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ShelGame
recumbent enthusiast

USA
254 Posts

Posted - 11/02/2015 :  06:21:08  Show Profile  Reply with Quote
Been sketching this for about a month now. I had decided that after the prone, I wanted an actual recumbent that I could ride long-distances.

I've given up on the prone, an am now pulling-ahead this project to this winter.

Most recent drawing:



I like the look of the X-Stream, but also the Reynolds Nomad. So, I tried to take the basic tubular frame design of the XStream, but dimensions more like the Nomad -- Lower seat height, and more slack heat tube angle, slightly longer wheelbase.

I no longer work in the same shop with the very talented professional welder that did up the aluminum prone frame for me; so, this one will be fillet brazed 4130 steel.

Cut wood for the jig this weekend. New Oxy/Acytelene bottles should be delivered this week, along with the 1-1/2" x 0.035 tubing for the frame. I already have the drop outs, bottom bracket, and mid-drive I've collected over the years.

Jig board still needs legs to get it up to working level.


Edited by - ShelGame on 01/23/2016 17:29:41

Speedbiker
human power expert

USA
3744 Posts

Posted - 11/02/2015 :  11:03:54  Show Profile  Reply with Quote
That should be a very nice riding bike! Keep us informed.
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shooky56
recumbent guru

USA
544 Posts

Posted - 11/02/2015 :  11:19:50  Show Profile  Reply with Quote
Will enjoy the reading Shel, good luck!

Very glad you're putting your head, neck and back in the rear of the vehicle.
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ShelGame
recumbent enthusiast

USA
254 Posts

Posted - 11/02/2015 :  11:30:45  Show Profile  Reply with Quote
I've never torn a rotator cuff before. I don't recommend it. For a week at least, it ached during the day, and there was no position in bed at all that would allow me to sleep. So, I 'slept' in the Lazy-Boy. I hurt this same shoulder 20+ years ago playing pick-up football (full contact, beer was involved) with college buddies. Maybe it was my youth, maybe it was the beer, but at that time it never came close to this.

After not sleeping well at all for a week (even after a 2x dose of Motrin); and realizing that just about any pressure in my right shoulder brings that pain back even after 4 weeks; I just don't see how I could ride the prone for very long anymore. I hate to not finish a 90% completed project, but there's no point in finishing it if I could never really ride it.
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warren
human power expert

USA
6087 Posts

Posted - 11/03/2015 :  07:59:03  Show Profile  Visit warren's Homepage  Reply with Quote
You can think of the prone as a learning experience. Now you know you can build a bike.

Looks great. Be sure to design it so you can switch to remote above seat steering. I think you will be happier with that. Maybe just make the remote steering pivot closer to 90 degrees to do that. It's ok if your head tube and remote steerer pivot are not at the same angle. Thant angle is just limited by the rod end bearing angle.

Your design looks good.

Edited by - warren on 11/03/2015 08:06:16
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warren
human power expert

USA
6087 Posts

Posted - 11/03/2015 :  08:03:22  Show Profile  Visit warren's Homepage  Reply with Quote
After 2 years of self-therapy my rotator cuff is 99% all healed up. I keep reading that doing physical therapy heals that type of injury just as fast as surgery.
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ShelGame
recumbent enthusiast

USA
254 Posts

Posted - 11/03/2015 :  08:20:59  Show Profile  Reply with Quote
I was thinking with this design it would be possible to make it USS, Remote OSS or Direct OSS with just a few parts changes.
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ShelGame
recumbent enthusiast

USA
254 Posts

Posted - 11/03/2015 :  08:28:38  Show Profile  Reply with Quote
A little more background info.

My weight estimate is 7.2lbs total for the bare frame.



Current gearing estimate (with a modified Trek R200 mid-drive casette):

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ShelGame
recumbent enthusiast

USA
254 Posts

Posted - 11/03/2015 :  08:50:33  Show Profile  Reply with Quote
quote:
Originally posted by warren

After 2 years of self-therapy my rotator cuff is 99% all healed up. I keep reading that doing physical therapy heals that type of injury just as fast as surgery.



