Convert your Bike to IGH
I just converted this bad boy from single speed to 3 speed and cannot believe how smooth it went.
Let's go for a quick ride then walk through the conversion step by step.
If the chain on your mid drive skips off the cassette or maybe you have a single speed and just want some extra help climbing hills or towing cargo - an internal geared hub can give you a simple, sturdy, low maintenance transmission.
Converting this eBike from single speed to 3 speed will help reduce stress on the motor and prevent it from overheating. With 186% gearing range, the Shimano Nexus 3 low gear can help tow heavy cargo up steep hills while the high gear will help me keep my legs in the game instead of ghost pedaling at cruising speed. This should also help me grind out a few more miles per hour when I need to safely maintain the flow of traffic. Internal geared hubs require less maintenance than derailleurs and also give the ability to use a belt drive.
The Nexus 3 is a small, simple, solid hub that can hopefully handle the abuse of the Bafang Ultra. We'll be beating on this thing in upcoming speed and range test videos - so make sure you subscribe to our YouTube channel to stay updated.
Let's talk about how to convert your bike to an internal geared hub.
First check your frame for compatibility before searching for wheel options. Make sure your frame has a horizontal dropout - if not then you'll probably just need to add an external chain tensioner.
Remove your rear wheel and measure the inside of the dropout. The new hub's over locknut dimension should match the frame dropout spacing, but usually you'll have a few millimeters tolerance. Some steel frames can also be adjusted slightly if needed.
Install the sprocket and mount the tire on the new wheel.
I had this wheel built by the Brooklyn Bike Doctor - he's a pro wheel builder and does great work, so give him a ring if you're looking for an affordable custom wheel. If you haven't already, checkout our previous video for some tips about how to get your hands on a perfect custom wheel.
When mounting a new wheel it's always a good idea to test fit for brake and chain alignment.
- Measure the axle and washer tolerances; after torquing the flange nut on the drive side, the axle should protrude 8-13mm - mine is just about perfect at 10mm
- I'm using an internal chain tensioner on the drive side which replaces this 3 mm washer.
- This green piece on the left side is a non turn washer which has a groove that fits inside the dropout. This prevents the axle from spinning out.
Reinstall and adjust the chain - this is very easy to do with an internal chain tensioner. I usually just finger tight the left axle nut, adjust the tensioner then torque both axle nuts. Double check that the wheel and chainline are both straight.
Now we can install the bell crank.
- Grease the push rod and insert it into the hub axle.
- The push rod should protrude about 14 mm.
- Slide the bell crank on the axle and torque the rear bolt while holding it in place.
- Make sure that the edge of the window is aligned with the end of the axle.
Remove the grip and install the shifter - then check the brake lever for clearance
- Route, measure and cut the shifter cable housing. It's always a good idea to leave a little extra just in case you need to move it.
- Slide the cap on the lower end of the cable housing.
- Insert the shifter inner cable through the housing then through the bell crank adjustment barrel.
Now we can setup and adjust the bell crank
- Set the shift lever to 2
- Fit the cable into the bell crank link.
- Pass the inner cable along the link groove then under the inner cable mounting plate.
- While pulling the inner cable tight, torque down the inner cable mounting nut while positioning the end of the link between the two white lines on the window.
- Next, turn the cable adjustment barrel to align the red line on the push rod with the end of the hub axle.
- From the top window, check that the yellow mark is between the two lines.
- While turning the crank, move the lever from 3 to 1 then back to 3. Repeat this two or three times and check in the bell crank window that the gears are being shifted. Move the lever from 1 to 2 again and make sure that the red line on the push rod is aligned with the end of the hub axle. If they are not aligned, readjust.
- After adjusting the bell crank, torque the cable adjustment barrel nut to hold it in place.
Now the fun part - double check all your fasteners and take her for a spin!
If you have any questions about something you're working on - let us know in the YouTube comments - maybe we can help.
Having a low gear will give this high powered Bafang Ultra some help at startup and reduce overall stress on the motor and battery. It also adds a high gear to maintain cadence which should help me get a few more miles per hour at cruising speed. These hubs usually require less maintenance and are easier to adjust than derailleurs. I've never been a fan of finicky derailleurs - they're an outdated technology and are not ideal for most high powered eBike applications. Have you ever seen a moped or motorcycle with a derailleur?
We'll be testing and beating on this hub in upcoming videos - so subscribe to our YouTube channel if you'd like to be notified. In the meantime support your local bike infrastructure and try commuting by eBike. Thanks for watching, see ya soon.