That’s an interesting idea! And it should work. I look forward to seeing a prototype.
I notice a bit of flex in the plastic saddles, but not in any of my carbon bases. It’s probably not enough to be annoying, unless you use a long extension handle like the KH T-bar which attaches to the front of the seat.
I’ve been remodelling foam for years. Every new edition of the KH saddle has had at least half the foam trimmed off. It is very difficult to get it flat. And not just flat, but thin (I forgot to add that it was another of my goals- a flat AND thin seat.
If you want a flattish seat, then you could just use the KH Freeride, which has an enormous amount of foam in the middle to fill in the curve. It’s flat, but as thick as a brick, and feels like a horse saddle. For me, it’s an unsatisfactory solution.
I’m not arguing against the idea of a lip- it will certainly add stiffness. My most basic idea was to cut out a sheet of heavy duty aluminium. A lip is one way of stiffening it up (although a rather good one). I had been toying with the idea welding a strip of metal around the aluminium plate for the lip, or just the front half of the saddle. That was before Pete came up with the idea of a flat carbon seatbase.
I wonder if any Trials or Street/Flatland unicyclists care to contribute their thoughts to this thread? Is there any advantage to a curved seat?
The interesting thing is that my favourite long distance road saddle is the Impact Naomi, and it is marketed as a street/trials/flatland saddle. The Naomi is the only saddle I don’t feel the need to modify, even though it is curved, and not quite as comfy as the flat carbon saddle.
Couly you not take and internal moult of a KH base with some clay / plastercine then flatern it and modify to suit and then make a female mold over that then take a male mold from that one to get the required internal final mold.
Then doing a layup of CF and GF at critical areas and maybe imbedding captive T nuts into the layup to make life easy.
Doesn’t sound too hard? I have a friend who taught himself CF and GF construction to build internal car trim / stereo cases for his cars, if he can do it i certainly can.
If I was to do this I think I may go a bit freestyle on the design a bit and thing the saddle base and make a sort of Uni / bike saddle hybrid.
Sounds like a cool project.
as A side thought I wonder what the material the standard base is made from and how malleable it gets at high temperatures as in would it be possible to heat it and flatten it and have it set again once it cools down
I think it will be great, but it also needs to be thin. Flat and thin gives you freedom to move.
You can stand up and unweight the saddle to soak up bumps and vibrations. A fat curved seat wedged against your crotch means you feel everything.
I haven’t tried this seat off-road yet, but the trimmed down seats I use work ok.
The other issue which I’m curious about, but have yet to test properly, is whether you gain more leverage because the handle is (marginally) lower and further away from you on a flat seat. That means you have greater pulling distance because the elbows are straighter. You generate most power when the muscle is close to it’s full length (the biceps brachii in this case).
This Site sells a kit that will do a 1’x1’ part so enough for a saddle for £47, maybe buy some glass fiber as well.
Might have a go next month seems very straight forward and with years of engineering work behind me I can’t see it being too hard (already read up on it now :p).
I think that’s exactly what GizmoDuck’s mate Pete did, and why I was asking after the spare KH base you have. Would work rather better than trying to flatten a plasticine mould, as you’d get all sorts of distortion (and I’m not sure I’d fancy trying to lay up on plasticine either). Though it does occur to me that GizmoDuck’s base does seem to be made from an internal mould rather than the external one I was thinking of. The advantage of the external mould is that it’s a lot easier to add a little material on to make a slightly narrower saddle than it is to remove a bit from an internal mould - presuming here that you’d also be thinking about going narrower given the option.
It certainly looks like thermoplastic so should be possible to do that with it - just be careful not to overheat so it distorts, you’re best off gradually getting a bit hotter until you get to the point where you can flatten rather than whacking up the heat first time. Go for it and let us know - I’d love to borrow a flattened base from you to make my own plug when you’ve done.
could you not build up the sides and pour silicone in then cut the excess off to an even thickness in relation to the base curve so when you lay it down facing up it will straighten out, you could then poor in something that sets rigid to make a male mold and then make a female mold off that with which to layup inside of? (you could thin down the female mold a bit first to thin it out.
I think I would just start from scratch and use desperation from my bike saddle (SI SLR) to sculpt the rear and then increase the center width a little (bike seat nose) to allow room for the UNI seat post mount and then widen a bit more for the Uni saddle nose and handle mount area, I have this feeling that I would want the front to rise little maybe just to angle the handle rather than to stop me coming off, I have no issue with the front of a standard Uni saddle as it is, just the width of the center and rear
I am quiet keen to have a bash to be honest but it will have to be next month as I have just laid out on a Kh29 frame and parts to rebuild my KH26 wheel as a 29er
However, it looks suspiciously like an existing KH seat profile when viewed from the top. And if you end up angling the nose upwards, then it will looks suspiciously like a KH seat profile from the side also.
Which defeats the purpose of a thin flat seat doesn’t it?
Like, but not the same. Feisty and me both have an issue with the width of uni seats - an SLR is significantly narrower. That and he’s only suggesting angling the nose up a bit - which will presumably be less than a current KH saddle. I think my first attempt at a base will be totally flat as it’s a lot easier to make that way with my planned construction method, though will add a bit of a curve with foam.
