Apparently all the new KH unis are shipping with a bike style rail adaptor. Has anyone tried these? I’m a bit concerned about the strength of such a seatpost. I’ve broken two standard posts, so I’m not sure if this will hold up. When/if I get a new KH, I’m definetely going to get a standard post and put one of my stiffeners on it. however, my design precludes brakes, I think. I’ll have to look into that.
SO, what do you think about these new seatposts? they’re likely to become the standard for all unicycles, so I’m wondering if they will be a quality standard.
Given that rails are the standard in the bike industry, quality can be as high or as low as you want to pay for. Assuming the rail bracket is well constructed, a rail type seatpost assembly can be very rugged.
I’ve been riding a Thomson elite seatpost with a wilder rail bracket for about three years now, and it’s held up to a pretty high level of abuse.
Nonsense. Anything with a bolt or clamp can be just as strong as a single piece. Seatposts are always clamped onto frames. If done correctly, they will never move. The same is true for a seatpost. When properly installed it will never move.
On a good seatpost (2 bolts; I think 2 bolts is the only thing that will work on a unicycle with all the extra forces) the friction doesn’t matter. The bolts are effectively pulling against each other. The only way something can slip is if one of the bolts’ threads slip. Which is not likely.
I have a Wilder bracket which looks pretty much the same as the KH rail adapter. It works fine, but it seems to add a lot of unnecessary welding and potential weakspots, and also raise the seat by a fair amount (problematic if you are short and use a Coker).
In order to make the bracket strong enough for MUni use, it has to be overbuilt and much heavier than the rails on a bike (how often does your bikeseat smash into the ground?). In my opinion, bicycles need rails because they need to have forward and backward adjustment as well as angle adjustment; whereas unicycle seatposts only need angle adjustment. You might be able to use a variety of lightweight bicycle seatposts, but the heavier bracket kind of cancels all that out.
A really elegant solution would be to have an adapter to adapt a bicycle seatpost to the unicycle seat. I know Scott Wallis made a really nice carbon fibre adapter (I’ve tried my best but can’t seem to pull up that thread). If someone else can post a pic to illustrate- I reckon that is that should be the industry standard.
Personally I think the industry standard for high-end trials and mountain unicycles should be a thomson directly attached to a cf base. It is just as strong, if not stronger than a thomson witha rail adapter, and it’s lighter than a thomson with a rail adapter. Not to mention you still get the good adjustability. The only problem is how to figure out how to distribute the clampin action on the other side of the cf base. I’m gonna try a small wooden plate in there and see what happens…
The KH rail adapters sould be plenty strong, and definitely stronger than the old posts. Just think about the placement of the welds on the seat, and how much weaker the lever is made.
Fuego - the reason you’ve broken two standard uni seatposts is because they aren’t very strong. In general they’re made by the welded seam method, rather than using extruded tubing. Tubes with welded seams are much weaker than extruded tubes. (Have a look inside yr standard seatpost and you’ll see a welded line, where the tube has been rolled into a cylinder and welded together.) For the majority of riders a standard seatpost is fine, as its never very highly stressed. In my opinion on a uni its preferable to have an average quality bike seatpost than a standard uni seatpost, as it will be much stronger.
Yeah, I’ve often wondered why exactly unicyclists seem to prefer the two bolt seatpost design. Has anyone tried a single bolt seatpost with any success?
actually it would be weaker, and the first thing to give would be the carbon fiber. I’ve seen a seat like that break on a 4’ drop. When you attach the seatpost directly to the seat, all the force to the carbon fiber is disributed in two places that are closer together than the four that it is designed for.
I have a thompson post with a wilder adapter that has a gusset welded to the back where the rails had snapped off. it’s heavy but when it breaks, the seatpost bolts snap or bend which is less than a 1$ fix.
The reason the KH24 and KH29 unicycles now come with a rails adaptor is that it makes an incredible difference to saddle comfort to be able to properly adjust saddle angle to personal preference.
The reason the KH20 trials doesn’t come with one is that most riders prefer the saddle at a fairly common saddle angle for trials (the one it comes with), and the rails interfere a little bit with grabbing seat out front.
The rails adaptor is similar to the original Canadian-made version except that it has an additional reinforcement bar across the back of the bracker where the rails attach to the plate.