2018 Rad City Conversion to KT LCD3 and Controller w/1500w DD Hub and 11 Tooth Freewheel

AHicks

Well-Known Member
Region
USA
City
Snow Bird - Summer S.E. Michigan, Winter Gulf Coast North Central Fl.
Well, it's done. Maiden voyage was taken, and now just tweaks here and there, tidying cables and wire harnesses, getting rid of minor squeaks and rattles. About 10 hours of time for the conversion, working at a retired old man's pace.

As you can imagine, a night and day difference noted between the original 750 watt electrical/electronic install and the 1500 watt conversion, which replaces all of that other than the battery.

Now, when you hit the throttle to get the bike moving from a stop or while crossing a busy street for instance, 1600 watts is registered on the display immediately, without delay, and the bike moves out without delay. Nothing crazy, but enough to establish some confidence that was missing with the original (for me anyway).

I had to try, prior to setting the 20mph speed limit, and found the bike will be running 30mph in very short order. I ran out of room while the bike was still accelerating. With the rear wheel off the ground it would register 45mph. Yes, that's MPH.

Power is just as smooth as original, and just as quiet. It's like the standard City has been doing steroids. Conversion looks nearly as clean as the original bike. The uneducated eye will not notice it's been totally repowered. The educated eye is going to have to look closely....

I would suggest this install was no more difficult than other bike conversions I've done, or more troublesome. It may have been easier actually as there was no time spent figuring out how or difficulty installing the battery! An accomplished DIY'er will have no trouble - especially if he is already familiar with bikes. RC hobby background certainly a plus. Will save a lot of homework on how the electrical works.

As this project requires messing with a freewheel, either removing it from the original wheel to use on the new wheel, or installing a new one, I thought I'd try the 11 tooth mentioned recently elsewhere and had that sitting here waiting. Man is that nice. I can now stay up with the pedals to something in the range of 20mph. A younger me could likely go much faster! Previosly I could barely make 15mph. On the flat I used to ride around in 7th gear most of the time. Now, that's 5th and 6th with 7th available if I want it. Highly recommended mod, even if you aren't repowering.

Would I do it again? Without a second thought.

Am I condemning the original 750 watt setup? Nope, not even a little. In today's market the fact it's doing as well as it is speaks for itself. It's also legal.

Would I convert a Rover? That's a tougher call, one that will likely depend on the rider. Reason being this setup is capable of pulling some serious power at higher throttle settings, and I'be be concerned for the original battery and associated wiring. When I checked out the battery that came with the city, it was all done with 14awg. For long pulls/wide open blasts, I'm thinking that might be on the light side. The motor will be looking for 35 amps or so. 14g may be OK for a short blast, but anything long term is going to have that wire getting pretty hot. In any case, the battery and it's wiring will be the weak spot in a 1500 watt system. The same can be said for the Rad City. The City user will need to cool it, but I think the mission the city is designed for is a little more conservative.

Does the conversion pull a lot of power compared to the stock motor? The conversion, in PAS 1 at 8-10 mph, is pulling 85 -110 watts. I forgot to note what the original pulls in that scenario. If somebody could share that info I'd be happy to edit this to reflect the difference.

Who would I recommend the mod too? Somebody that wants more, more everything, from their Rad City.

More later if I run into anything significant. -Al
 
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You've traded distance for speed, not a terrible thing, depending on your riding habits...my City is due in tomorrow, and I realize it wants my pedalling help, especially from a standing start, as well as over 20mph. I'd be cautious...even 12 ga. wire will only carry 20 amps, so your 31 amp draw had better be rather short.

Thanks for the instruction on how to!
 
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That's the way it might look to the uninitiated for sure. The thing is though, the LCD3 display and KT controller bring new meaning to the term "user definable".

So, an update, with maybe 50 miles since the conversion, and still messing with it to see what it will do.