I have thought about this project a bit more from the POV of the easiest way to do something, which seemed it would be cutting a bit of foam to shape and laying up on both sides of that - I reckoned that was worth a try at least to see if I could make something usable as a first step. At least until I realised the importance of getting the curved bit in the middle right - that has to fit the seatpost, and does require a decent surface finish, making laying up onto a former problematic. Will have to make a mould at least for that bit, though in a way that’s easier, as I can just use an existing base as a plug - or possibly even the top of a seatpost as a mould. Will have a play around sometime this week and see what I can come up with - though I am still going to have to bite the bullet of pulling apart an existing saddle to use for a cover/foam (and I only have Nimbus stapled ones).
But have you tried simply trimming the foam on an existing KH seat? There is a big lip that sits over the base. You’d save quite a lot of overhang width just by trimming that.
The carbon NNC seat is significantly narrower than a regular KH seat, even though the mold is the same width, because I used less foam and without the lip.
No - clearly that’s something I’m going to have to try, though as mentioned above I only own Nimbus seats, making it a little more awkward. I’d prefer to try with a s/h one, and not that I’ve been specifically looking, but strangely seats don’t seem to come up on the classifieds that much (could always cut up one of the ones I’ve got as I plan to replace anyway, but I plan to sell both the unis I have with Nimbus Gel seats on at some point, and it would seem to make sense to sell with the original intact seat).
Hmm - this saddle selection lark just gets more complicated.
Here is a good illustration of why curved seats are uncomfortable.
I’ve photoshopped the images so that you would expect the ischial tuberosities to sit on the widest part of the saddle (the back). In reality, or at least my experience, you slide forward on a curved seat so you end up sitting on the lowest part of the curve.
This shows the bony structure of your pelvis. It is up to your imagination to visualise what happens to the male genitalia. It sits just under the pubis. I can’t speak for females, but it’s probably not as significant.
If I have time next week, I’ll get someone to do some Xrays of me sitting on the flat seat vs curved seat. I will irradiate my gonads in the name of unicycle science.
So I’ve done some resin and glass work, it’s stinky and sticky, quite the mess and it can be hard to work with those pesky fibers always wanting to clump and stick out. FYI, carbon fiber is a PITA because the fibers are much lighter than the resin, so they tend to float, which makes getting the fibers “tight” together a bother. This is why folks vaummn bag CF lay ups. You can squeegee out the excess resin, but the fibers will want to move…
Carbon fiber to resin ratio is supposed to better than 1:1, so don’t use too much resin or it’ll be heavy and brittle. One way to overcome excess resin is to soak the first layer, then place the subsequent layers dry and press them down to fit (and soak up the excess resin.
I think you’d need the edging to reinforce the plate, but otherwise this could work. I have thought about doing this, but I’m still on the fence as to buying a Tig welder; they are so expensive. This might be a job for a certain Magura brake guy…calling Brycer, line one
I’ve done very little with carbon, but can’t say I’ve ever noticed a big problem with that with kevlar - which is even less dense than carbon. The secret is to use little enough resin that the fibres don’t really have the opportunity to float - less resin is in general better provided you have enough to wet out the fibres. Putting resin on what you’re laying up on and then applying the fabric dry as you suggest is good practice - though it takes a bit of experience to get it wet out well with minimal resin. If the glass you’ve used has been chopped strand (the most common type) then I agree with most of your assessment of working with that - I find woven material a lot easier, though you still have the sticky and stinky issues, which is why I’d suggest using gloves and always working in a well ventilated environment (people working with epoxy for a job will tend to use ventilation equipment as the fumes are harmful if inhaled on a long term basis).
vac bagging provides a better result in general - less resin and better compression - but is expensive, which is why you’ll not find it used with cheaper glass fibre products. For hobby stuff it’s a worth finding some way to compress the lay-up whilst it sets, whether that’s simply using weights with flat items, or tape wrapped around more complex shapes.
It’s great! Not nearly as twitcy as I thought once you get the hang of it. I had very little side to side wheel wobble. It’s quite a different feel having 100psi instead of 30psi in your tyre though! But I love the simplicity- it’s like learning riding your first unicycle. I’m not sure how much of that was the seat, and how much of it was the gear size.
It was less than a two hour ride, but my legs had that awesome achey feeling the next day. Quite a workout at ultra high revs.
Back before there were KH seats (which are much stiffer, but still eventually break), I reinforced my Miyata seats using carbon fiber, kevlar, or fiberglass. Without having real vacuum bagging equipment, I put it in plastic bags and submerged it in water to apply pressure to get it to stay in place. If you added some breather material to the bag, you could also get rid of some of the excess epoxy.
I’m not sure I follow your two images. In the second image it shows the rider’s body is parallel to the seatpost, and in the first it shows an angle between the rider’s body and the seatpost. Shouldn’t the angle here between the two setups be the same? Or does it not matter?
I think if you angled the front part of the seat higher in the first diagram, the rider could not move forward on the seat and there would not be the “compression of the jewels” as a result. They would be sitting on the flat back part of the seat.
My work PC has nothing else unfortunately
