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alevand
human power expert

USA
3541 Posts

Posted - 06/13/2018 :  09:14:17  Show Profile  Visit alevand's Homepage  Reply with Quote
I slit 2 pieces of 1.5x.035 4130 tube, worked them and welded two seams to make a 3x.035 tube. I also made a 2.7 in OD tube from .060 perforated sheet, with 50% opening. The stiffness, though, is lower and according to the IPA web site is only 30% of a closed sheet. It was less stiff than .065 wall 3 in OD aluminum tube. It looks cool ,though, bit was concerned about strength and went with the cr-mo tube.

I am using the 3x.035 for the carp VI main frame.



C:
Tony Levand

Edited by - alevand on 10/26/2018 06:36:24

alevand
human power expert

USA
3541 Posts

Posted - 06/13/2018 :  14:13:17  Show Profile  Visit alevand's Homepage  Reply with Quote
In the past I have made the rear triangle, well a triangle, using 1/2x.035 for the top and 3/4x.035 for the bottom member and a 1 or 1 1/4 from the main tube to the top behind the seat. This time I think I'll try a little passive suspension. For the same weight I can use two 1 1/2 x .035 tubes. The spring rate would be 290 lb/in and for 200 lbs rider and bike, the static defection as about .45 inch and stress in the tube 52 ksi. If I weld a cross member just in front of the rear tire, the differential spring rate is at least 3 lime higher, so I think the torsional stiffness of the frame should be adequate.

I was hoping to leave the main frame tube open at the end for stowage, but I could work the main tube around the two rear arms for a nice attachment.

Beam formulas:
http://ruina.mae.cornell.edu/Courses/ME4735-2012/Rand4770Vibrations/BeamFormulas.pdf

C:
Tony Levand

Edited by - alevand on 06/13/2018 14:13:34
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warren
human power expert

USA
6470 Posts

Posted - 06/14/2018 :  08:49:36  Show Profile  Visit warren's Homepage  Reply with Quote
Building your new LWB bike?
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alevand
human power expert

USA
3541 Posts

Posted - 06/20/2018 :  06:28:16  Show Profile  Visit alevand's Homepage  Reply with Quote
Hi Warren,

Yes, a new monotube carp. I still want to build a space frame bike some day.

I am trying to figure out a rear suspension. I want about 3 inches travel, +/- 1.5 inch. That should soak up the cracks in the pavement.

C:
Tony Levand
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Jerry
human power supergeek

USA
1475 Posts

Posted - 06/20/2018 :  08:58:40  Show Profile  Reply with Quote
Hi Tony,

My buddy Vic from the UK uses rubber vibration mounts with female threads on his seats for suspension. He loves them. https://www.grainger.com/product/2NPD8?cm_mmc=PPC:+Google+PLA&s_kwcid=AL!2966!3!166592448177!!!g!71841870799!&ef_id=WypdBQAAAWmzoJPV:20180620135621:s . Just a thought.
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alevand
human power expert

USA
3541 Posts

Posted - 07/16/2018 :  12:04:55  Show Profile  Visit alevand's Homepage  Reply with Quote



I want to make the BB shell from CrMo 1.5x.065 tube, if I can find where I put it...

C:
Tony Levand

Edited by - alevand on 07/16/2018 15:52:18
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warren
human power expert

USA
6470 Posts

Posted - 07/18/2018 :  15:13:19  Show Profile  Visit warren's Homepage  Reply with Quote
Another very interesting front end, Tony. It's a bit hard to see what's going on there, can you take a closer pic? Planning to have it ready for Northbrook?
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alevand
human power expert

USA
3541 Posts

Posted - 07/18/2018 :  21:17:10  Show Profile  Visit alevand's Homepage  Reply with Quote
Its an old existing front end that I welded on.

I still waiting for the BB tubing to arrive.

From an older post:




C:
Tony Levand

Edited by - alevand on 07/22/2018 18:44:10
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alevand
human power expert

USA
3541 Posts

Posted - 07/23/2018 :  16:33:52  Show Profile  Visit alevand's Homepage  Reply with Quote
I got the BB tubing today: A little overhang to stake the bearing.



