Micro Machines: Tiny crank and tiny wheel Megathread

[PedalSprell]

So you want to experience the joy of riding a super portable Micro Machine, or maybe share some advice yourself? Or are just curious? Well, you have found the right place!

The main advantage with riding a small wheel is how light and portable these machines are. You can bring and ride these everywhere. Pop off the seat post and they take absolytely no space at all. You can even stash them in your backpack!

A 19/20" with 75 mm cranks is a great option for speed and distance, while 89s gives you way more flexibilty. However, even 75s might be a bit light for a longer, flatter rides.

A 16" with 45 mm touring cranks is a great option for longer distances. 75s also get you comfortably around ofc, but 89s are just way to slow. 45s are not great for hills though, and you might want to have brakes at hand when going downhills. Luckily you can simply 3D-print brake mounts and strip them to your frame:

I just stole some back brakes from an abandoned bike. Oh, and since these 45s are not cottorless you will have to shim them: https://www.thingiverse.com/thing:6807747 You could of course try to mount these on a big 20" wheel, or even a huge 24" wheel, but on your own peril.

Seatpost: In contrast to the cranks and wheel you want your seatpost to be as long as possible for a longer ride. Especially with 45s, or you might not even be able to mount your Micro Machine at all, not to mention riding up curbs or slopes. I use a 500 mm seatpost for mine. My first attempt was on a 350 mm seatpost:

Winter cycling: Alas, you don’t get studded 16" tyres. Luckily, @ruari made a tutorial of how to stud you own and even lent me one.

When riding with short cranks the important thing is to keep that tiny wheel spinning. As long as you keep it spinning nothing can stop you! Please share a photo of your Micro Machine as well! And anyone else out there have a studded 16" unicycle I would very much like to know you better.

[TrevEv]

I have multiple times considered buying the UDC 12" uni and the EXTRA LONG seatpost. Just as something I could get away with riding indoors.

[MrHydra]

My smallest uni is a cheap generic 16" from Amazon… Which I described in nauseating detail here! Yours would probably look like it’s a Kris Holm uni next to mine

I haven’t ridden it much since to comfortably ride it I needed to steal a seat post from my 20", though I have another post on its way so maybe I can try some winter shenanigans on it

[PedalSprell]

@TrevEv

I have multiple times considered buying the UDC 12" uni and the EXTRA LONG seatpost.

I… Actually bought one! For both me and @ruari

It turns out they are so ridiculously long I would probably have to cut it even for my son’s 12". With 45 mm cranks even.

I think riding one with a 500 mm seatpost would be fun enough, and you could even use it for a 16"

[PedalSprell]

Awesome! I will dig into that post later! I love that photo with your 36er… This is actually the reason I bought the 16" in the first place…

…I actually thought it was a 20"! And now I simply Refuse to admit my mistake!!

[Syoten]

I have a 12" uni with 76mm cranks, and I use a 30cm seatpost with an extending post instead of a longer seatpost. My longest ride with it is 5km. I’ve been looking for shorter cranks and got 50mm cranks that seem similar to your 45s, but I could not use them because I couldn’t make proper shims.

[PedalSprell]

Wow, this looks awesome! I bet this thing barely weight anything at all. And if you collapse the seatpost this should get extremely compact.

Yes, 75mm cranks is a bit long/light for a longer ride. 50 or 45 mm should theoretically give a very nice riding experience on a 12". Well. Apart from the fact that any bump at all is a mountain

The problem is that the the cranks are not Cottorless/taper at all. They have a constant diameter/diagonal throughout the hole. You will indeed need wedge shaped shims.

Maybe you could try out the plastic shims I designed. It took about 5 mins to print and you might need to cut them a bit into a better shape with a scissor. When you tighten, they get crushed into a mold, and I haven’t experienced any slack so far.

It is also possible to force an ISIS adapter into the hole with a crank extractor. I did this by accident and had to hammer the adapter out with a bolt and hammer over several tries.

When fastening the deformed crank to the hub, it deformed into a Cottorless ish shape and fit quite snugly. I would highly recommend trying the plastic shims first. I count myself lucky I did not brake anything when that happened.

