Drewjet's Mountain bike w/3220 Astro 5000W Build Thread

[drewjet]

Objectives. Must be a badass ride. No commuting necesarry. Must be very controllable, enough low end torque to pull stumps and light weight. High speed not required, but I want at least 25 MPH.

I have slowly been collecting all the pieces necessary to build my Mountain bike. I have my ENO's back from LFP (Thanks again Luke) I have a SRAM Dual Drive, I have 8 Turnigy 6S 5000 MAH (although I only intend on between 2 and 6 at a time), I have a castle 110 HV and a Turnigy HV as well, I have a 90 tooth 219 Extron and a 12 and a 13 tooth and adapter for the front, My Motor (Astro 3220 6 turn 6 wire single shaft) and reduction drive should be coming soon from Matt (thanks Matt), and I have 2 bikes to choose from.

The first bike I bought specifically in mind for this project. It is a DK Charger Mountain bike (they also made a Charger BMX) it has Hayes Hydraulic brakes Dual suspension. I have been riding it as is in the trails around my house and really enjoy the bike just the way it is. I picked it up on Craig's List for around $400. I hear originally it was anywhere from $1200 to $2000. There was not a lot of them made so they are not real common.

I then started to see the difficulty in doing this bike as the triangle is obscured by the rear shock, and I really want the batts in the triangle. Plus the problem with chain growth, though that could be remedied with a tensioner.

The other bike is a Specialized Rock Hopper disc hard tail. No rear shock means the triangle is open and no growth issues. It has mechanical discs, but they could be upgraded to hydraulic easily enough.

So the question is which bike. I almost hate to give up the DK as I really do enjoy pure peddling sometimes. I have looked to find another DK with zero success. If I could find a mountain/DH/Freeride that has a triangle and the shock behind the seatpost that would be a consideration for buying a new bike.

The other question is, Do I use the SRAM. I want good speed control from 0 to about 15 as that is about as fast as I see going on most trails around here. So far there doesn't seem to be anyone using it in an off-road high powered application yet, so no good feedback, and I have guinea pigged myself enough. With the 2 speeds out of the Asto I should still get a top speed of around 26 in high. With the SRAM I could get with the same setup 11 MPH in Low Motor/Low SRAM and about 32 in High/High (Unloaded speeds)

Point me in the right direction sphere.

[deecanio]

HI Drewjet,

My money is on the dk but then im a sucker for full suss.
The easier option would be the hardtail.
Where do you plan to mount the reduction?
Hopefully i will have some answers for you soon, we have practically identical setups, sram included.
Interesting you mention using or not using the sram, if your patient i'll be able to tell if it works or breaks, if mine fails i'll know what single gear to use for the motor.
your dk looks like it has a symetrical swingarm which makes thing easier but its a nice bike if all goes wrong, mmmmmm
why dont you set the hardtail up initially and if i have joy with an almost identical setup you'll know you can swap it over?


D

[drewjet]

D, you read my mind. Have you finally settled on a direction for your rebuild? I have been reading your thread with great interest.

I am just waiting on my drive from Matt to see where/how it is going to fit best.

[etard]

Nice choices Drew!!

So it sounds like you are going delta/wye? Can you give more detail on how this will be accomplished? I only see frock motors doing this.

I really like that DK, never seen one before. And since you are enjoying riding it so much, I would put the electrics on the Specialized. Nice color on that one by the way. You didn't really deceive how you would mount the motor, so I assume on the downtube, with batteries and electronics in the triangle? At the speeds you are aiming for, I wouldn't mess with the dual drive. Also, for going less than 20mph I think the hardtail with a semi deflated tire on te back and not a whole lotta weight on bike paths would be the ideal route. But then again, if you are riding on bike paths, the dual drive should hold up in that regard, not sure of the power handling though.

How do you intend to put power to the rear wheel?

I have asked alot of LBS guys about the hydro vs. mechanical brakes, and they all say it has nothing to do with stopping power, more to do with feels and modulation.

