Trampa E-MTB with Skatetrucks -Ultralight Build

[nowind]

After three Trampas with Channeltrucks i want to build one with the Skatetrucks.

My aim is to get as light as possible, i would like to use this Board in skateparks and for jumping.

This is the Board:
Trampa Holypro 15degree in 11Ply with Ultimate Trucks and Superstar Hubs.
http://www.trampaboards.com/15-holypro-trampa-deck-on-10mm-titanium-trucks-superstar-wheels-ratchet-bindings--024-mountainboard-p-12326.html?selector_id=11868&qty=1&nochange=1&show_me=1
View attachment 14


I added some green DohDoh Bushings for better steering.
http://www.trampaboards.com/green-doh-doh-bushings--over-sized-washers-set--93a-shore--soft-p-640.html


I will use the new Innova 7inch Street Tires.
http://www.trampaboards.com/innova-inline-street-tyres--7-inch-tyre-p-12772.html

compared to the really light Primo Alphas you will save 65 gramm per tire.


I started to machine some new Motormounts which fits direct on the 9.52mm Axle.


They get really light with less then 90gramms:


Compared to my latest Channeltruckmounts i can save about the half of the weight. For this board i will not use any braces.
View attachment 8

Mounted on the trucks:


The mounts are glued to the axle and also screwed, i had to spotface the axle with 1mm depth and 7mm diameter.
View attachment 4
View attachment 5

Redesigned the 60 thooth sprockets with bigger cutouts:



If you compare to the latest sprockets i can save nearly 30% :



Will keep you updated.

Hang Loose
Jenso

 

[torqueboards]

Looks awesome... Can't wait to see more EMTB stuff..

 

[okp]

dopeness ! just wondering how light you can go never heard about this slick new tires

 

[whitepony]

sexy looking forward to the finished product!

 

[SteveS]

LOVE the motor mounts!

 

[okp]

come on Jens ! we want to see the video of you riding in your skatepark... this is going to be a killer for sure.

 

[nowind]

Yeah (-;

Have to work on the Lipo and VESC Enclosure, cant use the UK Boxes again (-; You know it have to be lighter

 

[randyc1]

Nice machining work !


How thick are the motor mounts ?, what motors will you be using .?

 

[nowind]

The Mounts are on the thickest point 16mm and on the thinnest 6mm.

Not absolutely sure about the motors, depends on how stable the Skatetruck is.
But it will not be an Highspeed EMTB, i need more torque.

I start testing with 2 APS 6374 130KV 3200W. http://alienpowersystem.com/shop/brushless-motors/alien-6374-outrunner-brushless-motor-130kv-3200w/
I dont like the 10mm shaft, it will be a pain in the ass to fit the sprocket (-;
This would be 32kmh with the 7Inch wheels on 12S with the 1:6 Reduction.

 

[nowind]

Hey.

I get the motors and the tools for machining the keyway in the sprocket.
I normally use the SK3 motors with 8mm shaft, i´m using in this case 2 M4 setscrew at 90degree.

So the Alien comes with a 10mm shaft and a keyway.


I want to use a 10tooth sprocket, the hub is only 13mm. So the remaining restmaterial is only 1.5mm.
No room for the full height of the key, this would be 1.5mm.
I decidet to mill down the Keys from 3mm to 2.2mm. The Keyway in the sprocket is 0.75mm, in the Motorshaft 1.5mm.



I will use highstrengh Loctide to glue the sprocket to the shaft.
https://www.maedler.de/product/1643/1624/574/loctite-603-oeltolerantes-fuegeprodukt
Used this before for the Pulleys from the Beltdrive, holds up really nice.





Hang Loose
Jenso

 

[oatnet]

Very cool.

-JD

 

[Vanarian]

That's ultra clean and shiny build like this that hook people into wanting to try new stuffs, I'd love to get a board like this

 

[Rikobonito]

like a piece of art ... AMAZING WORK !! Like the design

(I will googletranslate this to understand everything cause it seams to be necessary :lol: )

 

[nowind]

Hey.

After a while where i cant decide how to mount the electronics in a lighter/different way then in my other build, i decidet to make a test mockup to get this baby running.

So i heatshrinked the Vesc´s and mount my UK-308, with lightened Lid (-; ...


Its not shiny but it will let me know how the new parts/setup will work

So let me tell you that the mainproblem with my Lightweight Board is that i´m not a lightweighted Rider

I choose the thinnest deck from the 15Degree Holypro´s, its really to flexy for my 85KG.
You can see how the decks flex all the way down by a little JumpIn from the edge of the MiniRamp:

I have to use a Flexbridge again, maybe i split it to mount the Battery between it.

I choose the lightest Trucks with the 9.52mm Titaniumaxle, i bent them by one of mine Testruns.




Trampa tolds you about on they´re Shoppage that this kind of Axles should be used for younger/lighter Riders or Kitelandboarder who will have the Kite for softer Landings.
The Problem is known and its communicated clearly on the Shoppage, but i dont listened
Trampa has another kind of Skatetruck Axle, its a 12mm Hollowsteel Axle, i will be stronger then the 9.52mm one. I will give it a try.

I´m not willed to give up this build to fast, because its really nice to have a board with less then 10KG for jumping.
Compared to my Chaindrive-V2 Board i save more then 2.5KG. Thats a lot if you want to get the Board up in the Air.
From standstill i can easily spin it around 270degree, my other Boards only about 180degree.

One more thing i ´m not happy with is the sound of the APS Motors.
I never used anything else then the SK3´s, so i dont have much to compare.
And maybe the Problem is that i use them on 12S, on the APS Page are they limited by 10S.
The Power is really good, the Torque is amazing sick.
But by half to full throttle under load the scream like they will explode in seconds... They dont do but its a really uncommon sound to me.
I already testet it with 10S Lipo, it sound not as bad as with 12S but still not nice.

