Electric downhill/freeride bike

[Ratking]

Electric downhill/freeride bike

Hello
I've had this idea for a long time, and because of you and this informing forum the plans are coming to a start. My idea is to use a frame and geometry from a Spesialized big hit and turn that into a frame that contains all the components necessary to have a fun and light and nimble bike. I've had my share of fun with two and four stroke bikes, but this time I want a silent and stealth bike that can be used without bothering anybody. Off course there are some people that gets offended anyhow, but I cant please everyone.
As I said, light, stealth and nimble is my goal, the bike itself is 20 kg originally and I would like to get it under 30 kg complete. This is not a commute build but rather a have-fun-from-a-to-b project. If I get 15 km range and a light bike, thats more than enough. I thought a lot about how I should build this in order to met my goal, and heres a list over my expectations:

Light weight >30 kg

Stealth, would like it to blend in as much as possible.

Strength, should be as strong as the original frame.

Power, should be able to give me a hard time not flipping over.

Speed, would like to get 60 km/h with descent acceleration

Closed frame, no open wiring or things that people can steal or break. I need this bike to be bulletproof and tough

Bike, I want this to be a bike, not a motorcycle. So there will no other parts than a bigger frame. And thats just to contain all the parts from wether and people.

Finish, there will be no tape, strips or any other shady solutions. Thats one of the ugliest things I know about. This will be a bike I can enjoy without getting uppsett because its ugly.

And there I am. Lots of hope and expectation, but I am certain that I can make this if I have enough patience and equipment. I'll work in a work shop that has all the needed machines, I just need to learn how to use them.

I want to explain why and how I want the frame to be build. I tried to make space for the controller, batteries and gearbox/motor on a dh frame, but there where no way that it would fit ever. And if I could make it fit, It would have been a terrible sight. So I figured that I could build a clone of the dh frame but without any tubes but more like the stealth bike. I don't like to copy anyone, so I don't use any of their design nor measurement, I guess I'm just using the concept. I'm going to use 2mm and 3mm aluminum for the frame with lots strengthening profiles. I haven't done this before, so it learning by doing. If anyone have any input on how to build a strong frame from sheets, you are welcome tell.
I made a quick drawing in Sketcup. This is not the final design, I made some changes, but my hard drive just stopped working. And thats without any backup ;( . So I have to make every drawing from scratch again.

Big hit ramme3.jpg

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This bike will be build around:

Spesialized Big Hit DH bike
Turnigy 80-100-B 130K
Thomson right side gear head
36 fet controller from Lyen
Dual freewheel from sickbike
Either 16s2p or 18s2p 5aH lipo fro Hk.

I will have two freewheels on the crank and just a normal sprocket at the output from the gearhead. That way I don't need to drag the chain around when I use the bike normally. I got the idea from another member. I hope the setup is up to the task. I guess I will find that out sooner or lather. I've sourced out a cnc gearhed that have a reduction of 5 to 1. Since I don't want to push the bearings on the motor higher than 5 to 6k rpm this gearhead is good, but I should have more reduction. I'm shooting at 20 to 1 so the start from zero won't be so hard on the controller. Thats why I will use a 10t sprocket on the output shaft to a 48t on the crank. Thats 5 to 1+ 4,8 to 1. This is 24 to 1 in reduction. From the crank to the rear wheel I'l use a 36 or 30t sprocket. So the final reduction will be around 24 or so.

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I will take pictures from the build and hopefully some smarter guys than me will give me some input when they see something that could be made bether or is just plain stupid.
Thanks
Ratking

[Ratking]

I've taken som pictures of the bike and a spare frame that I will use when I make jig to weld the parts together.

[bzhwindtalker]

that's a freat project! best luck with building your custom frame!
I will folow your build updates

[boostjuice]

I'm very excited about this project! You are following a design type that I have often thought about, but never felt I could actually build without learning to tig weld aluminium as well as gaining access to good welding gear including a massive oven for post-weld heat treating. If you can pull this off you are a lucky guy!

[Ratking]

I am lucky indeed, but I don't have a oven to treat the welds, I just hope I can make it strong enough without. Since I already got almost all the expensive parts I just have to try. Even if I just have some hours with fun its worth it, because of everything I've learned by doing it myself.

[kfong]

Nice approach Ratking, I look forward to the build. I might do something similar one day when I learn to weld or perhaps an all carbon build if I don't.

[Ratking]

I haven't been able to make any of the parts to the frame yet. I think the most important part of the build is to think trough every detail before doing anything physical. I'll start with making the seat, fork and chocks mount in aluminum so when I have build the jig and have all the measurements its just to bolt them down and weld.

