Karl's V20 variable seat angle solution

Karl42

Karl42

Well-Known Member
Here are some pictures from last weekend's 400 km ride. Just before the ride I realized that I had forgotten to reinstall a fender to protect the seat raising mechanism from getting dirty, so I cut a plastic cup in half and taped it to the bike. And I'm glad I did, because this ride got very muddy.

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CoolHandChris

New Member
Karl42 said:
The whole thing is still a bit provisional, but I made my first ride test today:

The first impression is very positive. It feels very stable, and gives good support when climbing. Operation is straightforward. The upright seat angle is the resting position. To lower the seat, I push the lever under the seat and lean back. To raise the seat, I simply lean forward, and the seat will raise by itself.
The hill at the end of the video was nearly impossible for me to climb with the stock V20, because this path has a very rough surface with lots of debris on it, and I would usually lose traction. With the seat angle modification it is now super easy.
My only regret is that I haven't done this sooner.
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Impressive! I’m in the beginning stages of modifying my V20C to do the same thing.
 
3bs

3bs

whereabouts unknown
i love your work here. i think it is in the top 3 best trys, maybe the best. i cant tell you how many hours i spent on this and how many emails and experiments i had. also did comparison rides between my cb's for seat angle analysis. i cut seats, i used hinges, i used foam, i did all kinds of stuff. i had a few good versions, but, even on my longest rides and tours, i came to a few conclusions:
1. the single greatest comprimise bike and seat angle is found on the s30. a modern version of this bike should still be made. they are unicorns and for good reason. the best seat angle and break down for shipping the best. i still dont have one, but my neighbor does.
2. the single cheapest lighest and easiest mod to use is a foam wedge. i was delighted when cb started to sell one. i have an entire box of my experimental wedges.
3. all things considered, ultimatly i prefer the thor seat. i have them on the 20 and 40 i ride the most. i still have standard seats with foam on my other 20's and 40's but even with the thor i have a foam insert. recently bought two more thors to test an idea....
4. gearing is more important than seat angle. i have spent even more time on gearing and driveline.
5. i have ridden many multiday rides on the 20 and the 40. the longer the days the more i prefer the 20 as i get recumbutt on the 40 around 100. the steeper the climbs the more i prefer the 40, so i can push on my back. i have experienced wheels slip on both so bad i had to walk the bikes. nowadays i just dont go on those rides any more. i hate climbing no matter the bike, so, if i am going to be on the steepest climbs, now i just bring frankentrike. it is geared to climb, and if i get exhausted, because it is a fwd mbb trike, i just stop and rest, then i start up again. the seat angle on it is lower than a 20 with a little kick up at the shoulders.
 
chicorider

chicorider

Zen MBB Master
3bs said:
the single greatest comprimise bike and seat angle is found on the s30. a modern version of this bike should still be made. they are unicorns and for good reason. the best seat angle and break down for shipping the best. i still dont have one, but my neighbor does.
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Ditto. I have a V20c and one of the last S30s. That 30-degree seat angle (I think it's actually about 33 degrees) is a real Goldilocks setup. I've said a few times on the forum that if CB were to put out a short run of S30s based on the S40, I'd bet they wouldn't sit for long in their warehouse. I also understand that it would be an expensive proposition for a small company like CB They would probably have to raise the price to cover the cost. But boy-oh-boy, if they were to put out a S40-like S30, I'd buy one and sell my unicorn.
 
Karl42

Karl42

Well-Known Member
Last weekend I did a 600 km (400 mile) brevet with about 5000 meters (16.000 feet) of climbing, and the seat adjustment system worked flawlessly. Especially in these rolling hills where the route would constantly change between going uphill and downhill, having the ability to change the seat angle instantly was great, and I can hardly imagine riding without it now.

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Karl42

Karl42

Well-Known Member
Frito Bandito said:
That's Awesome Karl. Perhaps you can make a kit for it
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I put the updated parts list in comment #14 of this thread, and tried to document everything with enough detail. I don't want to make a kit for this, but I'll be happy to answer further questions or make more videos if someone wants to build this.
So if you (or anyone) is interested in building this and needs more detail, please ask your questions here in this thread so that the answers are there to see for everyone.
 
Karl42

Karl42

Well-Known Member
I just finished a one-week cycling trip from northern France to Germany, doing 1193 km (741 miles) with about 7500 meters (25000 feet) of climbing, riding significant sections on unpaved bike paths.
With the wide tires and the seat angle adjustment, the V20 now feels more like an adventure touring bike and not a road racer, and even with the fully loaded bags it handles very well and is fun to ride. In fact, the heavier wheels and tires make the bike much more stable than the much lighter carbon fibre wheels with road tires that I normally ride, and which make the steering a bit more wobbly. This also makes hands-free riding much easier.

The seat angle adjustment continues to work perfectly, and on this trip I actually used the upright position much more than the reclined one, as I now got fully used to it.

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Animal494

Member
bromclist said:
Nice. So you now will have the speed of V20 and the comfort of S40 (each when required)
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I wonder if the reverse can be done to an S40. Can this similar approach be taken to the seat of an S40 but the bottom half hinges “up” to give a 20-30 degree seat angle - then it can hinge down when you need the 40degree position.
 
Karl42

Karl42

Well-Known Member
Animal494 said:
I wonder if the reverse can be done to an S40. Can this similar approach be taken to the seat of an S40 but the bottom half hinges “up” to give a 20-30 degree seat angle - then it can hinge down when you need the 40degree position.
Click to expand...
I don't think this is feasible. To get a 20-30 degree seat angle on an S40 by hinging the seat "up", your hips would have to be so high that pedaling becomes difficult, and the handlebar would be in the way. And I don't see what kind of hinge mechanism would be able to support your body weight on the now raised lower seat.
 
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CoolHandChris

New Member
Animal494 said:
I wonder if the reverse can be done to an S40. Can this similar approach be taken to the seat of an S40 but the bottom half hinges “up” to give a 20-30 degree seat angle - then it can hinge down when you need the 40degree position.
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Exactly! I haven’t lost any mph ave at all and can see the road and obstacles perfectly.
Good point about making an S40 into a 30 or 20.
 
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Animal494

Member
A

Animal494

Member
Karl42 said:
Here are some pictures from last weekend's 400 km ride. Just before the ride I realized that I had forgotten to reinstall a fender to protect the seat raising mechanism from getting dirty, so I cut a plastic cup in half and taped it to the bike. And I'm glad I did, because this ride got very muddy.

View attachment 20491View attachment 20492View attachment 20493View attachment 20494
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Wow! That is super muddy for skinny tires!!

Can you tell me about your wider tire setup on the V20 you use for touring?
 
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