Modifications

Background

Much of the work described under the heading of Modifications details not only what was changed but the thought processes and development progression.

Mechanical Improvements

Footpegs: The first mod was to install a pair of wider footpegs made by Apico.

Handgrips: My favorite grips are Progrip 699. I use them on everything. These are much thicker than traditional dirt bike handgrips. They provide excellent cushioning.

Handlebar position: The top triple clamp permits two handlebar positions. Cindy preferred the more forward of the two. She also wanted the bars higher, so I made 20mm risers.

Rear brake pedal extension: Moved 20mm outboard. Later 30mm per Cindy's preference.

Lifting strap: There's no handhold at the rear of the bike for lifting. I added a strap cut from an old tiedown. It's fastened to the rear subframe's Weldnuts that mount the controller. Although the strap is a little too high and too far forward, it is better than nothing. Using it is like doing 100-pound curls.

Battery retention: The battery is held in place by three hand-tightened clamping screws. The two on the sides don't need to be fully removed as the battery enclosure is slotted. A helpful EM 5.7 owner warned me that if the bike goes upside down it's likely the battery will break through the top plastic beauty cover. He advised me to fabricate a retention system that does away with the slots. I did this by epoxying two large washers over the slotted holes.

Rear suspension: The shock is a basic Olle R16V. I returned it to standard (12 clicks out). It was at 9. The rear sag with Cindy aboard was 70mm (would like to see 80 – 90mm). The spring was already set to minimum preload.

Front suspension: It has some primitive 40mm Olle steel forks, which don't help the front-end weight problem at all. The manual says these forks provide 175mm (6.9”) of travel. I measured 172mm of travel. I have used 140mm doing nothing very challenging.

Rear Spring

The standard rear spring on the 5.7 is progressively-wound and rated 7 - 8 kg/mm. I replaced it with the softest standard Olle spring available. It is straight-would and rated 6.4 kg/mm (63N/mm).

Marzocchi Fork Transplant

The 40mm Olle forks are heavy and primitive compared to what I am used to riding. They are lightly sprung and exhibit a lot of seal stiction.

Since I have not been riding my OSSA TR280i, I decided to test its Marcocchi forks on the EM. These forks are well-fettled and work really well for me. The Marzocchis are 4 pounds lighter and more sophisticated (cartridge vs. damper rod).

It was a simple transplant as both have 40mm stanchions. Unfortunately, the Marzocchis are 17.5mm shorter (from axle centerline to fork cap) than the Olles. The length difference turns out to be about the same as the difference in travel. The front axle is also different, so I had to test with the OSSA front wheel and fender as well. This proved to be completely wrong for both steering and chassis attitude. I even tried sliding the tubes down in the triple clamps so there were several millimeters of fork tube below the top of the triple clamp.

Looking at the lightweight Tech forks that come on the ePure series, they have 39mm stanchions. They also appear to have the same extra half-inch of travel exhibited by the Olles. SplatShop sells them for 882 GBP (nearly $1200 USD + shipping), so not an inexpensive upgrade. I'd also have to deal with their slightly smaller (39 vs 40mm) stanchion diameter as well.

Making Spacers

I decided to use the Marzocchis and make up the difference in length with a simple spacer at the bottom of each fork tube where the cartridge is held in place. A longer M8 x 1.25 SHCS is also required (42.5mm versus 25mm). I achieved this by grinding 2.5mm off the length of a 45mm SHCS.

The spacer is 17.5mm with a 26.15mm diameter recess and locating step at each end. I made the recess 2.0mm deep although the mating step is only 1.5mm tall. I reamed the through-hole to 5/16" for a tight fit on the M8 SHCS.

I made an alignment tool from a 5/16" aluminum rod with an M8-1.2 thread at one end. It was long enough to go through the entire fork tube from the bottom and capture the cartridge. It made reassembly much easier.

The original copper sealing washer around the SHCS needed its ID enlarged slightly (via 5/16" reamer) to accommodate the non-threaded portion of the longer screw. In a belt-and-suspenders approach, I put some silicone sealer around the copper washer as well.

Additional Small Changes

Cindy found the 20mm brake pedal extension that I borrowed from the 280 OSSA to be suboptimal for small feet (although it worked fine for me). I then made one that moves the pedal outboard 30mm.

I removed five plastic beauty covers that weighed 1.6 pounds in total (enough to offset the heavier Dunlop rear tire). Speaking of removing stuff, below is a shot of the unnecessary electrics. In addition to the original Oh-Shit! clutch switch, the map switch, mode switch box, and on/off switch have all been eliminated.

Hour Meter

I emailed Trail Tech suggesting they sell an hour-meter for electric bikes. Their TTO gauges are the best available in my opinion. A technical service rep replied that they were working on just such a device and hoped to have it available at the end of 2021. I later learned that it's just powered-on time, not motor run time. Which is of limited usefulness in my opinion.

So implementing a true run-time meter is something I would still like to address.