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Soma Riff belt drive build

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  • Overkill
    replied
    I've gotten some questions about the baskets and the battery box so I'm uploading some build pics of those. First the baskets:


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    These are the blackburn local baskets. Its true that the instructions kind of suck and the racks come with all kinds of hardware for any kind of installation. I fiddled around with the parts for a good 3-4 hours before figuring out what went where. Note that the crossbeams seen sticking up here will need to be cut to size with an angle grinder or something. Once put together the rack is very solid.


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    Because of the way that the rack and frame are, i couldn't put the pieces right up to each other. I needed to use some washers and longer bolts. These bolts also loosen up after a ride. I added nuts on the inside (not in these pics) which helps a lot but I think the solution will evolve next year. Hopefully i won't need to loctite these in but thats a possibility.



    OK onto the battery box.

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    Here's a view from the working side of the bike. While both panels come off, one side needs the charge connector so I put it on the drivetrain side and made this the side I actually open.



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    Here is a closeup of the battery box. I made the gasket by putting black rtp on the frame, putting a bunch of vaseline on the inside of the side cover, screwing the screws tight, and then backing off i think half a turn on each screw. The earlier pictures showed those sheet metal nuts, but they only had a thread or two and i didn't feel good about them so I just welded in acorn nuts instead. I picked acorn nuts to minimize the sharp things inside where the battery is. Before making the gasket for the sides I put antiseize in each acorn nut so if any rtp got in there it wouldn't mess things up.


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    Next I started running the wires. The motor wires come in the bottom, the tail light comes in the upper right, and the cockpit wires come in the upper left. I put a layer of heat shrink around the wires for abrasion resistance. Where multiple wires come in (especially through the bottom port) I put some silicone inside the heat shrink to keep it watertight.


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    I used Sugru moldable glue to make gaskets for the wire entry ports. The outside I tried to sculpt into a nice shape, the inside was just functional. These are the motor wires.


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    This is the inside of the tail light wire entry. If you zoom into the second picture in post #32 you can see the outside of this cable entry. The sugru molds really nicely!



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    There are wires running along the inside of the box by the seat and down tubes, and I used 1/8" thick rubber sheeting in between them and the battery. Everything fits nicely!




    Last edited by Overkill; 11-12-2020, 07:25 AM.

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  • Overkill
    replied
    Blender sorry for the delay, here are the measurements.

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    Here's a pic of it before disassembly. note that the sprocket dish is facing out. When I had it spaced as far as it would go, the sprocket actually contacted the dropouts.



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    This is the stack of spacers that I used to push the cog away from the hub. They measure 28.5mm.


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    When it was all put together there was a little space on the outside of the cog so I used these spacers to take up the gap. The real difference is actually between 1 and 2 of these spacers but this was the closest I had and I don't think exact precision matters here. Although this means that the cassette lockring is actually resting on these rather than the cassette. If this is bad someone please let me know and I'll get the exact right spacer!


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  • Overkill
    replied
    Originally posted by Blender View Post

    Ah perfect, I was trying to figure out the rear cog being used so I could account for the spacing. Measurements would be awesome and I'll definitely drop mine in (once I get the parts in) for any other folks who plan on similar builds in the future. It sounds like you're using the Gates CDX 9 spline (page 38)? For some reason when I looked at Rider's thread, the photo it made it seem like his rear cog had more offset than the ones I've been finding online which only have a slight hump.
    I haven't forgotten this request! I have pulled the rear wheel off to install a frame lock and I'll take pics and measurements soon! Sorry for the delay

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  • Overkill
    replied
    Yep I followed riders build! My bottom bracket was 2.5mm wider and he had spaced in 2.5mm so i ended up spacing all the way out. I wondered if nuvinci spacing was the same as all the way out but either it wasnt or i couldnt find the info. It was years ago when i looked into it.

    Rider’s solution worked well for me!

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  • ncmired
    replied
    Originally posted by 73Eldo View Post
    I'm thinking a belt drive with one of the Nuvinci CVT hubs and a BBSHD would be a slick combo.
    Slick, yes, but the belt line can't be made to work. Well, not on any sort of standard/stock configuration frame.

    As Rider initially worked out years ago, the Sturmey can be used by configuring the cassette's freehub as a 1-speed with spacers to enable custom-tuning of the belt line:

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    The tradeoffs are wasted drive side spoke dishing and the limited gearing range. The Rohloff is the known and expensive alternative.
    Last edited by ncmired; 11-01-2020, 10:08 AM.