What kind of self-therapy have you done?
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Speedbiker
human power expert

USA
3744 Posts

Posted - 11/03/2015 :  09:41:59  Show Profile  Reply with Quote
Also, the only reason to run that shallow a headtube and is if you are using direct steering. But it will feel very slow and chopper-like. I would be surprised if you were happy with it when completed. If you choose either remote setup, then a normal angle can be used and Nirvana achieved. My son was riding his mtn bike home from work one night, jumped off a curb and his wheel landed in a hidden pothole, flipping him. Torn rotator and separated scapula resulted. After surgery he used the mtn bike parts to build a lwb, mono tube, OSS bent(no more flipping!). We used a 72 degree headtube angle with push/pull rod remote steering. The resulting bike is the only recumbent I have seen in 35 years that could be ridden no handed, while pedaling, and taking corners. Perhaps it indicates a need to rethink your headtube angle.
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ShelGame
recumbent enthusiast

USA
254 Posts

Posted - 11/03/2015 :  10:24:50  Show Profile  Reply with Quote
quote:
Originally posted by Speedbiker

Also, the only reason to run that shallow a headtube and is if you are using direct steering. But it will feel very slow and chopper-like. I would be surprised if you were happy with it when completed. If you choose either remote setup, then a normal angle can be used and Nirvana achieved. My son was riding his mtn bike home from work one night, jumped off a curb and his wheel landed in a hidden pothole, flipping him. Torn rotator and separated scapula resulted. After surgery he used the mtn bike parts to build a lwb, mono tube, OSS bent(no more flipping!). We used a 72 degree headtube angle with push/pull rod remote steering. The resulting bike is the only recumbent I have seen in 35 years that could be ridden no handed, while pedaling, and taking corners. Perhaps it indicates a need to rethink your headtube angle.



I'm glad you mentioned it. That's something I don't really understand (someone else mentioned it also). What difference does it make if it's direct or indirect steering? IE, why would having it direct steering make it seem 'faster'? Is it just the tiller effect? Or typical slop in the indirect steering mechanism?

The real reason I put the HT angle at 55 is to get a little more bite on the front tire when turning. With ~60% rear weight bias, I think the front tire will need some help turning. Adding HT angle should give it more camber when turning, and therefore more bite. But, maybe my logic is flawed?

I'm also not sure about the trail. I've read about others that have used as little as 1" of trail to reduce flop. I drew this at 2" as a first guess.

Edited by - ShelGame on 11/03/2015 10:26:52
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Speedbiker
human power expert

USA
3744 Posts

Posted - 11/03/2015 :  10:44:12  Show Profile  Reply with Quote
I fear your understanding is flawed. I see what you mean about laying the tire over using a slack angle, but that won't make it bite. Anyone who has ridden a chopper (sorry, I'm old school) knows when that tire lays over (chopper guys call it "flop") it wants to slide (greater surface area = less pressure). And steering will be slow and unresponsive. In short, miserable. But it will be stable going 100 mph down a mountain. Just pray you don't have to turn. Normally if people don't believe me I say "just build it and see". But this is too nice a bike to cut back apart to fix. Please consider a normal headtube angle.
Tony Levand's liner is lwb, remote steered, 700 X 20, what headtube angle is it? Tony?
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ShelGame
recumbent enthusiast

USA
254 Posts

Posted - 11/03/2015 :  11:04:11  Show Profile  Reply with Quote
I had read the opposite for some LWB bikes - that they tend to slide the front due to light loading of the front tire. Maybe that's only in 'adverse' conditions; and not helped by adding camber to the front.

I'll make another sketch; for sure it would make a more 'normal' fork possible with reasonable trail (I might even be able to re-use the prone's fork), and should allow me to shorten the wheelbase a bit.

