It’s been quite a few months since I posted the report of adding the pedal assist e-drive addition to my Surly Disc Trucker. Since then I’ve made a few alterations to the original setup.

You can see from the photo above that I’ve now moved the battery from the rear rack to the down tube. I decided to sacrifice one water bottle mount to achieve this move. The battery wasn’t really a problem on the rear rack, but I missed being able to strap longer items, such as tent poles etc., to the top of the rack. Also, weight distribution is now much better when the bike is loaded as in the photo below.

If the battery looks a little strange,
it’s because both photos show the battery with a waterproof cover.

The water bottle mounts on the down tube are relatively close together allowing only a couple of screws to hold the heavy battery. And the position of them would not allow an ideal allowance for removal of the battery. In order to keep the water bottle mount on the seat tube, I had to space the battery mounting clamps very precisely so the the battery could slide up off its mount and be removed or replaced. I also felt the the battery mounting plate really needed a third mounting point to assure that it would be secure over bumpy roads and trails. I searched out some inexpensive clamps on the internet that would fit onto the down tube and allow a more solid fixture for the battery mount.

The photos above and below show the DMR hinged down tube clamps that I installed, together with some short aluminium plates to further stiffen the battery mounting plate sideways. I used three of these clamps to achieve the ideal location for the battery mounting plate. The result is a very solid mount for the battery!

It’s nice to get the top of the rear rack free now for other items that can be located there. I always have a couple of bungie cords there to load any loose items like my windbreaker or rain jacket in “on and off” weather. If you’ve done any bike touring, in the Pacific Northwest, you’ll know what “on and off” weather is!

The next item I wanted to alter was the gearing. I wasn’t too fond of a couple of the original shift spacings on the 11-42 cassette so I bought a new Sunrace 11-40 8-speed cassette with a slightly different spacing. The new cassette’s large cog is 40 whereas previously I had a 42 cog. Reasoning was that I discovered that the 34 to 42 low gear that I had was not really necessary as the e-drive would compensate easily for the slight loss in the lowest gear. I also switched to a slightly narrower tire, from a 47-559 to a 40-559 which also lowers the gearing somewhat, resulting in very little change for the lowest gear. With having two front chainrings, I’ve found that the chainline when in the 44 front chainring is best when only using the four highest gears of the cassette. When in the 34 front chainring, all speeds of the cassette are smooth and within a reasonable chainline.

I’ve done some short bike camping trips fully loaded to the local (hilly) Gulf Islands and for the most part the 34 front chainring is the ideal size for loaded riding; I very rarely shifted up to the 44 chainring which seemed to only be useful on flat stretches of road.

Below are comparison gearing charts showing the two cassettes…

Gearing Comparison…
Left Image: 11-42 with 47-559 Tire
Right Image: 11-40 with 40-559 Tire

Even though I now had a voltage display, I was still not pleased with the small buttons on the VLCD6 display. When wearing gloves, it was hard to determine which button I was selecting in addition to the display’s readout being a little small for my old eyes! So after a bit more research, I found that it was possible to use a 500C colour display that one or two outlets in China were selling for the Tongsheng TSDZ2. I had already bought the one to two cable in order to use the VLCD6, so the 500C would be plug and play.

The photo above shows the 500C display that I installed.
The display has a speedometer style circular readout in addition to the numerical digital speed readout. The big advantages of this display is that is the colour screen is easy to see even in sunlight, has a battery voltage display, has large buttons that are easy to push and is still very compact – a really great upgrade! On the left side of the screen is a watt meter, however that is not functioning, as it would require some open source firmware installing into the controller’s circuit board – something that I am not willing to perform at this time.
At a later date, I did actually program new firmware to the controller and am very pleased with the result as the assist levels are more precise and the bike feels even more responsive for a more natural ride. I feel that it compares very favourably to factory built ebikes with Bosch drives.

There has been one other addition to my kit, not really to the bike but more of a battery maintenance issue. In researching Lithium-Ion (Li-ion) batteries, the consensus is that not constantly charging the batteries to full charge will result in better lifespan of the lithium batteries. Also, slower charging is a frequent recommendation. Fully charging the battery every time will allow for approximately 400 charges before the battery’s cells begin to degrade. Whereas only charging to 90% or 80% will result in the in a possible lifespan of 1000 or 2000 charges respectively! Click here for more information on this subject.
In order to achieve this better form of charging I purchased a “Smart” charger from www.eco-ebike.com who I found to be most reasonable on pricing and shipping. So for short trips I can charge to 80% or 90% and for longer ones I can fully charge to get maximum range.

Smart Charger

I’ve taken the bike out fully loaded on quite a few two-day “bike camping” forays to some hilly locations on the Gulf Islands. Some of the hills were getting to be a real chore with all my camping and cooking gear (sometimes with two days of water on board also – an extra 18lbs) loaded on the bike so it was a real treat to be able to ride all the routes without really straining myself. The real advantage is being able to “dial-in” the pedal assist in order to get a fair amount of exercise without becoming exhausted and wondering if I can make it to the next hilltop without over-stressing my cardio! Most of the trips were about 40 – 50 km return and ultimately these trips were to satisfy my battery range anxieties! From a full charge of my 48V battery (54.6V), I would return home with a reading of between 51V to 52V. I’m quite judicious with the levels that I use, and mostly ride in “Eco” level 1. But I don’t “spare the horses” on hills and up the assist levels as required.
Later in the year, I found that the throttle was not really necessary for a hill start because of the ability to just use a higher level of assist to get started on a hill or steep grade. The higher levels of assist give quite a boost when one starts pedalling. Subsequently, I removed the throttle completely. I also changed out the handlebars for a more upright position. I really liked these swept-back bars and ended up installing one on my other recreational bike too!
I also changed out the front derailleur shifter to a top mount friction shifter for a more positive shift between the two chainrings.
Below is a photo of the new handlebar and component setup in its present configuration. Very comfortable!

I have a slightly longer trip planned, so will post a later date with some information on how the battery range performs with some higher mileage days.