Another "stealth bomber" build.

[j bjork]

How it looks by now:

The side panels will get painted later on.
The shield for the controller will get shanged too, I will probably paint them at the same time.

My watt meter:

It was not intended for this bike, it only goes to 100A (actually 122A :wink: )
But it is just temporary.

 

[j bjork]

A little update of how my work on the sheap chinese controller went:

I think I killed a mosfet with static electricy, I noticed a little "pop" when I soldered next to a mosfet.
I connected a 20A fuse in series with the controller for testing when my soldering was done.
I can say that a car fuse blows rather spectacular at about 80V..

It blew both the sorce and drain legs of the shorted mosfet. It also shorted at least one more mosfet on the same fase but on the opposite polarity.
When I looked in to what mosfets are mounted, I noticed they are 80V. I run 20s, 84V fully charged..
I guess the 72V in the specifications is not nominal but maximum then :?
However, the caps are 100v.

I am thinking abut buying better mosfets and trying to get it running again, at higher power.
But I got some help and is now beta testing the SFOC5 :wink:

 

[j bjork]

I have been driving around in the woods pretty much these last 2 weeks or so.
It will probably be what I use this bike for mostly.

So I realized I need better protection for the wiring to the controller.
I also have a clearance issue between the fender and the controller when the suspension bottoms out.

I considered to move the controller.
Ither to try to fit it under the seat, but it would be a tight fit for for a comming 24fet.
And I think it would´nt be very good airflow there.
Or on top of the frame, in front of the seat. But I dont think that would look very good.

So I decided to leave it as it is, and build some protection:

First some cardboard templates.

I planned to make the sides of ordinary 3mm alu, but ran out of it.
So I had to use treadplate(?) for both parts of the sides and the bottom.

Now I just have to make some nice ending that doesnt restrict the airflow to much around the controller, and can be used to fasten the belly pan(?) in that end.

Oh, I mentioned the controller I am testing earlier. The SFOC5, here is a thread about it: https://endless-sphere.com/forums/viewtopic.php?f=2&t=30680

 

[j bjork]

I used a hall throttle earlier, but now I have changed to a domino:

I had some clearence issue with my regen thumb throttle, for now I just removed it.
I can´t use it with this controller anyway.

I had a problem with throttle runaway once, or what it is called in english?
Well, I had full throttle and a power wheele. I got close to a well, and eased on the throttle to fend off. But nothing happened
I crashed..

The groove leading up to the well is me.. The stick on the well was standing up before.
Actually, all the grooves are mine :wink:

It turned out to probably not be an issue with the throttle primarily, but interference in the 5v line from the temp sensor in the motor at high phase currents.

I also have a problem with high motor temp. But the motor does`nt really get hot..
I can get 160degrees c in the windings, but the shell is only about 40degrees c.

I thought it is time for some statoraid:

I drilled a 3mm hole, I used a tube on the drillbit to not go to deep. I did´nt take the motor apart.
I drilled close to the chainsprocket.

As i remember from the statoraid thread, I should just add until I get higher amps whith the wheel in the air. And it should take a little more than 5ml probably.
Well, I added 5ml, no difference. I added 2 more, still no difference.

I took the bike out for a spin, still got up to 160degrees c rather easy, and still about 40 degrees on the shell.

Now I have added the remaining 3ml, still no difference in frewheel amps..
I guess I will see if it makes any difference when I ride it.

 

[j bjork]

I had some computer problems, I just got a black screen when I turned it on.
But I was able to fix it, heating up the motherboard fixed the issue

Testing before I put it together again.

I have been riding on trails in the woods some more, but I have a problem with dents in the rear rim.

There are actually 3 dents in the picture, one of them is more obvius then the rest..
No problems with the front rim.

I don´t know if it is a problem with my rear shock settings, just a way too soft rim, or just how it is with a heavy hub motor.
Or maby a combination of all 3.
I guess I will try a bit softer compression setting, but I doubt that will solve the problem.

