Kona Ute mid-drive conversion: advice appreciated

[Peddlin' Pedro]

Finally got round to stripping the frame properly and scraping back the paint around corroded bottle and mudguard bosses and deck-mounting-points. The BB got a twice daily squirt of WD40 for the last three days as had a hunch it wouldn't go without a fight and I was right. State of the cartridge was pretty nasty but the shell is fine and the threads chased out cleanly.

I knew the bike had been neglected and likely been stored outside for some of the last nine years but I was confident the welds were all solid. My biggest worry was that some of the bubbled paint around either the downtube underside bosses or the seatstay bridge boss was hiding something bad, which could have been a write-off for a frame like this.

These areas, and others to a lesser extent, had a lot of oxide accumulated but it scraped back cleanly and none of it was deep. Hour's worth of scraping with a fine pick and wire brush shifted the worst of it so just need to sand the surrounding paint-edges before treating and re-painting. Will drill for the additional downtube battery rivnuts before treating and painting as makes sense to do it all in one go.

Tape in the pics shows either areas needing treating & painting or locations for additional battery mounting rivnuts. Headset and head tube are in good order though, so that's something!

 

[Peddlin' Pedro]

Contender for the year's slowest resto/conversion project? Besides the very real difficulties in finding suitable components, especially anything relating to wheels, every time I'm getting started something non bike-related derails me. Been making do with cleaning up components when I can grab time. Cleaning the rear mech was more like archeology than bike maintenance with all the years of hardened gunge and road-grime.

Finally got the first coats of paint on the frame chips today (the sweet smell of Humbrol!), installed the three extra rivnuts and got the battery mounted. Managed to mangle one of the rivnuts so had to grind off the flange and knock it through to start again. The battery just squeaks in there and still needs a bit of wiggling to get it out but it's accessible and solid enough on four points of attachment.

Got the day to myself tomorrow so hoping to fit the drive and get the drivetrain reinstated. Be interesting to see if the old Deore mech will cover the new 11-40t cassette with a Roadlink. New 26" wheels should also turn up in the next week or two; got a deal on an oldstock Halo SAS/Combat pairing at half the normal price and they'll be rock solid laced to the the Pro4s I tracked down, with a steel freehub body to boot.

 

[Peddlin' Pedro]

Still slow going but collected wheels on Saturday. Super happy with them despite white not having been my first choice of colours and actually think I prefer the 'beach cruiser' vibe. And, with the Combat/SAS being 30mm (int) the 2.4" Super Moto Xs measure up bang on spec so the BB only dropped by 8mm, which is perfect. Hoping to get the brakes and drivetrain set up over the weekend. Pic shows the old Conti 'Contact Plus' 42s against the new ones.
PS. Ignore the state of the garden; also a work-in-progress that got banjaxed by lockdown and now the heatwave

 

[Peddlin' Pedro]

It's alive, sort of... when it feels likes it...

First hiccup was the NDS-crank binding against the unit's BB face when torqued to 35 N-m, which is the absolute bottom end of what a square-taper crank should be tightened to; I'd normally go to 40-45 N-m. Had to file 1.5mm off the back of the crank to gain enough clearance but that's only a temp fix as the NDS q-offset is a daft 15mm+ that'll knacker my knee, hip and back with too many miles in that state.

Bigger problem is that on taking it out last night the motor was cutting out randomly at anything above 8-10mph and then stuttering on/off at random. It was also very slow to cut power when backing off the pedals, which led to some noisy shifts and heavier braking than should be needed. Worth noting that the displayed speed appears to be consistent and relatively accurate, i.e. no whacky readings showing 60mph at walking speed etc.

Having read through various posts on here and elsewhere I rechecked the head unit settings, speed-sensor placement, gap (~12mm, may need to increase) & attachment (not loose or vibrating) and all cable connections. Will recheck everything again today and have another go but open to other suggestions.

UPDATE: Swapped magnet to opposite spoke to get more clearance from sensor and it seems to be working perfectly, other than now having the displayed speed randomly drop to 6mph or less when I'm going downhill at nearer 18-20 (unassisted). Will move sensor again and see what happens. Fun and games!

ANOTHER UPDATE: moved the magnet back to the nds spoke and displayed speed no longer bouncing around and motor working as it should.