Edited by - ShelGame on 11/03/2015 11:05:19
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Speedbiker
human power expert

USA
3744 Posts

Posted - 11/03/2015 :  11:38:51  Show Profile  Reply with Quote
Yes, I said slide. And the culprit is CG, as you know. But once again, there is no free lunch. That front end is light. You can't trick physics. Nothing short of you leaning way forward will make that tire dig in. A slack fork angle is a move in the wrong direct, IMO. Proper geomety and a shorter wheelbase is a move in the right direction. Why do you think some of these designs never became popular, and few are still in production? Their handling was less than desirable. Why do you suppose the modern highracer is almost the standard in two wheel recumbents? Great handling, light weight, reasonable overall length. Even if you do a spectacular job building an older design that never found great popularity, you still end up with a bike that never became popular for a reason. But if that is what appeals to you, build and enjoy.
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Victor Ragusila
recumbent enthusiast

Canada
402 Posts

Posted - 11/03/2015 :  11:43:56  Show Profile  Reply with Quote
quote:
Originally posted by Speedbiker

I fear your understanding is flawed. I see what you mean about laying the tire over using a slack angle, but that won't make it bite. Anyone who has ridden a chopper (sorry, I'm old school) knows when that tire lays over (chopper guys call it "flop") it wants to slide (greater surface area = less pressure). And steering will be slow and unresponsive. In short, miserable. But it will be stable going 100 mph down a mountain. Just pray you don't have to turn. Normally if people don't believe me I say "just build it and see". But this is too nice a bike to cut back apart to fix. Please consider a normal headtube angle.
Tony Levand's liner is lwb, remote steered, 700 X 20, what headtube angle is it? Tony?



Interesting experience. I would have expected the opposite, because, for a given weight, more tire area generally means better grip, as tire coefficient of friction is not constant, and it increases with less pressure/area. Or it might be that either only some tires do that, or maybe the side walls of the bike tires have much less gripy tire than the center. It is always interesting to hear that reality doesnt behave like my knowledge tells me it should, it shows where my knowledge is not yet good enough.

Our first bike, ACE, had a rather slack steering tube, about what you have in your drawings. It steered ok, and it felt stable in a straight line. However, in turns it really wanted to go unstable. So you ride along with almost no input in a straight line, all nice and stable, but if you turn you had to really control it and prevent it from overturning. Not the most relaxing ride tbh. Our bike was a short wheel base, so the tire was very well loaded, and it never slide.

Edited by - Victor Ragusila on 11/03/2015 11:45:45
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shooky56
recumbent guru

USA
544 Posts

Posted - 11/03/2015 :  12:48:18  Show Profile  Reply with Quote
These guys (Thom, Warren, Tony et. al.) have cut more steering tubes apart to fix the geometry than most of us have seen. ... and it's funny, on another thread I was researching steering mechanics and the wiki pages I found say the same thing Thom is saying... they even call it "flop". They did NOT, I might point out, use the word 'chopper'! [pokes Thom]

Did find a web page steering calculator out there somewhere but it was to produce trail given wheel size, head tube angle and rake. Not sure that helps this convo though.

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PUGZCAT
recumbent enthusiast

Canada
459 Posts

Posted - 11/03/2015 :  15:20:01  Show Profile  Reply with Quote
Use any head angle and wheel size you want as long as fork offset is set to yield 2 to 3 inches of trail. Any head angle 55 degrees or steeper it will handle fine. 3 inches of trail will be more stable at speed but at slow speed the front wheel will want to flop over to put the weight at a low point, giving some steering feedback; which is a plus for long wheelbase 'bents (Easy Racer clones, etc) as they steer a little sketchy on tight slow speed turns. If the head angle is really slack, 35 degrees, even if the trail is right, the front tire contact patch becomes an arc when turning tight at low speeds causing front tire scrub rather than a smooth roll, but no front end wash out. All personal experience, long wheel base 'bent and my big chopper with a 35 degree head angle. Time to eat a Snickers as I'm morphing into "Sheldon Cooper".
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Speedbiker
human power expert

USA
3744 Posts

Posted - 11/03/2015 :  16:54:12  Show Profile  Reply with Quote
Use any steering angle you want? Yeah, as long as steering response means nothing to you. Sure, with proper trail most any angle can be stable and rideable. That doesn't mean it is optimal or even enjoyable. Too slack and it handles like a dog. Too steep and steering is quick. Pick the charactistic you want, but don't just throw a dart or pick what looks cool. Well, unless it is a chopper with 50" forks! Why do the vast majority of bicycles on the planet have headtube angles between 71 and 73 degree? Because physics and the idea of ideal handling have proven that range to be best. Deviate very far and I wish you luck.
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ShelGame
recumbent enthusiast

USA
254 Posts

Posted - 11/03/2015 :  18:17:10  Show Profile  Reply with Quote
OK, I decided if I'm going to a traditional head tube angle, I would find an off-the shelf fork and start there. Much easier than fabbing my own fork. So, I found a carbon, 20", disk-ready fork; which is actually very short (@289mm axle to crown), and has a 30mm rake (offset). To get to 2" trail, I had to go to a 72deg head tube angle. How about that. It's like it was designed for this.