I hope that this will work as planned, and this may be to inspiration for fellow riders that want a light, powerful ebike that can be used as a bike when needed(when the police is around ) and as a fun toy all other time. Its off course a bit expensive, still better than all other alternatives I've seen so far. But thats just my thoughts

[Ratking]

I finaly got time to mate the gearhead to the motor. I made an adapter out of 60mmx60mm aluminum. It's made so that the motor can be used in its original form. So WHEN I blow the motor its easy to swap for a new one.

I did not have enough time to start on the frame, but that dosent matter since I still have some details left to sort out.

Heres some pictures of todays work

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[mdd0127]

Beautiful work!!!

I'm building something somewhat similar. I just finished up mounting the solar panels on my shop so the actual build starts tomorrow! It's neat to see someone really digging in to a non-hub, high powered off-road build!

I'm going to sound like a broken record again and recommend some type of slipper clutch just because I want to see your bike on the trails more than on the bench.

Also, we may be finishing our frames close to the same time. Mine is made from a little thicker stock but it's all 6061 so I might have some extra oven space available when it comes time to heat treat. They charge you for the whole oven whether it's full of not so if things work out right time wise, maybe we can share the oven or something. Just throwing it out there.

[boostjuice]

You got the skillz and the toolz.

It appears that you could make the adapter thinner however. I realise you want to be able to swap a new motor in without much fuss, but cutting the shaft length down to allow you to bring the gearhead>motor mating surfaces closer would save you some precious space inside your monocoque frame. It's not like cutting a shaft down takes longer than a few minutes. Just a suggestion anyway.

What is the gearhead part number? and how much did it cost?

[Ratking]

Beautiful work!!!

I'm building something somewhat similar. I just finished up mounting the solar panels on my shop so the actual build starts tomorrow! It's neat to see someone really digging in to a non-hub, high powered off-road build!

I'm going to sound like a broken record again and recommend some type of slipper clutch just because I want to see your bike on the trails more than on the bench.

Also, we may be finishing our frames close to the same time. Mine is made from a little thicker stock but it's all 6061 so I might have some extra oven space available when it comes time to heat treat. They charge you for the whole oven whether it's full of not so if things work out right time wise, maybe we can share the oven or something. Just throwing it out there.

Hi!

I've thought about having a slipper clutch, but I've want to try without first. I'll just start out with a very low phase current limit, and hope that nothing blows. I would assume that a 36 fet controller handles some current. Also, I dont have any need to go from a dead stopp either. If I don't get the desired acceleration then I try to build some sort of clutch.

How thick aluminum will you use? I would love to get my frame heat treated, but I'm from Norway, and the shipping alone is too much. Thank you for the offer thou

Ratking

[Ratking]

You got the skillz and the toolz.

It appears that you could make the adapter thinner however. I realise you want to be able to swap a new motor in without much fuss, but cutting the shaft length down to allow you to bring the gearhead>motor mating surfaces closer would save you some precious space inside your monocoque frame. It's not like cutting a shaft down takes longer than a few minutes. Just a suggestion anyway.

What is the gearhead part number? and how much did it cost?

Thanks, that gives me motivation to build

As you say, its not hard to cut the shaft, when I made the part it just made sense to keep it as it, but since I still need to cut the shaft on the other end of the motor it would not be that much work. I'll think about it

I'll check the part number when I get home. I bought it off ebay, haven't seen any of those there for a wile

[mdd0127]

Beautiful work!!!

How thick aluminum will you use? I would love to get my frame heat treated, but I'm from Norway, and the shipping alone is too much. Thank you for the offer thou

Ratking

I'm using 4.5mm and 6.5mm plate, 13mm od , 4mm wall tubing. It's going to be a beast. I didn't know you were in Norway but the offer stands. The best quote I've found so far has been $300US for solution heat treat and $300 for artificial aging/stress relief.

About the slipper clutch. It would just make it more idiot proof.....not to imply in any way that you're an idiot , just if someone else wanted to ride it you wouldn't have to give them a half hour training session about when to hit the juice and how much. Not only will it help your gearbox survive, the motor, controller, batteries... everything will just be more reliable with a little slip in there.

[Ratking]

I'm using 4.5mm and 6.5mm plate, 13mm od , 4mm wall tubing. It's going to be a beast. I didn't know you were in Norway but the offer stands. The best quote I've found so far has been $300US for solution heat treat and $300 for artificial aging/stress relief.

