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I have a Sun adult trike with a western saddle. That's the kind of saddle that you plunk your whole bum on, instead of a standard bike saddle that you straddle and just your sit bones contact. Saddle and U support bar

This trike currently has the 19" U-shaped support bar and whatever the standard seatpost is (7/8" x ?). This makes for a very low saddle height, and has that big honking saddle. I'd like to replace this configuration with something higher up and a standard saddle if possible. I know about the 21" support bar, and longer seat posts, but this bike does not have reasonable seat stays, so no way to just go to a standard seatpost/clamp arrangement (I think).

The barely-existent seat tube stays.

So, the question is, does anyone have thoughts, or better, has seen a product, that would let me mount a regular saddle on this support bar/weak seatpost combination? I can get a longer support bar, and longer seatpost. I can change the angle of the support bar, though not the seatpost. I could weld on better seatstays, but with a 7/8" post, it probably still wouldn't be strong enough without something like the support bar.

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Looks like there might be welding in your bike's future. A competent welder might be able to attach some better seat stays that terminate below the clamp. Then you'd use a normal saddle on a normal seat post.

BUT there will be a lot of unsupported seat tube poking up. As a tall rider, I have over-extended seatposts leading to bent seatposts and cracked frames.

Your other option is to get your welder to make a bridge between the existing seatpost and the existing stays, and then mount a normal saddle on that using an old-school saddle clamp but rotated down.

The risk here is the saddle will fall sideways if the bridge tube is round, so perhaps your metalworker can find some half-inch box section and mangle the bike clamp so it goes around a square profile.

Edit: Here's a spin bike with something vaguely similar. The seatpost can adjust up/down, and the horizontal box section sits in a channel, and can't move sideways. It can move fore-aft if the hold-down bolt is released. On top of that is a short vertical round tube, where a normal seat clamp fits.

Own work

Also own work

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  • Ooh, that second part. Forgot about the funky posts for spinning bikes. Our fitness center has something like that. OTOH, that led me to this page: link. Still not quite right, but that gives me another idea. What about using a longer 7/8" seatpost, and the longer support bar, but then, instead of the wide bum saddle, mount the regular saddle to the support bar with two small U-bolts or one wider, more square U-bolt? The seat rails are perpendicular to the support bar.
    – user3224303
    Apr 18, 2018 at 18:10
  • @user3224303 good thinking - you'll either need to measure carefully or think how to include some kind of adjustment.
    – Criggie ♦
    Apr 18, 2018 at 21:59
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    Yeah! That's a lot like the one I spotted after you mentioned it. I like that one though, I've never seen suspension on a spinning bike before! It will take a bit of trial and error, because you're right, it will need to be adjustable a bit. Thanks! I'll post back after I've tried the u-bolt concept.
    – user3224303
    Apr 19, 2018 at 14:14

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