Its Finished - It even works !

[StuartsProjects]

I finally have finished with a conversion of an old (circa 2020 circa 2002) Titanium framed mountain bike.

It has a 250W rear Bafang hub motor, with 7 speed freewheel and 3 speed front gears.

The eBike controller and spare bits of cable are in a small two part bag by the top tube and steering column. This arrangement minimises the cables on show, the motor, battery and PAS cables run along the underneath of the battery holder.

The brakes are currently cabled disk brakes, and they are definitely not good, but serviceable. They were fitted because they were cheap and I did not realise the old Hope Mini hydraulics could be reconditioned. Hope have now done the work on them and they will be fitted at a later date.

It rides well enough, using around 80W of battery power on assist level 1 @ 12mph and around 135W of battery power on assist level 2 @ 14mph. Put the power assist up to 5 and as long as the bike is in a high enough gear you get up to 18mph without a lot of physical effort.

I see quite a lot of comment on here about apparently ‘needing’ more powerful, and not legal, motors so that you can power up hills. If you keep the bike in the gear you would use on the flat to trundle along at 14mph, then you would probably need a fairly powerful motor to keep going at that speed up a hill.

But this 250W motor manages just fine. When you come to a steep hill, you step down the gears to keep the cadence up and up the power assist to level 5. When going up a 1:9 hill I was getting around 550W of power assist with only the normal on the flat effort from me. Speed was not high, 8mph, but I don't see that as a problem.

Overall I am happy with the setup, the suspension and fatter tyres make the bike a lot more comfortable and safer on local urban roads than my Brompton. Keeping 3+7 speed gears definitely helps to make hills a lot more manageable.

Fitted with Schwalbe Marathon Plus on the front and Marathon Plus Tour 1.75 on the rear.

Weight with 36v 11Ahr battery - 18.5kg.

Thanks for the wise words.

 

[flecc]

Nice job Stuart, looks very neat and tidy.
.

 

[StuartsProjects]

Thanks.

The main 'neat and tidy' bit was using that two sided bag by the steering tube. The morass of cables that connect to the 1to4 cable for the controller and all the spare cable for brakes, display etc go neatly in the left bag and then a couple of cables run across to the right bag which houses the controller.

 

[sjpt]

an old (circa 2020) ... bike

I think your idea of an old bike and mine are very different.

Looks like a nice conversion, enjoy. I hope it lasts till it's old (in 15 years time or so).

 

[StuartsProjects]

I think your idea of an old bike and mine are very different.

Looks like a nice conversion, enjoy. I hope it lasts till it's old (in 15 years time or so).

Well spotted, a typo, its from 2002.

Fortunatly there was no 'corrosion' at all in the titanium ..............

 

[wheeliepete]

Nice neat build chap, was going to suggest moving your throttle to the LHS, but i see you've kept your front derailleur, maybe twist grip shifters would help the layout? What controller did you use?

 

[StuartsProjects]

Nice neat build chap, was going to suggest moving your throttle to the LHS, but i see you've kept your front derailleur, maybe twist grip shifters would help the layout? What controller did you use?

Yes the front derailleur is retained and it definetly makes the hills easier since you can still pedal fast enough to get the max assist.

I have been thinking of twist shifters, I have a little artritius in my left thumb which does not make it easy to shift the from sometimes.

Controller is a KT36ZWSRD-HY02L which has a rated current of 9A. I was thinking to buy a replacement to keep as a spare, rather than wait a possible age for one from the far East to arrive if I have a breakdown. It has the Mutual version of the Julet style connectors.

So any suggestions for where to find a replacement, possibly better controller ?

 

[wheeliepete]

So any suggestions for where to find a replacement, possibly better controller ?

I've not come across Mutual connectors, prob best get one from the same supplier to ensure compatability. I've only used the duel voltage 36/48v sine wave ones from PSWPower.

 

[StuartsProjects]

I've not come across Mutual connectors

They are physically the same as Julet.

 

[wheeliepete]

They are physically the same as Julet.

They may not be wired in the same sequence as with the Higo connectors.

 

[vfr400]

So any suggestions for where to find a replacement, possibly better controller ?

What do you meaan by "better"? You already have one of the best.

I'm looking at your photo of the handlebars, and I'm a little confused about why you off-set the LCD and put the switch where it's difficult to reach. There must be a logical reason, so what is it?

 

[StuartsProjects]

By better, I meant possible with a higher AMP capability.

And I wanted the LCD there, dont see a problem with it myself. Eventually I hope to replace the LCD3 with a less obvious LCD4.

If the assist switch was difficult for me to reach I would move it.

 

[vfr400]

By better, I meant possible with a higher AMP capability.

And I wanted the LCD there, dont see a problem with it myself. Eventually I hope to replace the LCD3 with a less obvious LCD4.

If the assist switch was difficult for me to reach I would move it.

It just seems a weird thing to do, when most people have the LCD in the middle and the buttons by your left thumb, where you can reach them. You'd make a brilliant guitar or piano player if you can reach that thumb button thing from the grip. I remember Jake E Lee stretching from 5th to12 fret with fingers so long that they looked like something out of a horror film, when playing a solo with Ozzy Osbourne. I can understand if you had done it to get an advantage, but otherwise it doesn't make sense. The LCD4 essentially replaces the thumb buttons, so would go in the same place.

