A Rohloff on an Electric Bike

April 11, 2012

A Rohloff Speed Hub is one of the sweetest pieces of bicycle technology ever invented….right up there with the electric bike and the hub motor. The Speedhub is an internally geared hub  (IGH) with 14 gears spaced evenly at 13.6 % resulting in 526%  total gear range roughly  the same range as a standard MTB 27-speed drive train. By following extremely low tolerances and keeping the system completely enclosed Rohloff claims to have comparable power loss by friction to an externally geared system (derailleurs) and will run virtually forever with minimal servicing (only an annual oil change).

The biggest downside to the Rohloff is (of course) this piece of sexy bicycle tech is expensive. $1500, and yes you could buy an entire electric bike (a cheap Chinese one) with that kind of money.  Says Bike Radar of the Rohloff  “A bombproof internal gear hub that gives impressive range and low maintenance for epic rides”  Well, epic rides are what electric bikes are all about, so lets take  closer look at the Rohloff:

The  idea for the Rohloff Speed Hub came when company founder was sitting on the beach with his girl on parked bikes which they couldn’t ride down the beach any further because the bikes’ gearing had been hit by waves and their components were getting sandy and gritty.   He was already a leading manufacturer of bike chains, and decided at that moment he would build a better bicycle transmission. That was 1998. The Rohloff Speed Hub came from the idea that a bicycle should be ridden anywhere, even the beach, even mud, even water…and not worry about getting your driveline dirty, crusty, or frozen stiff.

With a Rohloff equipped bike you can ride  through anything and not worry about even  cleaning the driveline when you are finished.  Just squirt some oil on your chain once in a while and you are done. The Rohloff is designed and made in Germany and has  sold over 100,00 units in 10 years.  The Rohloff is made to last with only routine oil changes (really, the internal gears are in an oil bath), and there are many cases of hard core cyclist riding Rohloffs tens of thousands of miles. The Rohloff is designed not only to last the life of your bike, but also your life. So, whenever Rohloff users upgrade their bike, they switch the Rohloff with them.

The Rohloff has a lot of other advantages other than just its rugged dependability. It gives you a straight chain line, so chain maintenance becomes less critical. Notice in the picture below, my Rohloff powered electric sand bike has a well-used chain that is very rusty from running on the beach, but because my ebike does not use derailleurs the chain still functions perfectly without so much as a creaking noise. This ebike has been ridden almost daily for 3 months on the beach on the water line and has been submerged in salt water several times:



The Rohloff drive line also provides a clean look comparable to single speed sprocket set up. The Rohloff allows you to shift from a dead stop without any force on the pedals, and to shift while riding you need to let the pressure off the pedals and then shift.

When coupled with an electric bike you get a lot of advantages with a rohloff. It takes maintaining derailleurs and casettes and dirty chains a thing of the past. You have enough to worry about with all the added complexity of a motor, controller, and battery on your E-bike…why not take away a lot of the cabling and mess from the equation that derailleurs bring?

One reason why some bicyclists are opposed to the Rohloff is  its weight.  The Rohloff weighs in at 3.7 pounds which will make your bike 1-2 pounds heavier compared to the usual gears/derailleur. However, to an electric bicyclist who is not really carrying his own weight (or his E-bikes weight), the weight gain is nothing…especially considering what an electric bike weighs…(typically 60-90 pounds)…so what’s a few extra pounds? For an electric bicyclist the weight issue (the biggest negative of the Rohloff other than its price) should not be an issue.

Another big advantage of the Rohloff is that it is possible to get ultra high gearing with just the addition of an extra large sprocket up front, or even better a Schlumpf Planetary crank set.  High gearing is extra important to the e-biker who generally travels at a faster speed than a conventional pedal-only bike.

Given the fact that Rohloffs are known to be relatively maintenance free, and considering the fact that an E-bike rider (especially a commuter) will probably put a lot of miles on his sweet Rohloff powered bike, a Rohloff can make extra sense to the E-biker since years of trouble-free service could end up paying for itself in the long run when you consider broken parts, bike shop shifting tune ups, etc.

All Rohloffs come with a proprietary twist shift gear. The electric bicycle rider is usually familiar with the concept of the twist grip (throttle)…so a twist grip shifter should be a welcomed tool as opposed to dual lever shifters on conventional bikes which can be confusing, and jankey to figure out which gear you are in. When you want high gear on a Rohloff, just twist the throttle as if applying speed, and click-click-click you’re in high gear.

The Rohloff is a piece of slick tech, and if it were cheap, you would see it everywhere.

One advantage of a Rohloff for an electric bike  is by getting rid of derailleurs is  you can give your bike a very slick futuristic look.

There are two main applications on an electric bike:

Mid Drive to the Rohloff Electric Drive
This is one of the sweetest spots in the electric bike universe.  A mid drive means the motor is in the center of the frame somewhere, so the weight is center balanced, the motor is geared to a very low speed using some kind of gear reduction system.This allows the motor to output on the right side along with the pedal drive train. So the rider and the motor pedal on the same chain going back to the Rohloff. This means the Rohloff acts as the transmission not only for the cycler, but also the motor. Having a 14 speed Rohloff as your shifter with a 1000 watt motor too it is pure slickness. The Optike 1100r is a great example of this application. Because of the possible low gears, the Optibike is an incredible and reliable mountain climber.

