My Surly troll half fat e bike


There are some really nice EM3ev triangle packs available for $45 on Nice and very well made. I think a lot heavier and larger.


Hi Spotty,

thanks for sharing, awesome build, really!
It looks a bit tame and old-school (somewhat like my current non-e-bike) but with the new 750W Bafang it's sure a blast on the road.
You must have earned a lot of disconcerted looks zipping bye ;)

Am planning a similar project, same motor, a Nuvinci in the back, kinda fat.
Restriction on going too fat is BB width as I'm reluctant to spend about 500+$ for a conversion kit so 73mm is the max.

First FRAME OPTION was the 26' Gravity Deadeye Monster SS ( but A) sold out B) no way to order from outside the US anyway. Karl Gesslein inspired this, he maintains a blog with TONS of INFO on DIY conversion (
The Origin8 Crawler would be perfect specs wise, has a built-in Nuvinci, fat tires, a narrow BB (, there are even built to order by lectriccycles ( but they simply lack sex appeal to me.
Though I used to be sworn in to 26' wheels I have fallen in love with the SURLY KRAMPUS as the planned build is intended for off-road conditions. However the TROLL is a serious contender.

Here a few questions:
Karl G. cautioned me about using a NV360 with a 750W motor due to excessive torque and advised me to play safe and install the old 4kg N171. Any issues with the hub yet?
Could you pls. post a pic from behind showing the chainline?
Did you grind off any of the BB width or just go with a single nut?
I didn't quite get why you changed the cranks. What was the issue with the original ones?

Thanks & Regards, Go-Coo
Hi Go-Coo,
Thanks for you nice comments the N360 hub and harmony gears are still working fine no issues to report as yet, I am mindful that people say the BBS 02 750w could damage/overtorque the hub, I don't abuse it with full thottle standing starts etc.
My local rides take in some steep hills and I am regularly applying full throttle but mostly it's only needed for short bursts to boost speed a little.
The bike has had it's last upgrades and now sports a Fox 32 CDT fork with 100mm travel and 15mm bolt thru axle, and because the bike is so quick I now have Shimano duel piston Zee brakes back and front for better modulated powerful braking, am running on schwalbe 2.35 x 26 big apple tyres as the big fat front tyre was drawing more attention than I wanted and did get a little bouncy off road at speed.
Had a test ride along a local canal tow path last week standing on pedals and riding trials bike style over an uneven bumpy section of the canal bike was more managable and faster with the suspension fork fitted, was a blast riding for a couple of miles just on throttle regularly hitting 25/30mph you can feel it shifting gear by its self the bike just picks up speed very rapidly, so as long as it keeps performing this way and does not fail I be happy with my choices.
To answer you questions I would prob agree the N171 could well be more robust, the torque and power of 750w motor doesnt really need the gear range offered by the N360 especially off road with it geared low.
I have a good chainline but am using a dished alcedoitalia 42t chainring with 16t rear sprocket see pic below , I have quite short legs and a niggling knee injury so prefer a shorter crank those are tandem cranks 165mm but I also have some 150mm cranks which I quite like too but have not tried on this bike.
I only use the 1st locking ring with plenty of threadlock applied the bottom bracket is untouched at 73mm have had no issues with it coming loose.
you posted some good links to other sites will be having a good look at them, quite like the look of the Gravity Monster and I very much like the krampus and think the 3" x 29" would be a great choice avoiding the BB issues of a full fat bike.
I have some 3" duro lepoard tyres which also fit the troll frame taking it very close to what a krampus offers have put some current pics below, good luck with your project look forward to seeing you finished bike.

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Hi Spotty,

Thanks for easing my mind on the single lockring and Nuvinci performance.
You really managed to align the chainline PERFECTLY! Hope I'll do...
A picture of the whole bike in it's current incarnation would be cool.
Still wonder how you manage to go so low profile?
I have found a source for the N171 hub and the cable but not the controller so far :(
I'll bug you with more questions later, especially about the lipo bat.

Take care and enjoy your rides,

Hi Go-Coo a few more pics the pair of 6S Zippy lipos I use fit easily into this small carradice canvas saddle bag, this is prob it's most stealth look, in general tho I keep the rack and useful panniers fitted.
The selle anatomica saddle was a recent and more comfortable for me replacement for the brooks B17 saddle that was fitted,the tyres in these pics are 1.75 x 26 marathon plus but I found the ride a bit harsh, fat tyres spoil you with a soft ride, the big apples on now are proving a good compromise giving the soft ride I prefer. The canals are very pretty in spring and summer with alot of wildlife to see am lucky they are on my doorstep and offer flat riding when I don't fancy the hilly roads that surround my home.
My range on these lipos is only about 12 miles on hilly roads, ( I go further on the flat canal paths) am waiting for Hobbyking to restock on Multistar 6S 16000 Ah batteries if you go lipo and you can get hold of them I would say a pair of these are the way to go other people are reporting good peformance and range with the multistars the 10C rating is plenty good enough for the BBS motors.

