Fully suspended MBB with 90 deg steering angle.

[Balor]

By they way, what tires do you expect to install? 28-40mm 26"?
If you intend to install fatter tires (say, 50mm 26") you may want to make negative offset a bit less - say, 4-5cm (remember, suspension sag will add some more trail), or you may run into wheel-calf conflict on very tight turns, or even a bit less if you'd like to install 700c wheels, but with add some angle to the steering - say, 85 or something.

My legs are pretty fat, so it may a complete non-issue to you.

 

[dtseng]

Balor, thank you for your valuable instructions. There is a government institution here open to the public. I will go there to use Auto CAD to get accurate drawings. The elastomer suspension is the cheapest and it can be bought on-line. I would use 2-chamber air shock. To build a prototype frame will be next years project as I will build my 2nd MBB frame with back rest angle around 20 degrees this winter. The drawing below is my design of pivot for swing arm. The end plug is tightened with 6mm allen key. The pivot is further secured by a quick release.

 

[Balor]

Since I can average 24 mph for tens of miles if I try hard enough (flat highway), I think some tuning is in order to see what is the bike's full potential.
I've scraped up on a 27.5 wheelset (cheap, but seems nice) and a set of Schwalbe G-one speed (40mm) and Pro One in 25mm (I cannot quite fit 700c tires at the front)

I'll try them both to compare how they stack up to 26" 40mm old stock Vittoria slicks, and then (hopefully it will work) use heat-shrinkable film to 'fair' the wheels turning them into DIY disk wheels.
I'll actually try it on BOTH wheels - I'm heavy enough that being blown about is not much of an issue, plus due to negative offset I'll have equivalent of 'aerodynamic trail' effect - front disk would actually add to stability at speed, unlike positively offset front wheel.

To qualitatively assess the effect (without a power meter, most unfortunately) I'll make a few test rides at a set HR and see how much it adds up in a more or less objective fashion.

 

[Balor]

Due to being on keto HR measuring turned out to be out of whack, so I just installed one rear covered wheel for now and went 'all in'.
Improved BOTH my PRs by about 1 mph, which seems about right. I've actually test-ridden local highway (by necessity) and noticed essentially zero difference in being buffeted by passing trucks compared to uncovered rear wheel.

 

[bladderhead]

People think crosswind pushes you sideways. I think that effect is really weak. I think that mostly it has a steering effect on the front wheel.

 

[Balor]

Really gusty winds - or really closely passing trucks - maybe. Didn't test it yet extensively.
Plus, I weight 300 pounds overall and hence have a ton of inertia. In Soviet Russia, YOU buffet passing trucks, ehehe.

The steering effect on the front wheel should indeed be greater, but with negative offset, like I said, I'll have 'aerodynamic trail' effect that should actually contribute to stability, instead of vice versa.
Full disk wheels front and rear is indeed a very bad idea on a bike with conventional steering geometry - small wonder they are pretty much banned everywhere but on track.

 

[Balor]

 

[Balor]

I did test the front disk on my 'test loop' and imporoved my KOM by 4 sec.. I suspect what was gained in aerodynamics mostly lost in rolling resistance on a rough road.

After puncturing front tire on a railway crossing on my way back (100 psi in a 23mm tire with 90 kg normal load is way underinflated I presume), I've ditched the disk wheel for now (cannot fit a larger tire, and disk benefits don't really shine with a fat tire).

Finally went for a longer ride (nice and flat), 190 km, nearly averaged 30 kmh:

https://www.strava.com/activities/1798895310

Again, not impressive, but a couple of miles faster than my previous bents and I've finally beat my DF niner average speed (though with half the climbing).

Some roads were truly brutal and I was very happy to have full suspension.

 

[Bentas]

Are you kidding? 190 Klm's average 30 Klm's an hour, that's 10 Klm's hr faster than I would do that distance, and on that beast. I'd say impressive is an understatement.

 

[Balor]

Well, I guess I suffer from skewed speed standards from too much Strava (not unlike shift in beauty standards from too much Instagram )

I mean, after seeing people average 42 kmh into 1% uphill for 5 minutes (solo) or do 120 km with average speed of 42 again (group of 3, road bikes with clip-ons.. and those are amateurs!) I get kind of depressed at seeing my meager results...
Well, at least (besides callouses on my palms from all the bar-pulling and minor sunburn) I'm totally pain-free after the ride .

 

[dtseng]

The bike in the current setup looks very impressive to me. I think recumbents should have suspension.

 

[Balor]

The bike in the current setup looks very impressive to me. I think recumbents should have suspension.

Yea, totally. Bents should have at least a couple of inches of suspension to equal *rigid* df bikes, and wider tires as well. Not being able to stand on pedals and hop large potholes or 'launch ramps' type of road irregularities is a pretty large downside... and on the other hand designing a suspension on a bent is easier due to lower CG and longer (usually) wheelbase. Win-win.
Of course, given very smooth roads none of that is needed, but that severely limits your routes and usually puts you in close company of heavy motorised traffic.

 

[Balor]

Yet an other FS, 90deg steering MBB Russia (not mine, but was inspired by my design):
http://velomobile.org/forum/viewtopic.php?f=108&t=15426

Much simpler construction, 20" wheels, folds compactly, claimed ability to carry lots of stuff, easy steering and good high-speed stability.
(Admittedly, I'd make wheelbase longer - cargo rack beyond rear wheel axle is not good for stability).

 

[cpml123]

I think yours look much nicer.

 

[Balor]

I think yours look much nicer.

Admittedly, so am I . But his was done with more utilitarian purposes in mind, and on a much tighter budget I presume.