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How do I figure out what's flexing. Flos or bike?
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During a Sprint today I kept hearing my rear brake rub on my wheels while climbing. The bike is a NP3 with a set of flo 90 carbon aluminum wheels. Wheels are very true and all the spokes feel tight. I also have quite a bit of room Between the Wheels and the brakes and it still touches when I'm out of the saddle. Please help!
Last edited by: Fishbum: Aug 6, 17 9:11
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Re: How do I figure out what's flexing. Flos or bike? [Fishbum] [ In reply to ]
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Flip the brake release lever up and the rubbing will go away.
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Re: How do I figure out what's flexing. Flos or bike? [jimatbeyond] [ In reply to ]
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jimatbeyond wrote:
Flip the brake release lever up and the rubbing will go away.


Still rubbing. Brake is so open it hardly stop's with brake lever fully compressed.
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Re: How do I figure out what's flexing. Flos or bike? [Fishbum] [ In reply to ]
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The wheel probably isn't fully seated in the dropouts.
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Re: How do I figure out what's flexing. Flos or bike? [jimatbeyond] [ In reply to ]
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jimatbeyond wrote:
The wheel probably isn't fully seated in the dropouts.


Horizontal drop out. Fully seated
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Re: How do I figure out what's flexing. Flos or bike? [Fishbum] [ In reply to ]
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Have you inspected the frame for cracks?
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Re: How do I figure out what's flexing. Flos or bike? [jimatbeyond] [ In reply to ]
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jimatbeyond wrote:
Have you inspected the frame for cracks?


No😐. Would it stick out on the paint job or are they tough to spot?
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Re: How do I figure out what's flexing. Flos or bike? [Fishbum] [ In reply to ]
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Here's a great article that explains stiffness: http://www.slowtwitch.com/..._Stiffness_3449.html

Maybe your spoke tension is low. Or, it could be a problem with the frame. You have a perfect storm with wide carbon wheels and the brake on the seat stay.
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Re: How do I figure out what's flexing. Flos or bike? [exxxviii] [ In reply to ]
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So now I'm thinking my p3 is flexing or it's in the HUD.
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Re: How do I figure out what's flexing. Flos or bike? [Fishbum] [ In reply to ]
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Fishbum wrote:
jimatbeyond wrote:
Have you inspected the frame for cracks?


No😐. Would it stick out on the paint job or are they tough to spot?


The paint would show it.
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Re: How do I figure out what's flexing. Flos or bike? [jimatbeyond] [ In reply to ]
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jimatbeyond wrote:
Fishbum wrote:
jimatbeyond wrote:
Have you inspected the frame for cracks?


No😐. Would it stick out on the paint job or are they tough to spot?


The paint would show it.

Inspected frame. No cracks. I'm bummed it could be flexing this much. Very annoyed.
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Re: How do I figure out what's flexing. Flos or bike? [Fishbum] [ In reply to ]
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Fishbum wrote:
jimatbeyond wrote:
The wheel probably isn't fully seated in the dropouts.


Horizontal drop out. Fully seated


Could the set screws in the drop outside be uneven. ? Even when they're adjusted to the same depth?
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Re: How do I figure out what's flexing. Flos or bike? [Fishbum] [ In reply to ]
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I'd get on a different bike and satisfy myself that doesn't rub in the same conditions. Then try the Flo in that bike and that back wheel in the NP3.
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Re: How do I figure out what's flexing. Flos or bike? [Fishbum] [ In reply to ]
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Wheels are stiff, frames are not.
Sometimes axles are flexy but that usually shows just by putting a heavy rider on the frame you will see the top of the wheel move towards the driveside at the seatstay.
Frames flex more laterally down at the BB under power so much more likely to get rubbing problems at a BB mounted brake.

Many frames rub brakes under sprint power, normally with alloy rims you simply don't hear it.
Because Carbon pads are generally very sticky and tend to make chirping or squealing noises when they touch you notice it and therefore conclude that it is the wheels at fault because you never heard it with your alloy rims.