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I understand everyone concern. However, with a properly programed BBS01 and a simple tap of the brake I can shift my junky 3spd Sturmey Archer. 500 miles and no problems. I understand that shifting under stress and a bad chainline can tear up a IGH, but I've learned to that a good chainlink and proper technique seems to solve the problem . A Gerasensor may also be a good solution. Lectric Cycles is now selling Shimano Nexus 3i with roller brakes and the Gearsensor. They are reliable.




Hi Spotty,

This is my current nonmotorized all-for-one bike btw, overall not unsimilar to your 1/2 Troll:

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As you inspired me to go a bit more low-profile I swapped the Table Top to the rear and put a smooth Crazy Bob in front.
It's a folding bike with an eccentric BB. Used to be a the chain cruncher version once.

OK, ride on!
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ken ferris

New Member
My troll with a 500 W 36V Bafang and Rolhof 14 speed hub has a couple of hundred miles on it now. Love the combo as shifting while stopped is a must for commuting to work. The Rolhof does not like to shift under load but after riding a awhile is becomes second nature to back off before the shift. The bafang PAS system feels on / off. level one 10 MPH level 2 15 and 3 21 MPH on flat ground. You can peddle more or less but you stay within a couple of MPH of the above. Not a problem you get used to it and if you want modulate use level one and the throttle. My other bike is a Karate monkey with a BMC V4 a lot more powerful (2 speed metro crank is the only gearing) but not as much fun.



Do you have a few pictures showing how you routed the cables?




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Hi Go-Coo,
Only got chance today to take some pics of wiring on my girlfrends bike I finished a month ago, this uses a 36v BBS 01 so the 36v battery is within the NuVinchi harmony voltage range 18v to 50v.
The power cable has a spur lead soldered in going in opposite direction to the main power lead to the motor I use an in line blade fuse 30amp to the motor and 5 amp in line fuse to the Harmony shifter the motor lead uses a EC 5 connector the harmony has EC 3 connector to avoid mixing them up, they are loosely coiled up inside a small triangle bag so I have quick access to them if I need to disconect them.
Some pics below and one of her bike to rehijack the thread lol, will include more pics and a run down of it's spec later am pleased with how it turned out she loves riding it .
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My bike is wired differently because my lipo battery pack can charge just above 50v, I use a seperate small lipo to power the Harmony unit.
A 4S Zippy 2000mAh giving 14.8v is used both are fused the same 30amp to motor 5amp to Harmony unit, it was cheap to buy especially compared to Shimano Di2 power pack, as I am already set up to charge lipo batts it is no trouble.
From storage voltage to 4.0 volts takes about 10 mins after a ride of about 12/15 miles the cells have discharged to 3.95v so it has more than enough juice to power the electric shifter, with the added bonus if I need to stop using the larger power pack to the motor I still be able to ride under my own power with a still fully functional gear shift.
In first pic you will also see I have a Speedict mecury wired into the system this provides useful infomation about speed, battery state, voltage drawn etc all displayed via my smartphone with bluetooth connection.
Only critcism of it is in bright sunlight you cant see the screen but on duller day its fine and looks great at night.

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Hi Spotty,

Your girlfriend's bike (Karate Monkey is it?) is just as awesome as your Troll, Wow!
You must love her at least as much as your own bike ;)

Thanks for all the great info and picks. I got to admit that my understanding circuits got blown though...
The idea of having a 2nd energy source for the Harmony and to install some fuses stuck never the less.

I'm still in the early stages of my project. Did a crude setup with crappy parts yesterday just to check the feel of the frame and the ergonomics (stem and handlebar) to know what to order. Next step is to rip it all off again and to spray wax the seat tube, lower chainstays and BB. Am still waiting for the rims to arrive to lace the wheels as well as a couple of other parts...

BTW I guess it's time to come out of hiding within tour thread and to open a new one...

Stay with me, ok?

Enjoy riding, fiddling and posting,


Well-Known Member
Sadly reducing the size reduces mechanical advantage significantly. I did a cursory search last night and found a few "standard offset" crankarms. Reported to be good replacements. But as I wrote, I'm building a small database and BBS0x FAQ, the report of failed arms is a bit of sensationalism. I think more cranks have been damaged by stripping and poor mechanical practice. I am certain two were in fact the stresses of very powerful riders, playing very hard and putting far more than average strain on the units. They weren't designed as off road mountain motors. I have been hard on one of mine, hauling well over the weight one would normally haul on a flat foot frame. No problems. I do need to snug things up and do an occasion "preflight". After all we've added motors to machines that weren't designed around the motor and the revers is also true. I have found a loose crank arm on one occasion and I had used a torque wrench to properly seat it. That could have torn up the aluminum crank on the steel BB shaft. Sorry I drifted off there. I will finish looking and find alternatives for replacement to add to the FAQ. If you find 170-175MM offset that fit, please share.

Thanks Louis! That's good to know. I've still got a Giant mtb waiting on one.