Using Rear spaced front hubs on a fork made for front spaced hubs...IS adapter ?- Mtbr.com
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  1. #1
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    Using Rear spaced front hubs on a fork made for front spaced hubs...IS adapter ?

    I am running into an issue with my latest build. My 135mm front hub is rear-spaced. My new fork (Salsa Beargrease aluminum) IS mount is for front spaced hubs. Does anyone make an adapter that will push my caliper out? I am running 616 Hubs (180mm center lock rotors).
    Thanks for the feedback!

  2. #2
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    You just need longer bolts and some 3 - 5mm spacers. I used presta nuts, you need to remove a tiny bit of thread so they slip over the bolts.

    Fatback Rearhub by bdroit, on Flickr

    Quote Originally Posted by Bacons View Post
    I am running into an issue with my latest build. My 135mm front hub is rear-spaced. My new fork (Salsa Beargrease aluminum) IS mount is for front spaced hubs. Does anyone make an adapter that will push my caliper out? I am running 616 Hubs (180mm center lock rotors).
    Thanks for the feedback!
    Lucky neighbor of Maryland's Patapsco Valley State Park, 39.23,-76.76 Flickr

  3. #3
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    Actually, I need to go in the opposite direction... The caliper is too far inward, I need to move it about 5mm outwards.

  4. #4
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    Remove the inside washers and slot the caliper bolt holes with a small rat tail file.

  5. #5
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    My apologizes, I did not connect all of the facts. The Beargrease fork is rear spaced and the Bearpaw is front disc spaced. Front disc spacing places the rotor closer to the fork. The example I showed is a rear disc spaced hub in a front disc spaced fork. White Brothers makes the only adaptor I am aware of that will move the caliper out. The unfortunate thing is that it is designed for post mount.
    Lucky neighbor of Maryland's Patapsco Valley State Park, 39.23,-76.76 Flickr

  6. #6
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    I would think the rotor would hit the mount. Usually there's only 4 or 5mm between the adaptor and the rotor. if you move the adaptor out, but there's still the IS mount, wouldn't there be problems?

  7. #7
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    Quote Originally Posted by PretendGentleman View Post
    I would think the rotor would hit the mount. Usually there's only 4 or 5mm between the adaptor and the rotor. if you move the adaptor out, but there's still the IS mount, wouldn't there be problems?
    No the I.S. mount is on the outside of the adapter, It works there has been a few people on here over the last few years that have done this same thing. I do think some adapters will work better than others due to the bolt placements.

  8. #8
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    Space the rotor out using a 5mm shim. That's what you do with carver forks and rear hubs. Carver do a kit with the shim and longer rotor bolts.

  9. #9
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    Here is exactly what I am looking for. Yes, I can reproduce this, but I don't really have the tooling to do so. I was hoping someone made these out-of-box.

  10. #10
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    I haven't seen adapters like that before, but I would think that some careful use of a drill, hacksaw, or dremel would get pretty close.

    Where are you located? Maybe there is a member by you with the appropriate tools that would help you out?

  11. #11
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    Quote Originally Posted by Bacons View Post
    Here is exactly what I am looking for. Yes, I can reproduce this, but I don't really have the tooling to do so. I was hoping someone made these out-of-box.
    You would depend on that to slow you down? I would rather buy a new fork or hub.

  12. #12
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    I've used it for two years, and braking has been very reliable, strong. I'm not plummeting on a Rockies downhill. Central Ohio mountains are called hills here.
    Nonetheless, I would like to see a mass marketed adapter at 5mm thickness to push the caliper outward.

  13. #13
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    If someone would make that adapter out of TI it would be plenty strong even for DH use.

  14. #14
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    Quote Originally Posted by blown240 View Post
    If someone would make that adapter out of TI it would be plenty strong even for DH use.
    Except if it's made with sharp edges.
    "It's only when you stand over it, you know, when you physically stand over the bike, that then you say 'hey, I don't have much stand over height', you know"-T. Ellsworth

    You're turning black metallic.

  15. #15
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    Quote Originally Posted by Bacons View Post
    Here is exactly what I am looking for. Yes, I can reproduce this, but I don't really have the tooling to do so. I was hoping someone made these out-of-box.
    With your hub/fork combination choice, this is pretty much your only option. Several people here (myself included) are using similarly-modified pieces with no negative results.

    With the center-lock hub, the only other option I can think of would be to go with a different fork.

  16. #16
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    The modified adapter looks like the only way to go, unless you are willing to change the hub or fork.

    It does involve removing a lot of material - more than I'd necessarily care to lose - but is not quite a suicide-rig either.

    If it was my bike, I'd get a front-spaced hub.

  17. #17
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    I had trouble wrapping my head around this issue, wondering how on earth you could run into this problem with a rear-spaced hub.

    To my knowledge FDS is 10 mm from locknut to rotor attachment, while RDS is 15 mm. This allows the left flange to be moved to the left for a greater bracing angle - laterally stiffer wheel.

    So the difficult combination would be rear-spaced fork and front-spaced hub. (Impossible to push the rotor inwards, so you have to butcher the adapter to move the caliper out.)

    With a front-spaced fork and rear-spaced hub all should be fine with a 5 mm adapter between the rotor and hub.

    By the looks of it, 616 front hubs are front spaced, not rear!

    Using Rear spaced front hubs on a fork made for front spaced hubs...IS adapter ?-img_0217.jpg

  18. #18
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    Quote Originally Posted by Saul Lumikko View Post
    I had trouble wrapping my head around this issue, wondering how on earth you could run into this problem with a rear-spaced hub.

    To my knowledge FDS is 10 mm from locknut to rotor attachment, while RDS is 15 mm. This allows the left flange to be moved to the left for a greater bracing angle - laterally stiffer wheel.

