Chain type for eMTB

I am deciding the components of the engine drive, and I have doubts about the type of chain to use, I have two option to use, chains type 05B (8 x 3.0 mm) or 06B (9,525 x 5,72 mm)

These are the specifications of each one:



Which is the most used for mountainboard? I have searched this info in forums and can not find it.

Thank you

If you ask me, I would just go with belts. Or if you have the budget… direct gears from @Nowind

I notice that I do not have much space, because I want to take advantage of some screws that the truck has to fix the motor mount. Also after asking in several places, I think the chain is much more economical.

On the other hand, most of the time I will offroad.

I show you a first version of my scheme so you can see the space I’m talking about

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I don’t know the numbers but you should be able to fit a 15 mm belt no? Either way, yes chain is usually always cheaper but if you don’t get thick enough chain it will break. They are loud, have pretty heavy rolling resistance and are pretty dangerous.

They are more economical but I think there is a reason for it

maybe this will help


I understood that the belts have more rolling resistance. I have to check my notes.

This is just my experience. I felt like my chains had heavy resisitance.

Just to give my pov :slight_smile: In my side, and after experience, chain got less resistance when carving or in downhill (when you do no use the motor, you got a really good freerolling/freewheel). But yes more noizy ! Dangerous ? Don’t know that… Is passe from iso 4B to 6B, all good. This time I can’t break it by hand :blush: (got a ligthweight 36T and heavy 42T from 9 to 11T motor to play with ratio)

Good choice man


Can you explain this to me better? I can not understand what you want to tell me, my English is limited. What means lightweight 36t and heavy 42t?

I was thinking about getting a 50t and 8-10-12t for play with ratio

Thanks for sharing your experience!

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:smile: mine too, I’m frensh guy speaking franglish … many hard times. Just to informe you, cause iso 6B start to be Big ! And the motor sprocket to (just show some possibilities) 50T ! In iso 5 yes Got a new never used 50T kit from e-toxx with the heavy version of the iso 5B chaine, with 10T (and more) for motor and around 2m of chain if you’re interessed by (now I’m using 06B version) like this :slight_smile:

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Definitely 04B / 6mm You don’t need any heavier/bigger.

I would not use, the screws of my wheel are 32mm from the center.

04B is it like the bicycle standard?

Nope! Much smaller…

Try this site…

I have a distributor in Spain with very good price, like 15€ plate an 1-2 € motor sprocket. But they only work since 05B.

What I am looking for is to get an idea of the real size of a 04B-05B chain, I can not find a comparative photo.

I use 04B …

yes, for sure, but once it breaks under your finguer, you think for more :blush: 05B are good compromise imo, but prefer iso 06B and follow the good old abacus !

EDIT : Ho you’re on little urethan wheel ! Its cool to see that !! Yes for this iso4 is lot more appropriate :wink:

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This chain is NEVER breaking. If you could break it with your bare hands or even your whole weight, I’ll give you my board!


I’m building a mountain board, I do not know if that makes a lot of difference.

:wink: already done like I told you ! But keep your board bro, looks really cool. It’s why I go 5B kit from e-toxx, but don’t try and upgrade again for bigger 06B (but for e-mtb no esk8) this is why.

In any case, for me the best rest DD by etoxx :smile: