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ShelGame
recumbent enthusiast

USA
254 Posts

Posted - 01/28/2017 :  07:32:54  Show Profile  Reply with Quote
With the LWB bike basically done after having it's maiden flight, it's time to start on the n+1 bike. I'm starting with this:



I picked this frame up from Warren last summer with the intention of making a bike for my sons (ages 10 and 13).

It's going to get 24" BMX wheels and tires; a seat from Thor, and several left over parts from the LWB build. And some new parts, too. Hopefully we can get this done in time for Waterford this year. But you know how that goes.

The big change is going to be the rear dropouts. The wheelbase is too short, and the HT angle is too steep at about 77 deg (IMO). So, I want to lower the rear of the frame. I think if I move the dropouts to the rear of the triangle from the bottom, that will extend the WB an inch and a half or so and lower the rear maybe an inch.

I also want disk brakes. So, I'm planning to make new dropouts with some aluminum stock I have left over from the old prone frame.

So, I'm now making measurements to digitize the frame layout in CAD so I can get the geometry of the new dropouts correct.

Edited by - ShelGame on 02/05/2017 08:24:46

Balor
recumbent guru

Russia
512 Posts

Posted - 01/28/2017 :  07:37:11  Show Profile  Reply with Quote
"The wheelbase is too short, and the HT angle is too steep at about 77 deg"

Too steep for what? Too low trail? What kind of fork you are intending to use? You are much better off with modifying a fork for no offset and you'll get a much better ride both low and high speed provided you will not end up with too much tiller.
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PUGZCAT
recumbent enthusiast

Canada
459 Posts

Posted - 01/28/2017 :  17:54:32  Show Profile  Reply with Quote
520mm rims?
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ShelGame
recumbent enthusiast

USA
254 Posts

Posted - 01/28/2017 :  17:56:23  Show Profile  Reply with Quote
quote:
Originally posted by PUGZCAT

520mm rims?



Correct.
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ShelGame
recumbent enthusiast

USA
254 Posts

Posted - 01/28/2017 :  17:57:48  Show Profile  Reply with Quote
So, I think this is where I want to take this frame. 2" longer wheelbase and a little slacker on the HT, with a fork I already have. Still seems pretty high to me, though.


Edited by - ShelGame on 01/28/2017 18:01:10
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PUGZCAT
recumbent enthusiast

Canada
459 Posts

Posted - 01/31/2017 :  15:42:46  Show Profile  Reply with Quote
Try the stock build, you might really like it as is.
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ShelGame
recumbent enthusiast

USA
254 Posts

Posted - 01/31/2017 :  16:09:20  Show Profile  Reply with Quote
Stock build = No rear disk brake option :(

Also, I don't have the original, near-zero rake fork. Using an off-the-shelf fork would end up with very little trail, I think. My guess is this thing would be twitchy to start with. Don't need to make it worse.
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Speedbiker
human power expert

USA
3744 Posts

Posted - 01/31/2017 :  17:49:41  Show Profile  Reply with Quote
Are your sons NBA prospects? How about 20" wheels?
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PUGZCAT
recumbent enthusiast

Canada
459 Posts

Posted - 01/31/2017 :  18:55:59  Show Profile  Reply with Quote
Steel forks are pretty easy to tweak to whatever offset is required, use fork gauges to get the dropouts trued up.
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ShelGame
recumbent enthusiast

USA
254 Posts

Posted - 02/01/2017 :  06:12:44  Show Profile  Reply with Quote
quote:
Originally posted by Speedbiker

Are your sons NBA prospects? How about 20" wheels?



Yeah, It's still pretty tall even on 24's. I thought about 20's, but I don't like the clown bike look. Maybe 451's...

Edited by - ShelGame on 02/01/2017 06:14:28
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ShelGame
recumbent enthusiast

USA
254 Posts

Posted - 02/03/2017 :  04:53:16  Show Profile  Reply with Quote
I drew a chainline on the modification above, and of course it doesn't work. The chain crosses the lower stay too much; would require a 2nd idler (like my LWB bike).

So, back to the original rear dropouts, with disk tabs added.

The over/under idler is drawn where the chain tube hanger was on the original bike. But, I think it might work better more to the rear.

I also think this frame might work with a Cruzbike conversion if I cut the front boom off. Hmm...

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PUGZCAT
recumbent enthusiast

Canada
459 Posts

Posted - 02/03/2017 :  16:07:39  Show Profile  Reply with Quote
520mm with 25mm tires, 570mm overall or 22.5 inches, a little lower than you thought!
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Speedbiker
human power expert

USA
3744 Posts

Posted - 02/03/2017 :  17:53:00  Show Profile  Reply with Quote
I think you'll want a flip-stem.
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ShelGame
recumbent enthusiast

USA
254 Posts

Posted - 02/04/2017 :  07:24:43  Show Profile  Reply with Quote
quote:
Originally posted by PUGZCAT

520mm with 25mm tires, 570mm overall or 22.5 inches, a little lower than you thought!



Good point. I actually have 28mm tires. That puts the OD at 22.7". Which really just reduces the trail a little bit. And, lowers the seat an inch.
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ShelGame
recumbent enthusiast

USA
254 Posts

Posted - 02/04/2017 :  07:27:37  Show Profile  Reply with Quote
quote:
Originally posted by Speedbiker

I think you'll want a flip-stem.