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  • Overkill
    replied
    Originally posted by 73Eldo View Post
    Nice. Is it a single speed or is there a 3 speed hiding back there? I really like the idea of a belt drive but so far don't have a frame that would accept one. I'm thinking a belt drive with one of the Nuvinci CVT hubs and a BBSHD would be a slick combo.
    Its a 3 speed sturmey archer hub. I wouldn’t mind a wider gear range, but as this was my first build i thought i’d stick to that one since reports were that it was strongest. I love the idea of the nuvinci though! One nice thing about the sturmey archer is that when i’m dropping into higher gears i just drop it without pausing. I’m not sure how hard that is on the transmission so its probably good that i got the strongest one. If i recall correctly a bbshd might overpower some igh’s. The cool thing about the eggrider is you can adjust things like motor ramp up speed on the fly with your phone.

    also, chainline is a thing. With other igh’s if it doesn’t line up perfectly theres not much you can do about it.

    the belt drive is why i went with a soma frame

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  • 73Eldo
    replied
    Nice. Is it a single speed or is there a 3 speed hiding back there? I really like the idea of a belt drive but so far don't have a frame that would accept one. I'm thinking a belt drive with one of the Nuvinci CVT hubs and a BBSHD would be a slick combo.

    Leave a comment:


  • Overkill
    replied
    Hi! The bike has been 99% done for a while and I've been riding it :) I wanted to wait until the mounting bracket for the headlight was fabricated before taking pictures though! Here they are:


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    Here's a good overall pic of the bike. When I planned it out I wanted it to be able to hold stuff to go to an office as well as yoga stuff, a lock and water bottle. I'm happy about how the yoga mat carrying solution turned out! The racks do loosen up a bit though. I added some nylon nuts and longer bolts to the rack mounts which helped but they still loosened up a little on a 30 mile ride. I've been trying to avoid loctite but that might have to happen. I love the color! The things in the spokes are monkeylectric persistence of vision leds that I pulled off another bike. They have hub mounted lithium ion batteries and are the only thing not powered by the main battery.


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    Here's a closeup of the battery box. One of the reasons I wanted to make it out of metal was so I could powdercoat it with the frame and I like how it turned out. Those marks in the upper left are from an angle grinder mishap but generally the matte black hides all my mistakes :D. I used black silicone and vaseline to make a gasket between the box frame and sides, and used sugru moldable glue to seal the cable entry points into the box. I'm not really going to ride in the rain intentionally but this enclosure should be pretty waterproof because Overkill! If you click on the image and zoom into the upoer left of the battery box you can see the sugru. I havent dont the front one yet because I’m still messing around with the stem height, I already lost the rosenberg magnetic charger cap but I had bought an extra so I'll just have to attach a cord to it this time. I used theft proof screws on the battery box plus pitlocks on the rest so hopefully if I just lock the frame it will be ok.


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    Here's a closeup of the drivetrain. I forgot to take a pic from an angle so you can see the cool black and silver alternating spacers on the rear hub so I’ll add it to the post later :)


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    Here's a pic from the front of the bike. My friend helped me fabricate a mount to attach the fisher fab house light under the front rack. It works better down there and keeps the cockpit much cleaner. If you click on the pic and zoom in a little you can see the mount. On the rear rack is a grin tech tail light and they are both wired to the main battery with xt30 connectors. I made the splitter cable using an xt90s with pigtails, xt30s with pigtails, and 6-8 gauge uninsulated step down butt splice connectors. I'll add a pic of that to this post later.


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    More detail from the left side. I used a surly fork with bottle braze ons so i could still put a water bottle on the bike since the battery box takes up the whole triangle. Both legs have the braze ons so I have one more place to install something if I need it. The bag is a cool handlebar bag made from recycled inner tubes that was on a different bike. I used double sided velcro straps to attach it to the rack.


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    This is the cockpit view. I wanted it to be as clean and minimal as possible. The XT shifters work well with the sturmey archer hub, and the eggrider keeps it super minimal, plus I can mess with the bafang parameters with my phone. I had a throttle on there, but honestly, the bafang throttle is such a cheap piece of crap that its not up to par with the rest of the bike. It even sticks if you use it at any less than full which I think is actually dangerous. If anyone ever makes a good quality thumb throttle for the right side I'll consider it, but once I got the pedal assist stuff tuned I actually prefer to ride it that way. If I wanted to use the throttle a lot I think I'd rather have a BBSHD on there. With pedal assist the BBS02 is more power than I actually use. in the first two gears i leave it on 2 or 3, in the fast gear it goes up to 7 or so. Being able to tweak the bafang parameters easily during a ride made tuning it a breeze! I love the eggrider. The ball thing is a ram mount base. I didn’t use the e-brake sensors on this build and i havent really noticed an issue. I played with the bafang parameters to cut the power immediately if i stop pedaling and if there is an issue these 4 piston XT brakes have tons of stopping power.


