TerraTrike Sportster EZEE Hub motor conversion


1 mW
May 8, 2018
Figured I'd post up some pics since I had trouble finding much about terratrike conversions, especially hub motors. Selected the ezee from Grin (great service and support!) because the main goal here is hill climbing assist and it's geared and has a reasonable weight and output. Also the sportster is an aluminum frame and the hub motor out on the boom would probably be fine but my wife wants to minimize the impact to the trike and potential hard shifts etc didn't seem like the best solution. It turned out to be perfect for this application, at about eight pounds we can remove the battery and use human power only without too much weight penalty. Picked up an em3ev battery which also is working out great, I was tempted to go the diy route but I have way too many open projects right now so I'm happy and the em3ev pack is well built and makes me less nervous about hazards etc.

The trike is still getting final tweaks and I have it adjusted for me so the blue tape is to mark my wife's boom setting and the old location of the front derailer which we are probably going to just ditch. Right now the front is a 50/34 compact setup and I am thinking about going single 42 tooth. Also the prodecotech sensor may get swapped for a Sempu that I am waiting for a replacement for, but so far this setup is working really well. Got lucky and a fairly local ebike shop had the Beam TS that they weren't planning to use due to safety (he cited the fact that pedal pressure would activate the motor, valid point but the cadence sensor/CA combo solves the concern). The Beam is prone to pulsing assist due to immediate feedback from pedal strokes but the CA averages it using the cadence input so that whole issue is completely solved by this arrangement.

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There was no good way to mount the torque arm in the correct orientation so I did a little bending and welding

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Made a tray for the battery so it can be removed easily, there is a bungee and a bent washer that slips into a slot on one side. The rack is the TT low rider, could have attached the tray without it but sooner or later we will want a bigger bag or something that can hang off the side of the rack. Pricey but nice rack.

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The beam ts/prodecotech sensor, the stock bracket works fine as long as you don't want to shift, derailer is 86'd.

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The other side, cables from the Grin 24 pole cadence sensor and the Beam bundled and shrink wrapped

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The cadence sensor, this is a nice unit, very slim and mounts easily.

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The wiring on the CA is pretty unsightly especially in the trike application, particularly the throttle/aux/everything pigtail. I removed it by taking the CA apart and wired the ebrake and d.aux directly in and soldered to the CA board. Had to add a throttle input which required drilling another hole very carefully, to lead out the throttle cable. All in all highly successful as the wiring is much cleaner now.

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Previously I made this accessory arm for the trike from some handlebar end extensions, added a tab to mount the CA so it would be as clean as possible, and angled to the rider. Needs some paint and a better welder :)

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Still have some cleaning up to do. Tonight I removed the front derailer and shift levers completely and added some split loom for the sensor wire and just buttoned up and cleaned up in general. Thinking about a 42 tooth front chainring as a good in between to the 34/50 setup. Pretty excited to get on a trail when we get some free time.


1 mW
May 8, 2018
Couple of pics I forgot, the CA wiring inside and the bits you get to remove if you take off the aux harness. This also removes the need for the ebrake plug male and female and the aux plug, those wires are being fed straight into the CA so it's cleaner but possibly less easy to service if the CA needed to be removed. The ebrake is the tripwire btw, I removed the jacket from the two wires and fed them back up toward the CA.

All this wiring is removed :) This is the CA multi plug, the ebrake plug, and the d.aux plug(s)

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Inside the CA, not hard to wire into it, tin the wires and feed them down through the holes and do your best to line them up. I checked for solder bridges with a meter before firing it up.

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The pas plug from the 24 pole cadence sensor, add the Beam torque output to the vacant position.

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The chain path is perfect with the chain on the inside chainring.

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The pas plug and the new throttle plug I added after removing the multi aux harness. I don't think we will add a throttle but this is the 5v for the Beam TS and will allow us to use a throttle if we want.

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1 MW
Apr 8, 2007
Eugene, Oregon USA
Thanks for posting and welcome to the forum. Nice trike and nice job on the conversion. Good pictures.

One of my riding buddies has a Terra Trike Zoomer he purchased new in about 2008. It also has an aluminum frame and a few years ago I looked at their line up and didn't see any aluminum framed tadpoles.

Anyway, he really loves that trike and how easy it is to pedal, but about the time he reached 70 he let me install a geared hub motor on his Bob trailer, which he was happy with for several years, and it let him climb hills up to 20% grade. But last year he grew weary of always dealing with the trailer and I installed a Bafang BBS02 on the boom. So, like you, he also had to give up his triple for the BBS02 46 tooth, but is happy with the 9 speed deraileur that gives him plenty of climbing ability and enough speed for us old guys. The extra weight on the boom hasn't given him any issues.

Happy trails on your trike!