Here is my experience on the installation of the Freedom Ebikes Kit for the Brompton bicycle which I completed a few days ago.
I live in a community in a hilly area of Hong Kong. All of my riding is within the community both for leisure and for running errands. I would typically do 6 Km at most each trip. I have had my Brompton M6R a little more than a year now. But even with the smaller chainring and 2x3 speed gearing, the hill climbs were a problem for me at my current level of fitness (or lack of). And part of the reason I don't do more leisure riding in the community is because of those hills. So I started thinking about installing an electric motor kit on the Brompton some time last year. My needs were simple. I just needed motor assist on the uphill portions of my ride. And because the distances I rode were small, a smaller battery pack was fine.
I ordered the Basic Kit from Freedom Ebikes (which cost USD900) and the package arrived in Hong Kong about 5 days after it was shipped. It came with a Tongxin 250W/260rpm motor built into a 16-inch rim, a small controller box, a twist-grip throttle unit, a 91Watt-hr (39.6V @ 2.3Ah) LiFePO4 battery pack, a 110V-240V charger and some hardware to spread the fork. The battery pack was fully charged and the with cell voltages ranging from 3.51V to 3.59V. The controller and Tongxin motor appear to be sourced from Outrider, a company in Hangzhou, China.
I had requested the thumb throttle option when I ordered but that probably got missed in the email exchange and I was shipped the twist-grip throttle instead. Rather than ask them to send the correct part, I decided to live with twist grip throttle and see how well it worked for me. The installation instructions included in the package were not very detailed. But they were adequate for anyone who has reasonable aptitude in things mechanical and electrical. Communication with the folks at Freedom Ebikes was fine; but I found that it would usually take a few days to get a response to queries.
The first thing I did was to widen to dropout slots in the fork to about 10mm (from the original ~7.5mm) to accommodate the larger axle of the hub motor. I also had to deepen the slot by about 1.5mm so that the supplied torque washer would fit properly. I used electrical tape as a guide to mark the area I needed to cut and did the cutting/grinding using a Dremel Tool.
The grinding bit supplied with my Dremel kit was perfect for making a nice, rounded dropout slot end!
Next, I widened the fork to accept the hub motor. The original fork spacing with the wheel removed was about 73mm. The fork had to be widened to about 93mm. I used the spreader included in the kit to spread the fork to about 110mm and it sprang back to the spacing I needed. The spreader also came with dropout torque washers that so that it would be secure on the fork with minimal risk of the bolt ejecting during the spreading.
I did a test fit of the motor and rim and decided that I would remove one washer from the wire-exit (left) side of the motor and move it to the other side so that the clearance on both sides between the motor and fork is about the same and the rim would be centred without any dishing adjustments. However, to do this, I had to take apart the power connector and remove the connector pins so that the washers and nuts could slip through.
The loop in the wire for the plastic chain stay hook had to be enlarged to fit around the larger axle. I tried to re-bend the wire loop but found it too difficult. Instead, I did some grinding of the inside of the wire loop so that it would fit around the axle.
I also checked the rim build for trueness and roundness but found adjustments unnecessary. Spoke tension seemed fine too.
Then I did a system check by connecting the controller and battery. Everything seemed to work.
I removed the tyre, tube and rim tape from the original rim and mounted it on the new rim. I think putting the tyre on the new rim was probably the most difficult part of the installation so far mainly because of the small diameter of the wheel. My thumbs were pretty raw after I managed to wrestle that tyre on with the help of regular tyre levers. I will consider getting a Simson Tyre Mate or a VAR tyre lever to add to my tool box in the future.
With the wheel mounted and the tyre inflated, I connected everything together and ran the motor again. Everything worked except for my wireless bike computer. It was either getting interference from the electric kit electronics or the fields from the hub motor. Speed readings were very erratic with the motor running. It was fine when the motor was not powered.
A quick folding check showed the same problem that others had with a Tongxin motor on a Brompton. There was inadequate clearance between where the cable exits the motor axle and the plastic chain stay hook. This resulted in a tight fit and paint being scraped off the chainstay by the protective metal sheath of the motor cable. I will devise a solution for this after seeing what others have done and giving it some thought.
I had to cut away the original handlebar grip on the right side to mount the twist throttle unit. The original grips were glued on so there was no way to slide it off. Cleaned of the residual glue and mounted the throttle.
I routed the cables and temporarily secured them with Velcro cable ties. Put the battery and controller unit into the right rear pocket of the Brompton C-bag. I folded and unfolded the bicycle many times to work out the cable routing. Then it was off for a test ride!
To get a feel of the way everything worked, I did slow speed runs in an open area behind my flat. I initially found the throttle sensitive at the low end. But after a while, I learnt to be really gentle with it. Then I did some tests riding up and down hills. On the downhill, there was no danger of getting too fast. Even with the throttle at full, assist appeared to taper off to zero as I approached about 20 Km/h. Riding uphill was a blast. On one particularly steep hill where I would normally be in the lowest gear, huffing and puffing away at 6 Km/h without assist, I was able to do about 18 Km/h without breaking a sweat! As with my earlier indoor test, I found that my wireless bicycle computer no longer worked reliably with the motor powered.
Other than the outstanding issues with the inadequate clearance of the chain stay hook, everything worked well and I am pleased. I may try installing a thumb throttle unit to see if I like it better than the twist grip one.
Here are the weight measurements I took:
Before:
Brompton without C-bag: 12.3Kg
Brompton with C-bag: 13.6Kg
After:
Brompton without C-Bag: 14.5Kg
Brompton with C-bag and kit components: 17.0Kg
So the full kit added about 3.4Kg to the weight of the bike. And about two-thirds of that figure is the weight of the motor.
I hope this write-up will be useful for anyone who is contemplating installing the Freedom Ebikes kit on a Brompton.
