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Strida belt wheel - for 5-bolt 130 mm spider

Strida belt wheel - for 5-bolt 130 mm spider 3d printed Mechanical parts Belt wheel on single-speed 130 mm bolt circle crankset
Belt wheel on single-speed 130 mm bolt circle crankset
Strida belt wheel - for 5-bolt 130 mm spider 3d printed Mechanical parts Belt wheel on single-speed 130 mm bolt circle crankset
Strida belt wheel - for 5-bolt 130 mm spider 3d printed Mechanical parts Belt wheel on single-speed 130 mm bolt circle crankset
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Strida belt wheel - for 5-bolt 130 mm spider 3d printed Mechanical parts Oblique view, showing teeth. There is a "retaining lip" on this side of the belt wheel.
Strida belt wheel - for 5-bolt 130 mm spider 3d printed Mechanical parts Oblique view, showing teeth. There is a "retaining lip" on this side of the belt wheel.
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Not a Photo

Strida belt wheel - for 5-bolt 130 mm spider 3d printed Mechanical parts
Strida belt wheel - for 5-bolt 130 mm spider 3d printed Mechanical parts
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About this Product

This is a replacement for the standard Strida folding bicycle belt wheel ("chain ring"). It fits to a standard 130 mm bolt circle crank spider. (The one in the photos is from Lasco -- it's available on Amazon. This belt wheel is designed to work with a standard 8 mm pitch, 12 mm width HTD or GT2 belt. The belt wheel has 100 teeth, like the standard Strida belt wheel.

The belt wheel in the photos was printed in "White Strong & flexible." I "painted" it black with a Scripto marker!

(The photos show the belt wheel installed on my recumbent bike, not a Strida!)


