Surly LHT e-bike conversion

Electrically assisted bikes, trikes, etc.
Posts: 180
Joined: 19 Feb 2009, 10:39am

Surly LHT e-bike conversion

Postby brucelee » 25 Jun 2019, 5:36pm

So, I've been thinking about an electric conversion for my LHT for ages (and ages), very much in the touring, help with the steep hills type vein. So 250W front wheel motor on a wheel that will take 28mm/700c Gators, drop handlebar brakes, maybe a bottle bat that will fit on the mounts on the underside of the down tube. Looking at :
My immediate concern however is what happens when I go round a wet corner up a steep hill with the motor at full whack ? I run my tyres at 120PSI so very little grip (and maybe even issues with quality of the rim....).
I have a topeak MTX quicktrack type rack so a battery that would adapt to that would be nice..
Can I do without the brake sensors if I have PAS ? any legal or practical issues here ? Are there alternatives for drop bar brakes ?
Don't mind shelling out on an expensive hub motor if there are efficiency / longevity issues and can build my own wheel. I saw a 250W hub somewhere that weighed in at 2.3Kg, seems like an awful lot for a 250W motor....
It's a very large frame so there is space for stuff.
mid drive rejected because want triple chain rings.
Rear wheel drive rejected because there is no way they will have done a strong enough rear hub and I want cassettes, mounted on a steel freehub and I'll have to rebuild the wheel with a different rim and then try to find good quality, funny length spokes at a reasonable price.
Many thanks in advance

Posts: 786
Joined: 16 Nov 2017, 5:40pm
Location: West Sussex

Re: Surly LHT e-bike conversion

Postby hemo » 25 Jun 2019, 7:28pm

Cassette hub motors are plenty strong enough you will not break one.
The issue is finding a 250w labelled hub motor as most are 350w labelled.
The hub motor linked to is the same as a Yose hub and is I believe made by Bafang, the RPM rating will max out at about 15mph.
Weight will be about 2.8 - 3.3kg.
Fitting may not be as simple as plonking it in the D/O's and tightening, axle is 10mm x 12mm so sometimes D/O's may need a 1.5 -2mm filing to allow the axle to sit deeper. The axle also has an anti rotation washer each side not unlike a hub gear set up so you will need to make sure the ARW's sit in nicely, other wise you run the risk of the motor torque turning in the D/O's twisting/ripping out the motor wire causing failure. Motor wire repairs are not easy.

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Joined: 10 Dec 2009, 8:03pm
Location: Blackdown Hills, Devonside

Re: Surly LHT e-bike conversion

Postby windysmithy » 25 Jun 2019, 10:47pm

I put a Tongsheng bottom bracket conversion on an old Dawes that looks like you wouldnt nick it.

various tongsheng stuff on youtube:

lots of other options, put the kettle on and have a look at:

id go for the tongsheng again, or maybe bafang

I bought a 500w 36v motor from these guys

about £300, and another 200 for a 13 AH battery from somewhere else.
It turned up, paid with Paypal so some kind of protection i guess, but returning it to chinaland under warranty probably wouldnt happen. No markings to speak of , and a simple fiddle with the control board to make any necessary adjustments. Took about an hour and a half to fit.

My daughter does a very hilly 17 miles a day on it and loves it. She used all of a triple ring before, and doesnt need it now. The last hill back up to ours is a good 1 in 4.

Posts: 786
Joined: 16 Nov 2017, 5:40pm
Location: West Sussex

Re: Surly LHT e-bike conversion

Postby hemo » 25 Jun 2019, 11:41pm

The TDZS is a different beast compared the BBS01 or 02 being that it is torque multiplier drive like Bosch and other mid drives.
Th BBS is a cadence drive range wise The TDZS will give more range from the sme battery.

the snail
Posts: 168
Joined: 5 Aug 2011, 3:11pm

Re: Surly LHT e-bike conversion

Postby the snail » 26 Jun 2019, 6:14pm

+1 for the mid-drive, like the tongshen. They will handle hills/weight better than a hub drive. You shouldn't need a triple with the motor, but I think it's possible to fit a double to the tongshen if you need to.