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warren
human power expert

USA
6118 Posts

Posted - 04/06/2012 :  07:19:25  Show Profile  Visit warren's Homepage  Reply with Quote
I'm not really into the whole MBB scene.
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Speedbiker
human power expert

USA
3758 Posts

Posted - 04/06/2012 :  07:52:45  Show Profile  Reply with Quote
I might try a mbb, but I will never go back to banging my knee in a middrive or fighting the chain affected steering.
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warren
human power expert

USA
6118 Posts

Posted - 04/06/2012 :  18:23:04  Show Profile  Visit warren's Homepage  Reply with Quote
Having bashed my knee on a few mid-drives, I can sympathize with you, Thom.

I did a real scale drawing to find actual dimensions, and determined that the crotch to BB distance on this bike is 37". I need it to be 33". Getting it to 33" would cause big crank overlap or seat / BB heights outside of my parameters. Back to the drawing board..,

-Warren.

Edited by - warren on 04/06/2012 18:27:21
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Larry Lem
human power expert

South Sandwich Islands
2524 Posts

Posted - 04/06/2012 :  20:48:57  Show Profile  Reply with Quote
See how high you'd have to sit to have adequate clearance. It might just be 3 inches. (That's why I call mine a midracer.) I use 650Cs and 150 mm cranks. You have 3" longer legs and are trying to use 700Cs and 170 mm cranks?

I'd like to see a side-view of Aure's bike. His seat height looks to be 20". How tall is he; how long are his legs?

Larry Lem
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PUGZCAT
recumbent enthusiast

Canada
459 Posts

Posted - 04/07/2012 :  06:37:53  Show Profile  Reply with Quote
I thought I was inseam challenged at a few hairs over 6 feet with a 32 inch inseam.
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warren
human power expert

USA
6118 Posts

Posted - 04/07/2012 :  08:25:21  Show Profile  Visit warren's Homepage  Reply with Quote
165 cranks, but yeah that's what I was trying for. What is the OD on a 650C tire? Maybe I'll just stick with the Nocom.
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n/a
deleted

2373 Posts

Posted - 04/07/2012 :  09:34:18  Show Profile  Reply with Quote
Warren,
Why not copy Larry's dual 650c bike and make changes needed to fit your leg length? That design works.
You can also go totally horizontal as the Auré bike. Alsio, If you build from scratch are you going to gain that much speed over the NoCom?

quote:
Originally posted by warren

165 cranks, but yeah that's what I was trying for. What is the OD on a 650C tire? Maybe I'll just stick with the Nocom.


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warren
human power expert

USA
6118 Posts

Posted - 04/07/2012 :  11:50:07  Show Profile  Visit warren's Homepage  Reply with Quote
I did some more drawing. With crank overlap and at least enough clearance for the chainring, seat height goes up to 17". That is very close to the 19" seat height of my current CF highracer. http://recumbents.com/wisil/stickbike/default.htm. Based on that I am going to abandon the dual 700C lowracer. I have enough bikes already, right? I can always try racing the CF highracer with dual wheeldisks and see what that does.

AA, I don't want to invest in another size of expensive disk wheels.

-Warren.
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alevand
human power expert

USA
2935 Posts

Posted - 04/07/2012 :  12:35:36  Show Profile  Visit alevand's Homepage  Reply with Quote
Well, Warren I have also given up on a low dual 700c short wheelbase racer, unless I have a stroke of inspiration, other than pedal blocks. The mule is going into the museum for now. It coasted down the hill just fine. Getting the drive setup around the big wheel is just too convoluted. I guess I'll build another race Carp.

C:
Tony Levand

Edited by - alevand on 04/07/2012 12:43:07
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Speedbiker
human power expert

USA
3758 Posts

Posted - 04/07/2012 :  13:58:22  Show Profile  Reply with Quote
MBB? See Warren's previous comment.
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Larry Lem
human power expert

South Sandwich Islands
2524 Posts

Posted - 04/07/2012 :  14:54:12  Show Profile  Reply with Quote
From Warren's Stick bike diary:
11/06/2011
I have been riding this bike weekly all year, and really like it. It handles well, goes up hills easily because it is so lightweight, and seems fast. It's certainly not as fast as the Nocom, but is much more civilized.

Warren,
Try dual disk wheels on the 700C stick bike/carbon high racer and see how fast it goes. Did you end up in the same riding position as the NoCom, or are you sitting a tiny bit more upright on the 700C bike?

Larry Lem
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warren
human power expert

USA
6118 Posts

Posted - 04/07/2012 :  16:19:32  Show Profile  Visit warren's Homepage  Reply with Quote
Hey Larry, I think the position is the same on both bikes. Yes, I'll try the dual disk on a wind-free day.

