Build Complete: Carbon-fiber full-sus internal-gear curb-jumper with roller brakes- Mtbr.com
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  1. #1
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    Build Complete: Carbon-fiber full-sus internal-gear curb-jumper with roller brakes

    MTB purists, go grab a beer, this thread isn't for you.



    There is no reason for this bike to exist. That's why I built it.

    ...okay, that's not entirely true. There is no conventionally good reason for this bike to exist, but the questionable reason that motivated me to build it is because I wanted to see what would happen. That's the Zen Buddhist definition of "pointlessness", btw -- doing something to see what will happen, rather than to achieve a pre-determined goal. I've been wanting to build an internal-gear bike ever since I was a teenager in the late 90's, browsing the primitive websites of the time and marveling at all the cool bike parts that existed. Maybe it would be great? Maybe it would suck? Only one way to find out! But first I had to go to college, learn something useful, start earning money, and finally work my way back around to this idea that had been simmering in the back of my mind for 20 years.



    I haven't kept up with bike standards since about 2008, so it took until 2016 before I suddenly realized that bike standards were changing in ways that would make this build impossible in the near future. So I bought a couple Nexus 8 hubs and bunch of IS-compatible roller brakes on eBay, while I could still find good parts in new condition...and then I stuffed them in a box because I had to move to a new apartment.

    In 2013 I had a nervous breakdown brought-on by long-distance-relationship stress, loneliness, mentally-exhausting work, and "redlining" on my bike for at least a half-hour every day to burn off stress. (as it turns out, that actually made things worse -- I was fit enough that I never passed-out when I finally broke down.) The resulting panic attacks put me in the ER, left me feeling like my skin was on fire, and made it virtually impossible for me to ride my bike; my brainstem couldn't tell the difference between a racing heart caused by exercise vs. a panic attack, and the last place I wanted to get lightheaded and dizzy was while riding a bicycle miles away from home. So I ended up pouring all of my hobbyist energy into building RC cars instead, but 6 years later I've finally recovered enough that I can hop on a bike and go for a ride without needing to carefully psych myself up first.

    I wanted an easier bike to ride, though -- something with a more upright riding position, more stable steering, and easier gearing -- but at the same time I didn't want anything resembling a heavy steel beach-cruiser. Cruiser bikes have never been my style, and I refuse to buy a bike that doesn't have suspension, because I don't live in the middle of a glassy-smooth featureless plain. So this past spring, in between working and taking care of my 4-month-old baby, I started shopping for a frame that would work with the Nexus 8 hub that I'd bought in 2016. After much wailing and gnashing of teeth, I eventually found and bought a 2012 GT Zaskar 100 Expert frame, a nice lightweight carbon-fiber full-suspension frame, on eBay from Australia. It's a 26er frame, which is well outdated now, but who cares? 26ers are all I've ever owned anyway.

    I found a RockShox Recon Gold fork to go with it, but the seller refused to ship it to me, insisting that I had to drive from DC to NYC to pick it up, and eventually the deal fell through. I "settled" for a much-nicer SID instead; the SID is fancier than I need, with its one-piece carbon-fiber crown and steertube assembly, but it fits and it works, and I got it for $450 instead of the original MSRP of ~$1300. Plus, fitting such a high-end fork to this bike added to the ridiculousness of the build, which amused me.



    That's when the shopping challenges (mostly) ended and the fitment challenges started, though. You might think that Nexave roller brakes were never intended to fit properly with large-stanchion MTB suspension forks, and you'd be correct. Fortunately I was able to determine that I could make the roller brake fit if I cut away a small piece of the outer fairing, which is just a dust cover and offers no structural support.



    The bigger issue was figuring out how to fit the IS-compatible torque-arm mount to a fork designed for post-mount brakes. There is exactly one company who makes the adapter I needed, KCNC in Korea, and I had to grind some material off both the torque-arm mount and the adapter to make everything fit. I even had to grind-off a side of one of the mounting bolts, but it's a hardened-steel bolt so I'm not worried about any loss of strength.



