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T O P I C    R E V I E W
alevand Posted - 08/19/2017 : 14:16:24
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?

Tony Levand
25   L A T E S T    R E P L I E S    (Newest First)
alevand Posted - 01/12/2018 : 08:25:59
I was thinking about gearing. I could have 3x8x1x1 = 24 speeds or 3x7x2x1 = 42 speeds or 2x7x2x1 = 28 speeds or 3x5x3x1 = 45 speeds or 3x5x3x2=90 speeds. I'm thinking 28 or 42 speeds, the 28 could be 32 , if I double use the large cog for a lower and higher range.

Tony Levand
alevand Posted - 01/11/2018 : 10:28:18
Next I want to build the forks:

Tony Levand
alevand Posted - 01/10/2018 : 10:17:47
I ordered an aluminum hub off ebay. In the mean time I found two steel hubs in the garage, one a front hub with a 3/8 axle, the other a joytec rear hub form the old neighbors deceased wife's bike.. You can see in the picture front hub flange is further outboard.

I cut the two with the pipe cutter, then ground them down shorter. I found that the flanges are only pressed in and was able to knock them out. I reversed the left flange, brought it to the edge of the hub, tacked it place and welded the two halfs. It was spinning pretty straight, but after welding is off a little.

Finished hub, I should have tacked the flange on the other (outboard) side:

Original weight was 200 grams heavier than the aluminum hub, now about 120 grams heavier, 320g.

Now I just have to find my bmx freewheel...

Tony Levand
warren Posted - 01/10/2018 : 08:28:09
Yes, the secondary chain needs a tensioner, and chain guides to prevent the chain from skipping off due to bumps and varying chain tension.
alevand Posted - 01/10/2018 : 06:56:02
I've decided that even with the narrowed cassette hub, that my legs interfere with the axle. I tried it without the skewer. My thought is to narrow an old hub and use a bmx freewheel sprocket and a mid drive. It will also get the derailleur out of the way. Does the secondary chain need a spring tensioner?

The Sovos hub looks best, the left side bearings are inboard, under the flange. Unfortunately I removed the cups years ago and are lost.
Tony Levand
alevand Posted - 12/27/2017 : 07:07:23
I gave up on FreeCad. It took me a hour trying to figure out why the crossection I wanted to sweep wasn't showing up in the menu to pick. After trying almost every permutation, I found that it cant sweep hollow sections, only solid rods. You have to make another sweep to cut it out. It is B.S. The assembly is BS too. Have to type in an angle and offset from the origin to place a part, a real pain. I couldn't get the bent tube where I wanted it.

Hi Irv, I tried using Blender a few years ago to design a shell, I think I went with K-3D. Blender is not really a CAD program, its more for animation. It does export STL file format. K-3D has no CAD export, So I made a DXF file of the points. The machine shop wanted $10k to CNC a foam plug. That was the end of that project.

I am trying google Sketchup over the web, as they don't have a Linux version. Another learning curve.

I am thinking that I might need a custom derailleur, one that doesn't stick out. I would use two cages, one on top instead of an idler, would take up chain slack. A short cage on the derailleur for shifting, but no spring. The derailleur mechanism would be inboard from the normal parallelogram.

I tried making a wheel in Blender,I couldn't figure out how to mirror the cone I used for the spoke envelope. I use a torus to make the tire

I make a wheel in K3D, pretty easy, but I don't know how to move it from the origin.

Tony Levand
IrvJamison Posted - 12/27/2017 : 00:11:00
Tony, what about Blender for 3D CAD?
alevand Posted - 12/26/2017 : 08:20:46
A few more hours of struggling and I modeled the axles and cassette. I imported a front hub from Grab Cad, but I wasn't able to change the placement in the assembly - sucky. This app has so much self praise, but it is really a pain to use. To make an assembly you first have to make a copy of the part, without the parametric sketch, then copy and paste it into the assembly. To change anythiny you have to redo it again, terrible, 2 to 3 times as much work as a normal CAD package, Inventor, I-deas ProE,as so much as I have used. If it wasn't 2 below zero (F) outside Id be working on real bike.

Tony Levand
alevand Posted - 12/25/2017 : 07:06:01
Freecad can import airfoil data:https://www.freecadweb.org/wiki/Common_Airfoil_Data_Import

After spend most of the morning I got this far modeling in FreeCad:

Further use of Freecad, trying to add the axles to the wheel, my feelings are that this is a micky mouse app. In sketch mode, trying to revolve a solid, it tells me I have too many constraints. In sketching it automatically changes units from inches to feet to yards, a real pain, why? There seems to be no switch for it.

I downloaded and installed BRL-CAD. It is not to my liking either, primitive, its based on late 70, early 80s mainframe CAD technology.https://brlcad.org To delete a solid it has a "kill" command.
Tony Levand
alevand Posted - 12/24/2017 : 07:13:21
I am reporting progress in the last 3 months on the 26 in fwd bike with 700c rear wheel, Renamed "F-26 Phoenix".

Please ignore the messy garage.

I want to find a 3d CAD program I can use to design it. I may have to use Virtual Box on my Linux machine. On shape has all the functionality of Solid Works or Inventor, is is very slow over the web. Design Spark requires windows. Free Cad is just non-intuitive to the seasoned CAD user.

I found this to be slow over the web :

I haven't tried this on wine:


Tony Levand
alevand Posted - 10/05/2017 : 06:47:11
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.

Tony Levand
SpiderMonkey Posted - 09/25/2017 : 06:07:28
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.

alevand Posted - 09/19/2017 : 14:33:38
Its not a MBB.

Tony Levand
warren Posted - 09/19/2017 : 11:14:54
This looks like another virtual pivot design. How is this one different from the last one?
alevand Posted - 09/17/2017 : 09:20:59
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.

Tony Levand
alevand Posted - 08/27/2017 : 14:09:37
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

Tony Levand
Jerry Posted - 08/27/2017 : 10:26:31
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!
alevand Posted - 08/27/2017 : 09:15:57
ERD = 517.7
hub dia = 45.6
Hub width 39.1
36 spokes
cross 3

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

Tony Levand
alevand Posted - 08/27/2017 : 08:59:04
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/

Tony Levand
alevand Posted - 08/27/2017 : 05:54:33
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.

Tony Levand
Speedbiker Posted - 08/26/2017 : 20:08:59
Even then you need to run it pretty hot and make sure your metal is very clean.
Johnsfwdbent Posted - 08/26/2017 : 19:42:29
Usually for aluminum wire they use a spool gun, it feed the wire at the gun for that reason!
alevand Posted - 08/26/2017 : 16:10:04
I tried test mig welding aluminum, wire keeps getting jammed.

Tony Levand
Jerry Posted - 08/25/2017 : 06:09:20
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!
alevand Posted - 08/25/2017 : 03:28:03
Yea, it would be better if it were welded.

Tony Levand

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