my first build: brompton at 30 mph

[cwah]

I just went to the steel shop recommended by Dave (thanks ), they said they can do it. I have to meet them with my bike this monday.. I almost want to find another place to get it welded during the weekend lol.

I can't go directly with my wheel because it has not been laced yet. I have to contact alan to lace it. I'll just meet them with the motor.

And I'm not sure to keep this motor anyway, I'll just ask them to provide 135mm dropout symetrical on both side. So it will be easy for me to change motor if I want to.

So my request will be:
- 135 mm dropout wide
- Stronger forkend able to handle 150 nm torque
- Forkend alignment to handle the motor
- Symetrical alignment to the bike frame

The rim would probably not be central because my wheel is not laced yet.. is it a big deal or shall I get it laced first (send it to alan and get it back will take some time)?

[cwah]

I'm soo impatient to have my motor fitted... Do you think I can do it with my wood bar or shall I go buy the torch and the car jack?

Well, I've done 3 bikes using wood. Don't see why someone else couldn't do it too. Only takes a minute or two. It will spring back some, so you probably want to go to at least 150mm before knocking the wood out.

I'm not sure wood would work with my bike. The leverage area is not good:


There is a central steel bar on the middle of the fork as main support. With the wood I'll mostly bend on the area with screws and not the fork itself.

[joe tomten]

Things to think about:

How big of a tire do you want to run?

Do you want that multispeed freewheel? and how will that affect the chainline?

[cwah]

As biiig tire as possible lol. But I think I'm going to be limited by the brakes.

And single speed freewheel is enough. Don't know how that can affect the chainline.

[joe tomten]

I have a Brompton front fork here, and the 16" * 1.95” hookworm won’t fit. A 1.5” Schwalbe marathon winter fits in there with room to spare.

If you want a fattie tire in there the flaring you have done will need to start far out from the axle - which might introduce it's own complexities. Probably best to stick with the least complicated bending and be happy with 1.5 to 1.75 tires.

[cwah]

Ok, will stick to the inital tire then.

I just noticed that my motor dropout is 145mm and not 135mm as advertised for single speed:


Shall I ask for 145 mm dropout or shall I shave the motor dropout shoulder?

[Ykick]

Your method of measurement looks suspect to me so I'd go with the engineering drawings and request 135mm. Leave the file and axle alone. If you can take an absolute accurate measurement and it's indeed 145mm then maybe request 140mm and man handle it with a pry bar while installing.

I'm only looking at cut-off pictures but my eyes question if the body of that motor is gonna fit inside the frame dropout without some serious reshaping?

[cwah]

I don't know either. If it need serious reshaping so be it.

I'll ask them to go for 135mm or 140 mm. I can still shave the dropout anyway.

[wesnewell]

I'm not sure wood would work with my bike. The leverage area is not good:
There is a central steel bar on the middle of the fork as main support. With the wood I'll mostly bend on the area with screws and not the fork itself.

Well, rethink how you are going to use the wood. And not like in your photo. Stand the wood on end on the ground. Put it between the insides of the *forks* sideways. Take a sledge hammer and pound the wood into the forks spreading them apart. If you don't understand, I'll try and draw a picture, but I'm a lousy artist.

[cwah]

I don't know if I'll do it correctly with a wood bar. It's quite a lot to be widened. I'll see tomorrow with the metal guy.

[cwah]

Just went to the metal shop. They said they can't do it because of the metal bar in the middle of the fork. The bar in the middle was added at the end.

They said I need to have a new fork with the right size... but there is no way I can have that.

[adrian_sm]

What rear brake are you planning on using?

The reason I ask is that if you don't need a rear disc brake, and you are running single speed on the rear, can't you modify the axle and reduce the required drop out width?

[cwah]

I'm thinking about it. Will check later tonight.

but the hub may be too big for the fork

[dogman]

Steel right? Cut the crossbar, bend the forks yourself, then have someting put back to restore the crossbar. Perhaps a bolted on piece of angle iron. The metal shop is just covering thier asses, so you are on your own.

Do what you can to the axle, so you just bend the forks enough to clear the motor shell.

[cwah]

Ok, you're right, I'm going to visit another steel shop. It shouldn't be that difficult

[d8veh]

I don't see what the problem is. A competent metal-worker, who has a hack-saw and welding set could make the frame do whatever you want. To me, it looks a small job to heat up the stays and bend them to the right shape. You could, like said above, cut that cross-piece and weld in an extension, but I don't believe that it's necessary.

[cwah]

Just went to a frame builder shop... He said it was possible but may need to change the rear fork... And may cost 200 to 400£ or more

How come just widening the bike dropout could be that expensive.

I'm about to give up and just buy the Crystalyte G209... Will check other metal shop tomorrow

[cwah]

News from my e-brompton build:
I'm now adding all the torque arms to my bike. I've 2 anti-rotation washer and:
- Conhistmotor torque arm (thinner) on the gear side:

- Cyclezee torque arm (stronger) on the other side:


This configuration should be enough to handle some torque

I'm trying to put the chain tensionner on top of the torque arm:


The chain tensioner is not yet aligned with the chain:


I'll have to keep filing the chain tensioner inside to allow it to go closer to the bike..

Now my biggest problem is that I've put too much strenght when I tried to tighten the motor shaft bolt. Now it's getting loose and I may need to change the shaft... but for that I'd probably need to purchase a new motor

[d8veh]

Cwah, I think that chain tensioner's going to cause a lot of problems. The way I understand it, all it does is keep the chain tight when you fold the bike to stop the chain falling off. As an alternative, couldn't you just carry a a bungee strap and hook it round the chain or between the chain and the frame just before you fold, and then remove it after you've unfolded.

I'm looking at your torque arms and the installation isn't the best. The axle will try and turn in the opposite direction to the wheel, so try and imagine what happens if they turn a bit. The one on the opposite side to the tensioner is too straight and the first bolt will slip. Ideally you need a right angle between the first two (from the motor) parts. Alternatively you need to get someone to weld the first joint so that the bolt can't slip.

I'm looking forward to seeing what you can get out of that motor.

[cwah]

The chain tensioner allow me to keep the chain tight when I fold the bike, but also to keep the chain on the gear when I'm pedaling. If I remove the chain tensioner, the chain would just fall off the bike.

I corrected the torque arm angle in the opposite side of the tensionner:


Is it better?

[cwah]

Now I've put my 4 lipo in a carton box:


When it's closed, just the cable is reachable:


For a total weight of 4.5kg:


I'll for now put that on my brompton front bag

[d8veh]

I've been reading your Saga on Pedelecs, but i won't post there, so I hope you see this.
Am I right that it's nominally a 250w motor with hall sensors? If so, It may be that you've cooked a hall sensor. Do you have another controller to try - even a low powered one that you can run with 36v or whatever just to test the motor?

[cwah]

Great thought Dave.

I have my initial bike controller.

Going to remove it and test it now.

Thanks

[cwah]

Just sawped with my other controller... And it worked.

It's definitely a problem with the controller

[cwah]

Here is inside the controller:


Not sure what to look at to fix however