    So that was the fork sorted. But I still needed to build the rest of the bike, and figure out how to attach the rear roller brake to a full-suspension MTB frame.



    At first, my plan was to use the normal method of attaching a rear roller brake to a frame, and I bought a few torque-arm clamps and figured out which one fit the best. But at the last minute, in an attempt to make the definitely-not-quick-release rear wheel somewhat easier to remove, I decided to grit my teeth and try cutting into the post-mounts on the rear triangle to make room for another post-to-IS adapter and torque-arm mount. This was the riskiest single modification I made during this entire build, because it involved cutting into the frame, and there was so much extra material around the rear post-mounts that I couldn't line-up the adaptor and torque-arm mount to approximate whether the brake would line-up correctly once I got the adaptor to fit. Fortunately the bike gods smiled on me (or at least one of the crazier ones did), and everything fit perfectly. So I was able to fit an IS-compatible front roller brake to the rear axle of my full-suspension MTB frame. Hey, there's nothing else about this build that makes sense, so why not?



    Most of the rest of this build was mundane stuff -- hunting down parts I wanted to use, most of which are discontinued and some of which were sold by brands that don't even exist anymore, because I guess I had some karma to pay-off after getting the roller brakes to fit so well -- but there was one last modification I made. Roller brakes are not intended to be taken apart, because Shimano is a Japanese company and Japanese engineers really like to design sealed devices that last a long time until all of the parts wear-out at the same time, but I want to be able to service the things I own. (even if most of my fellow Americans are content to just buy new iPhones every 2 years.) So peeked around the edges of the roller-brake fairings, marked where the retaining tabs are, then pried apart the roller brakes and cut slots into the lip that the retaining tabs hold on to. This way I can rotate the roller brake drum to the right position, and the drum will simply slide out of the cam assembly.



    This will make replacing the old grease -- and generally making sure the drum is lubricated with just the right amount of grease -- a hell of a lot easier.



    Oh, and since Nexus 8 hubs work way better when lubricated with gear oil instead of the stock Shimano grease, while I had the roller brakes off the bike, I cut a circle of felt to stick between the rear hub and the rear roller brake, to catch oil leaking past the not-at-all-sealed left bearing cone. This will reduce oil seepage that might cause the roller-brake grease to wash away prematurely.

    Okay, that's pretty much everything I have to say about this build. If you actually read that huge wall of text, here are some more pictures as a reward:















    Last edited by deusexaethera; 08-23-2019 at 08:05 PM.

  2. #2
    Wild-Eyed Rectum 'Recker
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    Pics or it didn't happen.
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  3. #3
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    You're right. There's no reason for this to exist. And that makes it seriously cool, for all sorts of silly reasons. Nice build, some bold moves, cutting some of that stuff up. It looks a trip. Enjoy it.

  4. #4
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    cool build. I love the weird stuff.

    The last 8 pics or so dont show up for me. did you upload them here or link from another site?
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  5. #5
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    Quote Originally Posted by Klurejr View Post
    The last 8 pics or so dont show up for me.
    Ditto, but I enjoy what I see so far -- well done OP.
    --------------

    [WTB] 1987 Cannondale SM800, 20", Pink with airbrushed graphics.

  6. #6
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    Pics are linked from Imgur.com. I'll double-check that links are correct.

    EDIT: Fixed. Some of the links used HTTPS instead of HTTP, and that was apparently causing problems. I didn't notice when I originally posted this thread because the images had already been cached in my browser when I uploaded them.

    ANOTHER EDIT: MTBR is showing the pics much smaller than I expected. You can right-click and select View Image to see larger pics.

  7. #7
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    Quote Originally Posted by Haint View Post
    Pics or it didn't happen.
    Fixed.

  8. #8
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    Thanks! I get bored easily.