PS. Got my first 'Ute shimmy' when I took a hand off the bars on a downhill run. Was quite exciting, and demonstrates the need for a steering-dampener on these things.

 

[Peddlin' Pedro]

Final tidying, choosing/installing a lighting system and sourcing replacement cranks aside, this project is pretty much done now.

Really important point to make about the Ute - as many have said before - is that it simply does not have the carrying capacity of the Surly, Yuba or Xtracycle alternatives; it's just too lightweight and prone to longitudinal torsional flex through the frame. It also does NOT like weight in front of the head tube, suffering from a severe shimmy with even just the 7kg of front rack and two locks if the bars become unweighted so this area is for light duty only. Still deciding if its worth trying a steering damper (as opposed to the fitted sprung steering-stabiliser) to try and tame the front end. Otherwise, some basic motorcycle techniques help a bit, like counterweighting the bars (not counter steering, very different) smooth power application, looking and planning ahead and speed management.

With the additional weight of drive and a large power pack and when loaded with a moderate shopping run's worth of stuff it's knocking on the limits of controllable handling, particularly at low speeds and in close quarters, i.e. in-town riding. Remains to be seen whether it can cope with a child seat and sprog added or whether the extra weight up high will make it too unstable. Going to simulate that by loading a coolbox with 20kg of sand and strapping it to the top deck. If it's too sketchy I'll be swapping all the new bits (other than the stand) onto a Yuba framset, restoring the Ute to stock spec and selling it on.

The (nearly) finished bike and new spec*:

*all new bits other than the centre-stand were bought specifically to be usable on another frameset if I ever choose/need to swap. Given the bargain I got on the Ute I've lost nothing other than some time (which I've enjoyed, so no loss) and should even make a few quid if I restore it to factory spec and move it on.

Have some new Xtracycle bag/sling combos on the way (NOS) so will unfortunately loose colour coordination of basket and bags as these original Ute bags are a bit tired. Still perfectly usable but the weather resistance is compromised due to some of the vinyl coating having flaked off the canvas. Keeping them to put back on bike when/if I sell it on.

The whole bike, looking spanky with white rims and chubby rubber:



Non-drive side, showing the controller housing used to hide connections and excess cable. Will need a bigger housing to accommodate a controlling relay for 48v lighting circuit if I go that route. Cables will be spiral wrapped when I've finished tweaking:




Cockpit, complete with Spurcycle-clone bell (effectively clears lemmings out of the way), Ergon cork grips (v.comfy) and upgraded 9-spd (from 8-spd) shifter moving the stock Deore long cage mech, which is coping fine with a wide-range 11-40t Sunrace cassette and didn't need a road link or even a longer B-screw.

Replaced the always crap Avid BB5s with new MT501 levers paired to MT520 4-pot calipers, grabbing stock Avid 185/160 rotors with stock adapters working perfectly just by removing the conical washers. Cages are old Spesh ribcages from the spares box fixed to rack with with oversized cable ties. Mirror also from the spares bin and still as useless as when it got consigned there in the first place.



Rear view, showing the Bluemels 65 mudguards and home-made mudflaps. Always dread doing mudguards on a new bike and spent a sweary evening setting these up.



And finally the Abus frame lock attached with two 12mm p-clips re-formed to fit the 19mm seat stays; there's way more tyre-clearance than the pics show. This is accompanied by an 8mm plug-in noose-chain and gold rated Kryptonite S4 Evo chain. An Abus AlarmBox will complete the security setup when they can send me one that actually works properly:





Only other finishing kit of note are the saddle and pedals. Saddle is a Rivet 'Pearl'
(got its rain cover on in the pics) which feels to me like Brooks B17s used to before they started using cheaper, thinner hides to cut costs and shorten the break-in period. Surprisingly comfy for a brand new saddle of this style with such thick leather, no doubt the cutout helps with comfort. Has plenty of range on the tension bolt so a good few years of adjustment available as it ages. Pedals are Bikester's own brand 'Red Cycling' flats. Super comfy, wide and grippy and absolutely no hotspots even after 60 miles in thin soled trainers. Only downsides are lack of spanner flats and the pins are razor bloody sharp. Be warned!

