OK, for this one, I again took a mtn. bike fork crown from the recycled bike shop, then cut the legs off the original Nimbus to retain the bearing holders. The nice part is that there’s a little lip at the top of the tube holes in the crown, so there’s no way for the crown to slip down the legs (notwithstanding a good clamping bolt). The ID of the aluminum seat tube accepted the standard 1" post. Again this saving “feelable” weight over the all-steel frame. It’s got the good-wife seal of approval!
There’s no fork “rake” in terms of an angle. The seattube is parallel with the legs. The only factor with this crown was that the seattube is slightly behind the lateral centerline of the legs. But that has no effect on rideability.
On the heliarced freestyle crown, the seattube is centered with the legs, as it was cut up to all match. This particular muni crown is untouched from how I got it out of the parts bin! It usually takes a few visits to find a useable crown. Some of the bike fork crowns are too wide even for a 3" tire!
Yes, I’d consider modifying frames for others, but I’d like a few more tries to gain some experience. You can definitely feel the difference.
That is one fine looking uni. I have been thinking about making one out of an old fork crown myself. My only suggestion would be to drill a SMALL hole where the sterrer tube/ seat tube is pressed into the crown and installing a rolled pin or small bolt to ensure that it doesn’t come loose and suddenly stop the tire. Being as most crown assemblies use a press fit with a shoulder on the bottom designed to keep the tube from PULLING out through the top crown only, there is nothing to keep it from being PUSHED out through the bottom of the crown
Recycled Cycles in Seattle sells used forks, used stems, used cranks, used anything from a bicycle. I bought the stem and bar ends and other misc. parts for my Coker handle at Recycled Cycles. It’s a candy store of used parts. They also sell Torker unicycles.
Bike Works way at the other end of Seattle, also has a big supply of used parts like forks and stems and bars and such.
Nice frame, is the stearer tube aluminum or steel? Manatou suspension forks dont have fork rake at the stem it’s down at the wheel, I’m not sure if the tubes are a press fit or have a clamp probably older ones have a clamp and newer ones are press fit.
Yes mazem, I bought the parts at Recycled Cycles at the base of the U-District on Boat Street.
The steerer tube is high-quality aluminum. I have found several crowns that use this tube, it fits a 25.4mm seatpost, and is 28.6mm OD, the same as my freestyle crown seat tube. I’ve seen lots of crowns with pressed-in steel steerer tubes, but those weigh alot and really wouldn’t save overall weight.
I now have some carbon fiber seat tubes in my possession, but the biggest issue is how to make a main-cap bearing holder that can fit into the ID end of a 1.0" OD tube.
I believe we will be following bike technology, and we’ll be seeing more carbon fiber frames in years to come. Doesn’t a carbon-fiber trials frame make perfectly good sense? Why heft steel??
You heft steel because it’s durable. You can bang it up, scratch it up, dent it up, grind it up, and the frame will still be fine. One wrong scratch on a carbon fiber tube and the frame is shot. We won’t be seeing any carbon fiber trials frames or carbon fiber muni frames for freeride style riding. Carbon fiber is the wrong material for a unicycle frame that’s going to get banged up. You don’t see any carbon fiber frames on freeride bikes or trials bikes. Aluminum frames have potential, but I don’t see carbon fiber happening. I’m still a bit leary of the aluminum muni and trials frames. They haven’t proven themselves yet. Steel is still the way to go for durability.
I can see carbon fiber frames for a XC 29er. A 29er designed for the style of riding at a 24 hour race or some other racing event. I can also see a carbon fiber frame for a Coker. But I cannot see carbon fiber being used for freeride style muni or for trials.
Even the carbon fiber seat bases have a limited life span when used for aggressive muni and for trials. Carbon fiber is nice, but isn’t the most durable material.
Titanium will work. It’s expensive for bike frames, but unicycle frames don’t have as much material and the tube shapes and butting don’t have to be as exotic.
Creative Gecko’s used titanium for munis. He used titanium for flex and suspension due to its potential infinite fatigue life. He wanted flex in the frame. Titanium can even be superior to steel in its ability to take abuse from crashes. It’s just expensive stuff and requires special welding in an inert atmosphere. The bearing holders for a titanium frame are probably going to be the most challenging part of designing a titanium frame.
And you don’t have to paint a titanium frame. Think of all the weight you’re saving by leaving off the paint.
A guy at the LBS i work at is learning how to make CF frames, so i told him he could make me a uni frame for practice. it’s going to be interesting. I figure i might as well just trash it! I think it will be fun.
anyways, I’ll have to tell you all how it goes, and keep experimenting, just because JC says it’s not a good idea, doesn’t mean you shouldn’t try it(allthough he’s allmost certainly correct). That’s how our sport has to be pushed.
<http://www.lahar.co.nz/> make downhill bikes out of carbon fiber, which seem to survive. I met someone with the softtail version who was using it as pretty much a freeride bike including dropping into the big quarry near where I ride which is really scary massive. If it had lasted for him for several years, then I suspect the big downhill one could put up with pretty much anyone’s riding.
Just thought I’d bring this back to the top.
Any news on this Ryan I’m interested in seeing how it would hold up because carbon fiber is alot lighter right? So you should be able to hop a fair bit higher.
Also how much do you suggest a titanium trials frame would cost JC?
Robbie: Alright, since I’m currently researching this anyways, I’ll give you an idea of the cost of an all-titanium trials frame. Figure about $28USD per foot of titanium tubing. Now, figure about three feet of tubing involved. There’s about $84USD already. Now, since high-quality end-mills can run about $50 a piece, think you’ll need about two fo them alone to make the bearing holders, so that’s $184USD. Now, fictor in the cost of the welding and gas, and you add another $20 at the bare minimum, more like $50. So, the baseline cost would be somewhere around $200. Then, factor in the markup of someone who put all this labor in, and you’d be lucky if it were as little as $250. But, since noone’s about to go mass-producing titanium trials frames, they’re all custom jobs. This means that if they make more than one, they’re most likely just to give it away to a friend or just someone they think will like it and use it. So basically, the cost is nothing to the recipient, except having friends who know how to obtain and machine and weld titanium, and being good enough that you need a titanium trials frame. Unless your to the point where you lift the uni large amounts during hops, you won’t see that much benefit from the titanium frame, other than bragging rights.