While attempting a 25K TT a few weeks ago, I inflated my tire to 60 PSI, hoping for less rolling resistance. It worked, however riding on such a hard tire at 15MPH or more is fairly dangerous, in that any unforeseen bump in the road could be disastrous. A softer tire will often absorb the same unforeseen bumps easily. In an attempt to compensate, I reduced the air pressure in my seat a bit to help with the absorption. I think it actually helped. The ride was a failure, but it wasn’t due to any UPD’s
Yesterday, for my 50-mile ride, I inflated the seat back to firm, and reduced the tire pressure to 45 PSI. It seemed like I didn’t have to pay nearly as much attention to the road as I did during the TT, but that could have been because I was traveling 3 or 4 MPH faster. Nevertheless, the ride was real enjoyable!
Steve Howard started a thread a few days ago discussing his 29er, and where it may fit into the scheme of things. I gave it some thought while riding yesterday. Obviously, one is going to feel more of the road with a 29er compared to the Coker for several reasons. First and foremost is that the tire is much smaller and will not roll over road imperfections as easily. Second, is that much higher tire pressures will need to used while riding the 29er. Pressures of 110PSI or more are possible and probably needed to minimize rolling resistance, and maxamize the tire’s performance. If an internally geared hub is ever used in combination with the 29-inch wheel, the above problems will be magnified because of the increased speed. A reasonably fit and skilled rider can realize speeds of 16 or 17 MPH for long periods of time. An unforgiving unicycle can be quite dangerous at these kind of speeds.
In my opinion the only solution is better frame geometry. A 29-inch frame designed to absorb radial shock similar to the big tire Cokers. It will have to be designed with precise diameter tubing, positioned at the proper angle to optimize shock based on the rider’s size, weight, and ability. Titanium may be the best choice for material because of its high absorption and strength properties.
I have the people with enough knowledge and expertise to build a frame already picked out, but I don’t have a hub yet. However, I do have a drawing so maybe its time to get off my bum and do something. Cokers are great, but I have always thought that something much better is possible.
I will be putting the second uni.5 hub on a Steve Howard 29er frame soon. I’m going to use a Nanoraptor tire (700c 52/47) that David Maxfield gave me because it wouldn’t fit his Telford I think. The recommended pressure range for the tire is 35-65 psig. The cross section (2.1") is similar to Coker size tires, the diameter is small compared to the Coker but quite large compared to the 24" on the original uni.5. Within the pressure range I expect the tire to be somewhat cushy but I will have to see. I intend to experiment with a two-speed static shiftable version this time. This will give me a 29" and 43.5" gear. At the higher effective diameter the rolling resistance might become quite noticeable for a real cranker but probably won’t for me who rolled slowly in to ninth place in the UNICON 10k unlimited on the uni.5 … out of a field of about 14.
What may also help is a frame similar to the Telford so you could add a Thudbuster suspension seatpost <http://www.thudbuster.com/>
Unfortunately a Telford won’t fit a 29er wheel. It will require a whole new frame or some sort of clever bearing block risers on the Telford to fit a 29er wheel. The Telford with a Thudbuster would make a great road uni. If only it fit a 29er wheel.
The large tire Greg has ready for his 29er will help reduce UPD’s and make for a smoother, safer ride. But unfortunately, I have a one-track mind. Finding a way to use a high-pressure tire in comfort and confidence is the most effective way to reach high speeds effiently. The biggest attraction with internally geared hubs is the ability to use high-end 700C bicycle wheel/tire combinations to acquire speed. Finding a way to make it work will be a major break through in the sport.
The soft ride beam that John mentioned could be a solution. I see them all the time, however I have never ridden on one. People that own them say there wonderful, in fact, tandem stokers swear by them. Stokers ride with all their weight over the wheel, much like we as unicyclist do.
Can you imagine what a unicycle would look like with a soft ride beam? The beam would have to attach to a frame way out in front of you, where it would angle back in at 45 degrees to attach to the wheel. There would virtually be no frame directly underneath! This would be one cool machine! And cost in manufacturing would be greatly reduced when compared to a well-designed frame, with precise tube angles in order to get the same dampening effect.
‘Reducing’ UPD’s sounds pretty scary at the speeds you’re talking about. One is too many. I have nasty visions of a broken body bouncing down the asphalt. Maybe a ‘soft ride’ unibike would be a project for me to consider to help smooth out the bumps. I’ll try to locate one for a test ride.
However, with this 29er idea, it sounds as though you may be joining me in the ‘open category’. This is good, as it will give me something to shoot for, since you will probably turn in a sub 1-hour 25k while I’m still looking for a route to use. The best I’ve found is a 1.5 mile loop (a little better than the previous 0.8). If I don’t find something soon, I may be forced to turn in a time for the ‘roundy-round’ category. Then again, I may take a vacation and pay you a visit for a little head-to-head motivation.
And be careful.
>Finding a way to use a high-pressure tire in comfort and
>confidence is the most effective way to reach high speeds effiently.
