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  1. #1
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    Fork length when going from 29 to 27.5

    Hey there everyone!

    Recently won an auction for a 2017 Trek Fuel EX 8 29er frame and shock. Lacks a fork. I want to run 27.5 wheels and tires on my bike, as I dig that size based on another bike I've ridden and enjoyed.

    The trek Fuel EX 8 29er came with a 130mm fork on it. If I get a 130mm 27.5 fork, will the fork itself be shorter? Should I seek a longer travel 140mm travel fork setup for 27.5, or just get a 130mm 29er fork?

    Love some input on this. Since I can't get overall length of forks specs anywhere, I'm stumped. I have tried googling various combinations of this question to no avail... and so I'm here!

  2. #2
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    If you look at the specs on other bikes that are 29er and 650b options the 650b always comes with a larger travel front fork.
    It doesn't matter what I ride as long as I ride it Rubber Side Down●~●.

  3. #3
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    Do you want 27.5 or 27.5+? You wouldn't want to run 27.5 wheels on that bike. The BB will be too low, and you'll mess up the geometry trying to correct that. If you ran 27.5+, then you'd use a 29er/27.5+ fork.

  4. #4
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    Quote Originally Posted by acedeuce802 View Post
    Do you want 27.5 or 27.5+? You wouldn't want to run 27.5 wheels on that bike. The BB will be too low, and you'll mess up the geometry trying to correct that. If you ran 27.5+, then you'd use a 29er/27.5+ fork.
    Sounds right to me.

  5. #5
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    Quote Originally Posted by acedeuce802 View Post
    Do you want 27.5 or 27.5+? You wouldn't want to run 27.5 wheels on that bike. The BB will be too low, and you'll mess up the geometry trying to correct that. If you ran 27.5+, then you'd use a 29er/27.5+ fork.
    Going 27.5+ is on my radar.

    I do have some 27.5" wheels I got for a screaming price off CL. I can run 27.5x2.6" tires on there and that isn't quite "plus" but it's a mid-wide option that may make it so the bike is only dropped a little bit.

    I can also find better forks for less money in 27.5 140mm travel. I can get Rockshox Pike's for $500 in 27.5 140 non-boost (I think these wheels are non boost, need to go measure) while 29" 130mm pike's are $800~.

    I've had the pikes before on a nice bike I owned briefly for a bit (forced to sell to cover some other life expense) and they were the most confidence inspiring forks I've ever ridden.

  6. #6
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    Is that bike 27+ compatible? some 29ers have a flip chip or some other way of correcting the geo btw 29 and 27+, or you get a really low BB.

    If you really want to run regular 27.5 wheels, then sell the frame and get what you want with the $.

  7. #7
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    Quote Originally Posted by d365 View Post
    Is that bike 27+ compatible? some 29ers have a flip chip or some other way of correcting the geo btw 29 and 27+, or you get a really low BB.

    If you really want to run regular 27.5 wheels, then sell the frame and get what you want with the $.
    Oh I've got all the standard excuses. Mostly I just got a screaming deal on the frameset and shock. You normally can't even get the shock for the price I paid on the frameset. I've got the bike build all documented out in a spreadsheet. I'm looking at about $1800 to build it out and the equivelant bikes are retailing for $3500 or so dollars, so this fits my budget nicely.

    Anyways, not sure the 2017 Trek Fuel EX 8 can flip to handle the difference.

  8. #8
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    Better look into 165mm cranks.....

  9. #9
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    Fuel EX 27.5+ has 2.8" tyres, a 140mm 29er fork and the Mino Link flip chip at the high position. With a 27.5 fork you probably would need to go up to 160mm to get a similar axle to crown length.

  10. #10
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    Manitou mattoc pro 2 2017 is imo better than a pike or fox 34 factory. You can get it off of chain reaction for $420 right now on clearance and set it to 140mm of travel which will still be great on that bike, you may even be able to get cr to set it before they ship it. These bikes are designed so you can easily get on and off of them while keeping the crankset just high enough to pedal over everything. A 140 fork with a 27.5 2.6 in the front or a 150 fork with a 2.3 should be close to a 29er 2.3 front. You will want to run a 27.5+ or 29er in the rear minimum. I would just get the mattoc and a set of wheels. Your better off just having great performing suspension and geometry than throwing off geometry trying to shave half a pound.

  11. #11
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    There's quite a difference between a 2.6 and a 2.8 or 3.0 tire. It's not enough to make up for lowered BB, even with 165mm cranks. The bike won't ride well. I'd run a 140mm or 150mm 29er/+ fork with 27.5+ tires....or 130mm with a 29er wheelset. I'm all for alternative builds but running standard 27.5 on that frame will only give disappointing ride characteristics. If you want a true 27.5 bike, build this one up and sell it before it hits the dirt.
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  12. #12
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    Some things just look better on paper. Either keep the 27.5 wheels for another build or sell and use the right ones. A great bike that rides like an average bike (or worse) is no bargain.

  13. #13
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    So I actually already built this bike. Went with 140mm boosted pike forks, WTB Asym rims with 35mm internal width and WTB Trailboss 27.5x3.0 tires. The overall wheel height when compared to 29x2.3" isn't all that much different either, maybe a 1/4" less height on the wheel, translating to 1/8" at the bottom bracket.

    I really love the bike, and enjoy the build.

    I'm building a more "OEM" correct 2014 Trek Fuel EX 9.8 carbon fiber frame out to run the legitimate 29" wheels it was meant for.

  14. #14
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    So did you also calculate the extra inch the bigger tires will compress when actually riding? I hope it works better than I think.

  15. #15
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    I'm actually running relatively high pressures and really happy with it. 24~ psi, feels great downhill, uphill, all around. Not getting as much squish as you might think!

  16. #16
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    24 psi? I'd think your 3.0 tires would be very bouncy!
    Did you find a deal on the Pike shock?

  17. #17
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    You'd think... but nah it feels great and planted! Climbs great to. Granted... I am a heavier dude at 230lbs.

    I was able to get a Rockshox Pike with boost in 140mm travel for $400 in pretty good shape. Seemed to be a pretty solid deal from all the other sales I see going on with Ebay and what not.

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