IN: 10.09 w x 10.09 d x 0.512 h
CM: 25.628 w x 25.628 d x 1.3 h
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@dan_kirshner See my direct e-mail.
November 26, 2014, 1:43 pm
@Raffineur, I might be able to do something -- it's a matter of repurposing my OpenSCAD script, which shouldn't be too difficult (it has parameters for tooth pitch, number of teeth, etc.) Costs should be similar to the ~$150 USD for this piece -- it's by amount of material. But it is not simply a matter of substituting plastic for the aluminum in the "Advanced Belt Drive" (for others interested: http://www.schlumpf.ch/hp/schlumpf/bilder/ABDS.1.engl.pdf). Note that this belt wheel is 12 mm thick -- inner bolt circle as well as belt teeth. Otherwise, stresses at the bolt holes would be too high for plastic. But I think the plastic would work with a thin "outer ring" (1 or 2 mm, say) integral with the 12-mm thick spokes and bolt mounting holes of this design, with separate thin outer rings that could be bolted on in multiples to either side of the belt wheel outer ring (like the Schlumpf design). We'd have to get clearer on specifications! I assume that you want 11-mm-pitch teeth for the Gates CenterTrack. I look forward to hearing from you!
November 25, 2014, 5:17 am
@dan_kirshner Dan, always a pleasure reading from you. Having this student do it seemed the most obvious way for me to do it. Not least because I do not know an experienced 3D printer apart from you. In case you are interested, here are the specs: The sprocket is based on the Advanced Belt Drive principle of discs that can be combined and are bolted together in parallel (Have you got their PDF?). 1. The adapter plate (chainring1) provides the link between crank and pulley. It has 62 teeth in the drawing and four mounting holes with a bolt circle diameter of 104 mm. Thickness of approximately 3.5 mm. I want it with 63 teeth, a five-arm mount with a BCD of 130 mm, and a thickness of 1 mm. I would need three of them. 2. The toothed discs (chainring2) move "only" the belt. The one in the file also has 62 teeth and a thickness of approximately 1.75 mm. Mine should come with 63 teeth and 1 mm thick also. I would need 8 of them. 3. The flanged wheels (chainring3) ensure that the belt does not fall down the sides. Thickness of approximately 1.5 mm. I would put it in the middle for Gates’s CDX CenterTrack system. It would also be 1 mm thick and have an outer diameter of 217 mm. The outer edge rounded off so the belt slides in easily. I would need only one. 4. And just to be safe a new flanged adapter disc. This is a combination of 1 and 3 in case the adapter disc should come to rest in the center, with a five-arm mount with a BCD of 130 mm and an outer diameter of 217 mm. Thickness 1 mm, outer edge rounded off. Quantity one. The discs have to be 1 mm thin because the front and rear pulleys must be exactly in line. The lateral position of the rear pulley can not be adjusted, so that must be done from the front. My setup permits adjustment in 1 mm increments, which should do. The design of no.s 1 and 4 does not really matter, but the arms should not be radial (straight) so as not to create a potential breaking point. The bolt circle diameter of the holes for the set screws does not matter, but of course must be the same for all four disks. If you have time and if you can do it, let me know how much they would be.
November 23, 2014, 10:09 am
@Raffineur, So you are going to use a Gates' 11-mm pitch rear cog for the Rohloff, and make a custom front pulley/beltwheel? You might want to compare costs of aluminum milling vs. plastic 3D printing for the beltwheel. I'm not convinced that the aluminum has any advantage over the plastic. Strida has been using plastic for years, and mine has been working fine.
November 22, 2014, 10:59 pm
@dan_kirshner Hi Dan, thank you for your reply. Somewhere in the internet (if only I could remember where) I have found .dxf files containing blueprints for a front and a rear 11 mm pitch (Gates) sprockets. My idea is to mill a front sprocket out of 1 mm aluminum sheets according to the principle of the advanced belt drive. I am going to e-mail you their English-language PDF file to dan_kirshner@yahoo.com. This seems a lot easier than making a 3D sprocket with Rohloff's special thread. I have now asked a 2nd year enginnering student friend to modify the .dxf files according to my requirements. Should he succeed, he can go on making them in a factory where he had had a summer job. Wish me luck ;-) Best regards Stefan
November 22, 2014, 10:33 pm
@Raffineur, Thanks. I'm not aware of any aluminum 3D printing process. I have seen someone who says they'll use a plastic print to make a mold into which they could then pour molten aluminum. There is also a (very expensive) titanium printing process available (direct laser sintering). The problem with the Rohloff hub is the threads: the processes do not have sufficient accuracy for the tolerances needed (even titanium appeared to be iffy, and it would cost a lot of money to find out -- on the order of 300 Euros/$400). I had a welder add some bolts to a standard Rohloff cog -- that's how this piece works: https://www.shapeways.com/model/711562/rohloff-gt2-8-28-tooth-bolt-on.html. But that limits the minimum cog diameter to about 28 teeth (8 mm pitch).
November 20, 2014, 5:36 am