C:
Tony Levand

Edited by - alevand on 07/23/2018 16:34:36
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alevand
human power expert

USA
3541 Posts

Posted - 08/08/2018 :  11:35:03  Show Profile  Visit alevand's Homepage  Reply with Quote
I ordered 36 290 mm 2.0/1.8/2.0 double butted spokes for the ryder23 700x17c rear wheel rim and Deore FH-M570 hub

C:
Tony Levand
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alevand
human power expert

USA
3541 Posts

Posted - 08/16/2018 :  16:35:36  Show Profile  Visit alevand's Homepage  Reply with Quote
Received the spokes today, they were out of stock, shipping from Chicago.

I squeezed the main tube in the vice so it would be narrow enough for the narrow BB. Next is to miter fit some tubing and weld the BB in.

C:
Tony Levand

Edited by - alevand on 08/16/2018 16:40:24
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alevand
human power expert

USA
3541 Posts

Posted - 08/20/2018 :  15:12:13  Show Profile  Visit alevand's Homepage  Reply with Quote
I use a 1.5 in x.035 tube and made it fit between the BB and main tube, it looked like a sine wave, abut 3/8 long. The BB is welded in. I want to add two .5x.028 in tubes to triangulate from the bottom of the BB and main tube. Then I can put the seat back on and figure out where to put the remote steering axis.

C:
Tony Levand
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alevand
human power expert

USA
3541 Posts

Posted - 08/21/2018 :  11:55:05  Show Profile  Visit alevand's Homepage  Reply with Quote
I welded in the remote steering and handlebars. I need to make the linkage and pivots.

I slightly miscalculated the seat to BB distance, a little short.

C:
Tony Levand

Edited by - alevand on 08/21/2018 11:55:58
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alevand
human power expert

USA
3541 Posts

Posted - 10/26/2018 :  06:38:41  Show Profile  Visit alevand's Homepage  Reply with Quote
I made the frame too short and it sat. Yesterday I welded in a 3.5 inch extension. I need to redo the remote steering and fork attachment, too much trail. Then make a seat frame from .75x.028 tube. Im dreaming of a front leaf spring suspension. Have to figure out how to make the leaf, maybe layers of sheet G-10 with hotmelt glue between for damping.

C:
Tony Levand

Edited by - alevand on 10/26/2018 06:44:21
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warren
human power expert

USA
6470 Posts

Posted - 10/26/2018 :  14:13:00  Show Profile  Visit warren's Homepage  Reply with Quote
Maybe carbon fiber plate for the leaf?
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alevand
human power expert

USA
3541 Posts

Posted - 10/27/2018 :  17:48:00  Show Profile  Visit alevand's Homepage  Reply with Quote
I redid the fork attachment, needs some more work, though. I need to move the remote steering back and make a longer rod.

I think carbon fiber plate is too stiff, its as stiff as steel. Its 10x stiffer than G-10, but 10x stronger, it could make a leaf that's 3 times thinner. For a spring I think id want a flexible material. G-10 is 2.4 Mpsi modulus and 24 ksi strength. I may use FRP.


... I have FRP rod, several diameters. I may try the 1/2 inch diameter and make a triangle of two rods, the apex at the ball joint. This will give it lateral stiffness. I may try a cartridge ball bearing instead of a ball joint rod end, and let the fiberglass twist slightly to compensate for the VPS offsets on large steering (~ +/- 8 deg twist). I'll have to make a whole new fork.

Id like to get more steering out of the VPS (virtual pivot steering), now its about +/- 30 degrees, making a 9.5 foot turning radius at lock. This also corresponds to the toggle point, using links at 90 degrees. I think a smaller angle would allow more steering before reaching the toggle point, but of course the tire interferes with the links, so the links would have to be somehow curved around the tire. Beyond the toggle point the mechanism collapses. The toggle point is when the virtual pivot is at one of the linkage rod ends.

C:
Tony Levand

Edited by - alevand on 10/28/2018 08:03:28
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alevand
human power expert

USA
3541 Posts

Posted - 10/31/2018 :  13:37:53  Show Profile  Visit alevand's Homepage  Reply with Quote
Rode down the block and back and down the hill. Seems stable with 6 inches of trail at 20 mph, hands off. Turns tight circles too. Need brakes before real test ride..