About the slipper clutch. It would just make it more idiot proof.....not to imply in any way that you're an idiot , just if someone else wanted to ride it you wouldn't have to give them a half hour training session about when to hit the juice and how much. Not only will it help your gearbox survive, the motor, controller, batteries... everything will just be more reliable with a little slip in there.

I absolutely see your point regarding the clutch, but I am aiming towards a slick and compact design, I don't think I have enough space for a clutch unless I really need one. I'm totally aware of the problem when other people try the bike, so I guess I just have to use it myself

I don't mean to be stubborn, but direct drive is one of the nice things with electric motor, I wouldn't take that away if it weren't necessary.
That said, this is my first ev build, so I may learn the hard way

[Ratking]

You got the skillz and the toolz.

It appears that you could make the adapter thinner however. I realise you want to be able to swap a new motor in without much fuss, but cutting the shaft length down to allow you to bring the gearhead>motor mating surfaces closer would save you some precious space inside your monocoque frame. It's not like cutting a shaft down takes longer than a few minutes. Just a suggestion anyway.

What is the gearhead part number? and how much did it cost?

Heres the part number; 32-313902-8132 Model; DTRS060-005P

[recumpence]

I concur on the clutch. 2 of my 3 bikes use them. They are fantastic if setup right and really add reliability to a system. That being said, if you have a stout enough setup, you will not need it.

Matt

[Ratking]

That remain to bee seen then . I don't have a clue yet, but I'm goning to find that out. I don't need to start from a dead stopp anyway, that seems to be the hardest effort for all the components in the drivetrain/setup

[mdd0127]

On an off road bike you can also have situations where extreme shock loading is possible regardless of rolling starts. Say you come off a jump a little nose heavy, you can pin the throttle to bring the front wheel back up mid air. When you land though, if you don't get off the power in time, the drive train will be going much faster than actual speed. Even running over little bumps while accelerating causes thousands of tiny jolts every time the rear tire leaves the ground. LOTS of forces to think about in bike design.

It's not just coincidence that every road going vehicle uses some kind of disconnect or soft coupling between the engine and transmission.

[Ratking]

You got the skillz and the toolz.

It appears that you could make the adapter thinner however. I realise you want to be able to swap a new motor in without much fuss, but cutting the shaft length down to allow you to bring the gearhead>motor mating surfaces closer would save you some precious space inside your monocoque frame. It's not like cutting a shaft down takes longer than a few minutes. Just a suggestion anyway.

What is the gearhead part number? and how much did it cost?

boostjuice, I couldn't get your idea of making the adapter/spacer thinner out of my head so I have decided to give it another shot. Since I need to cut away the other end of the shaft anyway there's no reason to not make it as compact as possible and after all, it will be lighter also. I measured the complete motor/adapter/gearhead at 262mm as is, with the new adapter and shorter axle it will be shocking 235 mm . Now that's a improvement I can live with. The reason That I will make such improvement is because I will incorporate the motor's mountplate t the adapter and just take the original one of. That way both the motor and adapter is made shorter, thus I win alot of space

After measuring a bit I made a drawing in sketcup, this is actually what I will make next weekend. There will be no room for errors, but it will make more space in the frame for batteries.
Do anyone know why some of the pictures just are shown as links and not as tumbnails?

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[Ratking]

I concur on the clutch. 2 of my 3 bikes use them. They are fantastic if setup right and really add reliability to a system. That being said, if you have a stout enough setup, you will not need it.

Matt

I'm not against one, just afraid that my bike will be thicker where it should not be, between the legs . Do you know how tick a clutch will bee?
Any way possible to make it fit a 16mm shaft?

[Ratking]

On an off road bike you can also have situations where extreme shock loading is possible regardless of rolling starts. Say you come off a jump a little nose heavy, you can pin the throttle to bring the front wheel back up mid air. When you land though, if you don't get off the power in time, the drive train will be going much faster than actual speed. Even running over little bumps while accelerating causes thousands of tiny jolts every time the rear tire leaves the ground. LOTS of forces to think about in bike design.

It's not just coincidence that every road going vehicle uses some kind of disconnect or soft coupling between the engine and transmission.

Thank you for pointing that out, I have to look into what kind of options I have for my setup. I don't doubt that something will break as is.

[Ratking]

Hello guys

I've been making a rough estimate of the cost to make this bike a reality and that is not a pretty sight. Here's my list containing what I feel I would have to have in order to have a fully usable bike.