One common problem with powerful mid drive electric bikes is the chain can break. A Rohloff is much easier on the chain than a derailleur system and allows the user to select much thicker chains than what could be used on a derailleur. It is possible to use a bmx chain or even a belt with a Rohloff drive if chain breakage ever becomes an issue.

Front hub motor Drive, Rohloff in the Rear

The other way to use a Rohloff is as just as a pedal gearing system, while the electric motor runs on a different drive line. The best example of this is a motor in the front hub.  One big disadvantage of a Rohloff to the electric bicyclist is it is not compatible with a rear hub motor. Many electric bicyclists opt to use a front wheel drive just so that they can run a IGH like the Rohloff in the back.

There are some disadvantages as well as advantages to running a hub motor up front. Check out our article on choosing between front and rear hub motor  here.

Here is a picture of the authors DIY E-bike with front-wheel BMC hub motor drive, and Rohloff in the back:

Although it is rare to see a DIY build like the one above with a Rohloff (most DIY’s are building cheaper cost bikes to save money) Consider this, of the 10 most expensive bikes, 4 of them have Rohloffs. Here is a break down:

The Optibike 1100r

This is a Rohloff maximized in an electric bike situation. The Optibike in 2011 entered 7 bikes in the Pikes Peak bicycle race, and all 7 bikes finished. Most of their competititors burned out before reaching the top, and only one other ebike finished a couple of hours behind the optibike. This illustrates the biggest advantge of this kind of small motor high rpm set up. You are able to keep the motor in the ideal rpm range while climbing.

The PiCycle KR Special Edition

Picycles chose a front wheel drive hub motor just so they could run the Sexy Rohloff in the rear.  This is the easy to do Rohloff solution, that any DIYer could accomplish if they want to spill out the $1500 for a Rohloff. What the Picycle adds which is out of the ordinary is also a Gates Carbon belt drive system to pair up with that Rohloff.

The m55

In an email I got from the makers of the m55 in Budapest (so far in testing), the Rohloff  is handling the 1500 watts the m55 puts out with no issues.

You can tell in the above photo of the m55 prototype that they did not design the frame with the Rohloff in mind or it would have a sliding horizontal rear drop out and a perfectly straight chain line. As it is, this bike has an unsightly chain tensioner which looks like a rear derailleur. On a $50k bike you would expect more.

The Blacktrail BT-01

Although many of its components are secret, the Blacktrail BT-01 uses either a Rohloff or the cheaper NuVinci depending on what motor configuration the owner is riding. As you can see in the picture the Blacktrail has an ultra clean chain line. The motor is contained in the bottom bracket. This is like an optibike on steroids (capable of speeds of over 50mph) and for $80,000 it better, and better come with a Rohloff and not the NuVinci.

In addition to these, there are 3 exciting bikes not yet released but are in production that use the Rohloff

The ktm egnition –

This ebike is featured on the Rohloff website. This Ktm Egnition  is nearing its release date. Read our story here. Like the Blacktrail, it uses the expensive and efficient Clean Mobile drive sytem running through the bottom bracket and the Rohloff in the back, and batteries down low in the down tube. This makes for a wicked combination for hard core trail riding…climb the mountain like an electric chair lift…then bomb your way down.

3rd Element Aspire

Very similiar to the KTM bike, also using a Clean Mobile sytem and Rohloff in the back.

Hot Rodding with a Rohloff

Some high performance race bike builders wonder exactly how much power you can put through your Rohloff. Rohloff says the maximum input torque for the hub is 100Nm (Newton Meters). They are saying that the Rohloff could handle roughly 1.5 horse-power, but it is rumoured the hub can handle much more.

I talked to Neal at Cycle Monkey in Berkeley, the USA distributor and service facility for the Rohloff.

So here is a guide for those electric mad men who are thinking of pumping a 5000+ watt rc motor through a Rohloff.

  1. Tou will indeed void your warranty running this kind of power through the Rohloff.
  2. The Rohloff has 6 nylon shear -pins inside the hub which is designed to sacrificially prevent damage to the gears in the case of higher torque loads. This means the worst you are risking is a $100 repair job if you do “fry” your Rohloff. You will know when these nylon shears break loose because the Rohloff will spin uselessly without spinning the tire when the nylon pins break loose.
  3. 11th gear is the straight through gear, in this gear you will not slip and it is the safest one to run high power through.
  4. The lower the gear the more likely you are to break the nylon pins loose…so when riding with a lot of power stay up high. Be careful not to apply too much torque when climbing steep hills in low gear.

It should be noted that last year Shimano released an IGH very similar to the  Rohloff called the Alfine-11. This system is considerably cheaper than the Rohloff (around $500 on the internet) but has proven not to be as robust as the Rohloff. We hope that Shimano improves on this product in the future because it could make a very worthy and affordable drive train solution in the future for electric bikes.

For those wondering why the Rohloff is so expensive, it is intricately hand made in Germany, and is a beautiful piece of machinery. To illustrate, check out this factory video:

Eric has been involved in the electric bike industry since 2002 when he started a 6000 square foot brick and mortar Electric Bike store in downtown San Francisco. He is a true believer that small electric vehicles can change the way we operate and the way we think.


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