I was actually thinking to build it up first with USS just because I have parts I can use for that. But, I was wanting to use 'regular' bike parts (like a stem). I'm not sure it will fit under the legs. The seat sits real low on the frame. I might have to find a flip stem...
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ShelGame
recumbent enthusiast

USA
254 Posts

Posted - 02/05/2017 :  08:31:01  Show Profile  Reply with Quote
Now I'm waffling on the dropouts.

I redrew it with the correct rolling OD, and the trail reduced a bit, but so did the wheelbase. So, I redrew the rear dropouts without lowering the rear. Also measured my older son's x-seam (at 13, 41" already, jeez). I'm still thinking about it. But, I like this so far.

The fork is a 26" fork, so this could still use 559's later on when the boys get bigger.


Edited by - ShelGame on 02/05/2017 08:34:06
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PUGZCAT
recumbent enthusiast

Canada
459 Posts

Posted - 02/06/2017 :  08:27:07  Show Profile  Reply with Quote
A flip stem is easy to cook up from a standard stem. Take a piece of solid rod cut to length drill a 3/8" hole thru the center for a bolt, clamp the now 5/16" wall tube into the stem, weld a U bracket with 3/8" holes on a tube with 7/8" inner diameter for a quill stem or 1 1/8" outer diameter for a clamp on stem, throw in some nylon washers for good measure.
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Speedbiker
human power expert

USA
3744 Posts

Posted - 02/06/2017 :  08:45:20  Show Profile  Reply with Quote
Don't forget a stop so the bars don't fall into your lap.

A word about USS: I hate how they look. I hate their terrible aerodynamics. But dang is it fun flying feet first with your arms down by your sides!
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ShelGame
recumbent enthusiast

USA
254 Posts

Posted - 02/06/2017 :  10:14:58  Show Profile  Reply with Quote
quote:
Originally posted by Speedbiker

Don't forget a stop so the bars don't fall into your lap.

A word about USS: I hate how they look. I hate their terrible aerodynamics. But dang is it fun flying feet first with your arms down by your sides!



Yeah, I know they're not the best. But, my thinking is they might be easier to learn with. Want the boys to stay on the bike long enough to get used to riding it. Wide OSS bars will be the alternate if USS doesn't work.

Once they get used to riding and want to go faster, then we'll go to narrow OSS bars.
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Speedbiker
human power expert

USA
3744 Posts

Posted - 02/06/2017 :  13:28:39  Show Profile  Reply with Quote
I don't agree with your logic about learning, but I doesn't matter. Get it together and get those boys riding!
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Balor
recumbent guru

Russia
512 Posts

Posted - 02/06/2017 :  13:37:53  Show Profile  Reply with Quote
Well, yea, as Foale's experiments with recumbent steering suggests (he also used boys as 'fresh test subjects' :)), OSS can be plenty intuitive so long as it is not tiller steering.
I think you might be better off with wide OSS right away, and than move to narrower setup.
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ShelGame
recumbent enthusiast

USA
254 Posts

Posted - 02/20/2017 :  17:37:21  Show Profile  Reply with Quote
Laced up the wheels this weekend. They're just laced, they still need to be trued. I ran out of patience.

I also mounted up the seat at 25 deg. I think that might be too low for my boys to learn on. So, I'm also going to put a 2nd set of mounting holes at 35 deg.

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ShelGame
recumbent enthusiast

USA
254 Posts

Posted - 03/16/2017 :  07:28:02  Show Profile  Reply with Quote
They're multiplying. Just bought this bike from a seller near my mom's house in North Texas. Not sure how/when I'll get it home to Ann Arbor. But, now I'll have 2. Probably keep this one as-is, no mods. Then modify the frame from Warren and move the parts over from the 'original' when the modified frame is done...


http://s1113.photobucket.com/user/ExclusiveSeniorPhotography/media/IMG_0439.jpg.html

Edited by - ShelGame on 03/16/2017 07:29:58
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Balor
recumbent guru

Russia
512 Posts

Posted - 03/19/2017 :  12:17:03  Show Profile  Reply with Quote
Nearly a literal steal for 200$. :)
I wish there was a market in used bents in Russia, would make my job at creating my prototype MUCH easier with a "donor" at hand...
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Joel DIckman
recumbent enthusiast

USA
129 Posts

Posted - 03/20/2017 :  06:43:22  Show Profile  Visit Joel DIckman's Homepage  Reply with Quote
Hello Shelgame - (Robert L.) -

I would like your Lightning crankset boom. I can't use the email on this board though, so please email me at my ordinary Hotmail email address:

joeldickman@hotmail.com

Thanks in advance, and safe riding,
Joel Dickman
http://lightningriders.com

These three prevent most accidents: seeing, being seen, & (usually) common sense.
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ShelGame
recumbent enthusiast

USA
254 Posts

Posted - 03/20/2017 :  08:37:32  Show Profile  Reply with Quote
quote:
Originally posted by Joel DIckman

Hello Shelgame - (Robert L.) -

I would like your Lightning crankset boom. I can't use the email on this board though, so please email me at my ordinary Hotmail email address:

joeldickman@hotmail.com

Thanks in advance, and safe riding,
Joel Dickman
http://lightningriders.com

These three prevent most accidents: seeing, being seen, & (usually) common sense.



e-mail sent...
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