-Warren.
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warren
human power expert

USA
6118 Posts

Posted - 04/11/2012 :  19:17:56  Show Profile  Visit warren's Homepage  Reply with Quote
Hey Tony, the Carp was pretty fast so another Carp is not a bad thing. You have never built a lowracer though, so why not do a 451mm front wheel lowracer? You could eventually put it in a 'liner.

I re-drew the dual 700C lowracer with dual 650 wheels. With that I can make the seat height 15" with proper crank clearances and a 15 degree seat. This may be worthwhile doing if I can find some wheels for cheap.

-Warren.
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rzon
Starting Member

USA
10 Posts

Posted - 04/13/2012 :  07:17:40  Show Profile  Reply with Quote
26x26 seat height 12" [P091011_09.58.jpg] [/
P091011_09.58.jpg]
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warren
human power expert

USA
6118 Posts

Posted - 04/13/2012 :  09:20:39  Show Profile  Visit warren's Homepage  Reply with Quote
Hey rzon, can you upload that picture to photobucket, then post a link to it?

Larry Z is encouraging me to build this Mike Burrows dual 700C bike. I think he just wants to watch me crash.



It looks one step more difficult to ride than a MBB bike.

http://www.bhpc.org.uk/mikes-new-bike.aspx
http://www.bhpc.org.uk/b2ornotb2.aspx

Mike says "It works but is not easy to ride and I am not sure I can be bothered to learn - life is too short!".

-Warren.

Edited by - warren on 04/13/2012 09:43:44
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PUGZCAT
recumbent enthusiast

Canada
459 Posts

Posted - 04/13/2012 :  15:23:09  Show Profile  Reply with Quote
Mike Borrows proof of concept thing would work better if it has a lot more fork offset to yield 2 inches of trail. It looks like it has a ton of wheel flop, that is the seat base is at it's lowest point when the steering is turned to the extreme, anti-self centering steering.
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alevand
human power expert

USA
2935 Posts

Posted - 04/13/2012 :  15:57:48  Show Profile  Visit alevand's Homepage  Reply with Quote
Hmm, two weeks to build a Carp race bike.

If I had to choose a 60/40 weight distribution, Id rather put 60 on the 700c wheel.

The Burrows through axle bike in the picture has zero or negative trail, looks like adjustable rake. Dig the leaf spring under the seat, if it isn't bouncy enough with that thin diameter tubing....

C:
Tony Levand

Edited by - alevand on 04/13/2012 17:42:47
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PUGZCAT
recumbent enthusiast

Canada
459 Posts

Posted - 04/15/2012 :  18:08:13  Show Profile  Reply with Quote
I've seen the YouTube video the steering looks pretty floppy.
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alevand
human power expert

USA
2935 Posts

Posted - 04/16/2012 :  05:10:32  Show Profile  Visit alevand's Homepage  Reply with Quote
Warren, I am going to try raising the seat from 6 inches high to 13 inches high.

C:
Tony Levand

Edited by - alevand on 04/16/2012 13:46:27
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tom porter
recumbent enthusiast

160 Posts

Posted - 04/16/2012 :  07:55:51  Show Profile  Reply with Quote
I thought about the same design about 4 years ago and came to the same conclusions that to straddle a 700c front wheel with a fairly low seat height wasn't gonna work. I might try drawing up a 559/700c design and see what seat height I can get by overlapping the crankarms. Why, because over the last couple of years I find that I no longer want to be lifting my legs about 3 feet in the air to start my dual 700c Z frame. You'll see what I mean in 20 years.

O---o
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rzon
Starting Member

USA
10 Posts

Posted - 04/21/2012 :  07:03:59  Show Profile  Reply with Quote
http://i1049.photobucket.com/albums/s384/rzonrzon/P091011_0958.jpg


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warren
human power expert

USA
6118 Posts

Posted - 04/21/2012 :  09:04:59  Show Profile  Visit warren's Homepage  Reply with Quote
Cool, rzon, what size is that front wheel?
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Speedbiker
human power expert

USA
3758 Posts

Posted - 04/21/2012 :  09:30:27  Show Profile  Reply with Quote
Where has rzon been hiding? He is definitely one of us!
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warren
human power expert

USA
6118 Posts

Posted - 04/21/2012 :  11:45:04  Show Profile  Visit warren's Homepage  Reply with Quote
According to his profile, Richard has been hiding in Wisconsin.
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tom porter
recumbent enthusiast

160 Posts

Posted - 04/22/2012 :  13:52:00  Show Profile  Reply with Quote
1st clue, the bike pic was taken from the upper balcony of the Milwaukee Art Museum/War Memorial overlooking Lake Michigan to the East.

O---o
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