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 Fully suspended MBB with 90 deg steering angle
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Balor
recumbent guru

Russia
531 Posts

Posted - 06/11/2018 :  16:18:50  Show Profile  Reply with Quote



130cm wheelbase, 90 deg steering angle, 5cm trail (about 6cm with sag), 30 deg seat, just enough seat to BB distance for a 174cm man to fit into with standard cranks, can fit tires up to 26" 2.0 - offroad capable.

Since I'm no builder, it is being fabbed by an other recumbent enthusiast from Russia from my blueprints (he made only FWD-TC recumbents before). The project is pretty much complete, and I think is a great success:

Builder hopped on and rode off right away, went for an 50 km offroad test ride next day with no fuss and was consistently faster than on MTB... he swapped bikes with his buddy and same was true for him as well. Suspension works great and does not seem to bob much (6cm of pure vertical travel, 35mm rearward axle path)

It would be not faster than true 'racing' bents (plus it is heavy) obviously, but the goal was to have a replacement for MTB for long offroad rides and brevets where there is really bad asphalt.

Once I'll actually receive it, I'll post updated impressions.

Garrie L Hill
human power supergeek

USA
1744 Posts

Posted - 06/11/2018 :  18:34:33  Show Profile  Reply with Quote
Very nice! What is the short post behind the shoulder area of the seat?

Garrie "carbon based lifeform" Hill
HPRA Co-Dictator of the East
for pics of some of my time and money sucking projects
http://s58.photobucket.com/albums/g277/cfbb/
and videos
http://vimeo.com/5513519


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Balor
recumbent guru

Russia
531 Posts

Posted - 06/12/2018 :  03:14:47  Show Profile  Reply with Quote
A mount for QR rack, I've had a similar arrangement on one of my first bents and liked it:

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warren
human power expert

USA
6265 Posts

Posted - 06/12/2018 :  10:36:58  Show Profile  Visit warren's Homepage  Reply with Quote
Looks very cool! I love the bent tube!
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Balor
recumbent guru

Russia
531 Posts

Posted - 06/13/2018 :  14:26:22  Show Profile  Reply with Quote
quote:
Originally posted by warren

Looks very cool! I love the bent tube!



Well, it's a bent. It should feature a bent tube! :)

Admittedly, when using wide tires and manuevering offroad, there is 'calf interference' issue according to the builder, which I'm familliar with but kinda forgot about (because it is not a problem at all during normal riding with 40mm tires on a bike with similar negative offset).

I'll see how actually bad it is, if bad enough I have a 'backup plan' of 24" front wheel and 165mm instead of 150mm shock - it should preserve geometry, but decrease offset and tire of smaller diameter should not interfere as much.

I really want an 'offroad bent', actually I've been wanting one since 2014 when I got my first one, but Azum max clone didn't work for me at all (numb feet onset - half an hour), and offroad LWB is way to unwieldy.
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PUGZCAT
recumbent enthusiast

Canada
464 Posts

Posted - 06/22/2018 :  10:45:04  Show Profile  Reply with Quote
Balor you are a design genius. I like the clean effective design, from Frankenstein-ing full suspension "Walmart" mountain bikes. Good handling, smooth riding and fast, checked all boxes got the job done.
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Balor
recumbent guru

Russia
531 Posts

Posted - 06/22/2018 :  11:17:38  Show Profile  Reply with Quote
quote:
Originally posted by PUGZCAT

Balor you are a design genius. I like the clean effective design, from Frankenstein-ing full suspension "Walmart" mountain bikes. Good handling, smooth riding and fast, checked all boxes got the job done.



I'll be very surprised if it turn out to weight less than 50 pounds, so 'lightweight' box remain soundly unchecked.

I actually kind of enjoy designing around constraints like that, but I bet I will not be too happy to actually lug it around :) Plus you may call me a genius once I'll manage to cram in remote steering and all wheel steer (and make it rideable to boot without weighting even MORE). Otherwise the concept is pretty simple :)

Also, I'm yet to ride it, it is still 'in the mail' and should arrive sometime next week.

