FS Frame + Cromotor + Lipo

[Rodney64]

I purchased a shimano 20mm hub but the issue was it needed a centre locking disc. I used the Chain reaction custom wheel build. I ended up having to purchase an adaptor pack so I could use the same discs front and back.

[gensem]

I purchased a shimano 20mm hub but the issue was it needed a centre locking disc. I used the Chain reaction custom wheel build. I ended up having to purchase an adaptor pack so I could use the same discs front and back.

I was asking about the fork.

I need a single crown one that takes 20mm axles
Is the manitol circus a bad call?

[John in CR]

Ok, im back from a spin with the new extended dropouts.

Things noted

DP420 seems to be strong enough to hold the bike together.

Epoxy and a bolt or two, right?

6-7kw is boring now that the bike is not a wheelie machine during aceleration.

and what do you weigh, 75-80kg? Put 35-40kg in your backpack and welcome to my world. 5-7kw is zippy. Why do you think I pushed my bike all the way up to 30kw? Then look at where Luke's CG is on his bike, and the acceleration he must get with the bike still able to mono.

John

[gensem]

Epoxy and a bolt or two, right?

One m10 and one m5 (or m6, dont remember) but the m10 is just filling the space that was use by the axle before and lots of epoxy.

and what do you weigh, 75-80kg? Put 35-40kg in your backpack and welcome to my world. 5-7kw is zippy. Why do you think I pushed my bike all the way up to 30kw? Then look at where Luke's CG is on his bike, and the acceleration he must get with the bike still able to mono.

Im actually overwheight now, like 90-92kg and the bike is weighting alot too... its not really slow its just not breath taking anymore.
Im hoping to find a decent fork locally so I can raise the power with confidence.

Luke is off the book, I think I would be happy with 20kw peaks

[gensem]

OK, i just had another break, now i need to think if its still worth to work on this frame or if I should just unleash the Warp frame...

[hillzofvalp]

CAn you reflect more upon your fork choice, sir. I'm looking to upgrade my rockshox Reba. I found it used.. rode it 1500miles when the bushings failed. Now it is rendered virtually useless.

[gensem]

Im not sure if my thinking is right. But the strongest single crown forks available are made for dirt jump. I think that any fork thats made for DJ ll do fine in a heavy eletric bike. Circus look awesome and costs half of what a quality fox would cost.

[gensem]

Pics of the failure

[fabiograssi]

Just the battery box mount? I can't see any sign in the frame...

[gensem]

Just the battery box mount? I can't see any sign in the frame...

There is epoxy on the frame side too... hopefully i wasnt riding the bike at the time. I was just showing the eletrics of the bike to a friend and Im gessing i shorted the throttle wire or maybe broke the resistor.
The bicycle tried to fly and made a nice dive over its nose, breaking the epoxy and making me rethink about the epoxy holding so much weight right above the front wheel.

[sacko]

A great read, thanks for posting.

Could I ask where you got the bag from?

[gensem]

A great read, thanks for posting.

Could I ask where you got the bag from?

http://www.falconev.com/

[John in CR]

Is that paint or just black epoxy? I'm sure you know it, but you have to get down to metal and metal for bonding with surfaces made rough for the epoxy for it to mechanically have something to hold onto?

[gensem]

Is that paint or just black epoxy? I'm sure you know it, but you have to get down to metal and metal for bonding with surfaces made rough for the epoxy for it to mechanically have something to hold onto?

Its just epoxy John... no paint at all. It was all clean but not very rough. I think I ll use my greyborg frame to make as a reliable plataform.
Btw I have already removed the cromotor covers to do the intake on the left and outtake on the right perimiter, but now blades for the time being. I ll also close the holes in the stator so the air ll be forced to thru the magnet/lamination gap.

[John in CR]

Is that paint or just black epoxy? I'm sure you know it, but you have to get down to metal and metal for bonding with surfaces made rough for the epoxy for it to mechanically have something to hold onto?

Its just epoxy John... no paint at all. It was all clean but not very rough. I think I ll use my greyborg frame to make as a reliable plataform.
Btw I have already removed the cromotor covers to do the intake on the left and outtake on the right perimiter, but now blades for the time being. I ll also close the holes in the stator so the air ll be forced to thru the magnet/lamination gap.

I figured you prepared it pretty well. That was mostly for the sake of others reading, which typically lengthens most of my posts.

Don't close stator spokes all the way. That would starve the other side for air. I thought about closing mine some, but didn't. My thinking is the 2 sides are divided by the stator to a couple of inches from the perimeter. Then as centrifugal force increases the pressure on the intake side it has nowhere to escape but thru the magnetic gap to flow out.

Note that the warmest part of the outer shell is always the intake side near the perimeter....never hot, but warmer, so maybe I should block most of the flow space between the stator spokes, which is huge space on Hubmonster. Maybe estimate the cross sectional area of the magnetic gap and leave less than that open in the spokes since flow resistance is surely greater through the gap.

Blades are very easy, and I believe important. I'd at least do them on the harder to remove wire side, so you don't have to open it again. Tin snips, aluminum sheet, epoxy and a bolt. They can only help, and can't hurt. I don't think they increase flow, since the air spins at wheel speed no matter what. I do believe they greatly increase the effectiveness by essentially creating thousands of puffs of cooling air per minute directly at the stator. Without them the flow will obviously take the path of least resistance. ie along the covers, not the stator.

