Project Excalibur

I’m gonna go ahead and start this now since I am making a little progress.

I started on the repair forum with the frame straightening. That’s done and the project is coming together.

I ordered Peugeot forks and a Tomos rear swingarm. The forks are an exact fit. The swingarm will require a little more cutting on the frame to make it fit.

Also, we have an electric hub motor kit on the way. 48V 1000W. My son is a rare kid that is afraid of going too fast. But, I think the motor choice we made will let him grow into it a bit.

Here’s a few pics and I’ll shut up for now.


Re: Project Excalibur

This is great!

Re: Project Excalibur

Made some more progress today:

- Cut the mounts for the swingarm to fit.

- bought some fasteners and junk to attach

everything. Then cut to fit.

- Mocked up with my son’s bike wheels.

- Realized his bearing grease was shot and

took a min to service those.

- Started to make a mounting plate for a

kickstand but reasoned I need to cut the

forks and get the ride height/angle fixed


Re: Project Excalibur

Those wheels/tires are bigger than standard moped gear but gives an idea. The forks are gonna need to be chopped around 3-4”. I don’t know if I have enough to play with. Never taken these EBRs apart but I’ll show pics of what the guts look like and how I do it (if it works).

I need to wait for the hub motor to get here and lace it up on a 16-17” rim. Once I have to actual wheels on, I can do more about leveling the seat and figuring out where to weld on the pedal crank parts.

So far, this project has been going very smoothly. I never wanted an electric moped before, but the idea is really growing on me.

Glad my kid pushed me into it.

Anyone one here have experience with these hub motor kits? I have become more trusting of inexpensive Chinese machines. Still have my concerns about whether it will work out of the box or last more than a couple months. The Amazon reviews were all good FWIW.

Re: Project Excalibur

Today’s work involved what may be considered “ruining” perfectly good, brand new forks. This is for my kid though and as you can see from the pictures, he is still barely y’all enough to mount this thing.

I read the wiki for shortening EBRs. Looking at how much I needed to drop the front end, I had to go pretty far with it.

These started off with about 3.5” of travel. I decided that he could do with 2” of travel since he weighs 60lbs and will be on paved surfaces with this thing. I know this would be bottoming out all the time if I was on it. Meh. That’s the price to play this one.

Anyhow, I unscrewed the top and bottom tubes, removed the spring and punched out the pin holding the spring-retainer-plastic-thingy in the upper tube.

Stuffed paper towel into both tubes far enough to block contaminates from getting in the grease while cutting and drilling. I cut 3” from the top and bottom tube.

At this point, if you moved the spring-retainer-plastic-thingy up 3” and put it all back together, you would be 3” lower with the same travel. The upper and lower plastic bushings (go on the outside of upper tube) need to be measured and holes drilled for them to be inside the lower tube for the full suspension travel.

To get that extra 1.25” of drop, I cut 1.25” of spring off.

The boot sits flush against the fork brace mounts and the lip inside the boot is engaged on the upper rim of the bottom tube. No more than 3” can be removed without messing that part up.

I ended up with forks that are 4.25” shorter and have 2” of travel before the boots hit the lower triple tree. We could shave the boot down some, but I think we’ll see how it goes.

Pics show the bike sitting on some old MB rims. Just to get a feel for ride height. OD is about 20”. I still haven’t bought rims because I’m waiting on the hub motor to get here. I know it is 36 spoke. There should be plenty of 16-17” rims that can work with it.


Re: Project Excalibur

Few other pics...


Re: Project Excalibur

Neat project. Those forks look like you might have gone too far,. Depending on how much weight the batteries add, that's always a concern

Re: Project Excalibur

It is definitely too far for an adult. I’m just waiting to see how it turns out. I could jam some stuff into the springs to stiffen them up if it’s constantly beating him up.

Moped suspension really sucks to begin with. The important thing, on this occasion, was getting it low enough that my boy can touch his feet to the ground.

