Electric Bike Conversions FWD 250W/Ridgeback Hybrid

[Warwick]

I built up the Ridgeback with a SRAM Automatix hub a couple of years ago as a runabout, but it's sat neglected a lot of the time whilst I used my other bikes. I had intended to put the EBC kit onto another bike, but it didn't fit, so the Ridgeback was chosen.

I bought the kit secondhand from the CTC forum for £81 (without a battery) and spent another tenner or so on bits and bobs to install it. Installation was complicated by the fact that I used a rack battery from a deceased Woosh Sirocco I gave up on. The EBC instructions don't exactly match the kit and their YouTube video shows a RWD installation, but the general ideas are much the same. The one issue I had was installing the pedal sensor. My bottom bracket isn't flanged (fnarr, fnarr), so I ended up glueing it into place, but rather unsuccessfully. It doesn't pick up the magnets and doesn't work. I may end up replacing the BB and sensor for reasons I'll explain below.

I took it out on its first 15-mile outing today. Because the pedal sensor doesn't work, I need to use the thumb throttle. That doesn't really suit my riding style, as I liked the Woosh's pedal assistance mode. Nevertheless, it does the job. One thing I knew would become apparent is the gearing. With only two gears to play with, I'd lowered the gearing with a 24-t rear sprocket. I think it's a 42-t front chainring. This means at 16MPH I was spinning out. I've set the controls to a higher maximum speed and the motor ended up doing a lot of the work that I'd rather do. I have an 18-t sprocket and I'll fit that later. I've also got another chainset with a 48-t ring to fit, if needed. That will significantly raise the gearing.

The EBC kit is noisier than the Woosh BB system, especially from starting. Once the wind gets in your ears that's not a problem, but the whine at lower speeds is distinctive. The bike pulls strongly and, being lighter than the Woosh, accelerates quicker. The thumb throttle is very positive and the display is very clear. I was able to ride along at 18-20MPH without a problem, even uphill. I'd expected the hills to be harder with a FWD system, but no, not the case. Once the gearing is raised, I'll be much faster up hills than the Woosh. Of course, I'm running narrower tyres with higher pressures, but it still feels more efficient.

The EBC kit inspires confidence. It's good quality by any standards. My expectations of poor quality Chinese goods were not borne out by the parts I fitted. I'm going to replace the pedal sensor soon and I'll report back again once it's fitted, but my first impressions of the combination are very positive.

For less than £100 I've gained a very nice commuter. Let's see how this week's commute goes...

 

[trex]

I think you would get more out of a geared hub motor if you have more gears. The Sram automatix is not really suitable for our hills.

 

[Warwick]

The rear sprocket has now been changed to an 18-tooth one and a new chain fitted. I did a few more tweaks and took it out for a brief test. The raised gearing suits the bike, and me, much better. I spin out at about 20MPH now, which is fine.

The motor is very torquey and acceleration from standstill is good. Weirdly, the pedal sensor works if I pedal backwards, but not forwards! At least I know it works! I'm trying to source the right BB with a flanged cup so I can get the whole of the controls working.

The wiring needs to find a better home. I've bundled it into a pannier. That isn't watertight by any means. I'm waiting for a bracket to fit a Topeak saddle pack onto. Then I'll bundle it all in there in a plastic bag and it'll be more out of the elements. I'd commute on the bike tomorrow, but it'll be raining, so it looks like Weds or Thurs will have to do.

I did toy with the idea of a 7- or 8-speed hub gear, and I may yet fit one. However, the Automatix hub is very simple. It has no cables and changes up into the higher gear automatically and is also much lighter. I have the option of fitting a 48t chainset to further raise the gearing, but I'll see how I get on for now.

 

[trex]

Weirdly, the pedal sensor works if I pedal backwards, but not forwards! .

try flipping the PAS disc. There should be markings with arrows on the disc.

 

[Warwick]

After today's commute, I'm very happy with the combination so far. I averaged 16.6MPH over 8.1 miles, which is what I was getting on the Woosh when I was fitter. The Woosh would allow me to go faster on the flat because of the gearing, but I'm able to cruise along at about 20MPH on the flat on the Ridgeback and go up hills faster.

I like the SRAM Automatix hub with the assistance. It changes down when I'm stopped or slow down, allowing me to make a quick get away and it then changes up to the higher gear automatically so I can get some decent speed up. Being well under 20kgs, this suits the set up well. It would not work well on the much clunkier Woosh Sirocco. It wouldn't work well on a very hilly commute, but the asssistance irons out my hills very well.

 

[bigearsbilly]

As for spinning out you can actually raise the speed you can twiddle at by practice.

 

[oniontrololol]

After today's commute, I'm very happy with the combination so far. I averaged 16.6MPH over 8.1 miles, which is what I was getting on the Woosh when I was fitter. The Woosh would allow me to go faster on the flat because of the gearing, but I'm able to cruise along at about 20MPH on the flat on the Ridgeback and go up hills faster.

I like the SRAM Automatix hub with the assistance. It changes down when I'm stopped or slow down, allowing me to make a quick get away and it then changes up to the higher gear automatically so I can get some decent speed up. Being well under 20kgs, this suits the set up well. It would not work well on the much clunkier Woosh Sirocco. It wouldn't work well on a very hilly commute, but the asssistance irons out my hills very well.

wow awesome build! Too bad I am not good with bikes or I'll attempt to fiddle around to build myself a custom ebike

 

[Warwick]

Thanks! It was relatively easy and would have been even easier if I had used one of EBC's new kits. The major complication was my choice to use another battery with different connectors. With a new kit out of the box, it would have been very straightforward.

Have a look at the EBC YouTube clips of an installation and consider giving it a go...