Batteries and charger

Quantity Stock Product description Price Weight
OK Z50004S-20 - ZIPPY Flightmax 5000mAh 4S1P 20C $395.88 7140
OK T-20PS - Turnigy T-20Pro Quality 16A Power Supply.. $74.97 2337
OK HKB610A - HobbyKing ECO6-10 200W 10A 6S Bal/Dis/Cy.. $119.97 2091
OK BOX-379g - Extra Length Cardboard Box and Packing 3.. $0.00 379
Total: $590.82 11947g

And here's the parts from sick bike parts:

Bottom Bracket Cartridge Tool (splined)
$9.95
Bottom Bracket Cartridge 153 mm
$17.95
Bottom Bracket Cartridge 206mm
$21.91
CHAIN - BIKE SPEED- KMC 8X-CHAIN
$16.99
Chain Breaker
$9.95
Crank Removal Tool
$8.95
Freewheel Adapter
$13.95
Freewheel Removal Tool for HD freewheel
$10.95
Chainring - Freewheel - 30 Tooth
$6.95
Chainring - Freewheel - 36 Tooth
$7.95
Chainring - Freewheel - 44 Tooth
$9.95
Chainring - Freewheel - 48 Tooth w/chain guard
$15.95
Cranks - Freewheel Crank Set
$22.95
Front Freewheel - Heavy Duty
$131.90
Kill Button Switch
$3.59


Sub-Total: $309.84

Controller 36 fet with 4110 fets 250$ pluss throttle and misc

There are several other items I need to buy as well so the final amount with shipping will be at least 1700$ in just parts. And that's if I can make the rest for free Can someone chime in with some wise words? I don't want to back out on this so if anyone can give me some advices why I should not now is the time

I will start to make a complete frame and take all the parts from my dh bike to see if my self made frame is up to the task. If not, why bother buying parts for near 2k$?

[bandaro]

awesome, will be watching this one, i also would be interested to know where that gearbox that you got bolted to the motor was from, and what it can stand up to.

as for the prices, you got the heavy duty front freewheel for $131, I got a white industries freewheel, heavy duty one from sick bike parts (uncut gears, just 5 holes in it for bolts) for $60, what one were you looking at?

[Andje]

Awesome plan, can't wait to see it.
Im a noob on here with so take my advice with a grain of salt I've prbly read about... 40% of ES i figure.
Gearboxes have been tried by others, things like gb off of angle grinders or other power tools, cyclone engines and hub motors have planetaries, i know someone tried the banebots gearbox, and someone else has found success with a much heavier tranny designed for motorbikes.
Basically, they all report eventual failure of the internal gb gears, usually they are planetary, i'm not sure if yours is worm screw or something. Someone on here went so far as to investigate replacement internal gears that might be stronger, but as far as i know the eventual report was that the size of gear that fits in a typical ebike sized gearbox is quite weak and prone to stripping with the power often attached to them. I dont think anyone has tried your specific gb, but if you can find all the stats about it and post them with your motor/power stats i bet someone on here will do all the math for you, it's the kind of thing that happens all the time.
Having read a lot about stripping gearbox internals, i would absolutely include a slipper clutch in such a build in an attempt to prolong the life of my expensive gb Msg Recumpence, if you search his builds you can find pictures of his slipper clutch mounted on a bike, from memory i think it's about 2 inches across?

[Ratking]

Awesome plan, can't wait to see it.
Im a noob on here with so take my advice with a grain of salt I've prbly read about... 40% of ES i figure.
Gearboxes have been tried by others, things like gb off of angle grinders or other power tools, cyclone engines and hub motors have planetaries, i know someone tried the banebots gearbox, and someone else has found success with a much heavier tranny designed for motorbikes.
Basically, they all report eventual failure of the internal gb gears, usually they are planetary, i'm not sure if yours is worm screw or something. Someone on here went so far as to investigate replacement internal gears that might be stronger, but as far as i know the eventual report was that the size of gear that fits in a typical ebike sized gearbox is quite weak and prone to stripping with the power often attached to them. I dont think anyone has tried your specific gb, but if you can find all the stats about it and post them with your motor/power stats i bet someone on here will do all the math for you, it's the kind of thing that happens all the time.
Having read a lot about stripping gearbox internals, i would absolutely include a slipper clutch in such a build in an attempt to prolong the life of my expensive gb Msg Recumpence, if you search his builds you can find pictures of his slipper clutch mounted on a bike, from memory i think it's about 2 inches across?

Hello

I've researched and thought about this for a while now, and maybe a toque limiter is the way to go for a more robust and smoother operating vehicle. More to come about this when I know if it could fit my needs.

I've also made the new adapter, and it much better than the first one. I will post some pictures when I get the camera.