 

[j bjork]

I have to do some work on my suspention, it is way too soft.
For the fork there was no problem to find different springs, they come in 5 options.
From extra soft to extra firm. No info on spring rate, but the stiffest is recomended for riders 90+kg, no mention of bike weight.
But I am almost 90kg, and my bike is about 60kg.. So I think the stiffest is what I want :wink:

I didn´t think finding a stiffer rear spring would be a problem, but it seems it is not so obvious as I thought.
I have a dnm burner rcp-2s, 200mm with 550lbs spring. I think I have seen those with 750lbs spring, but I have´nt found that now.
I looked at some other springs, but the stiffest was about 600lbs.
Does anyone here know of a suitable spring?

 

[\ (•◡•) /]

I have been riding on trails in the woods some more, but I have a problem with dents in the rear rim.

There are actually 3 dents in the picture, one of them is more obvius then the rest..
No problems with the front rim.

I don´t know if it is a problem with my rear shock settings, just a way too soft rim, or just how it is with a heavy hub motor.
Or maby a combination of all 3.
I guess I will try a bit softer compression setting, but I doubt that will solve the problem.

Howdy!, I must say that's probably the worst condition rear Rim I've ever seen on a ebike. So congratulations!.
I can say that I've been in the same boat. I've also bent a rear rim on my bike. It was a similar Chinese rim to your (mine was a 19 x 1.4). I've now changed my rear rim to a Excel A60 and haven't had any issues since, they're expensive but there's a reason. You may also want to look into 2 cross lacing if you're running anything more than say 8kw and using regen. Hope this helps

Edit: I forgot to say how great your bike has turned out, I love the battery box solution as well. Seems like you're a seriously good welder

 

[j bjork]

Thanks for the reply, about the welding I am self learned. My tig-welder is an old miller. probably from the 50:s or 60:s..
It is a big, power hungry beast

Yes, hopefully a better rim is the answer. This one looks like this after only a few weeks, I have at least 2 of those big bumps. And probably at least 5 smaller ones.
I´m not sure 2 cross lacing will be possible? Now, with 1 cross it looks like it is about the maximum angle on the nipples in the rim.

I will use this as it is for now, I´m considering going for 16" later. For now I am satisfied with this tire, but if I will change tire I will look at the 16 and 17" options.

About the rear spring, I took some measurements with everything still mounted on the bike.

It seems like the maximum lenght of the spring could be 135mm, but then it would probably be difficult to mount. So I think 5" or 127mm is about right. Maby slightly less.

The outer diameter is about 53mm, and the thickness of the spring is 8,5mm. So the inner diameter should be about 36mm or 1.42", I think 1.4" sounds about right.

I would like to find something in EU to avoid import charges, but it is not critical.
I have looked at some sites, and the most springs did´nt have mesurements. Only what shocks they were intended for. And they were for the most part not stiffer then what I already have.

I haven´t found much of anything on DNM:s webb page, but I haven´t wrote to them and asked so far.
I got some answers in another thred, and it seems like there are springs with 35mm and 36,5mm inner dia. So I probably have to take it apart to be sure.

 

[Choppa66]

Hi.
Bike looking great and coming along well. That back wheel is a beauty...must be an interesting ride riding it like that!?? any luck with finding a new spring for the rear shock? I have the same DNM and I think I'm going to have the same prob as you.

 

[j bjork]

Thanks, I haven´t noticed any difference in riding with the bumps in the rim. It was not strait from the start, and I don´t think it is much worse now.
I was able to buy 750lbs springs from DNM. The springs were not expensive, but shipping was.. I bought 2 just in case. So I might be interested in selling one of them, but I have not got them yet. So I don´t know the final prize with import fees etc.

 

[j bjork]

I have changed spring in the fork:

The old spring is the red, "normal"
The new is the black, "stiffest"
There are no info about spring rate. But I think normal was for about 70kg rider, and black for 90+
No mention about bike weight, so I guess my is a bit heavier than the average downhill bike..
So the stiffest spring it is :wink:

I have also changed front tire:

 

[Raketemensch]

I think the stiffer spring is the right call, since you also have to consider the weight of the bike, too.

