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alevand
human power expert

USA
2871 Posts

Posted - 08/19/2017 :  14:16:24  Show Profile  Visit alevand's Homepage  Reply with Quote
I want to make a dual 26 fwd or a 559c/700c fwd bike, fixed bb. I am first going to make a narrowed 7 speed hub, I have the 559 rim with 36 spokes holes. I am thinking of cutting a half inch or so out of the middle of the hub. Does any know or guess what percentage of the torque is transmitted through the hub with a symmetrical lacing, cross three?

C:
Tony Levand

Edited by - alevand on 10/05/2017 06:41:16

Speedbiker
human power expert

USA
3701 Posts

Posted - 08/19/2017 :  14:58:30  Show Profile  Reply with Quote
We know the cassette drives the hub, so both flanges are driven equally. But, we also know the cassette side spokes have much more tension than the other. I think you could use a Wheelsmith spoke tension gage or a torque wrench on the nipples to determine the difference in tension.
Many of us have built fixed boom fwd, but none used a narrow hub. Why are you? Also, a composite disk wheel eliminates the spoke tension issue.
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alevand
human power expert

USA
2871 Posts

Posted - 08/19/2017 :  17:41:33  Show Profile  Visit alevand's Homepage  Reply with Quote
It will have no dish, moving the left side inboard, so id say its 50/50 neglecting any hub compliance, so my hub reconnect needs to be strong in torsion. I was thinking of just a press fit tube over the hub with epoxy. Narrower, so my knees don't hit the axle as much.

C:
Tony Levand
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Speedbiker
human power expert

USA
3701 Posts

Posted - 08/21/2017 :  06:39:05  Show Profile  Reply with Quote
I don't think the hub needs to be that strong relative to the drive loads. But the initial load of building the wheel is substantial. I had an old ultra light Hi-E hub that the glued on flange came loose. I never noticed until I tried to true the rim. The rim wouldn't straighten because the flange moved. I think your plan is solid.
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alevand
human power expert

USA
2871 Posts

Posted - 08/24/2017 :  17:13:21  Show Profile  Visit alevand's Homepage  Reply with Quote
I used the tubing cutter and removed .67 inches from the center. The hub is .975 ID by 1.102 OD, so I don't have any tubing handy that would either press fit inside or outside.


... the spacer tube from a cartridge BB is about the right ID, if I remove the paint and electric weld on the inside, its steel though. I can epoxy it in and maybe a few pop rivets to hold it.

Torque would be 150 lbs on the pedal, 150 mm arms, and a 1:1 drive ratio, would be 900 inch lbs and half is transmitted through the hub, 450 inch lbs, the rivets would see a shear of 900 lbs. Aluminum 1/8 pop rivet has a shear strength of 170 lbs, 260 lbs for 5/32. Steel rivets are 310 and 470 lbs shear strength.

Bearing yield stress for 6061-t6 is 56 ksi, so a 1/8 holes bearing allowable is is .125*.070* 56,000 = 490 lbs and 612 for 5/32 rivets.

So I'll go with steel pop rivets 5/32 x 4 each side.

MS = 470*4/900 = +2 fastener shear

C:
Tony Levand

Edited by - alevand on 08/24/2017 17:48:34
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Speedbiker
human power expert

USA
3701 Posts

Posted - 08/25/2017 :  02:45:56  Show Profile  Reply with Quote
All the different loads that can go through the hub as you ride would be tough to calculate with simple math. I'd drill and tap before I'd use pop rivets. But fasteners and epoxy (JB?) should hold it. But watch out for hard bumps, drops, or potholes in turns that will blast the hub with a side load.
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alevand
human power expert

USA
2871 Posts

Posted - 08/25/2017 :  03:28:03  Show Profile  Visit alevand's Homepage  Reply with Quote
Yea, it would be better if it were welded.

C:
Tony Levand

Edited by - alevand on 08/25/2017 03:28:16
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Jerry
recumbent guru

USA
932 Posts

Posted - 08/25/2017 :  06:09:20  Show Profile  Reply with Quote
Will this bike be for racing, touring, commuting, or all around bike? Can't beat welding it or even brazing. I have never had much luck using pop rivets where there was uneven loads applied to them, like leaning the bike over when going around a curve at speed. Hitting a pothole in traffic!
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alevand
human power expert

USA
2871 Posts

Posted - 08/26/2017 :  16:10:04  Show Profile  Visit alevand's Homepage  Reply with Quote
I tried test mig welding aluminum, wire keeps getting jammed.

C:
Tony Levand
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Johnsfwdbent
recumbent enthusiast

USA
112 Posts

Posted - 08/26/2017 :  19:42:29  Show Profile  Reply with Quote
Usually for aluminum wire they use a spool gun, it feed the wire at the gun for that reason!
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Speedbiker
human power expert

USA
3701 Posts

Posted - 08/26/2017 :  20:08:59  Show Profile  Reply with Quote
Even then you need to run it pretty hot and make sure your metal is very clean.
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alevand
human power expert

USA
2871 Posts

Posted - 08/27/2017 :  05:54:33  Show Profile  Visit alevand's Homepage  Reply with Quote
I pressed the tube onto it yesterday, with epoxy. It didn't have the spoke holes offset right and it took about 400 in-lbs to turn the flanges, but once it broke loose it was easier to turn. The epoxy should be cured today and I'll put in two or 3 three 1/8 steel rivets per flange.

load per spoke = 150*6/2/9=50 lbs

Spoke diameter is 2 mm, length is 10 inches, so spring rate is (2/25.4)^2*pi/4/10*30e6 =14e3 lb/in assume 9 spokes take tension:

delta = 50/14e3= .0003 inch - spoke stretch from torque

spoke stress = 50/2*25.4*4/pi = 10 ksi

But, the spokes are preloaded in tension, so all 18 take load, +/- 5 ksi

Fatigue limit for 1/4 hard 303 stainless is 48 ksi.