    So the difficult combination would be rear-spaced fork and front-spaced hub. (Impossible to push the rotor inwards, so you have to butcher the adapter to move the caliper out.)

    With a front-spaced fork and rear-spaced hub all should be fine with a 5 mm adapter between the rotor and hub.

    By the looks of it, 616 front hubs are front spaced, not rear!

    Click image for larger version. 

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    I don't see anywhere on 616's web site where they specify what disc spacing their front hubs are. But, the fact that they use center-lock rotors makes re-spacing the rotor much more difficult. All adaptation has to be done at the caliper.

  19. #19
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    The spacing difference in the image I posted looks obvious to me, despite the front hub being in front. The problem Bacons ran into (rotor too outboard for the caliper on a RDS fork) would strongly suggest this as well.

    Re-spacing centerlock rotors is a futile effort, I agree with that. With a rear-spaced hub and front-spaced fork you need to move the caliper in (if centerlock) or shim the rotor out (if 6-bolt).

  20. #20
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    Saul, thanks for the posts. I've got my wires crossed here. I am, in fact, running a Rear spaced fork (Aluminum Beargrease) with a front-spaced hub. I am running that modified adapter with no issues. Sure, not ideal, but I love that Beargrease fork (stiffness, compliance and weight).
    I'd still like to see a commercially available IS adapter that was allowed you to move the caliper out by 5mm.

  21. #21
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    To gain the status of being commercially offered, the product should have demand and it must not be a liability to the manufacturer. An adapter that moves the caliper outboard by 5 mm doesn't have a large demand and the long-term durability and resistance against dumb users is a question mark.

    For this reason modification of existing adapters when needed is pretty much the only solution, but thankfully it is also a good one: you have the adapter and it's working fine. I don't think your bike would be any better if the adapter was a commercial one, as long as the modification was done neatly. If it isn't neat, you can buy another adapter and make a better modification (or have one made).

    I think custom parts like this have a special appeal to them. Like the chainring on my Moonlander: 58 BDC 33t stainless steel custom fabrication that doubles as a spider. I think a handful people in the world need one, it wasn't offered by anyone so I designed it and had it made.

  22. #22
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    Bacons- If you love the Beargrease fork, why not replace it with the Bearpaw fork? I realize the Bearpaw is 483mm A to C, instead of the 468 like the Beargrease, but it is front rotor spaced and would work with your hub.
    "I ride to clear my head, my head is clearer when I'm riding SS. Therefore, I choose to ride SS."~ Fullrange Drew

  23. #23
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    Nitrousjunky... the reason I cant swap is Ventana did a glorious job in matching the fork to the El Gordo goodness...

    Yes, I put the 616 hubbed wheels on my Mukluk... these are Salsa 2 hubs (yep, front if front spaced).
    Another nice by-product of the fork is it's less weight than the Bearpaw.

  24. #24
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    I tried that but it was over a half pound heavier. In it's defense it does have more clearance.
    Quote Originally Posted by nitrousjunky View Post
    Bacons- If you love the Beargrease fork, why not replace it with the Bearpaw fork? I realize the Bearpaw is 483mm A to C, instead of the 468 like the Beargrease, but it is front rotor spaced and would work with your hub.
    Lucky neighbor of Maryland's Patapsco Valley State Park, 39.23,-76.76 Flickr

  25. #25
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    Nice looking bike.

    Quote Originally Posted by Bacons View Post
    Nitrousjunky... the reason I cant swap is Ventana did a glorious job in matching the fork to the El Gordo goodness...

    Yes, I put the 616 hubbed wheels on my Mukluk... these are Salsa 2 hubs (yep, front if front spaced).
    Another nice by-product of the fork is it's less weight than the Bearpaw.
    Lucky neighbor of Maryland's Patapsco Valley State Park, 39.23,-76.76 Flickr

  26. #26
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    Gracias, Shoo.
    Since the pic was taken I mounted up the Bud/Lou on the Marge Lites. I get ample clearance on the Beargrease fork.

  27. #27
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    In case anyone is wondering about this, I just finished building up a new tubeless wheel set for my 2013 Beargrease using 616 hubs on Velocity Dually rims. Had the same problem with the front spaced hub on the rear spaced Beargrease fork. A friend of mine used a drill press with a flat bit to drill down the mounts by about 2mm. After a little adjustment wheel mounted right up! So happy, as I was thinking a new fork (or sale of the wheel set) would be necessary. Here is a pic of the finished bracket:

    Using Rear spaced front hubs on a fork made for front spaced hubs...IS adapter ?-caliper-bracket.jpeg

  28. #28
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    Quote Originally Posted by Optimus View Post
    Hell of a jump, dawg. Even though they're baggy shorts, I'm surprised that you can fit your balls into them.

  29. #29
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    dirt dawg shoots and misses.

  30. #30
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    Quote Originally Posted by Saul Lumikko View Post
    I had trouble wrapping my head around this issue, wondering how on earth you could run into this problem with a rear-spaced hub.

    To my knowledge FDS is 10 mm from locknut to rotor attachment, while RDS is 15 mm. This allows the left flange to be moved to the left for a greater bracing angle - laterally stiffer wheel.

    So the difficult combination would be rear-spaced fork and front-spaced hub. (Impossible to push the rotor inwards, so you have to butcher the adapter to move the caliper out.)

    With a front-spaced fork and rear-spaced hub all should be fine with a 5 mm adapter between the rotor and hub.

    By the looks of it, 616 front hubs are front spaced, not rear!

    Click image for larger version. 

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    Saul, thanks for the info. Still learning the finer details of bike engineering! Was looking at a fork but decided I better see what this front - rear spacing spec was about. Glad I did since the carbon fork would have been neither useable nor a good paperweight!

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