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  1. #1
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    Stumble: MT2000/Speedhub conversion; rear disc v. rim

    (cross-posted in Drivetrain forum)

    I'm bouncing back and forth on this. Give me your 2...

    I am fitting a Speedhub (Thanks again, Alex!) to a frame with 145mm dropout spacing. I've got most of the issues solved, but this one was unexpected:

    There is only one orientation I can run the external shifter box, as pictured. It doesn't work in any other position, and can only point down lest the cables interfere with the disc brake caliper.

    The housing, as pictured, is a quick 'n dirty mock-up. I think I'll need to run a slightly larger loop, but it ought not dip down much lower than the rotor (which is a huge 220mm, for reference).

    I'm worried about cable snags on low branches, shrubbery and vines, but looking at the mock-up, it doesn't dip as low as I originally imagined. Maybe I'm ok. (...and after rotating the picture to "level" I feel better -- so far I've been looking at this at an angle and it looks worse).

    Option #2 is to convert the hub to non-disc, eliminating the shifter box and cable routing hassle. Both options have pros and cons!



    Here are the details:
    - Cannondale MT2000 tandem. Mostly tame fireroad and singletrack; nothing kooky.
    - The spot of silver behind the axle nut & dropout is ~6mm worth of spacers to partially fill the difference between the frame's 145mm dropouts, and the Speedhub's 135mm OLD.
    - I'm using Rohloff's long threaded axle plate part #8233L, which is about 8mm longer than stock, to make room for the 6mm axle spacer stack.
    - I'll be redishing the wheel a few millimeters towards the non-drive side -- yes, a non-symmetrical Speedhub on a tandem.
    - There is a 10mm gap between the face of the frame's disc brake tabs, and the face of the disc brake adapter. If I stick with the disc, I'll drill out a piece of 3/8" aluminum bar stock to use as a giant spacer, rather than using traditional disc brake spacers (a stack of washers).
    - A Speedbone will not easily work with this setup due to the gap -- the Speedbone's "nub" will not reach inward far enough to engage with the hub's axle plate.
    - A non-disc conversion of the Speedhub would probably be easiest, but:
    - - - > Cost of the hub conversion (~?)
    - - - > Cost of Magura HS33 rear brake (~$100)
    - - - > Ugly exposed cable run off of rear brake post
    - - - > Prevents installation of a reserve / emergency rim brake for stoker

    Here are some shots of the long threaded axle plate:




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  2. #2
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    Smaller rotor, perhaps?

  3. #3
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    Just went out to the bike and checked.

    I could go down to a 203, but that would move the caliper over 1cm / 1/2", but also moves it down and slightly closer to the shifter box. I'd still have the cable interference.

    I wouldn't want to go any smaller than 203mm.
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  4. #4
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    I'm not trying to talk you out of big rotors. I just see it as quite a challenge going that route. From a practical point of view, perhaps it would be worth-while to get it setup and running with a 6" rotor to see how that performs.

    Some other ideas:

    -If you were to go with hydraulic, that would likely go a long way to improving a 6" rotor's performance.

    -If you stay cable, you could get creative and setup a disc/Vbrake hybrid system by splitting the cable out (again, using 6" rotor). I'd probably adjust one brake to activate first and the second to come on as an "aux" later in the lever's travel but I've never done this so experimentation would be key here.

    -A new caliper adapter can be made with as little as a file, a drill, and tap. You could make it to position the caliper in a more suitable location (about 12o'clock, perhaps), allowing more room for the shiftbox.

    -You *may* be able to manipulate the axle plate to allow mounting of the torque arm to the seatstay. Alternately, you can fabricate a new one to allow for a more suitable location of torque arm and/or use of speedbone.

    Looks like a fun problem/project. Keep us posted on what you end up doing.

    Good luck!

  5. #5
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    Couldn't you rotate the axle plate and position the shift box @ 6:00 routing the cable horizontal. Then fabricate a new anchor plate.

    Just a thought.

    PK

  6. #6
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    Quote Originally Posted by swift
    -You *may* be able to manipulate the axle plate to allow mounting of the torque arm to the seatstay. Alternately, you can fabricate a new one to allow for a more suitable location of torque arm and/or use of speedbone.
    Quote Originally Posted by PMK
    Couldn't you rotate the axle plate and position the shift box @ 6:00 routing the cable horizontal. Then fabricate a new anchor plate.
    Awesome, guys! Thanks -- exactly the out-of-the-box thinking I needed!

    Lots of room inbetween the hub and the dropout to rotate the axle plate to unconventional positions. And now the ugly torque arm won't be so ugly, 'specially after I take a grinder to it.

    Thanks for the idea.

    Check it out:





    Last edited by Speedub.Nate; 06-11-2008 at 07:10 PM.
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  7. #7
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    Quote Originally Posted by swift
    -If you were to go with hydraulic, that would likely go a long way to improving a 6" rotor's performance.

