Fox 40 29er fork compatible with a 27 wheel?

mad mike
Posts
15
Joined
11/21/2020
Location
Onsted, MI, USA

I have a chance to upgrade the fork on my 27" wheel DH bike to a Fox 40 that came off of a 29er. Does anyone know if this would work or what problems I may have in using it? I assume the lower legs are longer for a 29er?

Thanks in advance

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fleein_ian
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7
Joined
11/8/2022
Location
Fairfax, VT, USA
1/23/2023 7:18am

I would jump on it if it's in good condition. If I'm not mistaken you could drop the clamps down on the stanchions to compensate for the increase stack height? Can't do that on a single crown, of course. 29 and 27.5 axles/rotors should be interchangeable provided they're both 15x110. 

1
1/23/2023 11:53am

What axles and rotors? They are forks, not hubs.
DH forks these days are 20 x 110 mm Boost, all of them.

Mx

mad mike
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15
Joined
11/21/2020
Location
Onsted, MI, USA
1/23/2023 1:33pm

Thanks for the replies. I wasn't very clear in my question. These are dual crown Fox 40's and I wasn't sure if the 29er forks are alot longer than 27.5 forks. I am guessing that the lowers are but didn't know if the internals were different. I didn't want to "chopper" the bike. 

1
JVP
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234
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4/20/2016
Location
Bellingham, WA, USA
1/23/2023 3:21pm

Pop the numbers into here: https://calculator.bike/geometry_calculator.html

Only thing that changes are the axle-to-crown and maybe offset, which you can look up easily an plug into the calc.

1
mcozzy
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7/14/2021
Location
GB
1/24/2023 2:12am

Yes of course they have longer lowers to accommodate the larger wheel, approx 20mm. No you cant raise the stanchions as the seals would hit the crowns.

Additionally the offset would likely be larger on a 29 fork.  Whether you would notice a difference is debatable. 

Personally I would get the 29" to allow myself to mullet in the future. 

Edthorne
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4/17/2020
Location
CA
1/24/2023 7:05am
mcozzy wrote:
Yes of course they have longer lowers to accommodate the larger wheel, approx 20mm. No you cant raise the stanchions as the seals would hit the...

Yes of course they have longer lowers to accommodate the larger wheel, approx 20mm. No you cant raise the stanchions as the seals would hit the crowns.

Additionally the offset would likely be larger on a 29 fork.  Whether you would notice a difference is debatable. 

Personally I would get the 29" to allow myself to mullet in the future. 

You can raise the stanchions in the crowns to an extent, just likely not enough to fully make up for the longer axle to crown and increased wheel diameter. I believe Fox specifies about 20mm of adjustment, though it would be smart to release the air from the fork and make sure your lower crown won't hit the lowers when making any adjustments. 

2

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