C:
Tony Levand

Edited by - alevand on 10/31/2018 13:39:24
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Balor
recumbent guru

Russia
750 Posts

Posted - 10/31/2018 :  14:28:32  Show Profile  Reply with Quote
Ouch, 6 inches of trail. Do you notice camber torque on uneven surfaces with this much trail? It is pretty bad even with about 3, but likely 3x times normal load from yours.
I really think that using a return to center spring instead is much better because it does not lead to camber torque and does not use friction to provide return to center force - hence, is NOT reduced from your speed like trail force. Only problem is finding an unobtrusive enough place to fit it.
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alevand
human power expert

USA
3541 Posts

Posted - 10/31/2018 :  15:54:47  Show Profile  Visit alevand's Homepage  Reply with Quote
I can ride no hands! You don't know what your saying. Its virtual pivot steering. Trail has a different meaning, its self centering even with 10 inches trail..see the picture above. Ive ridden it with 30 inches of trail(1 meter), which is too much.

...Well motorcross motorcycles have 4 to 5 inches trail and they are much heavier and operate on all terrain.

quote:
4) Motocross bikes use head angles in the range of 27.5 to 26 degrees. A 26-degree angle means that the steering head is angled forward less and is at a steeper, quicker-turning angle. A 26-degree rake is the same thing as a 64-degree head angle. A 27.5-degree head angle is a slacker angle and gives a steering-head angle measurement of 62.5 degrees. Slacker head angles turn more slowly and improve straight-line stability.

5) Trail is a measurement of how far the contact patch of the front tire is behind the point where the steering axis hits the ground. The number is achieved by extending an imaginary line down the center of the head angle to the ground. Then, a perpendicular line is dropped through the center of the front axle to the ground. The distance between where the two lines hit the ground is the trail measurement. As a rule of thumb, it should be between 4 and 5 inches on a motocross bike (more on a chopper and less on a trials bike).


C:
Tony Levand

Edited by - alevand on 11/01/2018 07:54:30
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Jerry
human power supergeek

USA
1475 Posts

Posted - 10/31/2018 :  22:11:20  Show Profile  Reply with Quote
quote:
Originally posted by alevand

I can ride no hands! You don't know what your saying. Its virtual pivot steering. Trail has a different meaning, its self centering even with 10 inches trail..see the picture above. Ive ridden it with 30 inches of trail(1 meter), which is too much.

C:
Tony Levand



Ha ha ha, too funny Tony. How many bikes have you built Tony? How many has Balor built?

The only bike I can ride no hands is actually a trike.
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alevand
human power expert

USA
3541 Posts

Posted - 11/01/2018 :  07:54:55  Show Profile  Visit alevand's Homepage  Reply with Quote
I welded on rear the v-brake lugs last night. I need run a cable, fix the loose crank arm and seat before the next test ride.

C:
Tony Levand
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Balor
recumbent guru

Russia
750 Posts

Posted - 11/01/2018 :  10:32:32  Show Profile  Reply with Quote
quote:
Originally posted by alevand

I can ride no hands! You don't know what your saying. Its virtual pivot steering. Trail has a different meaning, its self centering even with 10 inches trail..see the picture above. Ive ridden it with 30 inches of trail(1 meter), which is too much.

...Well motorcross motorcycles have 4 to 5 inches trail and they are much heavier and operate on all terrain.

quote:
4) Motocross bikes use head angles in the range of 27.5 to 26 degrees. A 26-degree angle means that the steering head is angled forward less and is at a steeper, quicker-turning angle. A 26-degree rake is the same thing as a 64-degree head angle. A 27.5-degree head angle is a slacker angle and gives a steering-head angle measurement of 62.5 degrees. Slacker head angles turn more slowly and improve straight-line stability.

5) Trail is a measurement of how far the contact patch of the front tire is behind the point where the steering axis hits the ground. The number is achieved by extending an imaginary line down the center of the head angle to the ground. Then, a perpendicular line is dropped through the center of the front axle to the ground. The distance between where the two lines hit the ground is the trail measurement. As a rule of thumb, it should be between 4 and 5 inches on a motocross bike (more on a chopper and less on a trials bike).


C:
Tony Levand



Well, so can I, finally, despite quite rudimentary 'leg steering' skills on MBB. So could people on DFs of TDF bikes of yore with essentially zero-trail geometry, by the way!