If you goal is to test both ways, I don't want to discourage that. I don't like opening my motors multiple times, especially with big new phase wires often making removal of the wire side impossible without rewinding.

John

[gensem]

I think i prepared it fairly well, but I wont deny I could do it better if I did it again. Even tho is was a hard hit, i think the aluminium would have bent if the epoxy was able to hold it together.

I ll make a draw (in mspaint, hehe) of what im probably going to the motor. I aim to run the cromotor with peaks close to 20k using a fan cooled 4110 24fet controller , so I cannot miss and make the hub ventilation half as good, it has to be very good.

edit: I was actually thinking of a way to create pressure in the intake side, so all the air flow in the gap (closed stator), but im not sure the air would have enough pressure. I was trying to find some sort of simulator but i was not able yet.

[nechaus]

What about using some hose clamps where you can..
just something extra just incase it fails..


I got some spare carbon fiber, if you want a bit i can send you some and you could use it to wrap around you joints...

[gensem]

What about using some hose clamps where you can..
just something extra just incase it fails..


I got some spare carbon fiber, if you want a bit i can send you some and you could use it to wrap around you joints...

Thanks for the offer nechaus, but I already got the greyborg warp frame out of the shelf and i ll start building a zippy bike with it. I still plan to do some more stuff with the fastrax glued frame but I really need a reliable bike to use in my daily commute.

Still need to find a way to flow alot of air in a thin gap....

[John in CR]

I ll make a draw (in mspaint, hehe) of what im probably going to the motor. I aim to run the cromotor with peaks close to 20k using a fan cooled 4110 24fet controller , so I cannot miss and make the hub ventilation half as good, it has to be very good.

edit: I was actually thinking of a way to create pressure in the intake side, so all the air flow in the gap (closed stator), but im not sure the air would have enough pressure. I was trying to find some sort of simulator but i was not able yet.

If the stator is closed then the other side of the stator doesn't get fresh air flow. With single side exhaust you're guaranteed some flow through the gap as long as you get the exhaust holes out at the same radius as the gap. At lesser radius the flow would surely be less and more complex in nature. Centrifugal force guarantees pressure. It's not big pressure, nor is it tremendous flow, but with the stator transferring heat to much cooler air it transfers much more heat.

The thing that drives me crazy about the all too common exhaust holes well away from the perimeter is how do they expect the hottest highest pressure air to flow out? I'm sure it mixes somewhat, but it's not a guaranteed inherent part of the gas circuit. You have a good handle on it, so I'm sure you'll get really good results, and it will reject heat drastically better than stock.

FWIW, hubmonster gets no warmer running at 30kw peak than it did at 16kw. If anything it's cooler, because the really high power flows for a shorter duration, and windings don't heat up instantly.

Something I haven't tried but my more recent research indicates could significantly increase flow is some type of air dam or cowling outside of the intake to both increase pressure in that region outside of the motor and to make it flow more freely into the intake holes. Without it we're trying to get air flowing by the holes turn to go in. I forget who brought that idea up in one of the threads but I researched it and it should increase flow pretty substantially. If I ever start having heat problems with a ventilated motor, I'll try that first, because making something to give it a try wouldn't even require taking the motor off, much less open it up. I bring it up in case you end up pushing your motor well into saturation, and need more cooling than I do, that there's still something quite easy to try.

I still think flow volume is just part of the equation, and what you do with the flow inside the motor is equally important.
I look forward to seeing what twists you add to the approach.

John

[hillzofvalp]

was just showing the eletrics of the bike to a friend and Im gessing i shorted the throttle wire or maybe broke the resistor.
The bicycle tried to fly and made a nice dive over its nose, breaking the epoxy and making me rethink about the epoxy holding so much weight right above the front wheel.

I'm willing to bet you have a current throttle through the ca. If you break the throttle input green wire going to ca the ca is not smart enough to detect failure of the wire and will gofull current. I told Justin about this in the v3 forum but people don't seem to see the need.

[gensem]

Yes, I was using current throttle... but i dont know if it was just the wire or if the resistor played its part. I ll not use resistors or pots in my throttle anymore.
Either way if a broken wire ll just make the go full throttle, CA really need some sort of security on that. I mean anything over 5kw is really dangerous in berserk mode.

[hillzofvalp]

I know. There should be logic for that and this logic is very easy to employ.

[Emoto]

Hi Gensem
Ive got a cromotor on its way, and will be putting it in a specialized big hit dh frame, should be strong enough.
Here is a interesting motor, notice the cooling holes location, and the ratio

[gensem]

Thats a very diferent hub design...
Cromotor should work very nice on your frame, my only problem with the alu frame i was using is that cant stop raising the power.
I just started my greyborg build and im following John's ventilation thread.
Plan on putting 10hp to the ground and to do that I think I will need about 15kw on the battery side(according to ebikes.ca simulator).

[Emoto]

The thing about that motor the cooling, along the lines john is talking about, its the first ive seen commercially.
Ive been reading you thread for a while good to see the testing/ evolution, so decided the Dh frames are a strong option
Im havent decided on forks double vs single clamp, single clamps will give a lighter build of course
I read you thinking of going single clamps yeah?