due to liability concerns. Once the bike is modified like this the shop that modifies it technically becomes the manufacturer of the bike and is therefore responsible for the liabilities that entails. It’s quite a tricky thing and from what I found would only be supported in limited cases. It seems that R&M is one of the only brands that technically will support it at the moment but it’s not a change that should be made lightly. Haibike and Bulls for example said they will not.
 

dblhelix

Well-Known Member
Yes, this is correct and I have been reaching out to brands and Bosch to see what retrofits would be possible from a support side as the brand would need to provide the motor software or request it from Bosch. As a dealer we don’t have the ability to modify the software only minor things like updates.

It seems that most brands don’t want to support it due to liability concerns. Once the bike is modified like this the shop that modifies it technically becomes the manufacturer of the bike and is therefore responsible for the liabilities that entails. It’s quite a tricky thing and from what I found would only be supported in limited cases. It seems that R&M is one of the only brands that technically will support it at the moment but it’s not a change that should be made lightly. Haibike and Bulls for example said they will not.
How is Bulls relevant? If Reise & Muller is currently the major player in the Rohloff-equipped space, it makes sense that they are the only ones supporting the retrofit. Why wouldn’t they? There are no frame modifications, right? Just a request for a reflash to support E14?

Why is Rohloff making this kit available to its distributors? Surely this isn’t a rogue move that Bosch and Bosch brands are unaware of?

I’ve been given an estimate on parts and labor, and it’s <<< new bike price, thus worthy of consideration. You say “it’s not a change that should be made lightly.” Could you be more specific? If one of your customers requests this upgrade, will you do it?
 

Chris Nolte

Well-Known Member
I mentioned Bulls and Haibike as the article put out by Cyclemonkey as it was a bit misleading. Many have been under the impression that they could add E-14 to any bike. Most brands aren’t willing to support this. The reason R&M suggests concern about this change or any other change like it is they are legally not allowed to make these changes in Europe because each bike has its own unique certification and the bike would no longer be certified with this change.

In the US this regulation doesn’t exsist but there is a liability concern. Since the bike was not specifically tested in this new potential configuration and the way they can only make this change if they release their liability. It may seem pety, but this is the case across the board for all brand really. If a shop changes a fork on a bike with one not approved by the brand the shop would now be the manufacturer of the bike. It’s a really tricky thing that we are working to understand more all the time. Since the US is a very letitgious society it makes sense to practice prudence here.

Quite frankly, I think Cyclemonkey got a little excited about the possibilities without fully understanding the limits. They are the US distributor of Rohloff so they support the market with parts, they also support some the new smaller builders that build bikes and can source these parts. Bosch is aware of this and they will support this change if the bike brand is willing to support it, but only in this case. If they provided the ability to make this change without the bike brands blessing Bosch would take on the liability if something was to happen. Same thing with Cyclemonkey although they don’t have an OEM dongle (required to reflash a motor) to my understanding and modifying another OE’s bike would be cause for revoking their dongle.

The above is mostly the concern as technically the warranty and liability is modified with this change. That being said I think it would be worthy for you to consider and we would be happy to support you in this effort.
 

Tbone

Member
The issue is now mute for me. In fact, I'm typing this while waiting for renewal of my chain and rear sprocket--with the same equipment. It's just too complicated in Germany for me to do something as simple as modifying gear ratios on account of (excuse my French here) Bosh proprietary bullshit! My dealer, who I'm trying to support by paying him to handle all maintenance and inspections and other work on my over-expensive two-wheeled car alternative, told me that he wouldn't even install a different (larger) front sprocket on my bike. Without saying it, I got the impression that he was afraid of both Bosch and the tight-ass German regulations. On the one hand, though, I can understand the need for e-bike regulations in Germany. In the two years I've been e-biking there's been an explosion of these things. They are literally every where now. Luckily the Germans-- at least the city I live in (Düsseldorf)--has thoroughly thought through the whole biking thing here. Bike lanes, although not perfect, are a godsend here! That said, when I consider a new bike next year, I always thought I'd consider a Stromer as an alternative to Riese & Mueller. Guess what? Stromer is so obsessed with making 45kmh bikes, that I'm totally turned off by their 25kmh offering. A dealer told me that Stromer doesn't seem to be all that interested in Germany because of all the regulations. I rarely see 45kmh bikes here--and you can easily tell them apart from others because they have to have a license plate. I suppose for the US and Switzerland it's a whole other (free) market.

Enjoy all that freedom!

-T
 

Tbone

Member
Update: after telling me he wouldn't do it, my dealer finally installed 18tooth sprocket, replacing 17th tooth. And what an ordeal it was. Took half a friggin day, too. Here's a summary. Dealer suggested I needed new chain and rear cassette last fall. He said I didn't need new front sprocket, though. Ok. First test ride after new chain and rear cassette install today was a failure; drive train didn't work. Ok. Back into the shop. I had to wait another 30 or so minutes for him to then replace front sprocket. Ok. The thing is, the new chain wouldn't work properly with the old front sprocket. Why didn't they tell me that in the first place? I really don't care about the few bucks required to include a front sprocket. Ok. After he finally replaced front sprocket I took it for another quick test ride. It still didn't work. The chain wasn't working with the new front sprocket either. Why oh why? Ok. Mechanic then realised that he had installed a non Bosch front sprocket. Ok. Bike back into shop. Another 30 min and all is well, including a Bosch 18 tooth front sprocket (because he didn't have a 17th tooth) and all seems well. Ride home was strange though. I think the new chain and gears need some break-in. These über-expensive bikes are a bit prissy. Am I wrong?
-Rant and ride on, baby.
-T