The 13-15 Ah lithium packs are pretty small and lightweight. I think it is going under that top tube, mid frame. So the weight will be low and evenly distributed.

This is the most custom thing I’ve ever built. It’s fun to be free with design but a little scary considering how much time and money it could waste if we have to go back and redesign everything.

Hopefully, MA can help me see the problems coming and work around them.

Re: Project Excalibur

Matthew Chua /

this project looks cool. I'm trying to do something similar with a ct90, so i'll be watching for updates!

Re: Project Excalibur

So extremely satisfied with how this is going.


Your Tomos swingarms should also be listed as bicycle hub motor swingarms. Because they are an exact fit for everything I bought.

The shaft is flat on the top and bottom, to prevent spinning. It is a press fit into the Tomos swingarm for width and axle diameter. There are tabs pre-welded on that are perfect for locking a brake plate, securing the brake cable, and securing the motor power cables.


Re: Project Excalibur

I made a mounting plate for my caliper out of some scrap I had.

Started by making a cardboard template.

Cut out the steel with angle grinder. And marked the spot for the little button in front of the drop out. Drilled it.

Then placed the bracket on the button and marked the slot from the back. Cut that.

Then placed it back on and marked then holes for the caliper bolts. Drilled again.

It still needs some shims and finishing work. But it’s super stable and just couldn’t be any easier.


Re: Project Excalibur

I think I’ll add something else at the end of the dropout to secure it even more from wanting to tilt forward under braking. As it is, I fell that it would work safely.

Still haven’t found a way to do the front that I’m satisfied with. More to come tomorrow I hope.


Re: Project Excalibur

This is coming out awesome! I really dig that your building it from scraps. Those brakes look good, I have a set I scavanged from a mtn bike. iam interested to see how you adapt them.

Re: Project Excalibur

Today’s update:

I was trying to weld a 2cm long M6 nut onto some plate for my front caliper mount. My 1.6mm rods are too small. I tried 2.5mm rods and the welds look great but my puddle ran over into one nut hole.

Too much to drill it out.

I bought extra and will try again tomorrow.

Also, I was trying to do some more break-in runs and check temps on my kitted magnum. CDI flywheel slipped. I read the wiki about lapping. I knew that was a thing. Wasn’t aware that those flywheels are such a lousy fit as they come.

Messed up two things today. First day on this project that didn’t go well.

Re: Project Excalibur

> Papa _ Wrote:

> -------------------------------------------------------


> Messed up two things today. First day on this project that didn’t go

> well.

Much better than the day before the 'race' , when everything has to be redone . ;)

Re: Project Excalibur

Got the front caliper mount made and attached.

Cut from the same scrap angle that has been donating to this project. Shaped it on a V-block with a ball peen hammer.

I used as many tack welds as I could to stick it without warping or burning the tube. I am not a welder, but it’s stuck solid. If it got too hot, it would melt the plastic spring holder thing and I had no idea how to get that out.

Cleaned off the buckshot and filled the gaps to clean it up.


Re: Project Excalibur

Other pics

I doubled up the mounting bracket for the rear caliper. Puts the load on the top of the swingarm. So, no twisting there.


Re: Project Excalibur

I have a question if anyone can help me on this.

I bought 16” moped rims to use. Normal Mountain bike hub in the front and the motor in the rear. I have never laced any spoked wheel.

Do y’all know how to get those things together? Like, I can watch YouTube for how to do the lacing and truing. But the nipples and spoke lengths are not compatible. Can I open the holes up a bit on the hubs to fit moped spokes? Is there an acceptable way to cut spokes to length and thread the ends?

Re: Project Excalibur

You might be able to source the proper length spokes. Otherwise I dont see any issue cutting ones down and re-threading them for the nipples. I have not laced my own spokes but have experience with truing bike wheels. And I hate it.

Re: Project Excalibur

Is this the frame that was ran over by two different cars?