    -A new caliper adapter can be made with as little as a file, a drill, and tap. You could make it to position the caliper in a more suitable location (about 12o'clock, perhaps), allowing more room for the shiftbox.

    Looks like a fun problem/project. Keep us posted on what you end up doing.
    The Avid's mechs aren't bad (front only so far). The biggest problem with this bike isn't power, but heat build up. That was my desire to go big. I managed to heat damage 165mm rotors on my solo bike, and I've seen a tandem's rear 203 that gets hot enough to discolor it. Lots of dragging and other bad habits.

    I'm thinking a custom caliper might be the way to go just to get the right amount of offset build in. But first I'll try the block spacer, and see if that works smooth and silent.
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  8. #8
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    itsdoable, don't you have any thoughts to contribute? Come on now, you've had all day to think about it.
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    You could easily fabricate a new torque arm that runs nicely along the top of the CS or up the under side of the SS, and clear the disc mount & shifter box.

  10. #10
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    Quote Originally Posted by Speedub.Nate
    itsdoable, don't you have any thoughts to contribute? Come on now, you've had all day to think about it.
    Hey, I only saw it a few minutes ago... and I had to check mine to see if you could run the old non-disc cable system (no shifter box setup) and the rotor with the extra cm of space - Rohloff did that early on. But it didn't seem doable... yet. Things take longer with a sleeping baby in your arms, and you have to type with one hand...

  11. #11
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    Try running the shift cables over the caliper, like this:
    Attached Images Attached Images
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  12. #12
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    OK, I've had some time to think about it, and here's another option that should work.

    Use a 20mm thru-axle ISO to Post mount adapter for the 220 rotor, this will place the caliper 10mm further inboard and pretty close to a 203 rotor on the rear. I know you only spaced out the hub by ~6mm, but Cannondale tabs were always placed several mm outboard, so the caliper may be just right - or you may have to space the hub out by 7mm.

    A Post mount to post mount 160 to 180 adapter will take you up to 220, which is usually just a spacer. However, instead of a plain spacer, you can place a torque arm from the upper post mount up to the canti mount to stabilize the caliper and alleviate the forces at the disc tab. I've done this with a flat bar and some cup & cone washers from old V-brake pads. Rear ISO-like tabs are placed very close to the axle, so having the caliper spaced out that far puts a lot of load on them - I would use a torque arm with that rotor anyways.

    Grind or machine the post adapter to ~1cm thick at the lower mounting bolt. Use a smooth cap bolt mounted from the inside, and a capnut on the outside (disc tabs) to keep things clean. This should place the cab bolt head in the correct position for a OEM-2 torque arm - it's like a custom monkeybone. The caliper torque arm will help alleviate the loads.

    Shifter box can now go anywhere.

    Thats what I would try first - except I'd probably just use a 203 rotor and see how that goes. (but if I already had a 220 rotor, then I'd be inclined to use it!)

  13. #13
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    Quote Originally Posted by BigNut
    Try running the shift cables over the caliper, like this:
    I've probably run about half my Speedhub installations that way. It wasn't in the cards for this one.

    I didn't take a picture with the wheel mounted and the shifter box reversed, but here's a photo of what it looked like off the bike. The two "forks" off the end of the shifter box, plus the barrel adjusters, together extended far enough to "reach out" and almost touch the caliper & adapter. There was no clean way to get the cable in.

    This bottom chainstay routing the guys helped me work out yesterday is going to be the ticket.

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  14. #14
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    Quote Originally Posted by itsdoable
    OK, I've had some time to think about it, and here's another option that should work.

    Use a 20mm thru-axle ISO to Post mount adapter for the 220 rotor, this will place the caliper 10mm further inboard and pretty close to a 203 rotor on the rear. I know you only spaced out the hub by ~6mm, but Cannondale tabs were always placed several mm outboard, so the caliper may be just right - or you may have to space the hub out by 7mm.

    A Post mount to post mount 160 to 180 adapter will take you up to 220, which is usually just a spacer. However, instead of a plain spacer, you can place a torque arm from the upper post mount up to the canti mount to stabilize the caliper and alleviate the forces at the disc tab. I've done this with a flat bar and some cup & cone washers from old V-brake pads. Rear ISO-like tabs are placed very close to the axle, so having the caliper spaced out that far puts a lot of load on them - I would use a torque arm with that rotor anyways.
    Nice thinking. This is probably a better question for the brake forums, but here goes:

    I've got three 20mm TA forks in the house, but I haven't run any specialized 20mm adapters. I've always stuck about 4mm worth of spacers between the adapter and the fork, and everything has lined up nicely.

