sorry pchen92, i was riding today with 2 friends and totally forgot about the no load-watts
but if that is helpfull, i remember that we all 3 checked our wh/km and they where 34 wh/km up to 39wh/km. The 34wh/km is at 2500-3000W . the 39wh/km is from a bike running 3000W
got some upgrade Prats from Mike
so we did some upgrades in the last days, and also a "regular" service on the drivetrain of a frinds Smallblock kit and a rebuild of a friends Santacruz v10. Think this could be interessting for people having troubles with the Kit (when going higher Powerlevels then its made for).
The Smallblock Kit is rated 1500W, we do 3000-3500W now, and things seems to be stable and reliable now.
Time for a update and sharing some infos and Pics.
Starting at the beginning; i have ordered 5 Smallblock kits from Mike, just when he started offering the Kits. So all the Kits we have, are from the very first badge, think i was buyer number 29 or something. At this time, the axles of the jackshaft was made by softer steel then the axles he sells now. Also i think the mounting sheets are more stable in the newer versions.
one of the first made smallblock-kits
Dirty, but still fully funkctional
The biggest problem when goining higher in amps/watts on the smallblock kit, is the bending force created mostly by the 2nd reduction.
Means that the Jackshaft on the 219Chain-side is pulled toward the crankarm.
This can cause bending of the sheets and your 219 chain will no more be alined. This then can cause a lot of problems like 219 Chain fall ing off or causing premature wearout on the sprockets. it also can effect the Belt side because of the slaggered Jackshaft and so on...
So the most important thing to do, is to mount the Kit as rigid as possible to your bike. The Mounting clamp seems to be ok for 1500W, with 3000W+ you will need much more mounting-power.
Here some example how we did:
on a devinci wilson
on a Santacruz v10 (alu)
and there is an other example on a YT-Bike somewhere on page 1 of this thread...
As you see, we made a mounting-plate for each Bike. This plates connect the Bike with the motor and prevent things from twisting around.
Your goal when seting up a smallblock kit to your bike, should be to make it in the most stable way. This will save you much time and cost repairing it.
foto of a friend soldering his stainless-steel plate together
An other problem you will have with 3000W+ is Belt skipping on the small Motor-Pully. This causes wearout on the motor-pully and belt, that again causes more and more slipping and belts will rip. Replace it with a bigger pully will save you money.
You will lose some of the reduction ratio (originaly first reduction 1:5, we use 1:3.6), but works better for us.
wearout on pully
Belt slipping also can be caused by not having the correct tension on the belt. When you set up the kit, make sure everything is lined up 100% correct, Jackshaft have to be parallel to BB and Motor axle.
To set Belt and jackshaft:
give Belt the right tension with the set screws (right and left side, still parallel!). And now the most important part:
--> tighten the rings on the jackshaft. We take a flat screwdrifer and a little hammer to do this (so you dont have to remove the 90T Belt-pully only to tighten the rings)
Use the set screws only to set the jackshaft proper. The "screw on rings" on the Jackshaft are the "mainly force-holding" parts, preventing your jackshat from getting pulled toward the BB.
Wearout on Belt
Axle:
Mike will offer now 15mm stainless axle, so that will be fine for 3000W.
I still have the "first badge" 12mm steel axle that tend to bend, but no problemos for now, will se what happens at 3500W.
Freewheel at 1st reduction:
We did fill them with grease before, to make them silent, not sure if thats a good idea anymore.
You can still do that on the Freewheel at the BB, for more silence.
We destroied some of the ACS on the Beltside, then welded them. fotos somewhere on page 1 i think.
for us its the way to go with felding the FW (freewheel) on the 1st reduction, but you will have to pedal through the motor when you "delete" the FW there.
219 Sprockets:
the sprocket on the Jackshaft can wear out fast when using a low tooth count like 12T. I prefer a bigger sprocket, it will last longer, also make your bike even more silent. Downside is the lost of reduction ratio, more speed, less torque.
For the 219 Sproket on the FW-Crank, we use those extrons made out of kevlar.
I think they run a bit smoother and quiter but have actually no referenz to a alu sprocket.
Reduction ratio of 2nd reduction:
by choosing the 219 Sprockets you set your redction ratio. 12t to 92t is 92:12= 7,6666
so 7,6666 times the torque coming from the Beltside. Thats one of the highest possible reduction ratios, and would create much torque and low speed.
When offroad riding, Torque is often more fun then speed, but without speed, your bike is like a Goat, moving up every hill with 25amp with low speed but high effizient.
We prefer to run the motor at 40 amp with a smaller reduction ratio, so we can have enough torque for the hills and also enough speed (at 75volt)
also less reduction means gets less stress on all the Parts = more reliability
Chainline of the 219 Chain (second reduction):
most important - have to be parallel to the Belt. You can adjust this by the way you build your freewheeling-crankarm.
Every bike i builded with the smallblock kit needed a different spacing to get a good chainline.
