Stealth Torker: Ass-umptions, or: How I learned that .4mm can screw me.

So I got my Stealth Torker (zoom, kapow!) yesterday. As some of you know, I really wanted it to cannibalize saddle parts and then build a uni for my cousin with the rest of the parts. Using two other saddles and a set of Kinport handles, I put together two very sweet jet black saddles:

1)Regular Miyata, no air, black miyata cover with kinport handle/bumpers - this will be for my trials Yuni. (If I get the GB4 stiffener, this will be sleek, pretty, and solid)

2)Miyata airsaddle with black leather cover with the handle/bumpers from the stealth and all black seat post from the stealth. This is for the SpaceCruiser, an all-black 29" Pashley mini-coker that I’m working on.

Anyway, it all looks very sweet and I’ll post pics later. Here’s the PROBLEM. The pashley frame takes a 25.0mm seat post. I’ve been using a miyata (22-something-mm) with shims (ick). This new stealth seat post is 25.4mm. I assumed that if I hoped against hope the .4mm wouldn’t make a difference and I could make it fit. Boy, how wrong I was! That .4mm makes a difference. It’s very close, but that post will not go into that Pashley frame.

SO…anybody know how I can shave .4mm worth of the diameter off of that sweet jet black seat post?? I was thinking I could get some high-coarse sandpaper and spend the weekend trying to wear it down, but that can’t work, can it? There’s got to be a better way. And one of you geniuses must know the way.

You could force it through a very large draw plate or die (just on the portion that has to go in neck)… better start sanding now…


Check out the gallery pics:

I wasn’t too thrilled about the Torker logo on the rear bumper. I’m going for that smooth jet black look. Coincidentally, I’m building a platic model kit of the HMS Victory. I have a little jar of paint thinner for cleaning the enamel model paint off of my brushes. I don’t know too much about paint, but it dawned on me - if that Torker logo is just a basic enamel paint, I might be able to use the paint thinner to get it off. I wadded up a piece of toilet paper, dipped it into the thinner, and the Torker logo came right off. It was super easy and it looks great.


I wish you had posted some pics of the thing in its complete state before modifying stuff. :slight_smile: I’ll get to see mine monday I hope, so not too much longer to wait.


Sorry, I don’t have a camera at home, so I had to take all the pics at work. I’m sure Rhysling could hook you up with some pics - isn’t he getting his today? Also, has a pic up now.

I don’t know what this means. I hope your not suggesting that one of my options is for me to die :stuck_out_tongue: . Anyway, whatever I do, It will definitely only be done to the part that goes in the frame, I want to maintain the pretty black finish on the exposed portion.


you need to take .4 off the inner diameter of the Pashley seat tube.

you could slap the seatpost in a lathe, turn off the extra, and substantialy weaken it.
or you could take a big drill bit and do the opposite to the pashly frame,
weakening it to a similar degree.

but it’d probably cost more that a seatposts worth to get a machine shop to do it for you, if you don’t have your own lathe or bench drill, in which case you’d have aklready done the lathe thing.

Stealth Torker Photos

My photos still in the gallery:

Please post any updates to the Stealth Torker thread in the Unicycle Product Reviews forum too.

Does UPS deliver on Armistice Day?

Nick- Thanks for the paint thinner tip. Hope you can find a solution to your seatpost problem. 0.4mm is about 0.016" which is alot. The 25.4mm seatpost is nominally an inch but actually slightly under as I remember. I don’t know how to clamp your frame to get an undersized 1" reamer into the seatpost tube. If you wanted to turn down the seat post you’d have to do it in a REALLY short stock lathe or use a 4 jaw chuck and a live center. Regardless, the seat has to come off. Does the seat come off easily with no rounding of the carriage (coach, UK?) bolt holes? Has anyone tried?

It would appear so: .

Raphael Lasar
Matawan, NJ

Use a Miyata seat post (22.2 mm) and shim it to 25.0 mm

You could try this - but you might only get one go, so measure carefully and mark the seat post.

Keep the seat post in the freezer overnight (then handle it with gloves.)

Heat the seat tube by pouring hot water over it - wrap a rag or towel round it to hold the heat in place.

The seat tube expands, the seat post contracts. Seat post slip sin as far as the mark. Once it’s in there, though, it might be permanent.

Not joking - it is common to use the hot/cold treatment both to get parts to fit AND to get parts to separate. I had to do it with the handlebar clamps on my motorcycle.

