My Tern Project - Verge Si8 electrified!

[TimJohn]

Ok its finally complete. After much consternation and lurking for months on the internet, I made the decision to add an electric motor to my Tern Verge Si8. I wanted a belt drive big time. I had it with tedious chains, vulnerable detailers and rim type brakes. So I went to GRIN technologies (local Vancouver outfit) to supply the parts and since being a newbie I just listened to their recommendations and opened up my wallet.

I had some some small problems with the wheel insertion because the disc brake interference didn't allow free wheeling. So I had to remove a shim that was on the motor. Then the motor torque nut was changed to their designed torque arm (these guys are mechanical engineers) and the M5 nut that they supplied was too short for my fender mount. Luckily I had an M5 bolt from my parts bin. This was a little tricky because it was very easy to cross thread this because it is an aluminum front assembly. Once installed, it is recommended to place the motor in such a way that the power cable is pointing down. This helps to avoid water ingression into the unit. The motor is designed with seals and is supposedly water proof BTW.

I installed a front hub Bafang G311 (standard wind), Cycle Analyst V3.1, 36V 14 Ah Downtube Battery with Panasonic PF Cells. with a 25 Amp controller. I purchased a crank PAS and a throttle and so far I haven't install the PAS sensor because I don't have a crank puller. But I want try just the throttle for now and being a avid motorcyclist I like this arrangement. I also purchased a wire kit that helped tidy up the wiring. So my first thoughts after 10 kms...

The Cycle Analyst display has these big pixels and seems to be right out of the 80's era. Its very visible in bright sunlight and gives the essential information on the screen. Speed, battery status, realtime watts usage, amp usage, trip distance per charge (needs reset after every charge if you want to monitor battery usage). I am very, very pleased with the feel of this bike. Plenty of power for the hills in my neighbourhood.

The Cycle Analyst is accessible through a PC (Mac or Windows) software with the appropriate interface cable so you can fiddle with various parameters of the controller. You can also change the parameters through the Cycle Analyst display but its probably more tedious with only 2 button input buttons. GRIN setup the Cycle Analyst before I picked up the parts that matched the Bafang motor that I bought. I haven't played with parameters yet but you can tell this was designed by a bunch of engineering types. I like this even though its not simple. The thinking behind this is the way that I think. GRIN staff and support is great. They answered all my concerns and questions and their web site is filled with lots of technical information, videos and definitely lots and lots of products. Highly recommend GRIN to those who want to build their own.

 

[harryS]

A good solution to keep your belt drive! I just put Schwalbe Big Apples on my wife's 20" electrified folder. Today we took the fork onto the (lonely) crushed gravel part of our bike path to see how they worked. She says she feels quite stable.

Me, I was gingerly watching the ground. You might need to be careful on gravel with 25A at your command. My front drive bike will break traction going uphill on gravel (or on wet leaves) if I apply throttle with my 20 x1.75 Kendas. My wife rides a rear drive. We have little motors too, but they also have 12X gearing. Spin them fast and they climb hills well.

 

[Over50]

This is awesome. I've had my eye on the Verge Si8 for quite a long time now. I've thought about purchasing, if it goes on sale, just to have a compact non e-bike handy for convenient use. I owned and then sold the Eclipse S18 because at the time of purchase I thought 24" wheels would offer a better ride vs 20". I'm not sure the Verge Si8 was offered when I purchased my Eclipse. But I saw it later and regretted a bit not getting the Verge due to its IGH and belt. I think Tern should do more bikes with an IGH and it seems like the Vektron would have been an ideal candidate (but guess they need to keep the cost down). Hope to hear a write-up in the future about how the electrified version of the Verge Si8 is holding up. Just wondering what you were able to do for lighting since you must have given up the dynamo hub. Are you able to run the lighting off of the battery?

 

[TimJohn]

Over50...I have followed your write ups on the Tern S10 (both versions that you own) because I was very interested in purchasing the 2019 model. Excellent write ups. However, I did get a real good deal on a slightly used Verge Si8. So I love the internal HUB and belt so when I looked into an EV with the belt and a folder there weren't too many options and they were expensive.

