lightweight eMTB paper build - options

DIY Builds
#22

typically a tube is less likely to bend than a solid axle but who can ever tell with Trampa.

1 Like
#23

Err, I’m going to need a citation on that one. Did you leave off the “of the same mass” part of that expression?

Bc I find it hard to believe that with a hollow shaft and a solid shaft of the same OD, same material / density.

9 Likes
#24

Get the infinity trucks and don’t look back.
For e-mtb all the other trampa trucks just add on cost but no real value. IMO

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#25

If you’re not married to gear drive, take a look at the Trampa OBD. That’s what I’m rocking daily right now and I absolutely love it.

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#26

Not married, but open belts seem like they’re begging for rocks/mud/snow to snap. Have you had any issues with yours?

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#27

Oh shit, I was just reading your Light White build (again)! I didn’t realize you had also picked up a Bro. How do you like jumping/thrashing between the two?

I’m torn, bc I love the idea of flex like a snowboard, but the Bro gets great reviews and is 1kg lighter.

#28

I‘m not really riding my trampas after I got used to the Bro anymore.
I still have trampa decks on my quad and carver boards, but my main boards are with Bro decks.

Even though the Bro is a stiff deck, there is still a good amount of flex and a really nice pop in it.
That’s jumping of the small curb with the stiff flex Bro deck (I’m about 85-90kg with gear)

image
image1125×621 131 KB

4 Likes
#29

Damn, that says a lot. That good eh?

I was considering the med flex Bro, but I’m about 90kg, so that may bottom out if your photo is a reliable reference.

#30

I thought it would be risky but haven’t had a single issue to be honest. After riding through some super heavy grass for a few hours I took little compressed bits off the tensioner but that takes a second to brush off.

I also ran open belt drives on my previous mountainboard - I think it’s quite an underrated option.

1 Like
#31

Trampa decks flex more good for a softer ride but will bottom out on a jumper witch is super bad. Bindings it’s a obvious choice. Interested to see we’re you go in hubs tho

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#32

Definitely stiff flex for e-mtbing.
There is also the weight of the battery exactly in the center, so the deck will flex more like it would for analog riding only.

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#33

Different people different opinions I guess.
I have seen too many broken belts and in my opinion it’s hard to get a good tension in the beld without idler, but with idler you will get a shitty freeroll, so there is that.

I personally would always prefer chains over belts for mountainboarding, but chains do come with some downsides as well. They are more loud and maybe a bit more dirty.

5 Likes
#34

Absolutely - and different riding style means different individual needs.

The Trampa OBD can be purchased with 20mm belts, which we all know don’t last forever but they’re reasonably hard to snap and easy to swap out. The reason I recommended the Trampa OBD over anything else is because you’ve got the idler but you’ve also got a motor plate that can be adjusted for with a screw to get exactly the right tension while the rest of the system is already assembled. Of course, with the right tension comes a reasonable amount of freeroll.

I can support that - it was more the idea of not necessarily needing gear drive that I wanted to pose. I think it can add unnecessary weight depending on your riding style.

1 Like
#35
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#36

Not rocks, typically snow and sometimes mud. I’ve had a lot of rock incidents and never snapped a belt from them, even had sharp rocks penetrate all the way through the belt.

But then certain kinds of snow (not all snow) and you can’t go ten meters without popping a belt. Other kinds of snow never do a single bad thing.

If you don’t ride in snow, then obviously don’t worry about that.

2 Likes
#37

What’s the heaviest battery you can get away with on a jump board? Any opinions?

12s4p 21700 is about 4kg (9 lbs, 15.5Wh * 48 = 744Wh)
12s3p 21700 is about 3kg (6.6 lbs)
12s2p 21700 is about 2kg (4.4 lbs)
2x 12Ah 6s1p lipos is 3.2 to 3.4 kg (7.0-7.5 lbs, 532 Wh)
2x 10Ah 6s1p lipos is 2.6 kg (5.7 lbs, 440 Wh)

strangely not a huge difference in weight between lipo pouches and li-ion cylinders, but maybe the lipo zealots use smaller packs :man_shrugging:

2 Likes
#38

Lipos just make weight saving sense if you go with a low range pack.
12s 5-6Ah is where it’s at.
I can just recommend that setup if you get some good true high C rated packs.
So much fun, so light, close to no sag, but range is for the ass

1 Like
#39

Great pt, great pt.

I’m leaning towards 2x 6s 4.5Ah for lightweight and ‘flight ready’

Then a 12s4p 21700 P42A pack for non-jumping. Same BMS if I add some connectors for swapping.

Edit:
US - Battery Flight Restrictions - FAA

  • Spare batteries must be in carry-on luggage only
  • Battery terminals (usually the ends) must be protected from short circuit (i.e., the terminals must not come in contact with other metal). Methods include: leaving the batteries in their retail packaging, covering battery terminals with tape, using a battery case, using a battery sleeve in a camera bag, or putting them snugly in a plastic bag or protective pouch.
  • Lithium ion (rechargeable) batteries are limited to a rating of 100 watt hours (Wh) per battery.
  • With airline approval, passengers may also carry up to two spare larger lithium ion batteries (101–160 Wh)
  • Quantity limits: None for most batteries

United States Domestic Airlines Lithium Battery Policy

Airline Battery Packs & Loose Batteries (100 Watt hours or less) Battery Installed in Equipment (Laptop, phone, tablet, etc.) Large Battery Packs Smart Bags
Alaska Carry-on only, No specified quantity Carry on or checked 2 spares allowed in 100-160 Wh range, carryon only Lithium battery must be removed
American Airlines Carry-on only, “unlimited quantity” 2 of each device and 2 spare batteries per device for personal use. Carry-on only 2 spares allowed in 100-160 Wh range, carry on only with “airline approval” No policy
Delta Carry-on only, no specified quantity. Spares must be packed separately in carry-on as well. 160Wh per device can be checked or carried on, no specified quantity No more than (2) spares of 100-160Wh No policy
Frontier Carry-on only, limited to (2) batteries. Must be packed separately. Lithium metal max 2g, lithium ion max 8g Checked only Lithium metal max 2g, lithium ion max 8g No Policy
JetBlue Carry-on only, no specified quantity Carry-on or checked 1 spare max at 300Wh or 2 spares maxed at 160Wh each in carry on. Must notify flight crew No Policy
Southwest Carry-on only. Limit 20 per person Not specified Not specified Loose batteries can be “integrated” into smart bags
United Must be packed individually, not specified carry-on or checked 100Wh max in carry-on or checked bag Separately packed 100-160Wh allowed in carry on No Policy

Theoretically you could carry lipo packs that have been discharged to 3.0V per cell. Then your actual Wh would be lower. But somehow I doubt TSA would care about this nuance…

#40

@Andy87 looking at motors…

  • Maytech 6374 are 830g ea
  • Maytech 6365 are 760g ea
  • Maytech 6355 are 605g ea
  • Flipsky 6354 are 560g ea

What do you think is the smallest motor you could get away with?

#41

Hard to say without knowing your weight and your goals.
Dual 6355 could be good enough if you are light or don’t need too much torque.

1 Like