Subscribed

[drewjet]

I had the delta wye on my electrathon. It works just the same as on a frock motor.

Not bike paths but Bike single track courses. There is one about 3 miles from my house, and a few others a within 20 miles plus just general romping around anywhere the pavement ends.

I have taken the specialized on these trails and it is a fine bike as well. I doubt I would be doing any jumps more than about 2 feet.

I need to get the motor/drive unit in my hand to see how I am going to mount it, but would assume either the down tube or seat tube.

[drewjet]

My motor showed up yesterday from Matt. WOO HOO!!

After trying to see where it would go on the DK, I tried it on the Specialized, and it was much better. With the rear shock in front of the seat tube the motor would have to be too far forward. I think it will take a custom frame to get what I want for a full suspension bike. Also, the specialized has 3 gear rings up front already, no need to mod for more peddling options.

Next is figuring the mounting. The Specialized has an ovalish down tube and that would be extremely difficult to attach to short of welding something on. The seat tube is standard round and I have an idea of what I want to try.

The other decision I made was to go with a fixed gear hub in the rear. I want to see where performance is, and then if necessary I will put the SRAM in there. Also, I am unsure of it's off-road capabilities.

[drewjet]

Now that the Parts are all here and decisions have been made, time to start mounting the motor. I fabbed up this mount using a manual mill, and a jigsaw and a hole saw. It is not up to Recumpence's standards, but was for a test fit to see how it will work. It works fine but has some chain clearance issues. It will be cleaned up and used on the top, the lower mount will need some modification for the chain line.

[drewjet]

Now I can at least temp mount the motor and see the chain line. It will run too close to this mount as used on the bottom, so I can use that mount for the top and make a thinner one for the bottom. Also it is hitting on the lower chain stay, however, the motor drive freewheel is not all the way seated yet, it has about 1/4" to go, so hopefully that will give me the needed clearance. It sure makes me happy to see all that motor goodness at least somewhat attached to the bike.

[Grinhill]

Excellent work there, Drew!

Is that Extron sprocket adapter just a flat disc of aluminium with appropriate holes?

[damcard]

I also am interested in seeing a closeup of your adapter. I too am doing a wheel with the 219 and a large rear sprocket. Your brackets look very nice. -David

[drewjet]

Yes the sprocket adapter is simply a flat piece of aluminum. I used a jigsaw to cut the center and outer circle then drilled the holes to match the freewheel and Extron sprocket.

I have the second mount bracket half way done. It's quitting time, so hopefully will finish it tomorrow.

[damcard]

Hey Drew, overall your setup is very similar to mine in that you have two stages of reduction, approximately the same sprockets on the second stage. I am using a 24" wheel though. I also have a 3220 on the way but a 5 turn. I know you are aiming for almost half the top speed I am. I am not looking for stump pulling torque, but high speed instead. What pulleys do you have on your drive unit? I think I see a 72t for the driven pulley. What about your motor pulley? Also, can you list out your calculations for the speed/ratios you have. I want to compare to what I am doing. I am about to order my sprockets and may order some extra pulleys. -David.

[Kepler]

Very serious setup. I am a bit confused on how a rear cassette is added with this config though. I'm sure all will be revealed as the build goes on

[drewjet]

I got both mounting brackets done. I cleaned up the machining marks the best I could. You will notice that one appears offset. I did that on purpose for chain clearance. A first test fit looks as though it will work. I got the freewheels seated and I still have about 1/8" intrusion from the chain stay, so I will have to come up with either a idler gear, or a delrin guide. I think I will try the delrin guide first.

[drewjet]

Hey Drew, overall your setup is very similar to mine in that you have two stages of reduction, approximately the same sprockets on the second stage. I am using a 24" wheel though. I also have a 3220 on the way but a 5 turn. I know you are aiming for almost half the top speed I am. I am not looking for stump pulling torque, but high speed instead. What pulleys do you have on your drive unit? I think I see a 72t for the driven pulley. What about your motor pulley? Also, can you list out your calculations for the speed/ratios you have. I want to compare to what I am doing. I am about to order my sprockets and may order some extra pulleys. -David.

