Build Q128c motor

[John L]

Hi guys

I've only recently been feeling healthy enough to get back on my converted bike. I used the built Q128c wheel from bmsbattery. But after a few rides I noticed the spokes had loosened and there was a noticeable wobble. I tried to true it myself but I made matters worse!

So off to a local bike shop but the wheel won't fit his truing stand so he won't work on it.

I brought it to a big bike store. They agreed to true it. I mentioned about the extra spacing washers and the torque arms etc. But when I went to collect it they had only trued the wheel on the bike (admittedly for free and did a good job too). No complaints so far.

But they said they won't do any future work on the bike because "it has been modified with an unbranded ebike kit". As I wasn't trying to get work done under warranty I was really surprised by this attitude. The donor bike was bought from the same shop but was well out of warranty.

Has anyone else come across this? The wheel might well need to be rebuild with stronger spokes and I'm at a loss to know where in Ireland I could get it done. It doesn't appear to be a problem for a local bike shop in the UK to build a wheel.

I'm not confident that I could do it myself.

John

 

[Benjahmin]

Hi guys

I've only recently been feeling healthy enough to get back on my converted bike. I used the built Q128c wheel from bmsbattery. But after a few rides I noticed the spokes had loosened and there was a noticeable wobble. I tried to true it myself but I made matters worse!

So off to a local bike shop but the wheel won't fit his truing stand so he won't work on it.

I brought it to a big bike store. They agreed to true it. I mentioned about the extra spacing washers and the torque arms etc. But when I went to collect it they had only trued the wheel on the bike (admittedly for free and did a good job too). No complaints so far.

But they said they won't do any future work on the bike because "it has been modified with an unbranded ebike kit". As I wasn't trying to get work done under warranty I was really surprised by this attitude. The donor bike was bought from the same shop but was well out of warranty.

Has anyone else come across this? The wheel might well need to be rebuild with stronger spokes and I'm at a loss to know where in Ireland I could get it done. It doesn't appear to be a problem for a local bike shop in the UK to build a wheel.

I'm not confident that I could do it myself.

John

What a croc from the lbs ! I don't see the problem truing the wheel on the bike. Tried it myself a few months ago, using the recommended following method.
Have the bike upside down. Fit a cable tie, to the forks or frame, close to the rim. Cut the tie so that it just brushes the rim when the wobble puts it at it's closest. This is your reference point. Pick the point where the rim is furthest away, loosen 4 spokes (by 1/2 turn each) on the far side from the tie. Then tighten corresponding 4 by 1/2 turn each. To move the rim away from the tie do the reverse. Use 1/4 turns for small adjustments as you refine. Also pick your 4 spokes, use 1/2 turn on the inner two and 1/4 turn on the outside two. You may need to refit a new cable tie cut to a new length as you straighten the wheel. When you're done, remove the cable tie and proudly ride your self fixed bike.
Allow yourself plenty of time and a few cups of tea. It really does work. Oh, and it is a sit down job


p.s. Do remember which way is 'tightening' the spoke and which way is 'loosening'. Look at it, think about it.
And get a good quality spoke spanner so as not to round of the nuts.

 

[Nealh]

I also true on the bike and support the bike standing up and do the job with a cable tie as mentioned.
A trueing stand may not accommodate an ebike wheel as the axle is larger dia, I made my own simple wooden version and it works perfectly.

 

[wheeliepete]

Your wheel should be fine now you have it trued and the spokes tightened. Chinese built wheels are usually done in a hurry and often need some adjustment after a bit of use. Just keep a check on it for loose spokes in the future. Attitudes in bike shops varies where ever you live, as does the abilities of the people working in them.

 

[Benjahmin]

Forgot to add, you ping the spokes to check tension. All the spokes on one side should give roughly the same note. The other side may be higher or lower but again all should be about the same. You can do this to check for any loose ones.
Wheels often give you a clue if there's loose spokes, you get a horrible grating sound.

 

[John L]

Forgot to add, you ping the spokes to check tension. All the spokes on one side should give roughly the same note. The other side may be higher or lower but again all should be about the same. You can do this to check for any loose ones.
Wheels often give you a clue if there's loose spokes, you get a horrible grating sound.

Thanks for that. Very helpful. My previous attempts were based on very little research and I got the results I deserved. I concentrated on the loose sounding spokes but applied no method. I got concerned when I felt a wobble taking a tight bend!

Building a wheel or even truing one seems like a dark art. Looks like I'll have to get stuck in though.

 

[John L]

I also true on the bike and support the bike standing up and do the job with a cable tie as mentioned.
A trueing stand may not accommodate an ebike wheel as the axle is larger dia, I made my own simple wooden version and it works perfectly.

Thanks Neal. A homemade frame crossed my mind too. It'd be great to be able to true a wheel as it's the only work on a bike that I've been reluctant to undertake. Looks like I'll have no choice in the future

 

[John L]

Your wheel should be fine now you have it trued and the spokes tightened. Chinese built wheels are usually done in a hurry and often need some adjustment after a bit of use. Just keep a check on it for loose spokes in the future. Attitudes in bike shops varies where ever you live, as does the abilities of the people working in them.

I'm hoping the work they did will keep me going for awhile.

I was surprised by their attitude. They sell ebikes and have 5 or 6 mechanics in the repair centre. So working on my bike should be ok for them. But it was the manager who decided that they won't work on it again. Admittedly they are extremely busy doing 25 to 30 services a day and being booked out for the week ahead. They probably don't need my custom.

I'll just have to learn to do it myself

 

[wheeliepete]

I guess he prefers the easy, quick work that brings in more money, new tyres, new chains, new brake pads etc, just think kwik fit for bikes. I've ordered spokes and laced up wheels a few times, just not quite brave enough to take on the truing bit, but I know a couple of guys who love to build wheels.

 

[harrys]

It's not a dark art, but some writers have embellished it. It's just a procedure. Takes an evening to learn, and then you will have true wheels for the rest of your life, as long as your eyes and fingers hold out.,

Manager was right to do it on the bike. A lot can go wrong when someone undoes a home built bike. And then he gets blamed if your torque arms don't hold. I've done mine on an old fork clamped to my desk.

 

[John L]

It's not a dark art, but some writers have embellished it. It's just a procedure. Takes an evening to learn, and then you will have true wheels for the rest of your life, as long as your eyes and fingers hold out.,

Manager was right to do it on the bike. A lot can go wrong when someone undoes a home built bike. And then he gets blamed if your torque arms don't hold. I've done mine on an old fork clamped to my desk.

Fair point. I had no complaints about doing it on the bike. He did a good job. It was just the refusal to do any future work on the bike that irked me.

I suppose fitting a strong motor with a 48v battery to a bike is more than a minor modification. I guess he didn't want to be responsible for anything going wrong. I was just taken by surprise.

 

[Nealh]

My diy trueing stand works perfectly for front and rear.
And all made from scraps lying about.

 

[John L]

My diy trueing stand works perfectly for front and rear.
And all made from scraps lying about.

Excellent Neal Looks like it will take any width of axle you'd need. The coach bolts and bracket are very effective. Nice job. J