And of course the more trail you have (times normal load times speed roughly) them more return to center force you have and this is actually good...

BUT it also results in camber torque unless you overinflate your tire (admittedly, tend to UNDERinflate them) AND this force is reducted from your speed because it is due to lever arm from friction force of the contact patch, and it does not matter *what* type of steering you have to produce that lever arm/force as much as I understand tyre dynamics.

I mean, don't you feel your steering being pulled up inclined surfaces (say, ruts - including ruts in asphalt) with this much trail?

Since it depends on grip, it might be due to my tire being 'too grippy' for my own good though.
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alevand
human power expert

USA
3541 Posts

Posted - 11/01/2018 :  11:57:31  Show Profile  Visit alevand's Homepage  Reply with Quote
Im not going to get into a P_____g match discussion on trail. This VPS steering axis is not fixed, but moves, going from 6 inches in front at straight ahead to 4 inches to the outside and 2 inches behind the contact patch at full lock. Statically the front wheel centers straight with weight, just the opposite of wheel flop with a fixed axis. Ive never had a problem with a bike pulling to the right on a crowned road, Ive had problems with side winds in a full fairing with 12 inches of trail, but I think 6 inches with the front wheel exposed should be OK, its easy enough to adjust the amount of trail with the linkages.

I rode ten miles on the bike trail today with Flintstone brakes, pushing a pile of leaves at he bottom of the hill.. Met Jim on his Bachetta. He didn't like my bike at first, but then commented how smooth and stable it looked, and fast, he said he could not ride any of his recumbents no hands. Ive got 13 miles on it so far.

I ordered Kool Stop brake pads... Looks like I am out of weld on cable stops...Ordred.

C:
Tony Levand

Edited by - alevand on 11/01/2018 13:15:55
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Balor
recumbent guru

Russia
750 Posts

Posted - 11/01/2018 :  14:46:14  Show Profile  Reply with Quote
Well, that's not a pissing match, I'm genuinely curious!
So, you have positive trail AND negative wheel flop, which is indeed great! Wheel flop nasty, especially on MBB bents. But I'm experiencing camber torque with less trail, that's why I'm asking.

Point is, I have about 200 lbs of normal weight on my steered wheel - likely more than you and your entire bent combined to spare, when combined with about 60 psi in 40mm tire results in a *huge* contact patch, and it results in 'self-steer' (actually camber torque) not unlike one on a fat bike that I've experienced when I've run front tire inflated to 8 psi on asphalt (again, HUGE grip and about 4 inches of trail given steering angle and wheel size + my considerable weight).

I'm all for loads of return to center force, but using lots of trail have it's downsides, and 'negative steering angle' has it's downsides as well, so I'm really curious about VPS...
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alevand
human power expert

USA
3541 Posts

Posted - 11/01/2018 :  19:36:10  Show Profile  Visit alevand's Homepage  Reply with Quote
I ran the rear brake cable.


I got the rear brake cable routed, but NOS pads are hard as rock. Derailleur lost an idler when riding through the back yard....

I think the camber effect you mentioned is due to the large contact patch not being symmetrical about the steering axis and not due to excessive trail.

A LWB would have 35-40% weight on the front tire.

Search this site for VPS and MBB-VPSs,also on you-tube.

C:
Tony Levand

Edited by - alevand on 11/01/2018 19:41:04
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alevand
human power expert

USA
3541 Posts

Posted - 11/08/2018 :  07:20:05  Show Profile  Visit alevand's Homepage  Reply with Quote
Im thinking about getting the Shutter Precision PV-8 dynamo hub. http://www.sp-dynamo.com/8seriesdynamo%20hub.html

The weight is 390 grams, which is less than a standard front hub and my 6 watt, 12v friction generator. At 15 km/hr the hub supplies only 3 watts, .5 amp, though, and will probably put out 4 watts at 18 mph. No load drag is about a watt.
http://www.sp-dynamo.com/8-series-pic/8-7.gif

I bent, or should I say kinked up mesh seat frame pieces from 7/8 x.028 tube. I need to make one more U shaped piece before tacking together. I put a recurve for lumbar support.

C:
Tony Levand

Edited by - alevand on 11/08/2018 18:41:07
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