I am not sure on teeth count. According to Matt it is a 4:1 ratio. I will try and get a count when I am home.

For speed and gear ratios I made up an excel spreadsheet. You plug in wheel size, desired speed, KV, voltage and front sprocket, it will give you rear sprocket.

If you have your numbers I can run it for you.

[drewjet]

Here are some pictures of the sprocket adapter. I ended up moving the sprocket adapter to the inboard side of the freewheel to get more clearance between the 2 chains. This also moved it in enough to clear the chain stay.

DSCI0025.JPG (112.95 KiB) Viewed 1029 times

DSCI0026.JPG (90.59 KiB) Viewed 1029 times

DSCI0027.JPG (82.54 KiB) Viewed 1029 times

I hooked up my Turnigy 100 Amp HV ESC and a servo tester and viola, I got wheel spin. So I took it outside for a test spin. WOO HOO! That is way more power than what should be legal. Oh wait it is illegal. It was real tough to get a feel for the power as I had to keep one hand on the throttle servo and one on the handlebar. So I came back in and attempted to get my throttle trigger working. I failed. Best I could get was about half throttle. What the hell. let's see what this beast can do on half throttle. OMG! With only half throttle, from a dead stop it will throw you off the back. If I was moving a little, I could sorta control the wheelie, but I would run out of throttle to soon. zero to top speed (about 10 MPH) only took a few feet. I played around some more and I got my hall sensor twist throttle to get me full throttle. It was dark and late so I didn't get a chance to test it out, but the sun is coming up soon!

[Thud]

Sounds like fun Drewjet,
So is this the 1st running example of the broached free wheels in application?
looking for some comments regarding the set up when you get a minute.
have fun.....ya outlaw!

[AussieJester]

Good to hear you have tasted your first rc setup, impressive ain't they hehee

Very serious setup. I am a bit confused on how a rear cassette is added with this config though. I'm sure all will be revealed as the build goes on

Thud made a broaching tool sent it too Liveforphysis he set it up on an old hydraulic log spliter and is now broaching ENO freewheels so they fit onto Sram hubs...Theres a thread on it in the non hub section explaining from start to finish.

KiM

[Miles]

All 39 pages of it: viewtopic.php?f=28&t=13532

Or, if you really want to start at the beginning: viewtopic.php?f=28&t=12449

[liveforphysics]

Right on!!! You've got a setup geared for applying maximum torque from a 3220 to the hub of a 26" wheel. This should be an excellent proof of the torque holding ability of the ENOs. I'm not worried about the freewheels or splines in them in the least, but you will get to test how strong the ratchet paws are in your rear hub.

Fix that wiring up and hit this thing with as much torque as you can, and lets see how she all holds up.

Great work!

-Luke

PS: If anyone wants adapters from the ENO flange to the extron sprocket, it's a pretty trivial matter for me to whip them up in my CNC. I've got sheets of carbon fiber, aluminum, and whatever else you might want.

[Miles]

Fix that wiring up and hit this thing with as much torque as you can, and lets see how she all holds up.

Absolutely! We want to know the weakest link

[drewjet]

I got the wiring going, full throttle is available.

I AM OFFICIALLY SCARED OF IT!!!!!

Top speed is about 24 MPH. Need to hook up my CA to confirm. The throttle sensitivity of it at low throttle is too tight. You can't start from a dead stop, as it will just toss you off the back. So I peddle it a bit then ease into it. If I gun it at about 10 MPH it will power wheelie.

So far I have seen about 2800 watts, although it is hard to say for sure as looking down when the bike is trying to throw you off the back is scary.