  9. #9
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    Quote Originally Posted by deusexaethera View Post
    Pics are linked from Imgur.com. I'll double-check that links are correct.

    EDIT: Fixed. Some of the links used HTTPS instead of HTTP, and that was apparently causing problems. I didn't notice when I originally posted this thread because the images had already been cached in my browser when I uploaded them.

    ANOTHER EDIT: MTBR is showing the pics much smaller than I expected. You can right-click and select View Image to see larger pics.
    Thanks for the pics. That's one funny build.

    BTW, mtbr forces all images to the exact same width, regardless of original size (smaller, larger, who cares?). it's certainly better to start too big, rather than try to post smaller pics that get blown up. Irritating.

  10. #10
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    I hate it and i love it. It's awesome!



    I'm pretty sure that the SID carbon steerer has a specification for the maximum amount of spacers you can use, and you're waaaay above it. FYI.
    "Things that are complex are not useful, Things that are useful are simple."
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  11. #11
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    Quote Originally Posted by scottzg View Post
    I hate it and i love it. It's awesome!



    I'm pretty sure that the SID carbon steerer has a specification for the maximum amount of spacers you can use, and you're waaaay above it. FYI.
    That also was my first throught when I saw the picture, but I'm guessing from statements that OP made he is almost never going to stress the bike to that extent.
    Silly bike things happening.

  12. #12
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    Quote Originally Posted by Redlands R&C View Post
    That also was my first throught when I saw the picture, but I'm guessing from statements that OP made he is almost never going to stress the bike to that extent.
    Agreed. That said, a steer tube failure is really scary, and a spank spike or surly sunrise would make that bike EVEN COOLER. Especially a sunrise mounted to the WW fork.
    "Things that are complex are not useful, Things that are useful are simple."
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  13. #13
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    Quote Originally Posted by scottzg View Post
    agreed. That said, a steer tube failure is really scary, and a spank spike or surly sunrise would make that bike even cooler. Especially a sunrise mounted to the ww fork. :d
    yes!
    Silly bike things happening.

  14. #14
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    I never saw any specs about how many spacers I could put on the steertube. Do you have a link to those specs?

    That said, the main stress point is at the bottom of the steertube where the frame is constantly trying to snap the steertube off from the fork crown, which is why new bikes have larger headset bearings at the bottom but not the top. So I'm not entirely convinced normal riding of any kind would snap the stem off the top of the steertube. I think that would require landing flat after a huge jump with locked elbows to bottom-out the fork with lots of extra force left-over. Also, it was a huge pain to cut through that steertube. I don't think it's just CF; there's something else in there that's reinforcing it. It took twice as long to cut through it as it took to trim the end of my Easton CF seatpost, and it's a narrower diameter than the seatpost.

    I never heard of the handlebars you mentioned. I'll take a look at them. I'm kinda partial to Easton EC70s though, even if Easton did decide to discontinue their entire MTB product line.

  15. #15
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    Your fork is older, 2003/4ish? so it may not be very easy to find those. Also, my first forks I bought were in 1996-1998 and I don't recall them saying anything regarding maximum spacers either.

    A lot of it will depend on the brand/fork etc. When I worked at the SCruz/Salsa/Spec/CDale dealer, adhering to the maximum number was a given, but even that would range. Here is a link to Salsa, just as an example https://salsacycles.com/files/tech/8..._INST_F_A4.pdf
    Notice under the "Requirements for Spacers with a Threadless Stem" section, they say 50mm maximum of spacers.
    40-60mm I think (again, depends on brand/etc) is a general rule of thumb I try to keep with.
    Here is a link to the Surly Sunrise Bars -https://surlybikes.com/parts/sunrise_handlebar
    I enjoy them, I need to move them off my "townie" bike though onto something else. And get a BMX stem to go with it! Salt COMP Top Load Stem | SALT BMX PARTS
    Silly bike things happening.

