Lycan 3GDrive - Testing

Information about the drive

This thread has been a long time coming, and so has the testing…


  • 3GD means 3 gear drive - the drive has 3 gears…

  • 2.42 ratio with options to adjust ratio easily.

  • $250 (dual drive) retail (comes with extra gears)

  • Possible budget 3GD with a 3d printed case

  • Modular of course


Material Selections and Technical Information

Information as it stands:


All gears are produced traditionally using a hobbing machine.

  • Driven Gear - C45 Steel
  • Idler - PA6 Nylon but also considering steel - with an integrated 6200-ZZ SKF Bearing
  • Motor gear - C45 Steel with 3x m3 grubscrews and keyway , one grubscrew above the keyway. 8mm bore

CNC Components

6061 T6 Aluminium:

  • Gearbox case
  • Gear plate
  • Wheel Adapters
  • Clamps


V-Rings - Yet to decide what size.


Current Ratio - 2.42 with adjustable ratios planned for the future (2.62,2.83)


This drive was designed specifically for all types of street setups, I am working towards a drive that is compatible with all popular trucks and wheels on the market. These include:


  • Surfrodz TKP
  • HexXL is in the works
  • Surfrodz RKP (pressfit clamp) - use 90mm shoulder bolts
  • TB 218mm - Clamp is being designed

Wheels - Compatible Wheels 78-110mm urethane wheels

  • ABEC Core

  • Kegel Core

  • Cobra Core - Venom Mach 1 Wheels 78mm 6.5mm clearance :crazy_face:

  • Seismic Speed Vent Core - Ill be riding on this, likely that I am the only person who rides these wheels so keeping that part 3d printed for the time being.

I had fun making this GIF :joy:


Testing price $195 - I have already selected my testers right now (had a lot of PMs already about testing, it was hard to select 4 other people to test. @mmaner was obviously my first choice

$250 Retail

Full drive with no compromises on quality, aluminium case and 2 spare idler gears in case any break

Options to make a budget version for the futur

My plan is to supply gears drives with extra gears, so spare idlers in this case.


How wide is this damn thing?

Around the same width as a 15mm belt drive, with plans to save a few mm in the future

Can replacement gears be purchased

Yes of course

Anodising options?

Likely that I will keep the whole thing black. Testing units will be raw for the most part.

Benefits of the 3GD

  1. Wheel clearance - You are given the opportunity to use smallers wheels or have better wheel clearance, something you cannot achieve with other 2 gear urethane drives
  • TB 110ms 22mm~
  • 107mms 20.5mm~
  • 85mm wheels 10mm~
  • 97mm wheels 15.5mm~
  1. You can mount these drives as you would with a belt drive, as narrow as you want and in either direction. Something that cannot be done with other gear drives on the market because of motors colliding with kingpins and bushing seats.

  2. Theory - The idler acts like fuse - more to be explained later

Drawbacks of the 3GD?

    1. Additional parts that are prone to failure
    1. Higher cost

Can this work with Bergmeisters or other pneumatics? -

Yes but the ratio might not be ideal, I’d refer you to my all terrain gear drive instead. I will make a thread for that too.


The mounting plate

The case

Clamps - Pressfit Surf Rodz, two grub screws for additional security, especially for TKP



To do list

  • Design a nice TKP and Caliber 218mm clamp

  • Machine Kegel adapters

  • Try out different seals

  • Ride the damn thing - I will be riding with a 10S2P 30T , 177MM TKP, Seismic Speed Vent, Single SK3 6374 140KV

  • Try out different materials for the idler

  • Play around with different types of fastners


Beautiful product! That price is sweet too. I don’t even have a urethane board but this is making me consider…

I’m going to have an extra set of surfrodz too :thinking:


2 questions about it that others will ask at some point.

  1. do you need to lube the o-ring to maintain a seal? Or is it already good enough.

  2. what sort of maintenance do these require? Like grease and whatnot. Is there a specific kind you recomend or sell?

