Delta trike seat angles?

Joined
Jul 8, 2022
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94
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Sagle, Idaho USA
So today was the day I finally tried to change the upright angle of my backrest (seat) on my delta trike. This was done with some trepidation and some utube research (how to bend tubing without a bender) - in reverse. As it turned out, I was going from an 80 degree almost upright seat back to a 60 more or less degree- semi- recumbent angle. I tried simulating the suggested 50 degrees with a tiltable weight bench and it seemed to be too reclined for my tastes. Anyway- if this cut and try method works, it will not be too difficult to get another 5 or 10 degrees using the same Slit saw and re-weld method that I tried today.

Tip- I used my electronic angle finder- Pretty handy gadget- magnetic bottom and you can zero it at any angle , move it to your desired second surface and get the difference between the original spot and your test point.

After the tack welds were done the seat angle was 59.2 degrees in reference to the main backbone- which is where I zeroed the angle finder. The backbone sits fairly level with the ground, so 59.2 is fairly close to reality and probably will feel drastically different than my old 80 degree butt hurt angle I had before.
 
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When you tried the angle on the weight bench did you rig up something to put your feet where the pedals are. It'll create a completely different feeling to not doing so.
 
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Sagle, Idaho USA
Popshot- I wanted to simulate the pedals too- very good idea! and I also knew that the seat base would have to be raised in the front slightly. The weight bench did have that option at least, and I used it for the simulation, but the seat base on the weight bench is too deep to allow my legs to extend like they would be on the trike. At that point I had to reconcile my weight bench tests to the fact that they are tiny bits of information that did help, but were not the final answer.

At that point it was back to guessing what would work and did I have time and patience enough to pull this off? I did raise the front of the seat base about an inch by resting the plywood on the front frame tubing of the existing seat. That seems to be sufficient with the seat back lowered to what seems to be about 59 degrees.

So to make a long story short- I moved the upper set of shock mounting plates to accomodate the lowered seat back and also raised the ride height about 1/2 inch to make sure the chain would not rub the seat frame with my weight on the trike. The shock mounts are very similar to an old twin shock motorcycle in that there is a swing arm and two shocks, but with a motorcycle there is no variation of the chain height when the gears are switched.

I'm using my mig welder for all this and I'm learning as I go. My machine is most happy doing some point blank spot welds on the chromemolly tubing and that is what seems to work best for small areas. I do not need to show off my welding skills to anyone, just make sure things are strong enough not to dump me on the ground while riding this thing! I have a tendency to relax the stickout distance after the trigger is pulled in an effort to watch the weld puddle, but this invariably leads to max porosity in the welds and I end up grinding it all off again!

So right now the shock mounting plates are tack welded to the seat frame in multiple places and I took it for a test ride this afternoon- MUCH Better! The buns are much happier with some of my weight taken off them and I definitely noticed a big difference in the comfort level with the short amount of riding I did this afternoon. tomorrow I will re- inspect my tack welds and probably add several more to fill in the gaps. I want to ride the trike for a few days or weeks at this new angle and get a feel for how it works overall. I know that you said 50 degrees is the majic number, but the feeling I got while on the weight bench at 50 degrees was a bit much and I could see me having a sore neck instead of a sore backside if I took the seat back permanently to 50 degrees.

I sure appreciate your input and I am so glad to have you for a bike GURU! I am already getting positive comments from my neighbors who by the way just bought new electric upright 2 wheelers.

Next thing is to ventiate the seat back- probably with channels cut into the 1 inch closed cell foam packing material. That should not take too long to do and seems like it would improve the seat cooling.

Anyway the trike feels way better now and I'm looking forwards to some longer rides coming up very soon.

Hope you are feeling better with your back and can ride as much as you would like! I know that can dampen your spirits if you can't ride at all. I'm getting to the point (73) where I have to do some stretches in the morning just to be able to walk, so I know exactly what back pain is all about.
 
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Popshot- Some progress on the seat today by glueing the plywood layers together and adding a wood stringer along the back edge I was able to stop the seat sagging down inside the seat tubing frame.
This did two things- Sitting higher in the seat now also moves you back a bit. At first I tried 2 layers of foam to sit on, but that moved me back so far I could barely reach the pedals! So now it's just 1 inch of foam to sit on if I want to reach the pedals- trying the alternate seat back this afternoon which is front mounted over the seat tubing and moves you forward about an inch. Maybe this combination will satisfy all the parameters, but that seating position is about the trickiest thing I have had to do on this trike so far.
 
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Nottinghamshire England
if you download this Kett & lepus manual it has the dimensions of the Kett probably to the best selling delta in the world currently.