Richard
I live in a community in a hilly area of Hong Kong. All of my riding is within the community both for leisure and for running errands. I would typically do 6 Km at most each trip. I have had my Brompton M6R a little more than a year now. But even with the smaller chainring and 2x3 speed gearing, the hill climbs were a problem for me at my current level of fitness (or lack of). And part of the reason I don't do more leisure riding in the community is because of those hills. So I started thinking about installing an electric motor kit on the Brompton some time last year. My needs were simple. I just needed motor assist on the uphill portions of my ride. And because the distances I rode were small, a smaller battery pack was fine.
I ordered the Basic Kit from Freedom Ebikes (which cost USD900) and the package arrived in Hong Kong about 5 days after it was shipped. It came with a Tongxin 250W/260rpm motor built into a 16-inch rim, a small controller box, a twist-grip throttle unit, a 91Watt-hr (39.6V @ 2.3Ah) LiFePO4 battery pack, a 110V-240V charger and some hardware to spread the fork. The battery pack was fully charged and the with cell voltages ranging from 3.51V to 3.59V. The controller and Tongxin motor appear to be sourced from Outrider, a company in Hangzhou, China.
I had requested the thumb throttle option when I ordered but that probably got missed in the email exchange and I was shipped the twist-grip throttle instead. Rather than ask them to send the correct part, I decided to live with twist grip throttle and see how well it worked for me. The installation instructions included in the package were not very detailed. But they were adequate for anyone who has reasonable aptitude in things mechanical and electrical. Communication with the folks at Freedom Ebikes was fine; but I found that it would usually take a few days to get a response to queries.
The first thing I did was to widen to dropout slots in the fork to about 10mm (from the original ~7.5mm) to accommodate the larger axle of the hub motor. I also had to deepen the slot by about 1.5mm so that the supplied torque washer would fit properly. I used electrical tape as a guide to mark the area I needed to cut and did the cutting/grinding using a Dremel Tool.
The grinding bit supplied with my Dremel kit was perfect for making a nice, rounded dropout slot end!
Next, I widened the fork to accept the hub motor. The original fork spacing with the wheel removed was about 73mm. The fork had to be widened to about 93mm. I used the spreader included in the kit to spread the fork to about 110mm and it sprang back to the spacing I needed. The spreader also came with dropout torque washers that so that it would be secure on the fork with minimal risk of the bolt ejecting during the spreading.
I did a test fit of the motor and rim and decided that I would remove one washer from the wire-exit (left) side of the motor and move it to the other side so that the clearance on both sides between the motor and fork is about the same and the rim would be centred without any dishing adjustments. However, to do this, I had to take apart the power connector and remove the connector pins so that the washers and nuts could slip through.
The loop in the wire for the plastic chain stay hook had to be enlarged to fit around the larger axle. I tried to re-bend the wire loop but found it too difficult. Instead, I did some grinding of the inside of the wire loop so that it would fit around the axle.
I also checked the rim build for trueness and roundness but found adjustments unnecessary. Spoke tension seemed fine too.
Then I did a system check by connecting the controller and battery. Everything seemed to work.
I removed the tyre, tube and rim tape from the original rim and mounted it on the new rim. I think putting the tyre on the new rim was probably the most difficult part of the installation so far mainly because of the small diameter of the wheel. My thumbs were pretty raw after I managed to wrestle that tyre on with the help of regular tyre levers. I will consider getting a Simson Tyre Mate or a VAR tyre lever to add to my tool box in the future.
With the wheel mounted and the tyre inflated, I connected everything together and ran the motor again. Everything worked except for my wireless bike computer. It was either getting interference from the electric kit electronics or the fields from the hub motor. Speed readings were very erratic with the motor running. It was fine when the motor was not powered.
A quick folding check showed the same problem that others had with a Tongxin motor on a Brompton. There was inadequate clearance between where the cable exits the motor axle and the plastic chain stay hook. This resulted in a tight fit and paint being scraped off the chainstay by the protective metal sheath of the motor cable. I will devise a solution for this after seeing what others have done and giving it some thought.
I had to cut away the original handlebar grip on the right side to mount the twist throttle unit. The original grips were glued on so there was no way to slide it off. Cleaned of the residual glue and mounted the throttle.
I routed the cables and temporarily secured them with Velcro cable ties. Put the battery and controller unit into the right rear pocket of the Brompton C-bag. I folded and unfolded the bicycle many times to work out the cable routing. Then it was off for a test ride!
To get a feel of the way everything worked, I did slow speed runs in an open area behind my flat. I initially found the throttle sensitive at the low end. But after a while, I learnt to be really gentle with it. Then I did some tests riding up and down hills. On the downhill, there was no danger of getting too fast. Even with the throttle at full, assist appeared to taper off to zero as I approached about 20 Km/h. Riding uphill was a blast. On one particularly steep hill where I would normally be in the lowest gear, huffing and puffing away at 6 Km/h without assist, I was able to do about 18 Km/h without breaking a sweat! As with my earlier indoor test, I found that my wireless bicycle computer no longer worked reliably with the motor powered.
Other than the outstanding issues with the inadequate clearance of the chain stay hook, everything worked well and I am pleased. I may try installing a thumb throttle unit to see if I like it better than the twist grip one.
Here are the weight measurements I took:
Before:
Brompton without C-bag: 12.3Kg
Brompton with C-bag: 13.6Kg
After:
Brompton without C-Bag: 14.5Kg
Brompton with C-bag and kit components: 17.0Kg
So the full kit added about 3.4Kg to the weight of the bike. And about two-thirds of that figure is the weight of the motor.
I hope this write-up will be useful for anyone who is contemplating installing the Freedom Ebikes kit on a Brompton.
Richard