So I probably wont be breaking spokes even if only one side is reacting the torque.

So basically I took a dished wheel and moved the non drive side hub inboard and made it symmetrical.

As for side loading, as long as the spokes remain in tension, the hub will be in compression, and even then it took alot of force to press on the tube, rivets are just insurance.

C:
Tony Levand

Edited by - alevand on 08/27/2017 06:17:58
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alevand
human power expert

USA
2871 Posts

Posted - 08/27/2017 :  08:59:04  Show Profile  Visit alevand's Homepage  Reply with Quote
I use to do FEA for a living, back in 1988. I don't care about rolling, I haven't change that. Now I have to get the right spoke length and buy the double butted spokes. I have the Alexrims G6000 rim, 559x17. I wanted a big tubular section. http://www.alexrims.com/products/g6000/






C:
Tony Levand

Edited by - alevand on 08/27/2017 09:41:27
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alevand
human power expert

USA
2871 Posts

Posted - 08/27/2017 :  09:15:57  Show Profile  Visit alevand's Homepage  Reply with Quote
ERD = 517.7
hub dia = 45.6
Hub width 39.1
36 spokes
cross 3
http://www.bikeschool.com/tools/spoke-length-calculator

Length is 250 mm (9 7/8)

Here is the wheel FEA Thom was referring to: http://www.williamscycling.com/assets/images/product%20tech/Bicycle%20Wheel%20Spoke%20Lacing.pdf





C:
Tony Levand

Edited by - alevand on 08/27/2017 10:11:01
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Jerry
recumbent guru

USA
932 Posts

Posted - 08/27/2017 :  10:26:31  Show Profile  Reply with Quote
Welding aluminum with mig you do need a push-pull spool gun. Even then, with wire diameters smaller than .045, it will still bird cage if you bend the cable housing slightly, or let the wire stick out just a smidgeon too much. And aluminum cannot have any impurities at all. Need a SS wire brush and sometimes you need a chemical cleaner. What you have done looks good Tony. It should hold just fine after curing.

Math is the reason I dropped out of welding engineering school back in the early 70's. I could study and pass the test giving in class, but I could not retain the knowledge good enough to be an engineer. Also Calculus, thermodynamics, and inorganic chemistry was over my pay grade mind!
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alevand
human power expert

USA
2871 Posts

Posted - 08/27/2017 :  14:09:37  Show Profile  Visit alevand's Homepage  Reply with Quote
Ive ordered the butted 14/15/14 spokes and alloy nipples off ebay from Onley Illinois, suppose to be here on the 5th.

I was considering internal nipples, but then you have to take the tire and rim tape off to true it. There suppose to be stronger, since they are in compression https://www.dtswiss.com/Components/Nipples/DT-Pro-Lock-hidden

C:
Tony Levand

Edited by - alevand on 08/28/2017 03:44:02
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alevand
human power expert

USA
2871 Posts

Posted - 09/17/2017 :  09:20:59  Show Profile  Visit alevand's Homepage  Reply with Quote
I have a concept drawing. I haven't figures out how to pedal and steer at the same time. Only one of the two over the shoulder tubes is hinged, the other is fixed, so there is enough rigidity in the frame for egress.


C:
Tony Levand

Edited by - alevand on 09/17/2017 09:21:12
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warren
human power expert

USA
6049 Posts

Posted - 09/19/2017 :  11:14:54  Show Profile  Visit warren's Homepage  Reply with Quote
This looks like another virtual pivot design. How is this one different from the last one?
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alevand
human power expert

USA
2871 Posts

Posted - 09/19/2017 :  14:33:38  Show Profile  Visit alevand's Homepage  Reply with Quote
Its not a MBB.

C:
Tony Levand
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SpiderMonkey
recumbent enthusiast

USA
240 Posts

Posted - 09/25/2017 :  06:07:28  Show Profile  Reply with Quote
FWIW, I was reviewing my wheelbuilding book the other day and Schraner wrote that non drive side tension on the drive wheel was usually 60-65% of drive side.

--SpiderMonkey
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alevand
human power expert

USA
2871 Posts

Posted - 10/05/2017 :  06:47:11  Show Profile  Visit alevand's Homepage  Reply with Quote
Renamed project to Phoenix.

I current have the commuter Vision in the fixture. I plan to lower the seat to 13 inches, BB to 17 inches, change out cantilevers to V-brakes (for knee clearance) and put a new fairing on it. If the configuration is acceptable, I will continue with the 26x700c, FWD, FBB, VPS space frame bike after a long tour.

C:
Tony Levand

Edited by - alevand on 10/05/2017 06:49:15
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