So I have only 24 kms on it so far. I estimated with the 500 Wh battery, I should get 40 kms per charge. For comparison I can't really do because I haven't tested any other EV bikes. But I am very happy with the performance using a throttle only. I will install the PAS system as soon as I can get access to a crank puller. If there are any complaints, they would be with the Cycle Analyst. Its complicated and not for the non tech types because each motor has to be setup and there are some parameters that need to be setup with the PAS (being a crank torque or pace). The display is not the most up to date but I like it because its very easy to read. Large font and easy to read in the bright sunlight. It also gives some realtime data as you are riding about the battery (Ah usage, watts, etc...still learning about it). The Cycle Analyst has inputs for throttle, PAS sensors, motor temperature sensor, motor controller, brake switch to name the few I remember.

As for lights, I installed the GRIN accessory that runs off the Cycle Analyst. It is a higher voltage light (Roxim) that runs directly off the battery and is the brightest light I have ever had on a bicycle. According to their documents, it is 400 lumens.

 

[TimJohn]

OK I have had a couple more days with the conversion. So far, I have downloaded GRIN's configuration software that allows you to perform the Cycle Analyst setup in a much better way. Changing the parameters of the PAS sensor will be my next challenge as I just ordered a bike crank tool in order to install the PAS sensor (pedal cadence rather than the torque sensor... much cheaper). I am going to swing by GRIN sometime this week and ask for some guidance so I can at least setup some initial PAS parameters such as start off watts, rise time etc, max watts so I don't have an uncontrollable EV bike. It should be much easier performing this from my iMAC than the clumsy two button Cycle Analyst. The only challenge I have will be hauling my 45 lb bike up the stairs from the basement to my office and then hooking up the USB programming cable to the Cycle Analyst communication input. I have to decide either to have 3 way switch or a digital sliding switch or a button (+) and (-) type switch so you can perform realtime, as you are riding, control of the PAS sensor. I did say this was designed by mechanical engineers and it shows. Lots of technical stuff in their documentation and actually got me consumed trying to figure this all out.

I think I forgot to mention how much fun this has been. Seem to forget about riding the the thing but I see why most people wouldn't want to go through all this trouble and just open their wallets to a turn key EV bike.

 

[Laran]

How long can you ride with your battery? You do not plan to increase it?

 

[TimJohn]

I estimated from looking at my battery scale on the Cycle Analyst, I should get about 40 miles with a full battery. Now I have only had to recharge just once and I did this through my solar panel setup, so I think I need a couple or more rides and bring the battery closer to a full discharge before I can have a real sense of my range.

BTW I haven't installed my PAS yet. All of my riding, so far, has been with the throttle and I have been very careful. Once the PAS is installed I do want to put in a 3 way control switch so I can choose my PAS level (usually Bosch has a 4 level control through their Purion...ECO, Touring, Turbo ??) but the Cycle Analyst is more manual. I actually like it this way but I think the PAS would decrease my range because it probably would be engaged more often as I usually never stop pedalling.

So I do not intend to increase my bike's range (either by installing a second battery or converting to a higher voltage 48, 52 or 72 V). I am quite comfortable with 30 - 40 miles of range at this time. When you ask how long can I ride with my battery, in terms of time, I don't know. I think the range is the more realistic so that why I am assuming that the distance is a better measure that I hope answers your question.

 

[Laran]

You are a cool guy. I would not dare to ride with a gas installation
In general, the battery is decent. At a distance, you can take a spare, this will be enough.

 

[TimJohn]

OK I went GRIN technologies to purchase a PAS level control switch and after looking over the options I decided to get the CA3 Aux Potentiometer (POT). This allows fine adjustment of the power level from 0 to 500 watts and what you set it at will be displayed as you ride. This is a small knob that sits on the handle bars that you rotate to dial up the wattage (realtime control). Luckily when I was at the store, Justin (the owner of GRIN) was there and so I mentioned how pleased I was with my install and all the advice others have given me.

So when I mentioned the PAS POT I wanted to purchase he stepped outside to where my bike was parked and quickly stepped through the Cycle Analyst setup and adjusted the parameters so I could get up and go as soon as I installed the PAS sensor. Nice service and done with the enthusiasm of someone who loves his craft. I still have the throttle which I really like for scooting through without the need to pedal. I can think of a number of circumstances where this is advantageous.

Today, the crank puller arrived. I installed the PAS sensor and took the bike for a spirited ride. Wow this works so well and the fact that I can dial up the power as I am pedalling is a bonus. The Cycle Analyst module is somewhat clumsy so I have downloaded GRIN's iMAC utility and will play with it if and when I can haul the bike upstairs to my office (57 lbs). I am going to enjoy leaving the car parked.