Freewheels seem to be holding fine. I had some trouble with the adapter Thud made for me to go from Matt's drive to the 219 sprocket. It kept shearing the 2 10-32 Allen screws on the 2 flats ground into the shaft. I figured I would just drill and dimple the shaft, but it is hardened steel and laughed at my puny drill bits. So I put in 2 aircraft 10-32 screws that has a hex head on it. Tightened it down good and so far seems to be holding. I have a feeling the SRAM 3 speed wouldn't hold up to the abuse. I also don't think it is necesarry, I could just go to a smaller sprocket on the rear and have all the speed I want and I am sure it would still have crazy acceleration.

My next problem is the clamps I made. While once clamped down theydon't seem to be able to turn, but under all the pulling force of the motor it twists them around. One of the mounts is on top of the water bottle rivnut, so I drilled a hole and used a screw to try and index it. Still rotates. I haven't tightened the crap out of those mounting screws yet so I will try that next. It may take welding plates to the seat post to get it 100%.

Overall this is way cool, just need to fine tune it. Right now it is soldered up in Delta mode, I need to try in Y mode to see if a slower top speed will help out.

[drewjet]

What a difference the switching over to Y made. Top speed in Delta was 24 MPH. In Y it is 13.5 MPH. The throttle became controllable also. Man what fun. I took it on a close by trail and while you still have to be careful with the throttle at very low speeds, as you speed up to about 5 MPH it no longer wants to throw you off. A couple glances down showed it pulling about 500 watts at full throttle in a flat area of the trail. On the streets about 250 watts. Not much loss of speeds up the hills just hearing the motor grunt a little harder and the watts go up.

[Thud]

& this is with a turnigy 100A sentilion?
Sounds like a nice trail runner. Not to fast to pedal along & maintain the "synergy" & still get a great work out. Kind of a bionic biker now, anitcha' drewjet........

Now if we can set up a long travel mountain bike frame to do the same thing with the reliability of a rock...


(oh yea, you can dimple them hardend shafts with a dremel & a grinding stone)

[gwhy!]

I got the wiring going, full throttle is available.

I AM OFFICIALLY SCARED OF IT!!!!!

Top speed is about 24 MPH. Need to hook up my CA to confirm. The throttle sensitivity of it at low throttle is too tight. You can't start from a dead stop, as it will just toss you off the back. So I peddle it a bit then ease into it. If I gun it at about 10 MPH it will power wheelie.

So far I have seen about 2800 watts, although it is hard to say for sure as looking down when the bike is trying to throw you off the back is scary.

Freewheels seem to be holding fine. I had some trouble with the adapter Thud made for me to go from Matt's drive to the 219 sprocket. It kept shearing the 2 10-32 Allen screws on the 2 flats ground into the shaft. I figured I would just drill and dimple the shaft, but it is hardened steel and laughed at my puny drill bits. So I put in 2 aircraft 10-32 screws that has a hex head on it. Tightened it down good and so far seems to be holding. I have a feeling the SRAM 3 speed wouldn't hold up to the abuse. I also don't think it is necesarry, I could just go to a smaller sprocket on the rear and have all the speed I want and I am sure it would still have crazy acceleration.

My next problem is the clamps I made. While once clamped down theydon't seem to be able to turn, but under all the pulling force of the motor it twists them around. One of the mounts is on top of the water bottle rivnut, so I drilled a hole and used a screw to try and index it. Still rotates. I haven't tightened the crap out of those mounting screws yet so I will try that next. It may take welding plates to the seat post to get it 100%.

Overall this is way cool, just need to fine tune it. Right now it is soldered up in Delta mode, I need to try in Y mode to see if a slower top speed will help out.

The throttle problem is what im trying to resolve for my bike at the moment like you say its just not controllable enough when pulling away or trying to do slow controlled riding. The twisting of the clamps is something that did on my bike and i overcome this like this...

flea drive _mount.jpg (50.61 KiB) Viewed 960 times

This is simular power I was putting through my budget freewheel hub and it did eventually brake