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Discussion Starter · #1 ·
Howdy...I own a 2008 Fisher Ferrous 29er. I love the bike. It is bone stock.

Lately, I've noticed some flex in the front end. It seems to mostly happen in turns, but does happen other times as well...over roots, rocks, etc. It is reminiscent of the flex I felt when I used to own a 2006 Salsa Dos Niner. I sold that bike because of the flex. I do not plan on selling the Ferrous...the flex is similar, but not as pronounced as with the Dos. It doesn't throw me off line, but it is surprising at times, and it makes me feel less in control than I'd prefer.

Both the Dos and the Ferrous ran/run Reba forks on the front end. The Dos ran a Reba SL. The Ferrous runs a Reba Race. Both bikes use Bontrager Race disc 29er wheels. Both bikes carry my 180 pound ass. Fork air pressures are where they should be. Tire pressures are 40psi, with tubes. Stems at 90mm. Flat, big sweep bar.

So, the question is...do you think I'm getting the flex from the fork? The wheels? Is it poor frame choice on my part?

And a follow up...what have others done to combat similar flex issues. Should I go with a heavier front wheel laced with beefy spokes? Should I go for a different quick release fork?

Thoughts? THANKS!
 

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Expert Crasher
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Probably a combination of the wheel and fork. Can you convert your current hub to accomodate the DT Swiss 9mm RWS?
 

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Powered by ice cream.
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I had a similar issue with my Zion steel frame (also 180). It is the nature of small diameter tubing to flex. Either you like it or you don't.

I personally don't mind it with a rigid fork. For suspension forks, I prefer stiffer, large diameter tubing on the front end, and this usually means an Al frame.
 

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Reviewer/Tester
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That's pretty 'normal' on a Reba, they flex a bit. Your tire pressures seem too high to me though.

You can decrease the flex in a Reba a little if you use a good QR in the front wheel, like the RWS or a Shimano XT skewer...and tighten it down hard.

The more you can tie the bottom of the legs of the fork together, the less flex you will get...up to a point.

Running lower tire pressures will allow the tire to flex more over the roots and absorb the impacts and forces that might normally flex the Reba. Rims like the Stans Flow run tubeless with Panaracer Rampages soak up a tremendous amount of shock from the trail.

I run this setup with a converted-to-coil Reba on my MCR9 and it works very well for me @ 165lb over roots and rocks.

HTH,

R.

badgermtb said:
Howdy...I own a 2008 Fisher Ferrous 29er. I love the bike. It is bone stock.

Lately, I've noticed some flex in the front end. It seems to mostly happen in turns, but does happen other times as well...over roots, rocks, etc. It is reminiscent of the flex I felt when I used to own a 2006 Salsa Dos Niner. I sold that bike because of the flex. I do not plan on selling the Ferrous...the flex is similar, but not as pronounced as with the Dos. It doesn't throw me off line, but it is surprising at times, and it makes me feel less in control than I'd prefer.

Both the Dos and the Ferrous ran/run Reba forks on the front end. The Dos ran a Reba SL. The Ferrous runs a Reba Race. Both bikes use Bontrager Race disc 29er wheels. Both bikes carry my 180 pound ass. Fork air pressures are where they should be. Tire pressures are 40psi, with tubes. Stems at 90mm. Flat, big sweep bar.

So, the question is...do you think I'm getting the flex from the fork? The wheels? Is it poor frame choice on my part?

And a follow up...what have others done to combat similar flex issues. Should I go with a heavier front wheel laced with beefy spokes? Should I go for a different quick release fork?

Thoughts? THANKS!
 

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rider
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That Bonty Race wheel is 28h right? If so, you have some flex there also. Getting your wheels tensioned to the upper end of the scale will help. Not as much as wheels with more spokes, but it should help.
 

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Harmonius Wrench
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There are some great suggestions here and I'll add one more place to look: Your stem.

That said, even after doing all the suggested modifications or parts swaps you still have a bike with a longer top and down tube that has a longer lever arm acting on it with a really short, (in most cases) head tube. This will lead to the inevitable front end twist, or what I call "torsional flex" I haven't ridden very many 29"ers that don't have this to some degree.

Your example of the 2006 Dos Niner is a perfect example of what I am talking about. It has a very pronounced front end twist that can make it feel as though the back end is going a diffrent direction than the front end. I find that this is most noticeable when your front transitions to a diffrent camber terrain than the back wheel is on.

Anyway, yeah, I know exactly what you mean and most 29"ers do this to some degree. Notable bikes that don't have much of this are the new '08 Fisher aluminum models, Lenz Lunchbox, Salsa's new Big Mama, and a few others.
 

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Discussion Starter · #9 ·
THANKS for the suggestions...

Thank you to everyone who offered their input.

I may end up going the "cheap" route and putting a steel rigid fork up front...ot trying a better skewer for now. We'll have to see what the funds allow.

Regards,
-Bill
 

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i heart singletrack
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Guitar Ted said:
There are some great suggestions here and I'll add one more place to look: Your stem.

That said, even after doing all the suggested modifications or parts swaps you still have a bike with a longer top and down tube that has a longer lever arm acting on it with a really short, (in most cases) head tube. This will lead to the inevitable front end twist, or what I call "torsional flex" I haven't ridden very many 29"ers that don't have this to some degree.

Your example of the 2006 Dos Niner is a perfect example of what I am talking about. It has a very pronounced front end twist that can make it feel as though the back end is going a diffrent direction than the front end. I find that this is most noticeable when your front transitions to a diffrent camber terrain than the back wheel is on.

Anyway, yeah, I know exactly what you mean and most 29"ers do this to some degree. Notable bikes that don't have much of this are the new '08 Fisher aluminum models, Lenz Lunchbox, Salsa's new Big Mama, and a few others.
I'd also add the latest-generation Dos Niner to this list as well. It's noticeably stiffer laterally than the previous generations.
 

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Rebas flex, period, but they do have an excellent damping unit. That Bonty wheel most likely only exacerbates matters.

The cheapest/best solution short of going to a TA fork/wheel ($$$) would be to get something like a Surly nutted-axle disc front hub laced to a WTB Dual Duty FR rim. The slight weight penalty should be more than well offset by better handling and the confidence it should instill.

 

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Stem!!!!!

badgermtb said:
Thank you to everyone who offered their input.

I may end up going the "cheap" route and putting a steel rigid fork up front...ot trying a better skewer for now. We'll have to see what the funds allow.

Regards,
-Bill
I had to troubleshoot flex on the front as well. I have the Reba and the DT sqwers and the thomson stem and everything else mentioned.

I have found that believe it or not stems tend to flex more that we think. I put back and old EA 70 welded stem (looks like a tank) one bolt and no more flex. The stem is 225g so by todays standards that is like a ton, but the extra 50g on the stem solved the problem.

Same thing on my roadbike - went from a 125g Ritchey wcs to a 180 Bontrager race and all flex gone.

I am 6'2" 177lbs......
 
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