1 other question, will you go to helical gears at some point? I know they mesh smoother and are slightly quieter, but the cost can be absurd


These gears look sick dude. Nice job!!!


What kind of grease would you suggest using and when do u expect it to go retail

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Been waiting for these, and the AT ones. Definitely going to be my first gear drives.


Giggity. Nice drives and price! Gonna have to get me some of these.

For a name, Giggity drives?


“Moonage A Trois” Drive. Way better name. Got that hot, greasy 3 way gear on gear on gear action. Giggity. :dango:


These look pretty sweet! What is the all up weight?

Out of curiosity, what is the diametric pitch (or pitch diameter for metric) and face width of the nylon idlers? I ran some calculations with a 55mm diameter 10 wide 1 module wheel gear and the safety factor wasn’t even close to 1. It was like .75, and those idlers are probably 1/2 the diameter I think.

That was with a 70A sk3 with 3 N-m of torque at peak, though, which nobody will probably ever reach. I like the idea of a mechanical fuse but I personally wouldn’t want the gears to ever break if possible


Nah the name should be “3 geared donkey”


rekon you could make me one to fit onto evolve supercarves? I’ve got a build coming up that would beautifully use these


And also of curiosity, what method did you use to dimension it? I did a while ago for some comercial gear drive, don’t remember whose and the safety factor was also way down, but we have the gear drives running around without problems


The issue isn’t larger gears, like on AT boards, but smaller gears with narrow face widths made of plastic are exceptionally weak. Metal gears gave no problem whatsoever for this application and even a lower alloy aluminum I tested returned a safety factor of ~2.6 Realistically, we don’t stress out motors to their maximum torque capacities of around 3N-m for something like the 6374 SK3 anyway.

The process of finding the safety factor isn’t too bad, just find the maximum input torque, then find the maximum tangential force on the tip of the gear tooth, and then you have two options.

  1. find the cross sectional area and calculate a shear stress. This is the bad way of doing it and is pretty inaccurate but can be a good gut check.
  2. using gear module or diametric pitch, face width, quite a few boring strength factors, and finally the equivalent bending gear stress (which can sometimes be approximated with 1/3 the UTS of a material) you can get a much more accurate safety factor.

In the next few day’s i’ll upload a picture of all of my math on my development post. I don’t think acetal gears are possible for reduction lower than 3.0:1 but I am also being conservative. I would rather a gear drive never fail under any circumstance similarly to how a car’s transmission works. It’s annoying having to replace a belt let alone a gear.

But that’s just me; I haven’t crashed for a few years, my belt is looking pretty shitty and I could be due for another wipe out to remind me crashing isn’t all that bad haha


For me even using steel with 1 mm module it was still bellow one, using all correction factors that lower the maximum load by a lot, but in my experience most of the methodologies were made thinking about industrial applications that have to last forever with near 24/7 use

1 Like



What a brown nose. Sucking up to the mods Sheesh.

Pretty stuff moon berg. Like it a lot. Like a lot.


Uhhh that´s nice stuff!!!
Finally a drive for wheels below 90mm
Are you sure 250$ is the right value for retail?
It´s a steal for that price looking at the materials used, the full alu case, clamps, wheel adapter, R&D, tax, shipping to your place etc…
You barely will make any money from it…


Of course it isn’t. Its way too cheap but only a complete Dick bag would complain about the price.


Maybe he would consider offering a donation button for those who want to pay him more for the respect he has gained by developing this product and for his excellent work :slight_smile: @Andy87 I agree it seems low for the huge amount of work but I won’t complain either!

Some of us aren’t able to pay a huge upfront cost to buy the unit, which makes $250 very nice, but in the future could donate a little bit more to say thank you.


For dual, its very competitive. What do those bevel cut gears run per set? (The jet engine looking things where the motor is perpendicular to the hangar) I think its closer to $200 a Piece for them, but they are unique AFAIK. Considering the cheapest dual belt drive ive ever seen or used is $120, i think these @moon ones will sell out fast.