Before deciding on a "better" controller. How many amps can your battery give continuously and what speed motor do you have?

What's the physical size of your 18A controller, and how big in size can you go? It's difficult to tell from the picture, but it looks like the smallest size from the label. Where did you get it?

 

[StuartsProjects]

The battery is from eclipseEbikes, its rated at 23A continuous.

The controller has a raated current of 9A and a maximum of 18A.

Now the display was reporting 550W output when climbing a steep hill, which at say 38V is 14.5A.

Now to me it would make sense, in terms of long term reliability, to use a controller that had a higher rated current than 9A.

 

[StuartsProjects]

You'd make a brilliant guitar or piano player if you can reach that thumb button thing from the grip.

I dont play the piano, but my hands have probably benefited from a good many years spent Kayaking and RockClimbing both recreational and coaching.

The left thumb is not so good these days however.

 

[wheeliepete]

You can get a 10 amp, 20amp max. controller the same size as the one you have, but they can be prone to overheat when closed in a bag, ask Nealh. He upgraded to a larger 9 fet 11 amp, 22 amp max. one, I think, which runs cooler, but may not fit your existing bag. 22 amp may be a little high for your motor, but you can cut it back a little with the C5 setting. I'm still a little concerned that the pinouts may not match the julet ones found on every KT controller i've seen. You could check this with a continuity test before fitting.

 

[StuartsProjects]

You can get a 10 amp, 20amp max. controller the same size as the one you have, but they can be prone to overheat when closed in a bag, ask Nealh. He upgraded to a larger 9 fet 11 amp, 22 amp max. one, I think, which runs cooler, but may not fit your existing bag. 22 amp may be a little high for your motor, but you can cut it back a little with the C5 setting. I'm still a little concerned that the pinouts may not match the julet ones found on every KT controller i've seen. You could check this with a continuity test before fitting.

Thanks.

The current bag is 160mm x 110mm and and the controller is 90mm x60mm, so there is room for a increase in controller size. I have a similar bag but larger, 160mm x 140mm, on order, £4.

I though about the heat, and for short steep hills, say 1km, the controller does not get hot as such, but is on the warm side.

I had no idea in the beginning if the bag would be an issue heatwise, so I did concieve a plan. There is space at the back of the bag, between the tubes to fit something like a large PC CPU or Video chip style heat sink to the back of the controller that would take heat outside of the bag.

As for the wiring, the PAS is not difficult to check. A wise precaution would be to record voltages on the pins of the 1T4 cable connectors to compare against a potential different controller.

This would leave the motor lead, are there known to be variations there ?

 

[vfr400]

Now to me it would make sense, in terms of long term reliability, to use a controller that had a higher rated current than 9A.

These KT controllers and their ratings are fine. I don't think I ever heard of one blowing in normal use. If you had a 20A controller, that's how much current it'll allow on level 5, so it would get hotter.

Your present controller will allow a maximum of 18A x 40v, which is 720w, but the current is limited by the motor's back emf, so the only time you would see it is when you're going very slow with full power. You can test it if you have a throttle by operating the motor at full throttle with the wheel in the air, then use the brake to slow the motor right down for a short time. When riding on level 5 or at full throttle, you'll see that the power shown on the meter (power coming out of the battery) depends on your speed. The faster you go, the less power you get.

If you find yourself doing a lot of long hill-climbs, think about getting more air to you controller rather than upgrading it.

Get a bigger controller if you need more torque for hill-climbing, but bear in mind that it'll drain your battery quicker, wear it out qicker and when the battery gets tired, it'll start cutting out sooner than if you were running with lower current. Depending on your motor's max rpm, if you wanted more torque, it would probably be better to go up to 48v rather than run bigger currents.

 

[StuartsProjects]

Thanks for that.

There are some very long hill climbs nearby in the Caerphilly area, they were impossible on a Swytchified Brompton, no surprise there really the Bropmton only has 3 gears. Maybe when I get a bit fitter I will see what happens. For now I am happy enough with the current setup.

I contemplated the 48V option, but the batteries are a fair bit taller than the eclipse 36V batteries and probably wont fit in the frame triangle. The option for 48V would need a rear carrier battery, and for now at least I prefer the look of the triangle monted battery. Maybe 48V is an option in the future, perhaps when the panadamic is over and all the stuff stuck in Suez gets to the shops prices and supplies will relent.

 

[wheeliepete]

I had no idea in the beginning if the bag would be an issue heatwise, so I did concieve a plan. There is space at the back of the bag, between the tubes to fit something like a large PC CPU or Video chip style heat sink to the back of the controller that would take heat outside of the bag.

As for the wiring, the PAS is not difficult to check. A wise precaution would be to record voltages on the pins of the 1T4 cable connectors to compare against a potential different controller.

This would leave the motor lead, are there known to be variations there ?

I seem to remember Nealh tried fans on his, but still found it cut out, but I don't think it caused permenent damage, he just found waiting for it to cool down a pain. I think there's a very good chance that your controller is wired the same as every other KT, so I don't mean to cause you unnecessary alarm, just make you aware of the possibility.