Still messing with the variables to find a compromise. Even so, I just got off the bike a few minutes ago and put it on the charger with 27 miles on it. 1 of the 4 bars are still showing (a little over 46 volts remaining, mostly rider assist, but with a few strenous longer pulls). Too, I may have 2 sets of parameters when done. One energy conservative for flat lands, and another set that might be pushing things a little harder when riding at another location I frequent, which is typical coastal area with long rolling hills.

I've been lowering the available parmeters to limit the maximum output wattage/amperage a little at a time to see what I can get away with (enough power, without being too much). Today, I'm down by about half the available (to about 800w, easily handled by the existing battery and associated wiring) and still have way more punch available than the stock 750w setup.

This is new country for me, so just enjoying myself and exploring what can be done. The previous conversions had a little bigger batteries w/heavier wiring and 1000w motors. Those worked really well pretty much as they came out of the box. Even on the fairly long pulls up hills (which is the concern here) there was never a hint of an issue. What I'm finding so far hints strongly that my project will be a successful one, with much learned in the process.

And regarding the 11 tooth gear? IMHO, they should be standard equipment. Instead of riding around in 7th gear all the time, and not being able to stay up with anything over maybe 14mph, I can now stay up with it to something over 20mph. There is no downside as I see it. Instead of riding around in 7th I now use 5 and 6 and if wanting to put some grunt into going up a hill using low power (or unassisted) 1st through 4th offer PLENTY of advantage. -Al
 
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I'm evaluating gears as I ride...the current city 85/75/66/60/54/49/35" seems adequate for now...the 85" and the 75" are a reminder to spin...I don't mind a 100-110 cadence...Even a 13 tooth would give me a 92", but I'm thinking that my 30 year old self might be having some input here, too...and my 70 year old self is thinking about it. The knees are not what they were.

Shimano 12-32 set is a possibility, but I'd probably customize to 13/15/17, but need some narrower road tires to truly take advantage...I look down at these Kenda monsters (2.3") and realize they're a compromise for bad city streets, which I avoid...also able to still miss individual pebbles...I see them all.


For the time being, I'm reminding myself that spinning flushes out lactic acid, which I seem to be producing in buckets right now.
 
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I put that same 11-tooth freewheel on my stock Rover. In less than a year, it failed. And I don't ride aggressively or often. The first thing I noticed was that sometimes while coasting the pedals would want to rotate on their own. I thought that was odd but didn't know what was going on. Then I noticed the drivetrain would "slip" when pedaling. It only happened every so often so I ignored it. Now, about 90% of the time, pedaling the cranks doesn't engage the freewheel at all...thus, pedaling adds no thrust.
 
Well, the rush to the absolute minimum circumference gives a big top gear, but maximum chain wear. Thankfully, chains are cheap, and replacing one every six months is easy.

The top gear demand has convinced Rad to make an 11 tooth standard on the 2019 models. The maintenance responsibility remains with the owner, however, and, like spokes loosening and air escaping from tires, cables stretching, etc., something to keep in mind.

I opted for a 50t. chainring swap, giving me a 92" gear, an easy upgrade, and may go to a 13-32 IRD freewheel next year, which would bump the top to 100", more than enough for my road riding.
 
I put that same 11-tooth freewheel on my stock Rover. In less than a year, it failed. And I don't ride aggressively or often.
Putting the DNP freewheel on the Rover is a bit more demanding application, compared to the City and the Mini. Even though you might not do so, the Rover does invite off road riding, in possibly rougher terrain, and also allows a more aggressive (standing) pedaling position. This could put more torque through the chain and sprocket set. In comparison, the City and Mini are more easy going, both in their "relaxed" riding position and the "normal" places they might typically be used. I feel the DNP would probably have a better chance of long-term survival on the City and Mini.

Besides, the DNP only costs $34 bucks. Even if you had to replace it once a year, it's not gonna break the bank. Every rider should do what works best for them. I've been very happy with the DNP 11-28T on my Mini.
 
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