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Squalor
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Discussion Starter · #1 · (Edited)
I am having a 29er built and I am thinking of using the Paul Disc Unit attached to a tab on the chainstay (similar to the Kelly set up) so I can run discs.

What I need is the distance from the bolt hole on the tab to the front of the horizontal dropout, or whatever the appropriate measurement is.

The setup in the picture is what I am thinking of. Not my bike obviously, but it sure is nice.

Also would it be possible to just have a IS disc mount welded on with horizontal dropouts and just use the upper (or lower for that matter) bolt of the disc mount as an attachment point for the Paul Disc Unit?

Thanks,
LP
 

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Squalor
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Discussion Starter · #4 ·
The frame is being built by Walt Wehner of Waltworks. The frame was already partially built and his original customer changed his mind on some of the specs so I got a good deal on this frame.

I have a KM as well. They are indeed fine frames. I am actually passing mine on to my younger brother. This bike will replace my monkey.

Gotta love a Surly though!
 

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Squalor
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Discussion Starter · #5 ·
baker said:
Just curious, why would you want to go with this setup over ebb, sliding dropouts, etc? What are the pros/cons?

Thanks,
baker
The frame was already partially built when I entered the picture and I therefore got a good deal. The bb shell has already been welded in and it will not accomodate an ebb. Plus my ss disc wheelset is built with a Paul WORD hub so the Disc Unit seemed like a natural fit.
 

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lanpope said:
The frame is being built by Walt Wehner of Waltworks. The frame was already partially built and his original customer changed his mind on some of the specs so I got a good deal on this frame.

I have a KM as well. They are indeed fine frames. I am actually passing mine on to my younger brother. This bike will replace my monkey.

Gotta love a Surly though!
Wow! That bike looks very familiar.........Oh, yeah, there's one in my garage that looks just like it! :)

I agree. The Surly stuff is awesome! I have a 1x1, as well, that I use for the trails.
 

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lanpope said:
The frame was already partially built when I entered the picture and I therefore got a good deal. The bb shell has already been welded in and it will not accomodate an ebb. Plus my ss disc wheelset is built with a Paul WORD hub so the Disc Unit seemed like a natural fit.
aaaahhhhh.....now I understand.
 

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lanpope said:
I am having a 29er built and I am thinking of using the Paul Disc Unit attached to a tab on the chainstay (similar to the Kelly set up) so I can run discs.

What I need is the distance from the bolt hole on the tab to the front of the horizontal dropout, or whatever the appropriate measurement is.

The setup in the picture is what I am thinking of. Not my bike obviously, but it sure is nice.

Also would it be possible to just have a IS disc mount welded on with horizontal dropouts and just use the upper (or lower for that matter) bolt of the disc mount as an attachment point for the Paul Disc Unit?

Thanks,
LP
My Matt Chester is built to use the Disk Unit. Distance from the center of the dropout to the tab is 115 mm. Distance from the dropout to the upper IS tab hole is ~80 mm.

I did design and add an IS mount to my old VooDoo Nzumbi.

The slots are parallel to the dropout and I rotated the caliper forward so the wheel can be removed with out moving the brake.

Worked great and it still works great for my buddy that rides it now.
 

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To answer your question.

would it be possible to just have a IS disc mount welded on with horizontal dropouts and just use the upper (or lower for that matter) bolt of the disc mount as an attachment point for the Paul Disc Unit?


No, the short torque arm used is too wide and would foul the disk.

I had my 26" frame made with a single re-enforced canti boss and it is very neat but stopped with Canti's on the 29er.

 

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lanpope said:
The frame was already partially built when I entered the picture and I therefore got a good deal. The bb shell has already been welded in and it will not accomodate an ebb. Plus my ss disc wheelset is built with a Paul WORD hub so the Disc Unit seemed like a natural fit.
Although the Pauls disc adapter is a very nicely made unit that works well, it is a PITA to remove the wheel when you have a flat. If you still have the option of having disc tabs welded on, I would go with that, just make sure they are slotted so you can adjust that caliper, and have them as close to the seat stay as will go so the slave pistons sit forward of the axle (this prevents the rotor from binding on the caliper when you remove the wheel).