Looking good.

 

[j bjork]

Thanks, only considering my weight I was just on the mark between stiff and stiffest.. It would probably have been better with a slightly stiffer spring than this one, but it is a lot better then the "normal" one at least.

The rear spring is a bigger problem now, but it will take a while before I get a stiffer one. There was none in stock when I ordered.

I had to walk home again today, but this time it was a flat tire :?

I think this rim is pretty much done

 

[\ (•◡•) /]

Thanks, only considering my weight I was just on the mark between stiff and stiffest.. It would probably have been better with a slightly stiffer spring than this one, but it is a lot better then the "normal" one at least.

The rear spring is a bigger problem now, but it will take a while before I get a stiffer one. There was none in stock when I ordered.

I had to walk home again today, but this time it was a flat tire :?

I think this rim is pretty much done

Jesus Man you really can't ride on that, that's not safe...
i'm the guy who recommended an Excel A60 earlier, look at these or something similar for your new rim. However be aware that they use mx drilling, which have 8.5mm nipple holes, meaning you need either nipple washers, or need to go to custom made 9g spokes. (try not to buy from aliexpress, all of the spokes from there usually have cut threads, which are much weaker than the cold rolled threads usually found on custom quality spokes.)
I gotta ask what you are doing with your bike?, any 2 metre high jumps recently?
The fact that your shock has a lighter rear spring should actually mean your rim is under less stress. it's seems that such a cheap rim is 100% the issue from my eyes.
dish out and get a good branded rim, good options include: Excel A60, Excel Takasago, Sm pro etc.
Also look into getting a blank rim custom drilled for your hub (look at mx wheel builders in your area for this service)
hope this helps, i've been through this before, just never damaged a rim anything near this bad

 

[pwd]

Awesome build! Yep, that rim is trashed haha!

I was wondering about your experience with Statorade; did you notice a difference while riding after a few runs?

...
As i remember from the statoraid thread, I should just add until I get higher amps whith the wheel in the air. And it should take a little more than 5ml probably.
Well, I added 5ml, no difference. I added 2 more, still no difference.

I took the bike out for a spin, still got up to 160degrees c rather easy, and still about 40 degrees on the shell.

Now I have added the remaining 3ml, still no difference in frewheel amps..
I guess I will see if it makes any difference when I ride it.

 

[j bjork]

I have not done any jumps, only trail riding in the woods. The bumps are from hitting rocks and such.
I think at least the biggest bumps are from the rear suspention bottoms out, and the tire and rim taking the impact.

I have looked some for a better rim, but I havent found much for 36 spokes in 16 or 17".I think going 16" and a real dirtbike tire would be best. They have much beefier sidewalls, and should protect the rim better.
But they are 90/100x16, and I mesured the actual width on one: about 112mm. I would probably have to modify the swing for it to fit.
There are front tires for 17", they are 70/100x17. Those fit in the swing, but there are not nearly the same protection for the rim as the rear tires.
Cheap rims are avalible in 17x1,6" 36 spokes, and 16x1,6" too. But I think I would need at least 16x1,85" for a dirtbike tire.

Yes, the statoraid seem to help. I seldom see much more then 100 degrees c now. But it seems like it took some time before it got in the right place.
A problem with comparing though is I dont have a meter where I see the temperature. I can only see the highest it has been in the log on the computer after a ride.

 

[Raketemensch]

What was your older highest, just for comparison?

 

[j bjork]

The highest is 160degrees c. I have a limitation that starts at 130, and limits hard at 150. So you can´t really get much higher then that.

 

[j bjork]

Here is how my latest log looks:

It is just a photo of the screen, so it is not very easy to see everything..
But this time the controller is warmer then the motor. They are usually about the same temp now, maby +-10degrees c
Before statoraid the motor was always warmer than the controller, I think the controller usually was around 85 c when the motor overheated.
Here the controller overheated, and limited amps a lot.

