Kona Ute mid-drive conversion: advice appreciated

[Peddlin' Pedro]

Hi all,

Joined the forum a few years ago when first looking at building an e-cargo bike but struggled to find a base bike and ended up parking the project.

Just this weekend I've finally bagged a mk2 Kona Ute for a decent price and I now need to convert it into a viable daily-driver for ferrying a two-year-old and daily/weekly shopping around, on 10-20 mile round trips that include some biggish hills. I'd also like to be able to use it to lug the sprog and camping gear for three people out for weekend camping trips, with my wife on her own bike under her own steam (no tows!). It will also be used to get me to localish work meetings when that sort of thing starts happening again.

I'm a pretty strong cyclist but would like to be able to do the shopping run, complete with small and very vocal passenger, without needing a shower when I get home. I should also highlight that I have no interest in high speeds as I'll be carrying a child and reasonably heavy load on a bike not known for its rigidity*. I’m far more interested in help getting up the hills and I've got my un-assisted fun bike for when I want to practice my Sagan descending technique.

*would've preferred a Surly or Yuba but prices quickly get silly by the time you've added the bits needed to actually make them useful, assuming you can even find them for the Surly.

I'm also a competent bike mechanic and have built loads of bikes up over the years but have no experience of e-bike conversions, with my knowledge of same being from reading this and other forums and watching Youtube vids.

I'd be very grateful for some experienced advice on what my best options might be to meet the above requirements.

So far, in my blissfully ignorant take on things I've narrowed it down to mid-drive kits from either Bafang or the torque-sensing units from Tongsheng. I suspect the 250w BBS01 would be too weedy, though Brighton e-Bikes' ETM variant (rebadged BBS02, perhaps?) looks like a contender but he's out of stock. I'll be running hydraulic brakes so will need suitable sensors and while I'll start with the existing drivetrain I'm considering switching to a Nuvinci/Enviolo hub. Battery would obviously need to be suitable for load-lugging on both short runs and occasional longer trips with as long a usable lifespan as possible.

Recommendations for reliable sources for any recommended systems/parts would also be appreciated, though I'm already aware of Brighton e-Bikes, Woosh, Eclipse, Electron and em3ev.

Many thanks!

 

[peter.c]

My Kona unit had both bbso2 etm and a tsdz2 fitted as a lazy rider the etm from em3ev is best , as a cyclist the tsdz2 is better [it is also a better fit in the Kona frame ] the 48v is the best version uk legal from woosh .
or http://www.pswpower.com/ven.php? for other versions

 

[Peddlin' Pedro]

My Kona unit had both bbso2 etm and a tsdz2 fitted as a lazy rider the etm from em3ev is best , as a cyclist the tsdz2 is better [it is also a better fit in the Kona frame ] the 48v is the best version uk legal from woosh .
or http://www.pswpower.com/ven.php? for other versions

That's good to know, thanks. Cue the barrage of questions in response:

In what way is it a better fit? And how was the chainline? I'd prefer not to go any bigger than 42t, ideally 40 so wondering if that's doable on these?

Also, am I right in thinking that you don't need a shift-sensor on these units, i.e. is it quick enough in sensing you backing off pre-shift to cut the power in time?

 

[peter.c]

The fit is better both lock nuts will not fit on the bbs02 as the bb anti turn washer is wider, also tsdz2 has rear stabiliser mount
The chain line is also better but only with the standard chain ring as it is dished inwards [42t will be flat ]
The bbs02 had to have a chain guide fitted
Gear sensor not required with a tsdz2 in pas modes unless you are in turbo mode and stomping on the pedals
With the 48v tsdz2 you should not need the smaller chain wheel it has plenty of low end grunt, i rarely use the two larger cogs on the rear
Final point the tsdz2 is not as current hungry 48v 15a peak and the bbs02 etm wants 36v 25 amps peak and needs top grade battery cells to avoid sag

 

[Peddlin' Pedro]

The fit is better both lock nuts will not fit on the bbs02 as the bb anti turn washer is wider, also tsdz2 has rear stabiliser mount
The chain line is also better but only with the standard chain ring as it is dished inwards [42t will be flat ]
The bbs02 had to have a chain guide fitted
Gear sensor not required with a tsdz2 in pas modes unless you are in turbo mode and stomping on the pedals
With the 48v tsdz2 you should not need the smaller chain wheel it has plenty of low end grunt, i rarely use the two larger cogs on the rear
Final point the tsdz2 is not as current hungry 48v 15a peak and the bbs02 etm wants 36v 25 amps peak and needs top grade battery cells to avoid sag

Don't suppose you've any pics of your Ute with the Tongsheng fitted? I'm keen to see how much ground clearance you lose at the BB.

And regarding batteries, could you recommend a suitable pack/size that would accommodate the loads and distances I'll be covering, or is it a case of get what I can afford and more is better in both capacity and cell quality?

 

[peter.c]

the tdz in the frame

 

[peter.c]

the bbs in the frame

 

[Peddlin' Pedro]

Thanks for that. Hard to say for certain from the pics but looks like the tsdz2 has quite a bit less ground clearance than the BBS. Is that the case? And have you had any issues with the housing rotating under load and hitting the downtube?

 

[peter.c]

Always rest a bbs against the frame before i tighten with a mallet and Loctite
The tsdz2 had more ground clearance, as the motor is smaller and a tighter fit to the frame, its the photo angle and distance are not the same pic of another build

 

[Gavin]

Hi Pedro, I know nothing about these longtail cargo bikes, but they seem like a pretty handy tool. I'm curious about your "a bike not known for its rigidity" comment.

Are these Konas not up to the job?