Maybe someone here has these Motors too and can comment ?

Hang Loose
Jenso

 

[Trampa]

As Jens stated: Ultimate Trucks are not the choice for 85Kg riders + 10KG Board in a skate park. They are meant to be used by kite boarders on softer surfaces, lower tire pressure, landing their board with some kite support. Lets see how the 12 hollow perform.
10KG e-MTB setups are definitely interesting. The Flex bridge should give you a lot more stiffness, especially, when mounted with 5mm spacers. Use 4 to 6 bolts to mount them.

Frank

 

[okp]

thanks for the info, how are performing these tires ?

 

[nowind]

I like the tires.
They had tons of grip on concrete!
But to use them on loose gravel its fun too.

I hit a glass shard or something, only the outside rubber gets a cut. The belt is still ok.
View attachment 5

I think they are really durable, and of course they are light

I started to fit the 13PLY Flexbridge to the Deck.
I decided to cut it into two Pieces, i want to mount the battery between!
I machined the outside and the cutouts for the velcro Tape:

View attachment 2

If i had choose the next thicker Deck, wich has 150 gramms more, i had saved some gramms:


I mountet each Flexbridge with 3 X M6 Countersunk Bolts, also used Loctide 401 to glue it in place.


Hang Loose
Jenso

 

[nowind]

Hi.

For some reasons i decidet to reduce the operating Voltage to 10S Lipo.
-i hope the APS Motors will be thankfull (-;
-i save about 350gramms of wheight
-i got alot of these 10S Batteries from my E-Drift Trike Builds


Covered it in new black shrinktube:


Mount it with velcrostraps, also put some velcro on the underside:



The new type of fixing the battery will hopefully compensate the addet wheight of the Hollowsteel Axles so that the hole build will stay under 10KG.

I have to change the gearing to a 11 or 12thooth Motorsprocket, or use a good old Turnigy SK3- 149/168KV 8)

Hang Loose
Jenso

 

[whitepony]

nice idea, looks very clean and guess your flex is working out now

 

[Trampa]

Hi Jens, if you ad some spacers (could be a set of big washers) underneath the Flex bridges, you would ad a lot of stiffness. We never chopped them in half yet. I would put a thick bit of foam underneath the Battery. This will swallow some of the flex, so that the batteries don't get to much tension from flexing. Nice built so far Jens! The 12 hollow trucks will perform much better. If you end up at 10.5 Kg it's not tragic. Most important is the distribution of the weight, rather than the total weight. Your battery sits in the center of the board and won't affect the ability to spin the board around. As long as you cut down weight at the very edge (trucks, tires, mounts, motors etc.) you will have a very agile setup.

Frank

 

[Rikobonito]

Hi Jenso !!
What a conception !!! hopefully for us you test it hard !
I have the 3.2kW 170kv APS motor on my build like you know. VESC 1.14 motor 80A startup boost 0.03 to 0.05 (in video)

Maybe you seen some of my video too ?
here


I notice the difference to before on my e-sk8
[youtube]shL1H-r_mss[/youtube]
[youtube]TPcN76FxFjg[/youtube]
[youtube]azjnP0AVQcY[/youtube]
[youtube]gBdjYrNf0Qg[/youtube]
sorry with the sk3 test I have a bad esc
(I could edit and delete the video if you want :wink: )

hope it could help you!
Good continuation & good ride 8)

 

[nowind]

nice idea, looks very clean and guess your flex is working out now

Thank you, yes the stiffness is now better. Will seen soon if its enough for my bodyweight :?

Hi Jens, if you ad some spacers (could be a set of big washers) underneath the Flex bridges, you would ad a lot of stiffness. We never chopped them in half yet. I would put a thick bit of foam underneath the Battery. This will swallow some of the flex, so that the batteries don't get to much tension from flexing. Nice built so far Jens! The 12 hollow trucks will perform much better. If you end up at 10.5 Kg it's not tragic. Most important is the distribution of the weight, rather than the total weight. Your battery sits in the center of the board and won't affect the ability to spin the board around. As long as you cut down weight at the very edge (trucks, tires, mounts, motors etc.) you will have a very agile setup.

Frank

Do i get you right Frank that you suggest to put spacer between the Deck and the flexbridge? Why its better?
Yes i think the weight distribution is more important then the overall weight, but the 10KG are a "magical border" :lol:

Hi Jenso !!
What a conception !!! hopefully for us you test it hard !
I have the 3.2kW 170kv APS motor on my build like you know. VESC 1.14 motor 80A startup boost 0.03 to 0.05 (in video)

Maybe you seen some of my video too ?
here

hope it could help you!
Good continuation & good ride 8)

Hey. Thanks for the videos. That helps me!
You got a similar sound when you hit full throttle. This high frequency also appears shortly by releasing from full throttle!
Under load its being much louder by my setup.
After your videos i know now thats the normal APS Motor sound (-; nothing to worrie about !

Hang Loose
Jenso

 

[Trampa]

The Trampa Flex Bridge stiffens up your deck in the very center, where the bending momentum is is the greatest. If you mount the bridge directly onto the deck, your deck is roughly twice as thick in this area. If you ad some spacers, you increase the thickness further. On impacts the original deck is being stretched on its lower side, while the flex bridge is being compresses on its upper side.
It's like a double T steel beam, the further the upper and lower beam are spaced apart, the more loads it can take. The magic word is "constructive hight". The further you space the flex bridge of the deck, the more do your screws suffer! You could have saved the milling job, by simply placing two or three big washers underneath the bridge. You would not have weakened the bridge + gained additional strength. Next time....

Frank