    So exactly which adapters offer the extra 10mm of inset? I see adapters at Universalcycles.com listed for Marzocchi 20mm and Boxxer -- are either of these it?

    I'm going to stick with the shifter box and torque arm orientation as pictured, but I like your thinking on pairing up adapters and am going to follow that through. Hayes is also making 224mm rotors now, so they are another source of adapters to choose from.

    Edit: Actually, hold that thought -- I'm going to run down the street later today and pick up that aluminum bar to try out as a spacer. It'll be a more economical first step.
    Last edited by Speedub.Nate; 06-12-2008 at 10:02 AM.
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    That looks clean. Nice work!

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    Mister Nate..

    First I know getting to setup this shifter boxes is not that easy, well patience is necesary, but how about something like this so you can run the two cables really close to the chainstay.



    I hope it helps

  17. #17
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    Quote Originally Posted by patineto
    ...how about something like this so you can run the two cables really close to the chainstay...

    Know what? I've considered a Travel Agent / Rollamajig like that for a previous bike. My hesitation is that sealed cables work so darn well with the Speedhub, and I had a miserable experience with the one interrupted housing setup I attempted.

    No, I think I'm in good shape with this latest setup. In fact, I just picked up some aluminum bar to craft my disc brake spacer. I'm going to give it a shot with a hand drill today. If that fails, I'll have to wait for the weekend and I'll use the drill press at work.
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  18. #18
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    Quote Originally Posted by Speedub.Nate
    Know what? I've considered a Travel Agent / Rollamajig like that for a previous bike. My hesitation is that sealed cables work so darn well with the Speedhub, and I had a miserable experience with the one interrupted housing setup I attempted.
    Good point as usal Nate.

    So what about some of those V-brake noddles with a cable adjuster that some cyclocross rider use or even a stock V-brake cable noddle, yes I know the friction is pretty dramatic, plus they are kind of weak,,

    maybe a old throttle set of cable guide wires from a motorcycle, they are seal and they can be found in many angles and shapes,

    Just ideas for the fancy creative head of your to think about.

  19. #19
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    Quote Originally Posted by patineto
    So what about some of those V-brake noddles with a cable adjuster that some cyclocross rider use or even a stock V-brake cable noddle, yes I know the friction is pretty dramatic, plus they are kind of weak,,

    maybe a old throttle set of cable guide wires from a motorcycle, they are seal and they can be found in many angles and shapes,
    You must not had looked at the pics in post #6 -- an elegant solution, don't you agree? The cables enter straight, and the ugly torque arm is nearly invisible.
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    Quote Originally Posted by Speedub.Nate
    You must not had looked at the pics in post #6 -- an elegant solution, don't you agree? The cables enter straight, and the ugly torque arm is nearly invisible.

    Sorry Senor don Nate, I just read your first posting,

    yes you later work is pretty impressive, congratulation on figuring out this Spinning Rubic cube.
    Last edited by patineto; 06-13-2008 at 03:48 PM.

  21. #21
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    Quote Originally Posted by patineto
    Sorry Senor don Nate, I just so your first posting,

    yes you later work is pretty impressive, congratulation on figuring out this Spinning Rubic cube.
    Cool, yeah, I'm excited. I had pretty much given up on a Speedhub for the Cannondale until Thomas from Rohloff mentioned this spacer idea, a few months ago. Hopefully we will have it on the trail this weekend.

    Still got a few more steps to complete.

    - Stopped off at Bowlin in Berkeley yesterday and picked up some 30mm bolts for mounting up the brake. Thanks again for letting me know about them -- great resource for metric fasteners.

    - I picked up a 12 inches of aluminum bar today -- 3/8" x 1/2" -- to make the spacer for the disc caliper. First two holes, drilled by hand, were straight and perfectly spaced. I just need to cut it and sand the edges and that hurdle is behind me.



    - I've got a YESS ETR-B chain tensioner to install behind the stoker's bottom bracket cup. YESS provided me with an optional piece to help out with the wide chainline, which is pushed out to 57mm on this bike (due to the wide dropout spacing).



    - Speaking of which, I need to re-dish the wheel to account for those spacers. What's on TV tonight?

    - I can't believe how hard it is to find square taper bottom brackets locally! I'll drive out to pick up a 73 x 118 Friday. The Cannondale has 68mm shells, but the YESS tensioner throws off the chainline. A 73 x 115 plus 0.5mm chainring spacers would give me a PURRFECT Speedhub chainline, but alas, Shimano doesn't make a 115mm for 73mm shells. So my chainline will be 1 mm wide! Gah!

    - I've got a Hopey steering damper sitting here that I want to install. I'm stalling on installing the bracket; I don't want to punch the headset cup. But I'll break down and do it tomorrow.



    - Anne will be getting a Magura HS33 on her handlebar. She will now have final, absolute veto authority. Unless I can out-pedal her braking effort. Not likely.