 

[Over50]

...I am going to enjoy leaving the car parked...

Maybe you'll treat us to a video review once you finish all the fine tuning and have your final commuting set-up?

 

[TimJohn]

OK I tried up loading the video here but it's too big. So I up loaded it to Youtube:

Check it out....

 

[Over50]

Really cool. Way beyond my technical abilities but if I ever decide to convert my Spot, which I have thought about doing several times, you've laid a potential blueprint. The Spot is a belt-drive Alfine 8 with a dynamo front hub.

 

[TimJohn]

Hello Over 50,

I just looked at the Spot...nice road bike. The price is right and with a conversion, the kit that I used would run around $1800 (Can) with the parts I used. However with this model I would certainly go with a different front HUB motor. GRIN manufactures their own brand of gearless motors. It would require alot of research and some mechanical and tech savvy to complete this undertaking. If you like go to Ebike.ca and look around.

So it has been a fun journey and I have followed your postings. You have a real nice collection of e-bikes. I like the Terns but they don't make a belt drive version of their e-bike. Maybe that's the next step with tern. Good quality folding bikes and accessories are hard to beat.

My journey is not totally complete. There is a keyed on/off handle bar switch on its way and a vintage bell. So in total, I bought the Verge for $1500, the kit for around $1800 and approximately $700 in accessories (storage bag, big mouth pannier, new pedals, front Ortlieb bag, clock, Roxim light, tail light, and bell) so the total comes in around $4000 (Can). Thats compares to the Vektron Q9 that sells here in Canada for $4650 and the S10 that sells for $5250. Now that's not including adding in the accessories. But NO BELT drive with any of their 2019 e-bikes.

Time to get out and ride. Its been 3 days without getting into the car with my personal efforts to cut down on my use of fossil fuels!

 

[Over50]

Hello Over 50,

I just looked at the Spot...nice road bike...

But NO BELT drive (Tern) with any of their 2019 e-bikes...

I've attached a photo of the Spot which is a steel frame with IGH, belt and dynamo. I've done my best to configure it as sort of a light touring bike although it doesn't quite have the right geometry and I'm still trying to find the right combination of riser stem and handlebars. I've been contemplating trying to commute to work on it but haven't quite worked up the nerve. About 30 miles is the most I've done on the bike in 1 trip and my commute is usually around 36. The 30 was a weekend ride when I didn't have any time pressure. I love the bike and having it electrified and being able to use it for commuting would be nice. Perhaps a project for the future.

I've wondered why Tern doesn't do more with belt drives, particularly since they specialize in urban mobility. But they sell their models worldwide so perhaps that combination doesn't play well in some countries. Tern has another product reveal in the coming days and I'm not sure if it is a bike or a bike accessory. But I was hoping it would be a belt drive bike like perhaps a non-electric GSD. I wonder how the Verge S8i has sold for them. They released the BYOB with new folding technology recently but unfortunately no belt. Maybe something will transpire with this upcoming release. Attached is my Spot and some screen clips from Tern's pre-reveal email video:

 

[TimJohn]

OK then we all have to wait until July 9th...a few more days and lets see what Tern has up their sleeves. I think with your Spot, if you wanted to add a motor to it, it would be done as an educational process. Its nice to learn about what is involved in the building of an electric bike. I would have purchased the Vektron Tern S10 but hesitated because of the derailer system. I guess I got spoiled with the Verge Si8 and the thought of having to replace the chain, sprockets and maybe even the main front gear after 4000 kms wasn't very appealing.

So if they do release a belt drive, 8 speed HUB, disk brakes, Utivia display, USB outlet, folding Vektron Verge then I have to seriously consider buying one.

 

[Over50]

They did put the pre-reveal video on Youtube ... maybe we should start a contest and see who can guess what it will be ... I'm betting its not electrified if it is a bike:

They did the same with the BYB recently:

 

[TimJohn]

I think Tern is going to be releasing their BYB product on that date .... July 9th. Product is going to be shipped to the dealerships and as much as I would like to see them update their S10 or even GSD line with belt drives and HUBs, their reasoning is simply because of the costs. There is a price point that they want to be at with the Vektron and Cargo bike lines and this can't include certain options. Interesting ads though.

 

[TimJohn]

OK Tern just released a belt drive e-bike named HSD. This is their first. However, its listed for $3699 (US) that's the second least expensive model but its still not quite a full folder. Just the steering stem folds down and the bike is a full 65 inches long. It looks a lot like the R&M Tinker.