Re: Project Excalibur

Yeah spokes are tricky, technically you're not supposed to drill out the holes in the rim because they have a countersink to them but I think it would be ok. The threads are roll-formed and the thread rolling machine for Moped size 10 or 12 gauge is really rare. I have always just found spokes off the shelf in the right size, but there is a guy who used to post on here named John Rob Holmes who had a website doing custom ebike wheels and he makes spokes and sources them. I think it's called like jrh hobbies?

Re: Project Excalibur

ᴛᴇʀʀʏ ᴅᴇᴀɴ /

this is looking great!

maybe you already know this, but your rear brake caliper mount should be typically be fixed in relation to the axle and not fixed to the swingarm. the way you've got it right now means your wheel will have to always be all the way forward in the dropouts because the disc rotor needs to be fully in the caliper, moving the wheel back in the swingarm slot will move the rotor out of the caliper and can cause lots of issues, including the rear brake not working at all.

however i see this is a multi speed rear wheel, so if you've designed it for the wheel to always be all the way forward in the wheel slots and chain slack made up with a derailleur, then never mind all that.

Re: Project Excalibur

Yes it is.

The statistical odds of it being run over by three cars must be in my favor.

So, that’s like a built in safety feature for my kid.

Re: Project Excalibur

I looked up Holmes Hobbies.

I couldn’t get the Contact Us feature to work from the office.

I like that it’s a site dedicated to all things electric rc cars... and moped spokes.

Thanks for all the suggestions. I looked up the price of one of those spoke threading setups. Looks like I’m gonna be paying custom prices for these wheels unless I get more creative.

Re: Project Excalibur

This has been an extremely interesting thread so far!

Re: Project Excalibur

I was gonna say, the hub end is much more important, for your application and power level, you can probably make spokes from a bmx bike work. I have had good luck buying spokes made for smaller size wheel to use on stuff with big hubs and vise versa. My racebike uses a 16 tomos rim laced to a puch hub with 17" c70 spokes because the c70 has huge hubs

Re: Project Excalibur

The rims I got have big nipple


The bicycle nipples fall clean through. Maybe I should just use 20” kid bike rims and tires for now to get it rolling and work out a better wheel build after it proves itself worthwhile.

Or fit a tire directly to that hub motor. Then he can do wheelies up to a max speed of 10mph.

Re: Project Excalibur

It’s a top “tank”.

Plugged everything in today and made the motor spin. It worked. So, that’s reassuring.

The brakes all lined up perfectly. I’m a paranoid, measure 10x cut once, kinda guy.

Nice that there wasn’t any surprises for that.

I Gorilla formed the rear support bracket for the battery out of some thick aluminum. Just wrapped it around the same diameter pipe and then cleaned up the bends on my vice.

Not a whole lot of pics but there is progress. Just spokes and a pedal crank away from a test ride. My son says he wants to make it a no-ped. I think being able to assist with acceleration from a stop or going up hills will will make a huge difference in range. Pegs would be infinitely easier though.


Re: Project Excalibur

The spokes came in. First time ever messing with wheel lacing.

The hub motor, with 100mm spokes from Puchshop would be perfect in a 17” rim. The spokes are about 1/2” too long for the 16”. So I’m just gonna find a place that will cut spokes and finish the rear wheel.

Front wheel went better.

I had my boy sit on it and find a comfortable riding position for his feet. It turned out to be too difficult, for what this project is, to add pedals. So it’s an electric no-ped now.


Re: Project Excalibur

Making custom spokes is easy!

At least, way easier than I thought.

I bought the tool off Amazon for $40. Which is pricey for a small gadget but it works like a charm and quickly made threaded spoke magic happen.

Had to cut a piece of steel bar to chuck it into the drill. Gently clamp the spoke in the vice. Shoot a tiny bit of WD40 on it every time to help make perfect threads.


Want to post in this forum? We'd love to have you join the discussion, but first:

Login or Create Account