Lightweight Trekking Bike Build

[Deleted member 4366]

No problem with duty because I haven't paid it yet, and Awol gave me half of the £23.80.

I haven't been able to test the bike yet because I've been waiting for my new cranks for 2 weeks. I decided to chase the seller on Ebay, but when I checked the tracking, it showed that the item had been delivered 10 days ago, and worse still, there was a signature that wasn't mine. I was gutted. I chased around all morning trying to find the postman to find out where it had gone, but i couldn't find him today.fed up, i decided to sit down and have a rest and a cup of tea and try and rationalise, why, if it had been wrongly delivered, hadn't the recipient handed it back to the postman. It's very unlikely that anybody else could use it. Then I had a eureka moment. Maybe the postman delivered it when i wasn't in and hid it somewhere. Normally, they put a note through the door that says, "in shed" or wherever. I thought I'd have a hunt around, and there it was in the shed, so I can now finish it off.

Here's my new battery base - demoed in the bit that I cut off. The bottle holder's tongue goes between those two lugs and a cable tie prevents it from bouncing or being removed:

 

[drummerian]

glad you found the cranks!

would you mind pointing out the motor and controller?:
https://xiongdamotor.en.alibaba.com/productgrouplist-220560510/NEW_Double_speed_Motor.html?spm=a2700.8304367.0.0.6c0c14712oMzrX

 

[Deleted member 4366]

You have to email bonnie@xiongda.com.cn. She's very helpful and has quite good English.

 

[drummerian]

oh excellent, is it just known as their 'new superlight motor' and not shown on the site?

I will send her a mail, are you using a controller from them also?

 

[awol]

The bottle holder's tongue goes between those two lugs and a cable tie prevents it from bouncing or being removed

I wondered what the lugs were for, that's clever thinking. I was pondering this morning over it bouncing out going over bumps.

 

[Deleted member 4366]

the motor designation is YTW-06.

 

[jerrysimon]

When I checked the designation you quote it wasn't there.

Dave when I first saw that pic I thought it was a saucepan given the breakfast background!

I need glasses!

Jerry

 

[Deleted member 4366]

No click and collect on that one. you have to email Bonnie Xiong.

 

[drummerian]

Will get on that, did you get the controller/display from them also?

 

[Deleted member 4366]

Yes. I don't know if there's anything special about it, but it's a sensorless one and it has the connector for the speed sensor.

 

[Deleted member 4366]

OK, so I managed a first test ride last night. I'll try and give some objective comments:

The power is not bad. It's 10kg lighter than an average modern E-bike, which must help a bit, but all-up weight is still 100kg, so that works out that I'd get the same performance as a bike with 10% more power.

I took it straight to my 14% test hill. It couldn't pull me up without pedalling, but all it took was a few light pedal strokes to get to the top, so it's no torque monster, but not bad - about equivalent to your average 250w hub-motored bike. In fact, it probably gives a bit more torque than an average one.

Assistance runs out at about 20 mph with the 700c wheel.

It's not particularly quiet. Front motors always sound worse, but I've got a feeling that if I were racing a roadie, he'd be looking at the front wheel wondering where the motor was. When he couldn't see it, he'd shout "cheat" anyway. Maybe after it's run-in a bit, it might quieten down. I'm thinking that it's a real shame that they didn't put hall sensors in it so that we could use sine wave controllers.

Interestingly, I could feel the weight of the motor in the front wheel and steering. If I had been blindfolded, I would have said that it was a normal 3.5kg motor. Maybe the riding position with the new handlebars has something to do with it, but i don't think so. More likely it's just because it's quite a light bike with more than 10% of its total weight in the hub alone. Overall the bike rode pretty well.

Now the not so good bits. There's a delay of about one second when you start it with either the PAS of throttle. I thought that we had got past controllers that do that, and we'd only be telling stories about them to our grandchildren, in fact I can't think of any bike I've ridden before that had a noticeable delay on the throttle. You soon get used to these things, so it's not a deal breaker, but it would be better if you didn't have to put up with it.