Anyone have experience with carbon forks from China (hmmm...)?

Wheelbase is now just under 68", and the frame tubes didn't get much longer. So, weight should be about the same.








Edited by - ShelGame on 11/03/2015 18:26:38
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PUGZCAT
recumbent enthusiast

Canada
459 Posts

Posted - 11/05/2015 :  04:26:20  Show Profile  Reply with Quote
A lower center of gravity makes for quicker handling, all things being equal.
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warren
human power expert

USA
6087 Posts

Posted - 11/05/2015 :  05:32:00  Show Profile  Visit warren's Homepage  Reply with Quote
I have purchased a 700C carbon fork from China that has taken a lot of abuse and not had any issues. I am waiting for one right now. Your redesign looks good and the fork looks cool.
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Tom Schneider
recumbent enthusiast

112 Posts

Posted - 11/05/2015 :  05:35:44  Show Profile  Reply with Quote
WHo did you get the fork from? I could use one.

Thanks,
Tom
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ShelGame
recumbent enthusiast

USA
254 Posts

Posted - 11/05/2015 :  06:05:54  Show Profile  Reply with Quote
quote:
Originally posted by Tom Schneider

WHo did you get the fork from? I could use one.

Thanks,
Tom



I didn't buy it yet. I was wanting some feedback on the Chinese carbon bike parts. I found a couple of YouTube reviews of some carbon bikes from China - generally positive with only minor complaints about fit and finish when compared to US or European made bikes.

That, with Warren's feedback, is good enough for me. I'm going to snag one of these. You can get them on Alibaba. The manufacturer is Beiou, but they don't seem to have this part on their website. Only on Alibaba (for $137) as far as I have found. The same basic fork can be had with or without the disk mount; but this is the only one I've found (low height, reasonable offset, and a disk mount) that meets all of my criteria.
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ShelGame
recumbent enthusiast

USA
254 Posts

Posted - 11/05/2015 :  06:07:13  Show Profile  Reply with Quote
quote:
Originally posted by PUGZCAT

A lower center of gravity makes for quicker handling, all things being equal.



Yep, and this has a seat height about 3" lower (I think) than a 700c X-Stream.
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ShelGame
recumbent enthusiast

USA
254 Posts

Posted - 11/05/2015 :  06:19:48  Show Profile  Reply with Quote
http://www.alibaba.com/product-detail/UD-3K-monocoque-small-wheel-city_873676705.html?spm=a2700.7724838.8.17.RmlfSY
http://www.alibaba.com/product-detail/New-Arrival-Carbon-Fork-451-Bicycle_60133050264.html?spm=a2700.7724838.8.43.RmlfSY
http://www.alibaba.com/product-detail/road-carbon-bike-fork_858338352.html?spm=a2700.7724838.30.91.FmEvxT
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alevand
human power expert

USA
2908 Posts

Posted - 11/05/2015 :  07:27:03  Show Profile  Visit alevand's Homepage  Reply with Quote
Tight Ride Rob, I don't prefer mid-drives, added complexity, weight with lower efficiency and a lot of overlap. An idler near the seat works for me. I have enough gears with a triple chain ring. I have OSS too, besides being more aero OSS is easier to walk and hold up the bike ,the wide USS bars tend to run into things. Your legs must be shorter than mine, I usually have 43 inches from butt to toe. I envision it painted black with a nice tail box and rear wheel cover. The dual 1.5 x.035 tubes are plenty strong. There probably <40% weight on the fork. If you use v-brakes or calipers, check the crank arm interference when turning.

C:
Tony Levand
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