[ruari]

I used strips of metal from a can to make shims and they worked for a while but it was not a good long term solution. More generally shimming of any kind is always going to me substandard of course.

This is why @rogeratunicycledotcom needs to commision and sell proper 50mm cranks (I would settle for cotterless but ISIS also would be amazing), so that those of us with tiny wheels can actually get somewhere at a reasonable pace.

Also I have no doubt some madman will put them ona bigger wheel just because it is possible.

---

I must admit I have been tempted to shim up my 45mm cranks and try and put them on my 54 inch penny farthing wheel just to see if it was even possible to turn the wheel. That would be a gain ratio of 15.24!!! If I do it, I will make sure to post pictures despite penny farthings being largely off topic for these forums.

[PedalSprell]

@ruari

This is why @rogeratunicycledotcom needs to commision and sell proper 50mm cranks

I think 55 mm would be a better choice, as we already have 45 mm for 12" and few would enjoy 50 mm on their 20". Even better: 60 mm cranks would be just perfect for a 16". A gain ratio of 3,39. That is exactly how I love to ride around town. And you could put them on a 20" without worrying about brakes as well.

@ruari

I must admit I have been tempted to shim up my 45mm cranks and try and put them on my 54 inch penny farthing wheel just to see if it was even possible to turn the wheel. That would be a gain ratio of 15.24!!! If I do it, I will make sure to post pictures despite penny farthings being largely off topic for these forums.

If you do this I highly doubt you will be able to post any pictures anywhere, as attempting to ride would have to include a downhill slope.

[ruari]

@PedalSprell

60 mm cranks would be just perfect for a 16"

Mad4One used to sell 60MM cranks IIRC. The top one in this list

Maybe @MAD4ONE can confirm and also confirm if they will ever be back.

[PedalSprell]

Wow! Are these ISIS or cottorless?

[Eric_aus_Chemnitz]

It’s ISIS.

[Wheelou]

@TrevEv

I have multiple times considered buying the UDC 12" uni and the EXTRA LONG seatpost. Just as something I could get away with riding indoors.

A getaway 12“ uni - love the idea!

[JimT]

With normal off the shelf cranks it is relatively easy to drill and tap new threaded holes most any place you like.

[PedalSprell]

A friend suggested this actually. So you drill a hole for the tap and then drill the hole again with the tap in the photo to make the grooves for the pedal. And for that you need the tap fluid, some kind of oil, so that the tap comes easily out again?

How does these new holes perform over distances or frequent pedal switches, compared to the existing holes?

[JimT]

@PedalSprell

So you drill a hole for the tap and then drill the hole again with the tap in the photo to make the grooves for the pedal. And for that you need the tap fluid, some kind of oil, so that the tap comes easily out again?

You can buy a left and right hand tap set like Park Tool 9/16-20 tap set. It is best to use a drill press to drill the holes and tap the treads so they are square to the crank arm. I have put thousands of miles on the ones I have did with no problem. More pics here.

[pierrox]

Whoa! Talk about niche in a niche sport hey!
How is the riding? I would assume the smallest pebble on the road might throw you off, no?

[PedalSprell]

@pierrox

I would assume the smallest pebble on the road might throw you off, no?

With a low seatpost, yeah. Muni was rater a challenge. Rocks like this was pretty much insta UPD:

The brakes helps a lot ofc. Bumps downhill is less of an issue.

But after switching to 500 mm seatpost something magical happened. I can do bumps and small curbs without big problems, even with 45s. It became a matter of shifting my weight and using my momentum. But if caught unaware on a rock or bump, a 16" will throw you off indeed.

@Unicycle.com

An important thing to remember is that although these smaller wheels are more suitable for younger children and smaller riders, they don’t handle rough terrain well. They’re best for riding on even, flat surfaces - even indoors, if possible.

Oh well.

[JH33]

What is your normal crank length?(when not on 45s)
I can’t tell from the photo, because my brain is used to the look of a bigger wheel.

[PedalSprell]

I would say 75mm, but I just recently got them. I have actually ridden more with 45s though The photos are with 89 mm or 125mm, which is probably best for Muni anyways. I did try 150 mm though and that was …interesting.

NOT great for Muni at all!!