Cheers,

Tom
 

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Have Walt do the math. He can make a drawing showing the range of wheel positions, and knowing the ISO dimensions, can design a caliper mount to work. There are a few different ways to do it. be careful of the twin parallel slots, as seen on the white bike above. That set-up will work for some calipers, but not with all. Could be perfect for you, though. Make sure he measures any rear caliper before designing the mount. You'd hate to have the caliper hit the mount, preventing proper wheel positioning.

Good luck with it.
 

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itsdoable said:
Although the Pauls disc adapter is a very nicely made unit that works well, it is a PITA to remove the wheel when you have a flat. If you still have the option of having disc tabs welded on, I would go with that, just make sure they are slotted so you can adjust that caliper, and have them as close to the seat stay as will go so the slave pistons sit forward of the axle (this prevents the rotor from binding on the caliper when you remove the wheel).

Cheers,

Tom
Yes, it is more difficult to change a tube/tire with the Disk Unit but if you run the torque arm as long as possible you can slip the hub out of the dropouts and fix a flat without removing the brake caliper and arm.
 

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D.F.L. said:
Have Walt do the math. He can make a drawing showing the range of wheel positions, and knowing the ISO dimensions, can design a caliper mount to work. There are a few different ways to do it. be careful of the twin parallel slots, as seen on the white bike above. That set-up will work for some calipers, but not with all. Could be perfect for you, though. Make sure he measures any rear caliper before designing the mount. You'd hate to have the caliper hit the mount, preventing proper wheel positioning.

Good luck with it.
For the parallel slots to work the caliper must be positioned directly over the axle, 90° to the slots. Then it works perfectly (and has for 3.5 years).
 

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The trick with ISO disc tabs on a horizontal wheel mount is to get the caliper body 90° to the slot as Shiggy says. To remove the wheel, you have to first slide it into the slot so you can remove the chain, then out. So the rotor must be able to clear both ends of the caliper. The problem is every caliper is different, so depending one where the ISO mount is placed, some will be more forward, some further back. Also, if you don't use the twin parrallel slots, the caliper will move off the 90° position when you move the position of the axle (ie when you take up chain wear, or change ratios).

That being said, there is a little clearance on most calipers for some leeway. Also, we have used a notched rotor (like the Avids, or the new wavey rotors) on a frame where the a round rotor would jamb because the Hayes caliper was too far back. All you had to do was align the notch as you pulled out the wheel - no need to loosening the caliper.

Personally, the eBB is way simpler - but you already said that wasn't an option.... 8(

shiggy©®™ said:
Yes, it is more difficult to change a tube/tire with the Disk Unit but if you run the torque arm as long as possible you can slip the hub out of the dropouts and fix a flat without removing the brake caliper and arm.
Yes, been there, but with the torque arm & brake hose still attached to the bike, there is not enough play to take the wheel out of the rear triangle, so you have to change the tube while the wheel is still half in the bike. Fiddling with that in a mosquito & black fly infested trail, trying to check the tire for thorns... it's just alot nicer if the wheel comes out easily.

Cheers,

Tom
 

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You can also visit Hayes's site and down load their technical drawings for disc mounts. Then you can simple determine how much fore/aft adjustment you want in your horizontal dropout and simply put the mounting holes into a drawing in relation to where the axle is.

You don't need to use perfectly horizontal slots for the disc mount since the amount of adjustment needed is 1:1 for the axle and disc mount slots.

This is just a pdf file, but if anyone wants the autocad file of this drawing e-mail me and I'll e-mail it to you. It works great. Has 15mm of axle adjustability with about 7mm long disc mount slots.
 
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