As for new developments, we've added a head tube gusset (just in case) and I've ordered a 'cruzbike type boom' that is compatible with superman bars clamp:



Should be stiff enough yet MUCH more adjustable than cruzbike arrangement.
If I like it, I may design an other bent around that concept, but not with adjusability, but light weight in mind. My bad back actually complains about lugging 50+ pounds up stairs, I don't have a ground level garage.
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SpiderMonkey
recumbent enthusiast

USA
268 Posts

Posted - 06/25/2018 :  11:40:02  Show Profile  Reply with Quote
Having taken delivery on a fully-suspended, 47-pound 'bent recently, I'm always surprised at how much the weight matters when you're carrying it around. I notice it so much less when I'm riding it (even uphill. Sure it's slow, but it's geared LOW.)

That is one nifty-looking machine.

--SpiderMonkey
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Garrie L Hill
human power supergeek

USA
1744 Posts

Posted - 06/25/2018 :  20:49:08  Show Profile  Reply with Quote
Hmmmmmmmmm......



Garrie "carbon based lifeform" Hill
HPRA Co-Dictator of the East
for pics of some of my time and money sucking projects
http://s58.photobucket.com/albums/g277/cfbb/
and videos
http://vimeo.com/5513519


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carolina
recumbent guru

USA
843 Posts

Posted - 06/25/2018 :  21:11:10  Show Profile  Visit carolina's Homepage  Reply with Quote
That g. Hill guy is really sompin:) Still modding lowracer, cut frt off again.

velosRus.com
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Balor
recumbent guru

Russia
531 Posts

Posted - 06/28/2018 :  08:40:49  Show Profile  Reply with Quote
Well, it seems it weights about 49 pounds when assembled, so color me surprised :)

Ok, I've got it, assembled with one gear (33x11) and one brake and went for a short night ride (otherwise I'll not get any sleep :)).

So, how it handles? Lugging it around is still a pain due to heavy and somewhat floppy front triangle (real steering angle turned out about 88 deg or so), but once you sit down and push the pedals the beast transforms.

Steering is absolutely rock-stable at any speed past snail pace, mentioned wheel-calf conflict is not noticeable with 40mm tires. It does not feel like your typical MBB at all - even pedal steering effect is barely noticeable at speed! (color me surprised again - likely due to longish tiller)

I'll need to try this on one guy that tried my previous bents before and did not like them, whether he'll 'ride off' this time :)


Suspension works wonderfully and allows one to simply fly over huge potholes that my neighbourhood supplies in abundance :).

Low BB feels and pedals great.

Fit... is tricky though, like I suspected the builder made the frame a bit larger than I asked for, and given very limited tolerances it feels I'm overextending a few mm even on 150mm cranks. I actually have cranks as short as 140mm, but those are road double and it will result in rather 'virtually tall' gearing with cranks that short.

I'm contemplating cutting a notch in my seat to move it forward those missing few mm.

Pictures after I'll finish assembly.

As for the 'showel' hint - our parents actually have a titanium showel (it was a gift), ehehe.
Unfortunately, that's way out of my budget.

Aluminium - maybe, but I think I'll leave the suspension parts steel, make the frame from basalt fiber and boom from aluminium - Cruzbike.
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Balor
recumbent guru

Russia
531 Posts

Posted - 06/29/2018 :  16:45:11  Show Profile  Reply with Quote
Maiden voyage!
https://www.strava.com/activities/1670046779



I daresay it is fast enough for a FS bent with body position (low BB) and crank length I'm not familiar with yet.
"Cruzbike cockpit' with 'seagull bars' is great and short cranks allow for comfortable arms position without my knees hitting anything in the process.
I should note that road on that track is very bad, with lots of potholes and rough, weathered asphalt. Funny enough, front suspension seems much 'smoother' than the rear - likely due to heavy front weight bias (hence much larger suspended mass) and rearward axle path.
Among 3 MBB bents I've tested (Zorkra Clone, MBB with negative angle and this one) - this is the most easily steered bike, despite front triangle weighting a ton. One-handed operation is trivial, riding no-hands is ALMOST doable even for an oaf like me! I bet I'll get the hang of it eventually.
Basically, ride has a 'relaxing' quality that my previous MBB bents sorely lacked. You don't feel like being from one small hand twitch from lying in a ditch :) Yet, you can 'swing the boom' for power and pull the bars and stomp the pedals and get rewarded with feel of power NOT being lost anywhere.
I should note that suspension does NOT bob at all at least when cruising on flat ground - something that came as a surprise for me, actually.
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