 

[Peddlin' Pedro]

TSDZ2 performance and riding characteristics

Drive: 48V 7250W TSDZ2, limited to 25kph (no interest in high speeds on this type of bike)
Power pack: Hairon 48V 17.5Ah with LG MJ1 cells
Supplier: PSW Power

Frame-specific handling issues aside, I'm thoroughly impressed by the performance and ride feel I get through the TSDZ2. I don't find the power curve too aggressive when pulling away and even with a moderately heavy load on an already heavy bike, the 'Tour' setting is more than adequate to pull away smartly if you've selected the appropriate gear.

And that's an important point; you still need to choose the right gear for the terrain whilst considering the cadence limitations of the drive in its unmodified configuration. Getting half way up a climb and realising the drive's bogging down and going for your granny gear is a good way of wrecking your drivetrain. Likewise, powering up a climb in a big gear with the drive on 'Turbo' may be fun but it's only ever going to result in hammering your battery performance and again over stressing your drivetrain; a good way of snapping chains, making gear teeth go all pointy and prematurely fatiguing battery cells.

Shifting ahead is particularly important as if you don't back off early enough the drive will still be working when you go for the shift; result: noisy shift and more unnecessary wear on the drivetrain.

I did 68 miles in total over the last three days with quite a lot of climbing - some at 16-18% - and with some moderately heavy loads. I never felt like I was going to run out of go and soon got used to shifting ahead and moving through the assistance levels as needed in order to maximise range. At 68 miles total covered the display was still showing two of six bars occasionally dropping to one on the final climb home and the battery itself showed two of four leds. I've no doubt it could manage north of 75 miles on a charge or possibly even a bit more but I've no intention of emptying the tank on a bike that weighs as much as this. The unassisted ride home would be pretty miserable.

I'm now planning to swap in an 850c display and run the open source firmware to see if I can stretch the range and get an even longer usable life out of the power pack

My example is obviously specific to this bike and my relatively high overall fitness and moderately high unassisted power output. Someone who doesn't cycle as much as I do would undoubtedly get less range on the same bike or potentially quite a bit more on a lighter bike. Either way, I really enjoy the relatively natural ride feel and the fact that every ride so far has felt like a 'good legs' day. Looking forward to more.

 

[Swizz]

TSDZ2 performance and riding characteristics

Drive: 48V 750W TSDZ2, limited to legal 25kph limit (no interest in higher speeds on this type of bike)
Power pack: Hairon 48V 17.5Ah with LG MJ1 cells
Supplier: PSW Power

Frame-specific handling issues aside, I'm thoroughly impressed by the performance and ride feel I get through the TSDZ2. I don't find the power curve too aggressive when pulling away and even with a moderately heavy load on an already heavy bike, the 'Tour' setting is more than adequate to pull away smartly if you've selected the appropriate gear.

And I guess that's an important point; you still need to choose the right gear for the terrain whilst considering the cadence limitations of the drive in its unmodified configuration. Getting half way up a climb and realising the drive's bogging down and going for your granny gear is a good way of wrecking your drivetrain. Likewise, powering up a climb in a big gear with the drive on 'Turbo' may be fun but it's only ever going to result in hammering your battery performance and over stressing your drivetrain; a good way of snapping chains, making gear teeth go all pointy and prematurely fatiguing battery cells.

Shifting ahead is particularly important....

....I did 68 miles in total over the last three days with quite a lot of climbing - some at 16-18% - and with some moderately heavy loads. I never felt like I was going to run out of go and soon got used to shifting ahead and moving through the assistance levels as needed in order to maximise range. At 68 miles total covered the display was still showing two of six bars occasionally dropping to one on the final climb home and the battery itself showed two of four leds. I've no doubt it could manage north of 75 miles on a charge or possibly even a bit more but I've no intention of emptying the tank on a bike that weighs as much as this. The unassisted ride home would be pretty miserable.

I'm now planning to swap in an 850c display and run the open source firmware to see if I can stretch the range and get an even longer usable life out of the power pack

That's all interesting to know. Am hopefully going to put some shakedown mileage on mine this weekend and what you have said re gear changing early makes sense, if not confirming my regret for not going for a Nexus gearhub.

Am really stoked by the range you have achieved and will be interested to see how the Samsung celled 14.5ah I have will perform on the lighter bike.

Re the firmware, have you not considered the fork that keeps the tongsheng display or are you also looking for the extra features of the 850c?