  16. #16
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    It's a 2012 model. Maybe 2011, but definitely not 15 years old.

    I'm using 60mm of spacers, so my setup is at the top end of the range you mentioned.

    I looked at the Surly Sunrise. It looked great until I noticed it was made of chromoly steel. No vibration-damping and prone to rust? Damn, so close yet so far.

  17. #17
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    Ah yes, I glanced over the images without closer looking. Post mount, not older IS mounts like my vintage SID with same blackbox crown/steerer.
    The Deity highrise bar would be a good option.
    There is so much paint on my sunrise bars, that I bet it would take forever to rust out. Not to mention the thickness. And yes, STIFF.

    Many custom Steel/Titanium handlebar options out there too.
    Silly bike things happening.

  18. #18
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    I really like CF handlebars and seatposts for their vibration-damping characteristics. Maybe I'll see if I can find a higher-rise EC70 handlebar. But I'll take a look at the Deity highrise bar you mentioned as well.

  19. #19
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    v1.1 update:

    Everything I build and declare "complete" inevitably ends up being revised a few times before I'm really totally happy with it. (I guess nobody should trust me with a job where I might get to announce "Mission Accomplished!" ) This bike is no exception. So why do I keep saying "Build Complete"? Because "Initial Operational Capability Achieved" is longer and doesn't sound as good.

    After the prodding I got in this thread to lower the shim stack, I tracked down a riser handlebar with a 40mm rise instead of the 20mm rise I had before; this let me lower the shim stack by 10mm and raise the handlebar by 10mm at the same time, which has an unexpectedly significant effect on my comfort when riding the bike. As I get older and spend more of my waking hours sitting at a desk, my neck gets stiff more easily and leaning forward while riding becomes more uncomfortable. Now I'm contemplating raising the handlebar on my Christini AWD too.



    You can also see I installed a headlight of sorts -- a knockoff Surefire flashlight with a floody LED lamp installed, running on a pair of lithium-ion batteries, attached to the stem using two lower-halves of a pair of rear-reflector clamps, joined together to make an unholy monstrosity that is surprisingly useful.





    Seriously, why aren't bicycle headlights designed to mount to the stem? It annoys the crap out of me to have the headlights mounted off-center on the handlebars. It looks bad, and the people who design bicycle headlights should feel bad.



    In drivetrain-related news, I disassembled the Shimano Alfine chain tensioner and drilled a new hole for the tension spring to fit into, to reduce the tension applied to the chain. Shimano doesn't often cut corners in places that actually bother me, but this is one instance wherein they did: The Alfine chain tensioner uses a roadie-style short cage, but the spring actually feels stiffer than the spring in my SRAM X.0 long-cage derailleur on my Christini AWD. That translates to much more tension applied to the chain, which in-turn increases drivetrain drag. I couldn't lengthen the chain to reduce the chain tension, because the chain was already as long as it could be without going slack when I shifted the front derailleur down to the small chainring. (I know Shimano never intended for the Nexus internal-gear hubs to be used with multiple-chainring cranksets, but frankly they have no-one to blame but themselves for failing to ask me about it first. )



    I also replaced the chain itself; the original chain was taken from this bike's predecessor, and I thought it still had some life left in it, but I was wrong. It was loud and chattery, and even though my Park chain-stretch tool said it was okay, after further examination it turns out the chain had been wearing unevenly; different parts of the chain gave significantly different readings using the chain-stretch tool. I've never seen that happen before. I keep overestimating how much wear bicycle chains can handle before they need to be replaced, which of course is why I bought the chain-stretch tool in the first place. The chain had stretched about 2mm over a span of 106 links, which I guess means it's worn-out, because the new chain is smooth and quiet.