 

[j bjork]

Here is another log from today:

Here I gave it full throttle on the way home from the woods. The controller was already hot, so it limited the amps a bit. But without statoraid I am pretty sure the motor would still run in to temp protection.

I have a dirtbike (front) tire om the back too now, it seems to use more amps than the old tire. But I have also ridden on more demanding trails. But before I seldom run in to temp protection on the controller.
I sure leave a more visible mark on the trail now, it have its benefits though. It is easier to find my way back if I dont know where I am :wink:

Yeah.. I still have the same rim
I cant really say if the tire have protected the rim better, there are so many bumps. I don´t know if there are any new ones :lol:

 

[j bjork]

My new rear springs have arrived, so now I have changed to a 750lbs spring instead:

It is better, it did´nt bottom out on a "normal" trail. But it was close. The rear wheel still jumps around quite a lot, but maby that is normal with a heavy hub motor..
It looks like the new spring is longer, but that is just the picture. They are the same lenght, but less turns. I think they are the same thickness in material too, but I haven´t mesured.

I made a case for the charger and pcu too:

The charger is screwed in place. So now I can easily carry it around. And there is room for the airflow for cooling too, both for the charger and pcu.

 

[Raketemensch]

That's pretty sweet.

 

[j bjork]

There are not much news, I have been riding some more and doing other things.

I have shortened the front fender though:

It used to hit the controller when the front suspension bottoms out.
I thought it will brake sooner or later, I will deal with it then.
It did´nt, the threads did.. So I cut the fender and put in helicoils.
I don´t know about the look, but whatever. As long as it works It probably don´t do very much to keep dirt and water from the bike and rider now, but at least it protects wiring and brake cables from the tire..

But I think I wont be riding for a while:

You can see the tube between the rim and tire in two places
I wasent sure if the mx tire was enough to protect the rim, it was hard to tell if there were any new bumps after a ride. There were so many already.. But now I know :wink:

The plan was to try to use this rim the rest of the summer, then go 16"
The mx (dirtbike) tires are 90/100-16", and seems to use 1,85" rims.
I have measured one of these mounted, it is about 94mm wide between the stubs(?) and 111mm on the stubs.
The swing is about 103mm in the region, so I will probably need to modify or build a new swing.

 

[Dung]

Hey j bjork

Oh man ur rim, what can I say about it... Where did u bought it? I have same frame as urs and I have 19" rim. The plan is to use 3,5" tyre, do u think it fits the swingarm?

 

[j bjork]

I bought it together with the motor from qs motors.
I don´t know if a 19" 3,5" tire will fit, it will probably be tight.
I had no problem with a 17" 3" tire, there were some room left. I don´t remember how much though, but probably at least 10mm on each side.

I have been in contact with a company (wheels and parts) that can get an Excel rim 16x1,85" with custom angle for the spokes. I don´t know what model, but probably not A60. Excel don´t have any rim like that on their web, the A60 that is..
That would cost about 2000sek, or a little over $200.
I think that is a bit much, but it seems like that is how it is.

But then I need spokes..
They take 30sek each for the spokes. But they also take a measurement charge of 150sek for each spoke type, I guess there will be 2 types. And a set up charge for the machine of 250sek for each type.
That sums up to 1880sek or about $200

They also want me to send them the motor, even though I have sent them all the measurements and a technical drawing. But I guess with that prize it is just as well, so I don´t get spokes that don´t fit.
And they want to build the wheel for another 900sek.
Well, if I have to send them the motor anyway, maybe I just as well let them build it..

Add some shipping to all of that, and it is at least 5000sek, or $500 And I will need a tire and tube, and I will need to modify the swing arm.
And I mean, it will definitely be a better wheel. But what if I break that too?

Does any of you have a better source for custom spokes, or a better idea?