    - Other than running the cables, that's all!
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  22. #22
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    OK, Yea!!! Whoopie! We turned and burned it tonight!

    We just got back with the RohlONDALE from Lake Chabot, where we took it out for a shake-down ride. It performed as expected, and we're both pretty stoked that it all worked out.

    Shifting was perfect. I bought this hub "with all of one ride on it" from Alex at MTBTandems.com, and I swear it shifts lighter and smoother than any of the well traveled Speedhubs on our other bikes.

    Maybe that's because I used SIS housing instead of brake housing? Maybe its because this is the "newest" hub we own? Whatever, I look forward to putting some more miles on it to see how it can possibly improve any more with break-in..

    I geared it at 40x16. That gives us a climbing gear equivalent to a 22x32T derailleur setup, which is lower than what we had been running with previously. I'm hesitant to go any lower. There are trails where we could use the extra limp-along gear, but I don't want to take any more off of our top end gearing, and I don't want to stress the hub.

    Because today was the first day Anne didn't have to dress prepared to kick the chain into a lower gear, it was her first time out on clipless since an ernest but ill-fated attempt a number of years ago. No objections tonight, and I proved to her that they release when I dumped the bike in a sandy turn.

    Our one complaint is something that doesn't bother me much on the solo bikes, and is only a little gripe for Anne: the well-known gears 7/8 hang-up. It nailed us on a tall roller just before it crested. I took a second to realize what was happening. I let up off the pedal stroke, but Anne didn't sense what was going down and continued to push. We quickly came to a dead stop in the tallest gear, and I couldn't even shift down at that point because Anne was basically stomping on the pedal to keep us from rolling backward or falling over.

    So we'll need to work on some concise communication to keep that from happening again.

    Anyhow, the conversion made it around the loop, and I'm stoked.

    I'll put up a picture / build thread at some point in the coming weeks, so that anybody else curious about performing this conversion can follow along. I hit a number of snags that I want to mention, and that will take me a little time to take the right photos.
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    Bonehead move, one any of you Speedhub nerds affectionados will appreciate.

    Post-ride inspection this morning, and I observed the cables in distress, external shifter box had rotated forward a few degrees, nearly contacting the chainstay. Uh-oh! (Shoot! Should have snapped a picture...)

    Meanwhile, the torque arm was still firmly affixed to the tab on the chainstay, and no sign of loosening of the fixing bolt.

    So's I unbolted the contraption, and as many of you have already concluded, the axle plate wasn't exactly "secured" to the hub.

    Over the past days, in the process of experimenting with different axle plate orientations, I only used two of the five bolts to temporarily hold the plate in place between fittings... and they weren't even tight!

    I am surprised the pedaling torque didn't sheer them into two, since these skinny matchstick bolts are the sole connection between the hub and the torque arm. They didn't look tweeked as I unscrewed them, half-expecting the heads to twist off. I tossed them in the trash, just to be safe.

    Here's a shot of everything put back together, properly bolted and torqued to spec.

    BTW, I had slight concerns about the rear brake, because I added an additional 2-3mm of spacers in addition to the 3/8" (9.5mm) aluminum block, to achieve the correct caliper alignment over the rotor. It's hanging w-a-a-a-y out there. But I worked it hard on a steep and somewhat tricky descent (coupla' steep, rutty turns), and it performed very well. You can guess from the photo that it got quite hot, and Anne has a burn on her finger to attest!

    Last edited by Speedub.Nate; 06-21-2008 at 04:30 AM.
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  24. #24
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    Nate,
    Nice work. Can you provide some insight into the difference the larger rotors make for braking?
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    Quote Originally Posted by BigNut
    Can you provide some insight into the difference the larger rotors make for braking?
    Alex, I'll need a volunteer to drive this thing and provide you that feedback. I'm unable...

    I went straight from the underpowered HS24 rim crusher up front to the Avid + 220mm Formula rotor. Never tried anything smaller. And that happened concurrently with the switch from the flexy Moto FR to the 20mm ATC fork. All I can tell you with any certainty is that those two component changes were confidence inspiring, and really caused us to pick up our descent speed.

    We've stuck with the Magura in the rear up until now. Not quite as drastic an impact as the switch to disc up front, but on Thursday night's ride, my braking hand felt better for it.

    I think I mentioned in another post that I'll be mounting a rear HS33, for Anne to squeeze on. The discs are a giagantic improvement -- like I said, "confidence inspiring" -- but since they're causing me to run faster and take more chances, I want a just in case brake as a backup.

    Hey, didn't you get a handful of V9s awhile back? Haven't you tried them? Somebody on Bikeforums wrote that Hayes discontinued them. What have you heard?
    Last edited by Speedub.Nate; 06-21-2008 at 08:13 AM.
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