You can space on the crankarm or you can space (a little) at the BB.
in the front, those 2 rings, i used to space 1-2.5mm on the BB-shell on one bike. there are still enough threads on the BB-cup to hold it tight.
here we used a spacer-disc made out a sprocket-adapter from sickbikeparts
Chain tension is also important. To set this, dont use the setting screw on the jackshaft. Use the setting screws under the motor. Once set, screw the lower sheets tight.
on this place, we welded the sheets togehter to stop them from moving. this works, but then you cant set chain tension anymore.
Other people drilled a hole through the overlaping lower sheets and put a crew through.
When you cant adjust the chaintension anymore, but want to make a change in the 2nd reduction-ratio, you will have a problem with chain-length.
first we just tried different sprocket-combination until we found a combination that gives the chain a "tight fit".
Later we realized that you just have to find one fitting reduction ratio.
So lets say you have a "tight fit" by using 14T (on Jackshaft) and a 80T sprocket (on Crankarm).
Now you want more reduction (more torque, lower speed) and still tight fit, you have to use a 83T on the Crankarm. So 3 tooth more or less will result in a longer/shorter chain with about the same chaintension.
If you want to make a different setting using a bigger sprocket on the jackshaft - lets say a 15T instead of the 14T - you would need a 81T on the Crankarm, and so on.
This "theory" is not mathematicaly proofen, but seems to work . Hope this will save you some hours trying to find possible combinations
An other way to get a better chain-tension on the 2nd reduction, is by adding a Chain-tensioner.
i builded it from a normal singlespeed-bikechaintensioner.
if your chain is only a little bit loose, this will help.
We had that one case where the chain was quite loose and running to a small 219 sprocket (12T), that + the tensioner caused the 219 Chain to get stiff and wears out the sprockets very fast. not even a good WD40 treatment made a differenz there.
new chain
gefickte chain...
...causes gefickte sprockets...
... so dont forget to set your chainline right and regulary oil your chain with WD40 will last your parts much longer.
FW-crankarm with the HD Freewheel, you need this when going higher power. Cheaper ACS starts to wobble fast when increasing power.
The HD-Freewheel isnt cheap ( 80 USD) but reliable. We tried it with the ACS (25 USD) but they fail at 3000W. there is also a UHD freewheel available now thats even stronger, but the HD does the job at 3000W
ISIS BB (bottom bracket).
this is a very reliable part, doesnt need upgrade
just make sure your BB-treads are cleen when screwing it in. Dont hurt the fine treads by screwing it in inclined... if you allready did, go to a bike-mech they have the cutting tool to fix this
3rd reduction:
the 3rd reduction or "final reduction" is from your FW-Crankarm to you bike-gears. We lazercutted the Crankarm-Plate from 4mm Stainless steel (3mm had be enough...) and used the sprockets with the 5 hole-patern.
they hold up, have no comparison to the original Crankarm.
Crank-Sprocket (Bike chain sprocket):
i like to use a 36T-40T Sprocket on the crankarm, for this size you can also find chain-guards from Downhillbikes. Also smaller sprocket sizes are more easy when you want to adjust your chainline more to the center of the bike (when using the bigger gears). Most Frames have limited space, in some cases its impossible to fit a big sprocket like a 48T.
Some of my friends like to use 44T or 48T, matter of taste...
chain-guards from Downhillbikes:
Bike-chain can drop when juming/landing, since i installed one, no more chaindrop.
Picture somewhere on page 1
Casette:
For the Casette, i use the cheapest sram or shimano, cassette 9 speed, its haevy and solid (the more expensive ones are usually lighter and less strong)
on those cheaper 9speed casettes, the smallest sprocket is usually 11T, biggest is 32-36T.
You will not drive at 3000W on the 11T, its to small, it will brake. I use only the 3 biggest gears, most of the time i use the biggest sprocket (lowest speed, highest torque). So i have setup the bike speed to around 40-45 km/h in the slowest gear, still enough torque for me... for now...
Bike-Chain.
As i use a 9x cassette, i also use the 9x Chain, same principle as the asette --> take the cheapest one
We also tried the 55 USD KMC-Ebkie-chain... the cheap SRAMs and Shimanos are more reliable at 3000W
Hub:
the DT-Swiss is our first choice, it have no pawls but axial ratchet. It can full power starts for long times.
On one Bike i have a Division Hub, thats one with pawls, and it holds 3500W now. On an other Bike, the hub (with pawls) failed at 2500W.
The DT Swiss hub on a friends bike have 4000 km now, looks still like new when we opened it.
Wheel/Tire:
we use a lot tires with this kit, so we like to use cheap DH-Tires second hand from Pro-Riders (at 80% profile they normaly change them)
Screws:
We replaced most of the screws with stainless steel-screws, locktight everything, use nordloch-discs and nylon nuts.
if i have forgot something, pleace write me and i will edit it.