ISO04B is way too weak.
ASA25H is not that bad but won’t last for a long time. Yet you won’t kill your motor axle if something bad happens (piece of metal or big stone inside the trasmission). In that case the chain will break.
ISO04B and ASA25H don’t mix well with dry lube (Squirt for exemple).
ISO06B is very strong. Take care of 8 mm motor axles. Il can be cut if something gets into transmission, depending on how the mount is built.
I never used ISO05B.
You can’t really use 06B on a street board, as a 25T sprocket is already very large and eats at your clearance. Your gearing options are therefore very limited, even if you can go down to 8T pinions.
25H is pretty strong, as it’s commonly used for 49CC minibikes. it’s kind of similar to the 04B in terms of size, but the H in it makes all the difference. More options in terms of gearing. 10T pinions on 8mm axles, and maybe up to 40T sprockets on street boards. As reference, a 36T sprocket with chain on has a diameter of 78mm, which leaves a good clearance on big street wheels, like the rubber 105, TB110, cloudwheels, etc…
Even if not metric, 25H looks like it’s a well established standard, that is available in metric parts of the world. And it’s cheap.
I have a dual 6374 running chains now for almost 3 years. 25h works fine for me.
Yah I wouldn’t go under iso5. Been running iso 06 for a few years and all good.
Anyone try silent chains? Ramsey Products | Silent chain for power transmission and conveying overview
Locking bushings are nice. No need for a key way.
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Hello All
Thank You a lot for this article and comments. Iam mechanical designer and my next build will be on chain. Based on this I refreshed my university education and made some research with basic calculations. Please check it, mainly chain riders and please let me know Your feedback on this theory.
At first european 05B are more or less in the same strength category like ASA25 and 06B is equal to ASA35H. What is very iportant for us is the pitch of chain which is together with tooths define diameters of sprocket. And diameter on wheel should be so small as is possible ,to have enought space out of road. On the other side, motor sprocket should be so big as is possible to avoid “polygon effect”. See fallowing link. Sprocket Design Tutorial - CAD - Chief Delphi
Therefore in case that You would like to have fast board (slighly more than 50km/h) and still usefull torque , my recomandation is to choose motor with low kv and gear ratio aroun 1:3. For efample 140kv and 10:36 (or 9:35)with 06B chain.
In industry , to have long chain life, motor sprocket should have odd number of tooths and wheel sprocket even number of tooths. Reason is to have equal abrasion for complet setup. I do not want to put all rules here, You can check Your gear ratio here: ⚡Chain and Sprocket Calculator | RPM and Chain Speeds
Iam already made few of calculation. I would like to use motor Flipsky 6374 140kv 3,5kW. This motor have max. torque 8N/m. My targer was to use ASA25H chain becouse of small pitch, unfortenatly with this motor Iam slighly cross safety border line. So I must choose B06 or ASA35. Iam from Europe so B06 is for me most avalible. If You are not able calculate it, You can use following pictures. It looks for me also usefull.
Thank You All for reading this comment and please let us to know if this theory was tested by You.
Can I achieve the same result if it’s the other way around?
I mean my motor sprocket is 14t even and 65t odd for the wheel.
My other board have 12t by 47t.
All 25h systems using using motorcycle timing chains.
It is general rules, to be honest I have nothing to compare how big influence have this rules on lifecycle, Mainly is inportant to avoid thath both sprocket will have even number of tooths or both will have odd number of tooths. But also it exist combination which will works also with it. Anvay according attached link on calculator, Your nombers will worrk great. Iam not sure what is your axial distance, but it should be ok. As Iam wrote this is theory from industry.
Sorry. This is correct. Iam used different chain typ for first calculation. It have just dimensional ipact 
FRC robotics forums love it, wish they had updated earlier maybe I would have used it more.
Could you show off some previous robotics work? not enough shown on this forum.
Introduce Yourself and Share Your Plans (SERIOUS)
^^ in this thread
i have used 04b, 05b and 06b chain on emtbs. 04b too weak/ small for emtbs but on a small longboard works great. 05b is lightweight should only be used for low power jumper boards and 06b is double the strength of 05b imo the perfect chain for power to size ratio for mtbs, have a look at chain wax it works a treat for protecting chain from dirt ingress (when ya chain gets crispy)
Thank You for Your experiences.
Gentleman’s
Did You try go-kart chain? It looks like alternative with small pitch and high strength. I suppose that availability of sprockets for us will be an issue.
Sprockets can be machined easily enough.
How do the specs of go-cart chain compare against 06b?
I think the main problem with 06b chains (for MTB) is the diameter of the wheel sprocket and the lack of ground clearance. If you can make an improvement there without sacrificing robustness, only then would an enclosure become really practical.
Let see: ČZ Řetězy s.r.o. - Kart chains
Pitch is less then 06B and strengts is very similiar. So it can solve clearence issue. Just this chain is not roller chain but bush. That mean need to be often changed and maintanned becouse chain is not rolling on sprocket, but sliding, probably noice will be also different. Noice and colour of sound will be probably different. Sure, sprocket can be mashined, just it is not so comon tooth profile, so Iam not sure if anybody is able to produce it. Anyway I will made both variant B06 and 219 drawings to check price.
Because sprockets are widely used in industry, it is usually easy to obtain the CAD drawings for whatever chain type you want.
for example :
And their shape and flatness are good matches for laser or waterjet cutting, which is quite affordable and easy to get done locally. Typically much cheaper than CNC
That is clear. I was talking about 219 chain and needed dimensions. Did You already tested 219 chain?
Iam little afraid to covering chain. If You would like to use it, You must be clear that You will check extension of chain. So You will change chain befor will be break and block gears in cover.
Just remark. Custom sprocket for cart chain 219 type if fckn expensive:( I made drawings and received few offers. Price was include motor mount on gear drive level 