My combination is fairly similar to what you may be looking for–a Telford with
Thudbuster for comfort, using a high-pressure 700 x 48 Continental Top Touring
tire. It is a great combo for the 10 mile loop I do on Bainbridge. It does fine
on the hills that I can just barely struggle up on my Coker. It feel light and
nimble, but I can’t say that it’s as fast as the Coker–and it lacks the
Coker’s cruise control.
Bainbridge Island, WA
but soon to be Mitchell, SD
Maybe somebody can convince Softride to donate a partial frame (minus headtube, downtube, seat and chainstays), then rig the bottom bracket like a monofork, and there’s your Softride Uni. Simple, right?
Jagur, you may know already, but in case you’re interested, the Kanji (Japanese-Chinese character) beside the Nurb is inochi (ee-no-chee), which means “life”.
> it would angle back in at 45 degrees to attach to the wheel. There
> would virtually be no frame directly underneath! This would
> be one cool machine!
Definitely. I would like to try one. It might ride a little strange, due to
the displacement of weight to the front (and possibly rear), but as a road
machine, this should not be an issue. I’ve ridden on a mountain bike with a
Softride beam and suspension handlebars. That was interesting.
It would be a much more involved and expensive solution than using a
suspension seat post, but surely it would be elegant and an interesting
experiment. You would need to have a lot of adjustability leeway, to allow
for preload. I wonder if this would be a problem for times when you need to
raise up off the seat? I’d want mine with a “static” handle, meaning that
the handle be attached to a non-moving part of the frame.
Dan, I think the Telford with a Thudbuster will give you the ride that you want. You would just need to get an internally geared hub for it, and figure out how to get your hands on a Telford frame. The Telford will fit a 700c wheel with either a skinny racing tire or fatter touring tire. The Telford just won’t fit a 29er tire. The Thudbuster on the road is so smooth.
I’m not convinced that a skinny high pressure tire will be good for unicycling at high speed. All it takes is a little bump or a little rock to make control difficult at high speed. A suspended seat or fancy forgiving frame will not make the skinny high pressure tire roll over bumps and rocks any better.
I think a fatter 29er would end up being better. Overinflate the 29er, shave down the tread and you have a road tire good for a uni.
Why are the big wheel unicycles with the hard wheelchair rubber tires so hard to ride fast? Why would a skinny high pressure tire be any different?
how about a suspension design like this?(you could get a shock that is adjustable in travel from bolt to bolt to change ride height/characteristics and instead of that idea, you could drill several eyelet holes on the frame where the shock attaches on either side to do the same thing.
How much do you think a frame like this would compress when mounting? If the seat is positioned the correct distance from the axle for quiescent loading, how much higher might it be before getting on? Would it be difficult to mount because it is higher when unloaded? Could your feet ever leave the pedals as the frame responded to a bump and the seat went above the quiescent position?
Also, although the frame could be made lightweight, the joint is bound to introduce some lateral squirreliness (a dynamics high-tech term). You know what a giraffe frame feels like and this would be exaggerated. However,as someone pointed out, it’s for a road cycle so other quirks sometimes don’t (or shouldn’t) matter.
Softride claims the seat will sag about 1/2" to 2" when you sit on one of their road bikes. But that’s on a road bike where you have some of your weight carried on the handlebars. On a uni the seat carries all your weight. I would expect that a softride uni would sag even more. I’m guessing that the 1/2" number is for time trial setups where you have a lot of weight on the handlebars and the 2" number is for more upright posture on a more traditional road bike.
The sag could indeed be a problem if you hit a bump and the beam lifts you off the pedals. On a road uni the seat is up real high, unlike a muni, so there won’t be much flex in the legs to be able to extend the legs and keep the feet on the pedals. But if you hit a bump that caused that much of a boing (a technical dynamics term) in the beam you would have been launched off a standard uni frame too.
The Roundy-round track is fine for the TT. Roundy-round, or out and back, meet the requirements. The important factor is to not have any tail wind and/or down hill advantages over other riders. It is virtually impossible to have either of the two advantages with Roundy-round. And as someone brought up a while back, it is possible to have a tail wind advantage in and out and back course, if timed just right, but it would be difficult. For now, we need not worry about technicalities as much as just doing it. We can refine technicalities later.
I encourage you to get out and ride the Roundy-round course for 15 miles and turn in your time. I will then start a spreadsheet for the unlimited category. When I get my soft ride beam uni frame, and mount it on my uni5 hub, what out!
Speaking of head to head competition, while riding the other day I was presented with an unexpected head to head challenge. A couple of kids on string rays watched as I rode by. Both of them immediately started after me in hopes of riding along side to better check me out. But me with my competitive personality didn’t care that they were curious children. I proceeded to turn my cranks as fast as I could to prevent it from happening. I heard a lot of panting behind me, but they had no success in catching up to this big bad boy. I kicked their ass! Doing so felt great! Boy do I have a warped personality!
You are more than welcome in SLC. There are a lot of country roads to ride along. And who knows, maybe we can find a couple of small children on bikes to pound!