80mm 29er fork as 650b?

[zarr]

I've read a lot about converting a 26er fork to 650b,but what about this app?
I have one sitting around and wondered how it would work.
Any thoughts?

[shiggy]

I've read a lot about converting a 26er fork to 650b,but what about this app?
I have one sitting around and wondered how it would work.
Any thoughts?

Check the axle to crown race length. The 29" fork will be ~35mm longer than a similar 26" fork. Add another 12mm of height for the 650B tire and you could be raising the front end by 47mm. That would slacken the frame angles by almost 3 degrees.

[talabardio]

You could put an 80mm 29er fork on a 650b bike that uses a 100mm fork, and things will be fine.

[DeeEight]

Given the growing availability of 650B forks, the only thing I'd put into a 29er fork is a 29er wheel.

[zarr]

I think I'm going to start off with a rigid fork til I get a 650b fork AND frame.
but I would like to use a rigid fork on the build with a 26er rear wheel and a 650b front wheel.
I have a 457mm fork (Nashbar mtg rigid fork and a 405mm fork.(crown races not installed).
...Am I right thinking the 405mm fork would be best with a 26er wheel and the 457mm fork with an alternate 650b rear wheel?

[jabrabu]

I was considering putting a 100mm 29er Terralogic fork on a Jamis Dragon, which is designed for a 120mm 650b fork. The A-C length would be nearly identical, and I love the terralogic fork on a hardtail.

[shiggy]

I think I'm going to start off with a rigid fork til I get a 650b fork AND frame.
but I would like to use a rigid fork on the build with a 26er rear wheel and a 650b front wheel.
I have a 457mm fork (Nashbar mtg rigid fork and a 405mm fork.(crown races not installed).
...Am I right thinking the 405mm fork would be best with a 26er wheel and the 457mm fork with an alternate 650b rear wheel?

No. With a B front and 26 rear a 440 A-C fork would be right. A 405 fork will steepen the frame angles by ~2 degrees.

[zarr]

No. With a B front and 26 rear a 440 A-C fork would be right. A 405 fork will steepen the frame angles by ~2 degrees.

Thanks Shiggy.
What if I used a zero stack headset frame with the 457mm fork, used a inferno27 rim and a V-rub Trail Taker tire. Doesn't the Trail Taker have a low profile?

[shiggy]

Thanks Shiggy.
What if I used a zero stack headset frame with the 457mm fork, used a inferno27 rim and a V-rub Trail Taker tire. Doesn't the Trail Taker have a low profile?

I can not run all of the geometry numbers for you. You need to know what the frame specs are and all of the other variables and figure it out for yourself.

[bbense]

FWIW, I'm using a 100mm 29'r fork on my 26' Anthem X with a 650b wheel. It does slacken the geometry a noticeable amount, but overall I'm pretty happy with that. I would say try it, but be prepared to accept the changes in handling.

There are also some fairly drastic changes in position on the bike that go along with the changes in geometry. ( Seat needs to go forward and bars need to drop quite a bit to keep anything like the "old" position, likely need a shorter stem as well ). I think unless the bike starts out with relatively steep XC angles ( 71 on my bike ), it might be too much of a compromise.

I did it because I got a decent fork relatively cheap. Also, there aren't many XC weight 650B forks out there, at least not at $350. What I want is an XC weight bike with more all mountain geometry. Plus I just enjoy tinkering with stuff...