    I didn't want to throw away the old chain, though, because it's a Wippermann stainless-steel chain and it's still as shiny as the day I bought it. So I cut a few pieces off and upgraded my Park cassette wrench to be the shiniest cassette wrench in all the land:



    One last thing that I couldn't take photos of is the roller-brake shoes. The front roller-brake is producing a satisfying amount of braking force now, but the rear roller-brake was lagging behind badly -- even if I stood up and leaned forward so my chest was overhanging the handlebars, I couldn't make the rear tire skid with the rear roller brake. So I took it apart to check on its break-in progress, and I noticed there was asymmetric wear on each side of the V-cross-section brake shoes. They must've warped slightly when they were cooling-down after being manufactured, or something. So I cleaned out almost all of the roller-brake grease, leaving just a thin film on the inside of the brake drum, put everything back together, and now it generates much more braking force. Between the poorly-contacting brake shoes and the generous amount of roller-brake grease, the shoes just couldn't get a good grip on the inside of the brake drum. Removing most of the grease will help to accelerate the break-in process, but still provide just enough lubrication to avoid gouging the brake drum; it will require periodic examination to make sure it still has enough grease, but since I modified the drums to be easily removed that isn't a problem. Once it's fully broken-in I can slather it with grease and ignore it for the next few years. I'm guessing warped brake shoes have a lot to do with owners' complaints about roller brakes being mostly useless for braking quickly, because the front brake on my bike works great; only the rear one has been temperamental thus far. I guess I can understand why Shimano doesn't want people taking these things apart, because they will malfunction if you put them back together wrong, but it's still irritating that they made them quite so difficult to service. It's a good design, it just isn't an "install it and forget about it" design like they apparently wanted it to be -- or at least their quality control needs to step-up a bit if that's their goal.

    If you read this whole post, here's a picture of my baby examining my rims for defects as a reward: http://i.imgur.com/T9Q3bhW.jpg

  20. #20
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    Hmmmm...

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    Quote Originally Posted by mileslong View Post
    I passionately remove rocks and corners and other stuff I find too hard to ride.

  21. #21
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    Quote Originally Posted by DIRTJUNKIE View Post
    Hmmmm...
    Hmmmm?

  22. #22
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    Quote Originally Posted by deusexaethera View Post
    Hmmmm?
    Hmmm...as in I like it and hate it at the same time. I was scratching my head. Pretty much like most of the comments in here. I guess I fall into the “mtb purists” category you warned us about in the beginning. You definitely had a vision with this build though. I commend you on that.
    Quote Originally Posted by mileslong View Post
    I passionately remove rocks and corners and other stuff I find too hard to ride.

  23. #23
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    To be honest, I like it when people can't decide whether to love or hate the things I do. It's one of the few ways I allow myself to indulge my sadistic tendencies. Speaking of which, I really ought to repost this on Pinkbike to see if I can make any heads explode.

    Yep, I knew what I wanted this bike to be and it definitely succeeds at being whatever it is. I think if people got to ride it, they would compare it quite favorably to a typical steel-frame no-suspension cruiser bike. It's quite comfortable but also capable of riding down concrete stairs without catapulting the rider headfirst.

  24. #24
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    26er? Intearnal gears and a weird brake system, all crammed into a carbon Zaskar? What's not to like?
    I definitely want to give it a try!
    The revolution starts now
    When you rise above your fear
    And tear the walls around you down
    The revolution starts here

  25. #25
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    this is some top level macguyver shit! Amazing work and wonky AF. Love it!

  26. #26
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    Quote Originally Posted by mattithundrrr View Post
    26er? Intearnal gears and a weird brake system, all crammed into a carbon zaskar? What's not to like?
    I definitely want to give it a try!
    Quote Originally Posted by richardjohnson View Post
    this is some top level macguyver shit! Amazing work and wonky af. Love it!
    Thanks!

  27. #27
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    Tiny update on the roller brakes: I swapped the shoes front-to-rear, and now the rear brake works as expected. As a bonus, the front brake didn't lose any braking power due to the swap.

    Everything else continues to work correctly and hasn't needed any adjusting. Good times.

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