This is my trike with the following dimensions.
BB to floor 21"
Front of seat height 15"
back seat height 30"
base length 10"
angle back 53'
angle seat base 24'

So I can put more power out when BB approx 6" above front of seat
When I put my hand between my legs seat front is under crown jewels
seat base slopes upwards else you have the feeling you are sliding out of the seat all the time - unnerving when braking.

Helps ?

Paul
 
Joined
Jul 8, 2022
Messages
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Location
Sagle, Idaho USA
if you download this Kett & lepus manual it has the dimensions of the Kett probably to the best selling delta in the world currently.



This is my trike with the following dimensions.
BB to floor 21"
Front of seat height 15"
back seat height 30"
base length 10"
angle back 53'
angle seat base 24'

So I can put more power out when BB approx 6" above front of seat
When I put my hand between my legs seat front is under crown jewels
seat base slopes upwards else you have the feeling you are sliding out of the seat all the time - unnerving when braking.

Helps ?

Paul
Paul- yes this helps and I see why you said you like the pedals above the seat! The hase BB is more like mine and almost level with the front edge of the seat if I'm looking at it correctly. The pictures of the Hase are pretty good but the chain line is totally different from mine under the seat. I'm still experimenting with the seat padding, but now I have a useable 2" of foam underneath with no serious issues. The thicker seat back I put back on today did move me forward enough to reach the pedals again. Now for some way to keep from sliding forwards and still not hit the backs of my legs. Maybe some softer foam, but your store bought seat seems to have solved that problem quite well. of course it's much easier when the BB is so high I don't know how far upwards any part of the seat can go on mine without being in the way of the leg muscles. And if you had rear wheel drive you'd have to run an idler pulley for sure.!
Thanks vey much for the download .pdf it shows a lot of details that I would never have had access to!! The Hase trikes are pretty spendy I think and they have a ton of little parts. Now that I have seen the details i don't think I'm wanting to own one even if they were half the price. I think they can charge that much when they can be sold as a medical device where the insurance company is paying for some portion or all of the cost, but over here it does not work that way.
 
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The pictures of the Hase are pretty good but the chain line is totally different from mine under the seat.
Only because they adjust the pedal seat length by telescoping the boom and those small idlers take up chain slack without you having to break the chain.

Paul
 
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Pretty good design, but complicated and expensive. Do you know if the front edge of the seat has tubing or is it like a sling side to side? The pics do not really show that detail.
 
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Hard too say , all the versions I have seen do not.
It makes no sense to have a bar there otherwise you can't have any sag [ comfort ] in the seat base ?

Paul
 
Joined
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Location
Sagle, Idaho USA
Hard too say , all the versions I have seen do not.
It makes no sense to have a bar there otherwise you can't have any sag [ comfort ] in the seat base ?

Paul
Paul- That's what you would think- if there were a straight bar inside you would feel it right away. So the Hase has what you would call a "sling" seat as opposed to a hard shell seat with a pad like yours.

Mine is sort of half sling and half hard shell and it also is structure to the whole trike. If I could change one thing on mine it would be that front bar, but on mine, removing that bar would take away any longitudinal strength it might have, and a new frame member would have to be dreamed up and installed without interfereing with the steering which is why I have not done it already. Another reason is that the front bar is only .875" in diameter and if the seat edge was a sling, it might still sag enough to drop below that dimension and interfere with the chain line, or the chain would touch the new seat brackets ("U" shaped tubing ) that is normally found on a sling type seat.

If the center spine of the frame was more like the AZ frame of the Aurora or some others he designed, you could easily adapt a sling seat or a hard shell design to it, but alas! I am not in either ball park for the time being.

On a brighter note- did you see this video on You Tube? - recumbent racing with lots of videos and different designs- some are much like yours!
I watched the whole thing and I was about worn out by the time the race was over! HA!
 
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Tillerman6

You could alter your seat and put the plywood base inside your existing frame and then pad it.

Sort of like this seat AtomBlaster plans , it can be easily made without a tube bender just mitre the corners

Yes he has made a whole series of video's riding races in the UK , I met him at Darley Moor last Monday and a big crowd of riders.

This is a typical UK race BHPC Hillingdon


Paul
 
Joined
Mar 2, 2022
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Nottinghamshire. UK
Tillerman6

You could alter your seat and put the plywood base inside your existing frame and then pad it.

Sort of like this seat AtomBlaster plans , it can be easily made without a tube bender just mitre the corners

Yes he has made a whole series of video's riding races in the UK , I met him at Darley Moor last Monday and a big crowd of riders.

This is a typical UK race BHPC Hillingdon


Paul
Thanks for that Paul, downloaded the PDF. Pity I didn't see you at Darley, I was there on Sunday. Really enjoyed the racing. If I had a bike with me I would have gone around the circuit.
 
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