 

[Swizz]

Ooh forgot to add, how has the speed sensor magnet faired after the mileage covered?

Am not impressed with the security of mine to the spoke at all. Considering assembling it with epoxy once it's final position has been settled upon.

 

[vfr400]

75 miles from a 48v 17.4Ah battery would be 8Wh/mile. At an average speed of 12 mph, that would be 100W average from the battery,or 80W at 10 mph; or 80W and 64W average assistance.

If you pedalled at 100W and went up a 17% hill with an all-up weight of 150kg, assuming that your controller is limited to 18 amps, you would go 10km/h and draw 850w which is 136Wh/mile, so you could do 6 miles of climbing that steep.

 

[Peddlin' Pedro]

That's all interesting to know. Am hopefully going to put some shakedown mileage on mine this weekend and what you have said re gear changing early makes sense, if not confirming my regret for not going for a Nexus gearhub.

Am really stoked by the range you have achieved and will be interested to see how the Samsung celled 14.5ah I have will perform on the lighter bike.

Re the firmware, have you not considered the fork that keeps the tongsheng display or are you also looking for the extra features of the 850c?

Yep, I'm pretty chuffed with the range, though part of that is undoubtedly due to me not being very good at not putting the watts in myself. Let us know how you get on with your pack.

I hadn't realised they'd forked the firmware project. Don't suppose you've a link?

 

[Peddlin' Pedro]

Ooh forgot to add, how has the speed sensor magnet faired after the mileage covered?

Am not impressed with the security of mine to the spoke at all. Considering assembling it with epoxy once it's final position has been settled upon.

They're not a great fit are they. It's been okay but I cranked it down pretty hard. Wrapping the spoke in some ptfe tape is on the snagging list so that should help it stay put if I clout a pothole or get carried away off road. Used to work with old bike computers so no reason it wouldn't with these.

 

[Swizz]

...hadn't realised they'd forked the firmware project. Don't suppose you've a link?

The Empowered People blog is a good read & it gets a mention ⅓ of the way down this post.

And here's the Wiki on it.

May do this with mine once I have gotten a good feel of the motor with the stock firmware if there is room for improvement.

All I have ever read of the open source firmware is how much it feels to a good off the shelf eBike.

 

[Peddlin' Pedro]

The Empowered People blog is a good read & it gets a mention ⅓ of the way down this post.

And here's the Wiki on it.

May do this with mine once I have gotten a good feel of the motor with the stock firmware if there is room for improvement.

All I have ever read of the open source firmware is how much it feels to a good off the shelf eBike.

Ah, cool, thanks. I did read through the Empowered People blog a few months back but must have missed that bit. Definitely on the agenda for next steps, though it may not be on this bike after this morning's test ride.

Took it out with the bags loaded up and a 15kg cool box strapped to the top deck to test the handling. With the combination of crosswind gusts and the weight high up the handling was... interesting? Okay once it's moving but sketchy as hell pulling away and at low speeds. Besides the known issue of a lightweight but slightly twisty frame, the relatively short wheelbase for this kind of bike (more 'mid-tail' than 'long-tail') means that when the bags are full you end up with quite a bit of weight aft of the rear axle. Excessive weight behind the rear axle on any bike causes screwy handling but the Ute has a really big overhang in relation to its wheelbase, and that results in a tail wagging the dog situation compounding the other handling issues when over-loaded.

That aside, the drive system again worked brilliantly. Being able to increase the assistance to accelerate from a standing start up a hill while minimising pedal-induced front wheel-wandering made what would otherwise have been completely unmanageable, just about doable, if a bit hairy.

It's a shame, as when moderately loaded but without the additional weight of motor and battery the bike handled fine. Even moderately loaded with the drive system on board it's okay. With the drive system plus equivalent of a week's shop and a nipper on board though it just tips over into being too much of a handful to feel confident riding in town traffic. If it was just me riding it I'd probably be okay but having a child on board just makes it too risky if I also want to carry a decent size shop and maybe even a pushchair. The other consideration is that while I could just about get away with it, my wife who's considerably smaller than me wouldn't have a chance of keeping it under control.

Needless to say, as soon as I can find a Yuba Mundo frameset in stock this will be getting restored back to factory spec and sold on, albeit fully serviced and with a new BB, cables and a decent centre stand. I'll post in the classifieds section when I've found a replacement but anyone who's interested let me know. It's still a really solid light-duty cargo runabout in either original form or with a conversion kit, and it's a pretty simple conversion too.