Dan, I think your work is great. Can you also print 3D objects in Aluminum? I have a folding bike with 20" wheels that I want to equip with the Rohloff Speedhub and a belt drive. There are two problems: a. Getting the primary gear ratio right. Gates's 70 tooth front sprocket has too large a diameter to fit my bike, and with the 60 tooth one and the smallest 19 tooth cog, I only get 3.16. I would rather have 3.3 or 3.4. b. As I had already told you, my preference is a belt with an 8 mm pitch over Gates's ubiquituous Carbon Drive System that uses 11 mm. But there is no rear cog for the Rohloff Speedhub. At any rate, I could live with any ot the following: 1. A custom-made, err 3D printed rear cog for 8 mm belt pitch (8M), 22 teeth and an inner thread M34x6 P1. It would probably be better to make it 12 or 13 mm wide so I could use Gates standard industry belts. 2. A custom 62 tooth front sprocket for Gates's CDX CenterTrack system with a five-arm 130 mm BCD. 3. A custom 18 tooth rear cog for Gates CDX with the inner thread for Rohloff. Any advice? Thanks a lot, Stefan
November 19, 2014, 2:27 pm
@dan_kirshner Actually based on pure looks, if I didn't know what it was, I think it is quite aesthetically pleasing. However I can certainly see how it would be heavier and it looks obviously more complicated - in that sense it lacks style. Nice to have a Brompton Crank. I've never had one myself but they make great bikes and I love their 2 speed derailleur/internal hub combination (similar to a SRAM dualdrive). Really friendly helpful folks too. I emailed them asking about that derailleur wondering if I could adapt it to a cargo bike I was building (because I would love to have a good gear range AND a chain case enclosure) and they just sent me all these great technical drawings and specs to be helpful. That idea didn't work out but I appreciate their help with it. @Kdawgdj and of course you need to split the frame somehow to get any belt on it. How does the Schlumpf ride? I've always wanted to ride one. Got to see one at a show but never yet able to try it.
September 22, 2014, 4:57 am
@RUSL_bicycle The second photo...
September 20, 2014, 6:32 pm
@RUSL_bicycle Here are a couple of pictures of my old beltwheel setup -- a cut-out of the Strida beltwheel bolted to a single-speed crank/chainring. Functional, but no style points!
September 20, 2014, 6:32 pm
Ah I see. Yea I meant GCD not gcb, sorry about that. Anyways, so that means I would have to redesign something like this but with the proper fitting teeth to fit a gates belt. I spoke with someone about a year ago who said I could get any length of that specific belt made. I saw you made a cog for the rohloff and love both of them. I have to get more comfortable with the idea of actually making something from this resource, period! Thank you for your help!
September 19, 2014, 4:36 am
@Kdawgdj The 130 mm BCD is pretty much an industry standard, so this "beltwheel" should work with any 130 mm "spider." I don't know what "gcb style" is -- this works with standard 8 mm-pitch (tooth-to-tooth distance) belts -- HTD, GT2 should both work. (Note that the Gates "Carbon drive" belts, which Gates makes especially for bicycles, are non-standard -- they have an 11 mm pitch.) So you need a 8 mm cog for whatever internal hub you have (like this one: https://www.shapeways.com/model/711562/rohloff-gt2-8-28-tooth-bolt-on.html, which I made in stainless steel, and has been working well for several years now). Finally, you either need to be lucky to find a belt the right length, or do something to take up any extra "slack."
September 19, 2014, 4:22 am
@dan_kirshner my schlumpf hsd only requires five bolt pattern 130 mm BCD pattern, like your specs emulate. Should I be wrong in assuming this belt drive would fit on my schlumpf as well? Because I believe this would be great to possibly use in a belt conversion of my ICE Sprint, using an internally geared hub in the rear as well. Or does this bicycle you have this built for only have a certain type of belt and not the gcb style? An amazing idea, nonetheless!
September 17, 2014, 5:40 am
@dan_kirshner great, yes, I'd like to see. I haven't really ridden a Strida, or not for long if I did. But my good friend/co-apprentice (bike building) grew up in Seoul, Korea where there isn't much space for full size bikes and her first bike that she learned to ride was a Strida. She rode a 16" Brompton when I knew her and she felt a 20" Bike Friday was big. She complained that the strida belt was noisy in the rain. It's cool to be able to print a usable bike part. I guess you can make it thick enough for strength? I have yet to make a bike part and I wonder about the strength limit compared to metal - how to best design. I think I'm going to start with some cable stops.
August 27, 2014, 5:31 am
@RUSL_bicycle - it works fine. Nice and quiet. It also saves some weight compared to my previous cobbled-together setup based on the stock Strida beltwheel, and it looks a lot better, too! (Hmm, I'll post a photo of the old one -- you'll see what I'm talking about!)
August 25, 2014, 7:13 pm
I suppose I should have said: Genius, how does it ride @dan_kirshner?
August 18, 2014, 8:50 pm
Genius! How does it ride?
August 18, 2014, 8:49 pm
  • White Strong & Flexible

    White nylon plastic with a matte finish and slight grainy feel.



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