When I first got the motor, there was a bit of resistance when I turned it by hand in the forward (freewheeling) direction, and there was a lot of resistance to turn it backwards because of the high reduction ratio. It must, therefore, have some sort of clutch in it. During the ride, it freewheeled pretty well. On a slight slope, it carried on accelerating past 22 mph after the motor had maxed out at 19 mph (battery not charged fully), so the ride was pleasant enough. Initial resistance is pretty common in hub-motors, and it normally reduces a lot as you go past say 100 miles. When I got home, I tried turning the motor by hand, and to my surprise, the backwards resistance had reduced to the same as the front. That must mean that the clutch works in both directions somehow - maybe centrifugal?

So, to summarise:
Good points are light weight, good torque and easy installation.
Bad points are the start-up delay, noise and maybe freeness. I think the noise and freeness will improve.
Overall, I think most people would like this bike with it's easy handling from the light weight, and the power is at least as good as most. Obviously, it's going to be a lot easier to ride without power than just about any other bike; however, it's not e-bike nirvana. For that, the Q128C motor at 48v with a sine wave controller is going to take some beating. Bosch and Yamaha don't even come close.

I've asked Xiongda about how the clutch works and whether there's any other controller options.

 

[Kenny]

Thanks for the detailed report Dave.

I hope the Bafang Mini Hub due at the end of this year is a little quieter, with no power delay.
Also the Bafang mini rear hub motor has cassette gears which I prefer.

 

[Deleted member 4366]

The delay comes from the controller, not the motor.

 

[topographer]

14% with light pedal strokes? Very impressive.

 

[drummerian]

Apologies to drag up an old thread. d8veh, I'm interested to see how you sorted PAS on this. I am building a similar bike up with an external bottom bracket and am trying to come up with a neat solution for nice reliable PAS.

In previous builds I have drilled out and epoxied the magnet ring to the granny gear, it hasn't failed yet but I don't love it...

 

[Deleted member 4366]

It's dead simple. You dremmel out a 25mm hole in the magnet disc, remove the spacers from behind the bearing holders, swap the sensor onto the other side of it's bracket so that it reaches forwards instead of backwards (might have to drill holes if fixing points are asymmetric), put the sensor bracket behind the LH bearing holder and clamp the magnet disc between the bearing and the pedal arm.

 

[drummerian]

It's dead simple. You dremmel out a 25mm hole in the magnet disc, remove the spacers from behind the bearing holders, swap the sensor onto the other side of it's bracket so that it reaches forwards instead of backwards (might have to drill holes if fixing points are asymmetric), put the sensor bracket behind the LH bearing holder and clamp the magnet disc between the bearing and the pedal arm.

View attachment 24274

Nice one, surprised you can put the clamping force through the plastic OK but if it works it works! I guess this just offsets the left hand crank arm out by the width of the plastic disc (If I am understanding the explanation correctly)

 

[drummerian]

apologies, just found this thread. makes more sense now:
http://www.pedelecs.co.uk/forum/threads/how-to-fit-a-pas-without-disassembling-the-bb.17154/

Only worry is that the plastic spacer is there to prevent you preloading the bearings too much, any thoughts on that?

Thanks again

 

[Deleted member 4366]

Nice one, surprised you can put the clamping force through the plastic OK but if it works it works! I guess this just offsets the left hand crank arm out by the width of the plastic disc (If I am understanding the explanation correctly)

Assuming that you have a standard 68mm BB, there will be a 2.5mm spacer behind each bearing holder, which you chuck away. That gets you a possible 5mm gap between the pedal arm and the BB, but the sensor bracket takes 1mm and the magnet disc is about 6mm thick, so you end up with just enough room to get the pedal arm on. You only need to pull the pedal arm against the magnet disc, it doesn't need any clamping force, but the plastic threaded piece that goes in the spindle pulls everything in the BB together.

If you have a 73mm BB, this method won't work.

 

[cwah]

Thanks for the report. I wouldn't buy due to the noise!

For the battery, how many cell did you use? And no BMS?