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    Here's a shot from the other side of the bike in all its none more black glory!





    Last edited by Overkill; 10-28-2020, 01:00 AM.

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  • Overkill
    commented on 's reply
    Yep thats the one. The dish in the cog is asymmetrical. I think i actually have mine either facing in, or its facing out but then not spaced all the way out. I seem to remember the spacing it all the way out and also dishing it out was too much. I’ll take some pics and measurements this week!

  • Blender
    replied
    Originally posted by Overkill View Post

    Im not in front of the bike right now, but i ended up using spacers to push the rear cog exactly as far out as possible and it was perfect when I did a test assembly. I just got the frame back from powdercoating and facing so its possible that the spacing might decrease slightly as the frame wasnt faced during the test assembly. Im hoping to assemnle it this week and can note the final rear spacing when i do.

    when you say parts list do you need more info than the amount of spacing? Afaik you would just use whatever combination of spacers gives you the magic number. For the cog its just a gates rear cog in the right size for the gear ratio i want
    Ah perfect, I was trying to figure out the rear cog being used so I could account for the spacing. Measurements would be awesome and I'll definitely drop mine in (once I get the parts in) for any other folks who plan on similar builds in the future. It sounds like you're using the Gates CDX 9 spline (page 38)? For some reason when I looked at Rider's thread, the photo it made it seem like his rear cog had more offset than the ones I've been finding online which only have a slight hump.

    Leave a comment:


  • Overkill
    replied
    Originally posted by Blender View Post
    Overkill, do you happen to have a parts list for the rear cog and spacers/washers you ended up using? Unfortunately, I can't really tell from the photos. :-/

    I've looking to try a similar Gates CDX build with the Strumey-Archer CS-RK3 and BBS02, but with the Soma Juice (29") rather than the 27.5 Riff. I've been hoping to ballpark the rear cog spacing, and given both the Juice and Riff have a 73mm BB, I imagine it shouldn't be too far off to line up the rear cog.
    Im not in front of the bike right now, but i ended up using spacers to push the rear cog exactly as far out as possible and it was perfect when I did a test assembly. I just got the frame back from powdercoating and facing so its possible that the spacing might decrease slightly as the frame wasnt faced during the test assembly. Im hoping to assemnle it this week and can note the final rear spacing when i do.

    when you say parts list do you need more info than the amount of spacing? Afaik you would just use whatever combination of spacers gives you the magic number. For the cog its just a gates rear cog in the right size for the gear ratio i want

    Leave a comment:


  • Overkill
    replied
    Originally posted by ncmired View Post
    I have a pair of 650B Super Moto 2.8 tires on my pack mule, and so far they've held up fine, rejected a few nails, and are surprisingly fast. Based on these results, I bought a pair of 20" by 2.4 for my peewee bike. They'll go on when I convert the bike to IGH.
    Its great to hear that you have had positive results with these! They were the only plus sized tires i could find that seemed set up for high miles and speed.

    Leave a comment:


  • Blender
    replied
    Overkill, do you happen to have a parts list for the rear cog and spacers/washers you ended up using? Unfortunately, I can't really tell from the photos. :-/

    I've looking to try a similar Gates CDX build with the Strumey-Archer CS-RK3 and BBS02, but with the Soma Juice (29") rather than the 27.5 Riff. I've been hoping to ballpark the rear cog spacing, and given both the Juice and Riff have a 73mm BB, I imagine it shouldn't be too far off to line up the rear cog.

    Leave a comment:


  • ncmired
    replied
    I have a pair of 650B Super Moto 2.8 tires on my pack mule, and so far they've held up fine, rejected a few nails, and are surprisingly fast. Based on these results, I bought a pair of 20" by 2.4 for my peewee bike. They'll go on when I convert the bike to IGH.
    Last edited by ncmired; 07-17-2020, 10:05 AM.

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  • Overkill
    commented on 's reply
    So far they are great! I think they arent as flat proof as the thinner ones and i’m hoping that isnt an issue. My frame is still waiting to have the headset pressed in after powdercoating so i havent put many miles on them yet
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