I wish to build a fast and portable unicycle, useful both on and offroad.
Don’t have enought money to Schlumpf so I came up to two ideas. Everything starts from this uni:
I could have it pedal assisted to go fast (right now it is about a 42" virtual wheel) and to let me climb hills… again a money problem to me.
I could use a Sturmey Archer hub, but I cannot find a hub driven by both sides (I could easily add a sprocket on the left side of the hub, but it spins in a different speed that the right driver sprocket!).
IF ANYONE KNOWS HOW TO SOLVE MY S-A HUB PROBLEM I’LL BE HAPPY TO SHOW YOU A NEW GEARED IDEA. If you own designs or ideas I could try it if it will cost less than 1k € (I’ll pay to have the hub machined and assembled and for a lot of money I’ll wait to have it pedal assisted instead of geared)
Consider that Huni-rex crancks are not directly connected each other. Consider that I can change the direct gear ratio (150%) by changing the sprockets
The Huni-rex is not a good off-road machine due to the pedals being so low to the ground. You can have pretty bad pedal strike problems even on flat ground. The cheapest solution is a 29er. Maybe with the new triple hole cranks that unicycle.com just came out with. I don’t want to discourage innovation, but there’s not a cheap, reliable solution to the geared hub right now.
A sturmey Archer may work, as they do have some fixed-gear hubs, but durability may be an issue, and keep in mind they only work to gear down, rather than up. If you asked the company, they will undoubtedly tell you it wasn’t designed for a unicycle and they can’t guarantee it will work. For the money that you would use to create a geared setup, you could have 2 wheels, if that’s a solution that’s reasonable for your needs. Geared wheels are extremely cool though. In general I have found custom work to ALWAYS be more expensive than you think in the end, but always rewarding as well. Because the huni-rex is a jack-shaft style, another concern is having the play from 2 different geared systems. I’m sure some other riders who have done more custom work can chime in.
You may be interested in a few wheels that Justin built up:
Long story short: Save yourself the effort and save up for a Schlumpf, if you REALLY want a geared uni.
Let’s assume you find a solution (I don’t know of any of the shelf bike hub that fits the necessary criterium of being driven on both sides, and most designs I’ve seen don’t allow an easy modification for that to be changed). You’ll likely be in for a 500€+ investment for machining, and your hub. But that’s PROTOTYPE 1. It’s highly unlikely to work well on your first attempt. All the time and effort would be much better spend on a Schlumpf.
Disclaimer: I’m not saying I don’t want to see people try new geared hub solutions. All I am saying is, if your goal is a geared uni, buy a Schlumpf. Building your own solution is likely going to cost a completely unreasonable amount of time and money. Only if, as we germans say: “the journey is the reward”, meaning you enjoy the engineering and building more than actually owning the hub, I would consider a DIY.
I already own it: I use a 3.5" on flat and pedal stroke isn’t a issue. I find that low PSI may require a bigger tire to avoid pedal strike on rocks, but since it is a in high gear it is a road or XC uni right now.
I bought my first 29 this week and I already put it on sale. :o
A Sturmey Archer can only gear down and I like it… I cannot ride a 42" uphill rightnow.
Already talk to Justin: the huni-rex is lot easier to PAS but it require about 1500€ to have it. It is the perfect uni to have it PAS cause it don’t require any special geared hub motor: just a DD drive. But I can’t afford it
So it turns out that my problem is again the left side of the Sturmey hub. Any idea to solve that specific issue?
Instead of Schlumpf I’d go e-uni for the same amount of cash (but lot of time to fine tuning). Consider that it isn’t a 29" with a Direct Drive motor. It is a 40"-45" (easy to modify) with a DD motor. But I cannot spend all that money.
I’m looking for anyone who had seen or teared apart any old S-Archer hub (no more than 50€ on ebay!!!): I can even control the chain driven gear mechanism. I spent a lot of night-time looking for a SA hub which could be modded to work on the left side, but cannot find any. Already emailed S-A and they told me that the late models cannot have the left side spinning different from the rim (I need it to spin connected to the right driver, not to the rim). So I’m wondering if anyone experienced in that kind of old stile hub can remeber a hub which could be doable for my idea… I’ve never touched a S-A hub, I’ve spent a lot of time watching videos and images online