 

[Peddlin' Pedro]

Always rest a bbs against the frame before i tighten with a mallet and Loctite
The tsdz2 had more ground clearance, as the motor is smaller and a tighter fit to the frame, its the photo angle and distance are not the same pic of another build

Okay, thats a relief. Can I also ask what type of battery you had on your Ute? Was it a side-loading version, or did you find there was enough room in the frame for a slide-down type? And can you offer any other tips specific to fitting the TSDZ2 and suitable battery to the Ute?

 

[Peddlin' Pedro]

Hi Pedro, I know nothing about these longtail cargo bikes, but they seem like a pretty handy tool. I'm curious about your "a bike not known for its rigidity" comment.

Are these Konas not up to the job?

Hi Gavin,

They’re hugely capable bikes but Kona prioritised weight (and cost) over stiffness, and went with relatively small alloy tubesets without any ovalisation or other forming that would have improved stiffness.

The less rigid frame means they cant be loaded as heavily as something like the stiffer and steel-framed Surly, Yuba or Xtracycle, but the Ute is still pretty versatile and significantly less expensive than those competitors. The mk2 Ute (and later) is still better than the mk1 as they increased the downtube size and tapered the head tube to try and firm things up a bit.

There’s another alloy long-tail that would have been good but isn’t available in the UK: the Mongoose Envoy. Light, really stiff and sells for well under $1000 new In the US, but the UK Mongoose distributor wont bring them in, yet...

Have you been looking at long-tails yourself then?

 

[Gavin]

I've just finished my first ebike build and am wondering if a longtail would suit me better. I was watching a Ute on ebay at the weekend but didn't bid.

I'm a compulsive tinkerer, and the idea of a longtail with downhill forks and a BBSHD mid-drive has a certain appeal

 

[Peddlin' Pedro]

I've just finished my first ebike build and am wondering if a longtail would suit me better. I was watching a Ute on ebay at the weekend but didn't bid.

I'm a compulsive tinkerer, and the idea of a longtail with downhill forks and a BBSHD mid-drive has a certain appeal

Got to ask: what did you build?

Can definitely see the the appeal of a powered offroad long-tail but I'd be careful about trying to put too much power through the Ute. It's not just the less rigid frame to contend with but the 700c rims. The combination makes it flexy and tall, which is why the current version has 650b and more forming of the tubes. I'm no Cipollini but I can get the back-end squirming if I really stamp on it and that's without a drive installed yet.

Slow steady application of torque and it should be fine but cranking away at 1000W is likely to get the back-end disagreeing with the front. If you wanted a more offroad long-tail then I'd say the Surly is the one to go for as it's pretty tank-like in build, but a lot more money and again, sourcing the Xtracycle bits needed to make it useful is nearly impossible these days.

Really need to start a campaign to persuade Mongoose to bring the Envoy into the UK as I think it'd make an epic powered offroad camping/fun wagon! Check this out:

 

[Gavin]

I put a TSDZ into a modified early nineties Specialized Hardrock (my profile pic).

That's a great vid, and summarises exactly the sort of easy off roading (apart from the balance beams) that I like to do. Speaking as an ex-motocrosser, the back end disagreeing with the front is when the fun starts happening (though maybe not with your kid on the back)!

 

[Peddlin' Pedro]

I put a TSDZ into a modified early nineties Specialized Hardrock (my profile pic).

That's a great vid, and summarises exactly the sort of easy off roading (apart from the balance beams) that I like to do. Speaking as an ex-motocrosser, the back end disagreeing with the front is when the fun starts happening (though maybe not with your kid on the back)!

Nice bike! Always had a soft spot for Spesh hardtails, my last being a 2001 Rockhopper A1 (+ lots more letters). Loved it. How're you getting on with the TSDZ?

It's a cracking vid isn't it. I may try again at persuading them to bring a few in to test the market. I've nothing to do with the bike industry but my background's in marketing and I'm almost certain they could shift a few, especially if they're anywhere near the North American pricing. Plus, I really want one myself so purely selfish in motivation

Know what you mean about the fun starting when the back end breaks, different matter when it feels like it's got loose but the wheel's still tracking! And as you say, best left for when there's no passenger.

 

[Gavin]

Thanks. Complicated build but good fun. The TSDZ is great- being a torque sense, it still gives you a good workout but you go quicker. I'm mustering up the courage to do the firmware upgrade (this was one of the reasons I bought the TSDZ) but it looks a bit scary.

I see what you mean about North America pricing- even accounting for the low spec, that's peanut money for a bike like that. If ever there was a time to try to get them to import, it's now, with bike sales going through the roof.

Aside from the official import channel, I wonder if you could persuade a dealer over there to ship one here. If they packaged it up "sympathetically" you might find you could avoid import duties....

 

[JohnDaBike]

Hi Gavin, would you be kind enough to share some of the issues you encountered during the conversion of your Specialized Hardrock? I have an even earlier Specialized Hardrock, without the front suspension, and I am awaiting the delivery of a TSDZ 48v & 13ah battery. It would be helpful to hear of your experiences before I start my conversion.

 

[Peddlin' Pedro]

Hi Gavin, would you be kind enough to share some of the issues you encountered during the conversion of your Specialized Hardrock? I have an even earlier Specialized Hardrock, without the front suspension, and I am awaiting the delivery of a TSDZ 48v & 13ah battery. It would be helpful to hear of your experiences before I start my conversion.

That would be good but should probably be another thread in its own right, otherwise things start morphing into other things - as I've already done with my Mongoose digression, sorry! - and content starts getting harder to find.

 

[Gavin]

Hi John, welcome.

My tale of woe is in another thread somewhere- I'll try and find it for you.

It used to have solid forks- I fitted the Marzocchi's