Me likey your hot/cold solution. I might try that. I think the size differences are just that close. I would be worried about it being permanent, so I’ll noodle with the idea.

Jagur & Evilewan:

That might be the way to go, using a drill to shave off the inner part of the Pashley tube. I wonder if the metal brush attachment for my Dremel could do enough damage.

Great ideas that require equipment that I don’t have. I guess I can try to find somebody with a reamer if I can’t get the inner diameter thinned out otherwise.

I had to do plenty of seat post swapping. The seat post came off of the Stealth Torker saddle with no problem. The post came off of my older Miyata that came with the Pashley in May. The post did NOT come off of the miyata that came with my Trials Yuni in September. I cut some screwdriver slots in the two stubborn carriage bolts and the whole thing is now sitting in my freezer. Hopefully, I should get it taken care of tonight. If not, I guess I’ll have to cut them off and go buy new carriage bolts. Bumpers and handles came off all saddles with no problems.

The shims thing is the typical solution, but I don’t like the shims. Actually, getting a post that doesn’t require shims was one of the reasons I’m going through all this. To have a)black, 2)shimless seat post would be a beautiful thing to me. The funny part is, if I do give a unicycle to my cousin built around the rest of the stealth parts, she’s going to be stuck with shims. Better her than me.

Don’t do that. The seatpost will be stuck permanently in the frame. At best you will not be able to adjust the seat height or remove the seatpost. At worst you will end up cracking the frame.

I know the frustration of those darn 25.0mm seatposts. My DM Ringmaster Advanced also has a 25.0mm seatpost. It’s impossible to find a stock unicycle seatpost that will fit. I managed to get a 25.0 tube extension braised on a Miyata seatpost that I’m currently using on my 20" DM. It’s not an ideal solution (it doesn’t look good). One of these days I’ll get it fixed up right. But it’s a pain because it will require custom work.

If you are brave you can try reaming out the Pashley to fit the 25.4 seatpost. A 1" diameter fitting brush (used to clean the ID of copper pipe fittings), some sand paper, and a short wooden dowel ought to do it.

Here is what a fitting brush looks like:
A shop that sells plumbing supplies will have them.

Just be very careful when doing this. You’ll need to make sure that you keep the ID constant. You’ll need to make sure that you keep the ID nice and round. Don’t take off more material that you need (you can’t put it back once it’s been sanded off). As you’re working you’ll need to periodically clean out the metal dust and check to see if the seatpost fits yet. I repeat, don’t remove too much material. It’s going to take you a couple of hours to do this by hand.

This can be done. I did this to make my DM Vortex to fit a 27.2mm seatpost. The Vortex originally took a 27.0 seatpost and I wanted to use a 27.2 seatpost.


You ROCK, Man -you actualy got him to put it in the freezer. :wink:

A draw plate is used to reduce the gauge of a rod or tube. The plate opening is about the same size as the tube, but tappers to slightly smaller at the exit apeture. The tube can be started through the hole with a malet, then the protruding tip siezed and ‘drawn’. You get a slightly longer tube, as a bonus. I made mention of this mostly as farce, akin to attempting to manufacture a primative rocket launcher while fighting an alien reptilian to the death on some strange and distant world. :stuck_out_tongue:


Yeah, somebody mentioned that putting the saddle in the freezer helped with those stubborn carriage bolts. I noticed that when I cut the screwdriver slots, the bolt got warm and soft so that the screwdriver ended up stripping the new slot when the bolt didn’t turn. I figured the cold would eliminate the softening. Unfortunately, I think it also made the bolts expand and made them even tighter in the nut. So, in the end, the freezing didn’t really do anything for me.

I have the el cheapo cordless dremel, so I’m cutting into the carriage bolts bit by bit, pausing to recharge the little battery. 3 hours in between cuts is wearing on my patience. I should have gone the extra $15 for the wired Dremel.

John Childs:

Thanks for stopping me before I did something that could have damaged the frame. I think I’ll try that wire plumbing brush. A 1" diameter brush should shave the pipe out to a 1" inner diameter, right? That should be what I need. I’ll have to head out to the hardware store tommorow to see if I can find one of those.

I think the idea is to put the seat in the freezer before you have tried to take it apart. That hardens the plastic so that it is less likely for the square carriage bolt holes in the plastic to round as you unscrew the nuts. If the plastic is already stripped, no amount of chilling is going to help.