I really should get a set of calipers. Thanks.
looks like 70mm diameter from bolt center to other side of the “circle” of bolts. Add a few mm to account for the extra material of the flat head bolt and it’s about 80mm.
So it looks like this will fit fine. https://www.gearsandsprockets.co.uk/06b-1-30t-steel-platewheel.html
Might even have room to go a bit smaller for more top speed and ground clearance.
They have an overview of diameters
https://www.gearsandsprockets.co.uk/3-8-06b-platewheel-simplex-sprockets/
30t is about 100mm with chains. So 12.5mm clearance on gummies 
You thinking like 28t or 27t then?
It’s a just for fun project. I don’t mind to scratch the chains a bit 
My problem with sprockets is that I don’t have the tools to drill the hole pattern accurately and maybe take some material out of the center.
Yah I’ll need to find someone with a drill press for that.
Had one before my parents moved to Mexico to retire lol
I even don’t have a drill man 
I don’t think either my drill or my budget for bits would want to do it by hand lol
You see my problem… still manage somehow to build some nice boards 
Yeah I guess it’s very practical to make whipped cream as well.
But seriously I don’t see how I can drill a 50mm diameter hole out of a 5mm steel sprocket on which the center was already removed without any proper place to fix the sprocket
I don’t mind doing it for you.
A drill press, drill, power drill, dremel etc.
Just did the numbers with 28tooth; it almost perfectly matches the gearing I have now on 200mm tires.
You’ll pay for shipping. A round file will do the job.
I would also gladly pay for the Feierabend Bier than 
@Mainflow if you’e drilling these I’d happily pay for 2 sprockets + drilling fee + shipping to USA.
I can give it to Klaus
Really old post, but is there any failsafe of the heelstraps in case of an accident? Like on ski.
Nope.
You go down with the ship, like the captain…