Lots of nice features but the devil is in the details and these are not totally available right now from what I read. I like the Bosch Active line plus but no indication of their display (Prion or Utivia?). The rear rack is designed to carry lots of load and it can be tilted up just like the GSD for semi compact storage. I would have liked a folding frame so until they add a belt to one of their Vektron lines, I'm afraid I will pass since it will not fit into my car (Scion xB first generation).

So back the main theme of this posting. I took the converted Tern Verge Si8 for a ride today but with installed PAS sensor, I have a dial up POT to set the wattage level. I set it to 200 watts so when I pedal it, with a 0.5 second delay, applies assistance up to 200 watts. Since I install a standard wind G311 motor that was designed for 26" wheels, my max speed cut off is slightly lower than 32 kms/hr. This works wonderfully for my style of riding. Plenty fast enough for me! I don't quite understand why anyone would want to go 60 -70 kms/hr (40-45 miles/hr). I have motorcycles for that. Anyway, I can also dial it up to the max (500 watts) which I haven't tried yet.

When I ride, I stay off the busy streets even though there are designated bike lanes and bike routes all over the city of Vancouver. After years of riding motorcycles in this city, I have become very defensive and there is less risk when taking the side roads and even the lane ways. So riding at 25 kms/hr is plenty fast on the side streets of my part of town.

I live right centre of the city. You can throw a dart at the map of Vancouver and that's where I live. With the densification of our city, the building of lots of new low rise apartments/condos, there has been an increase of car/truck traffic around here. Thats one of main reasons I bought into an e-bike. Beside not wanting to burn fossil fuels, I aim to decrease my car use. So far so good. Really enjoy riding this and for those you are sitting on the fence regarding e-bikes, just do it!

 

[Over50]

They are advertising that the HSD stores flat and upright. So I think it will be slightly less bulky vs the GSD even with its front suspension. Schwalbe Big Bens vs Super Moto X. Tested to 375 pounds gvw. Single battery apparently. The higher end options have IGH (Nexus) and a belt. The brakes aren't quite as stout with MT4s and not the MT5 quad pistons of the GSD (appears to me). But yes, their materials say several of the details are still TBD. I like Tern's direction and focus on really useful stuff. Nice bike.

But on the other hand, you're really the cat's meow with that converted Verge S8i. You've got the best of both worlds with the compactness of the 20" folder, belt and Alfine and electrified. I'm envious. Tern should have done that with a belt and IGH Vektron.

 

[TimJohn]

Here is a summary of what I did to my Tern Verge Si8. Number one, the reason I did it because I really am sold on the Gate's belt drive - Shimano Alfina 8 speed hub:

1) Purchased the 20" laced Bafang G311 front hub motor, GRIN's Baserunner controller, GRIN's Cycle Analyst 3.14 dash board, throttle, PAS sensor, 36V 14Ah battery and associated cabling and program cable from GRIN technologies at about a cost of roughly $1700 (Can)

2) Installed newer quick release pedals.

3) Installed the front hub motor with GRIN's torque arm mechanism because he Tern's front forks are aluminum.

4) Installed GRIN's potentiometer (POT) for precise real time control of the controller's output. Can be dialed in from 0-500 watts as you are riding.

5) Installed the throttle on the left side (unusual because I ride a M/C and it's on the right side)

6) Removed Tern's magnetic clamping mechanism that is used when folding the bike...replaced special tie down.

7) Installed a on/off switch because the controller did not have one but I ordered a handle bar keyed switch and has yet to arrive.

8) Bought new Swabe Big Apple tires (yet to be installed).

9) Installed the 36V 14Ah battery on the rear rack for good balance.

10) Installed a 100 DB alarm that is controlled with a remote (no tracking though)....real loud!

11) Installed a handle bar watch ... nice black face one that matches the bike

12) Installed a Roxim 400 lumens light that runs directly from the Cycle Analyst power outlet. Has an on/off handle bar switch.

13) Installed a newer front carrier bag by Ortlieb - 7L and essential for our Vancouver rain ...thanks to Over50 for the recommendation

14) Bought tern's carrying bag before I made all these additions...just tried it and it works for transporting the bike with the front bag removed and battery still in place

So that's about it...oh forgot...added an old fashion bell.

Now if the newer 2019 Tern HSD was a true folder and it's too long at 66".

IT WON"T FIT INTO MY CAR and I need room for my better half's folder as well.