 

[oniontrololol]

Thanks! It was relatively easy and would have been even easier if I had used one of EBC's new kits. The major complication was my choice to use another battery with different connectors. With a new kit out of the box, it would have been very straightforward.

Have a look at the EBC YouTube clips of an installation and consider giving it a go...

too late now I just bought a Whoosh Karoo last week. I might consider building one after I've fiddle with ebikes to see how they actually work. In your build are you able to swap out for a more powerful motor if you want more power?

 

[Warwick]

I don't think so. The front wheel would need to be changed and the controls might be different.

In any case, I quite like adding my own effort to my rides, and I find 250W powerful enough. A 500W motor would add speed, but then you have to look at whether the brakes, etc. are capable of safely handling that sort of speed.

My Ridgeback has rim brakes and I wouldn't want to go much faster with that set up, good though the brakes are. I had intended to fit the kit to an Orbit bike that would have had an Avid BB7 front disc brake. I think the Karoo has BB5s, doesn't it? If you're ever tempted, the upgrade to BB7s is worth it. I've had both.

I like the look of the Karoo. Woosh seem to have taken a good turn. I had one of their older offerings and was not at all impressed, despite the service from the company being good. It now sits, minus battery, gathering dust in the garage.

 

[trex]

I always find it worthwhile building your own bikes. You get exactly what you want and often for even less than woosh prices. Still, £81 is pretty much a new record. The downside is that you won't be happy for very long, there will always be a new project somewhere in the back of your mind.

This is my current bike:

 

[oniontrololol]

i recognise that battery haha. I am just curious what I can do to upgrade the power of the bike without having to purchase an entire new conversion kit. People seems to be able to mix & match their parts for a conversion which is rather interesting. I am far from mechanically competent enough to build / convert my own bike.

 

[Warwick]

EBC do 500W kits and offer a conversion service, I think. I'm fairly sure you can tinker with the Karoo's LCD display to increase the maximum speed over the legal 25KPH limit. On my Woosh this was the work of a few seconds.

 

[footpump]

warwick I have the ebc rear wheel kit 36v 250w the pas gizmo that they have ( the 2 part one where you may have to glue the sensor to the bb seems a bit of a faf)
however alan at ebc told me they have another more easier fit vertion, which I got from them.

it is a all in one unit that slides onto the square taper of the bottom bracket, its kunteng and works with lcd3 led unit but needs different calibration set up.

not quite finished build and have not got to that stage, cant recall exact part number of sensor though suggest you ring for info

 

[Warwick]

Thanks footpump. I've contacted EBC to see if it's suitable for my build. Whilst I like the throttle, I prefer the pedal assist mode.

Tomorrow's task is to put the wiring somewhere much less water prone so I can use it in most weathers. Given the forecast, I'm also going to fit the Schwalbe Winter tyres. My commute has some cyclepaths that are distinctly frosty in this weather.

If the weather's kind, I'll take a photo or two and post them on the relevant board.

Update: Tyres fitted (took longer than usual due to the torque arm). The saddle pack wiring task was not done, because there isn't enough space between the saddle and the battery rack for the pack. Instead I sliced a small slit in the pannier and put the cables through that. Not ideal, but better than it was. I might later go for a frame bag to do the job. I also fettled the v brakes into not rubbing on the rims, so I'm all set for tomorrow's cold commute.

 

[oniontrololol]

EBC do 500W kits and offer a conversion service, I think. I'm fairly sure you can tinker with the Karoo's LCD display to increase the maximum speed over the legal 25KPH limit. On my Woosh this was the work of a few seconds.

thanks for the tip, I just found the 'tinkering tip' on the LCD manual hahahaha.

 

[Warwick]

More observations:

Now I'm used to the SRAM Automatix hub, I think it works really well on an ebike. The lower gear is great for quick starts on full throttle with a 38t/18t combination. Spinning out at 21MPH is fine. Where it shows a weakness is on hills. You have to stop pedalling for a brief while to allow the hub to change down to the lower gear. Once that's done, the lower gear works well on steepish hills - rather too well! It soon gains enough speed to change up to the higher gear, which isn't necessarily what your knees need. I'm hoping the switch to the new pedal sensor EBC sent me will help out, so I can adjust the level of assist to suit my riding style.

All in all, I'm still very impressed with the set up. Once my fitness improves and I've fitted my thinner, higher pressure Schwalbe City Cruisers, I'll consider the 48t front chainring option. That should up my maximum speed to about 25MPH, although I'll sacrifice lower speed flexibility.

My next project may well be a RWD kit for my MTB, although my Birdy might also be in line. Decisions, decisions...

 

[Ruadh495]

try flipping the PAS disc. There should be markings with arrows on the disc.

Not the disk, the red sensor. That's assuming you have the standard EBC PAS sensor and I'm guessing you have fitted it on the left. It's supposed to go on the right, but that's a faff as you have to remove the chain ring. So mine's on the left too. On the left the red sensor unit has to be inverted. If you have the red sensor unit on top of the bottom bracket the cable will be emerging fro the front of it. Which means the mounting ring doesn't fit round the shaft but sticks up. The mounting ring side has to be away from the magnet disk or the sensor won't work. Bend the ring over and cable tie to the bottom bracket, (though I'm considering moving mine to the chain stay). It's OK to bend the ring, it's just a mount.

Or you could put the sensor outside the magnet ring, but then it's a pain to secure and catches your trousers.

 

[Warwick]

Thanks for that. EBC have sent me a Kunteng all-in-one sensor to fit. I've got the day off tomorrow to get it fitted and try out. Hopefully that will make the two-part sensor redundant.

 

[Ruadh495]

Does that go on the left? In my opinion that's where the PAS sensor belongs, away from the chain. A friend of mine is considering an EBC kit at the moment, might be worth specifying the new sensor. Thanks.