 

[vfr400]

I don't want to sound unkind, but I just can't see the point of these bikes, when a simple kids' trailer solves all cargo problems without interfering with handling, and you can take it off when you don't want to carry anything. Can somebody convince me that my thinking is wrong in case I'm missing something?

 

[Swizz]

I don't want to sound unkind, but I just can't see the point of these bikes, when a simple kids' trailer solves all cargo problems without interfering with handling, and you can take it off when you don't want to carry anything. Can somebody convince me that my thinking is wrong in case I'm missing something?

Yes, if you mainly use the luggage space and don't want to faff with trailers!

@peddlin_pedro Have ridden a Yuba Mundo 2nd generation and that was really good - can recommend taking a look at one of those.

 

[Peddlin' Pedro]

I don't want to sound unkind, but I just can't see the point of these bikes, when a simple kids' trailer solves all cargo problems without interfering with handling, and you can take it off when you don't want to carry anything. Can somebody convince me that my thinking is wrong in case I'm missing something?

It's not an unreasonable question and like @Swizz said, the benefit of any cargo bike is the ability to load them up with people and materials and not need to hitch/unhitch trailers for storage or when negotiating anti-scooter measures and other restrictions so common on shared use paths in the UK or when needing to turn the bike around in tight quarters.

They're also much easier to manage in traffic and being narrower than most trailers can cope with moderate offroad duties where trails and paths may be narrow. Bikes like the Surly can also manage pretty serious offroad riding so they make great explorer bikes. While the load-carrying ability of a long-tail is generally less than a Bakfiets or box-bike style, they're inherently easier to ride where the cycling infrastructure is less developed or entirely absent, as is the case in many UK towns and cities. The larger wheels of a long-tail also cope with poor road surfaces better than Bakfiets and the roads round here are more like bridleways and farm tracks in many places. Climbing and low-speed handling is also much easier on a long-tail.

The issues I'm having are nothing to do with anything inherent to long tails but everything to do with me pushing beyond the limits of what the bike was designed to do. The Ute is a brilliant, lightweight and easy to handle mid-tail cargo bike and the slightly shorter wheelbase means it handles far more like a normal bike but with much greater carrying capacity. The problem is simply that I've maxed out the capacity. I'm a heavier rider at 98kg and need a bike that can cope with me, the drive system, a child & child seat and a moderately large load of shopping and/or other cargo. I always knew there was risk it would be too much to ask of the Ute - hence buying parts that can be easily swapped onto another frame - but I've lost nothing in the experiment bar some time, which I've enjoyed.

I've also ridden a Mundo, a Big Dummy, a couple of Xtracycles while in the US (in LA traffic!) and a Freeradical conversion and they were all brilliant and loads of fun, so have no worries about swapping to a slightly longer bike.

It's been an interesting experiment and I'll continue to enjoy riding the Ute until I can get a replacement ordered. I'm also very grateful for all the advice that forum members have so kindly offered as I've got to grips with mid-drive conversions. Looking forward to the next one now

 

[denmancentral]

great build. i'm about to install a bbs02 on the same frame, with 26 x 2.4" tyres. i agree about the original 29" wheels, quite unstable at low speed. Just wondering, did you get the 300mm Ursus Jumbo for 28/29", or the shorter one for 26" wheels? in the photo it looks only just long enough as the front wheel is touching the ground.

 

[Peddlin' Pedro]

great build. i'm about to install a bbs02 on the same frame, with 26 x 2.4" tyres. i agree about the original 29" wheels, quite unstable at low speed. Just wondering, did you get the 300mm Ursus Jumbo for 28/29", or the shorter one for 26" wheels? in the photo it looks only just long enough as the front wheel is touching the ground.

It was the larger 28/29” version. There’s a bit more clearance in reality as the lawn (weed patch) in the photo is quite uneven; front wheel clears around 1-1.5” on flat ground.

26 x 2.4” on wide rims is definitely the sweet spot. While it rolls really nicely on 700s the slightly smaller wheel with higher volume tyres makes it a bit more sure footed and far more comfortable. Good luck with the build; they’re great bikes, just not quite up to what I want to do with it.