So get a heavy guy to sit on your bike, if the wheel moves sideways at the top when he does, your wheel is the problem and you could do with looking for something with a better designed hubb with a larger diametre axle.
If it doesn't. it's your frame and more than likely this is what it will be.

Most times it will rub on the left downstroke before the right due to the chain trying to shorten things up on the right side.
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Re: How do I figure out what's flexing. Flos or bike? [Fishbum] [ In reply to ]
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Fishbum wrote:
During a Sprint today I kept hearing my rear brake rub on my wheels while climbing. The bike is a NP3 with a set of flo 90 carbon aluminum wheels. Wheels are very true and all the spokes feel tight. I also have quite a bit of room Between the Wheels and the brakes and it still touches when I'm out of the saddle. Please help!
I would put my money on the Flo wheels. I have an older P2 and with my training wheels (low alu rim, lots of spokes, made by wheelbuilder.com) I can put the brakes really close to the rim and I'll experience zero rub. Also, when I grab the wheel by the rim and try to pull it towards a brake pad there is absolutely zero movement of frame nor the wheel itself.

When I put a flo wheel in (the version with extra spokes) there is tons of flex and I always need really open my brake pads by a lot (so much I actually need to adjust the brake cable). Otherwise when I ride where will be serious rubbing whenever I stand up. When I grab the rim and pull it towards the brake pads the wheel moves/bends a lot (without the frame moving).

For that reason I'm not too excited about Flo wheels. Price is great and they've stayed true and have been free of any real issues, but the flex in the wheels is way too much. I've mentioned it here before and the Flo guys didn't really seem to believe me yet I'm sure it's the wheel that is flexing.
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Re: How do I figure out what's flexing. Flos or bike? [Benv] [ In reply to ]
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Benv wrote:
. I've mentioned it here before and the Flo guys didn't really seem to believe me yet I'm sure it's the wheel that is flexing.

I don't believe you either. :)

Unless the spoke tension or hubs are seriously jacked up, I find it hard to believe it's the wheels.
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Re: How do I figure out what's flexing. Flos or bike? [trail] [ In reply to ]
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trail wrote:
Benv wrote:
. I've mentioned it here before and the Flo guys didn't really seem to believe me yet I'm sure it's the wheel that is flexing.


I don't believe you either. :)

Unless the spoke tension or hubs are seriously jacked up, I find it hard to believe it's the wheels.
Suggest an experiment or test I can do at home so I can compare both wheels. Or, as a minimum, explain to me why some wheels do not move / bend in my frame when the flo wheel does.

I'll also add that riding my training wheels is a much harsher ride - the wheels absorb a lot less vibration than the flo wheels do. Which again points to compliance. But happy to do an quantifiable test if you will suggest one.
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Re: How do I figure out what's flexing. Flos or bike? [Benv] [ In reply to ]
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Benv wrote:
trail wrote:
Benv wrote:
. I've mentioned it here before and the Flo guys didn't really seem to believe me yet I'm sure it's the wheel that is flexing.


I don't believe you either. :)

Unless the spoke tension or hubs are seriously jacked up, I find it hard to believe it's the wheels.
Suggest an experiment or test I can do at home so I can compare both wheels. Or, as a minimum, explain to me why some wheels do not move / bend in my frame when the flo wheel does.

I'll also add that riding my training wheels is a much harsher ride - the wheels absorb a lot less vibration than the flo wheels do. Which again points to compliance. But happy to do an quantifiable test if you will suggest one.

I'm having a hard time thinking of a good test. I'm just going off my personal experience as a bike racer with 3 pairs of Flos. I like my brake pads set really tight to the rim. And as a road racer, I'm not the most powerful dude in the world, but I frequently get over 1100W or so. And I just never have an issue with brakes rubbing or any other sign of flex. Similar to Zipp and HED wheelsets I have (I'm a wheel whore).

I did admit it could be a manufacturing or assembly error. I just have a hard time believing it's a general characteristic of Flos.
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Re: How do I figure out what's flexing. Flos or bike? [trail] [ In reply to ]
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Obviously that could be the case, that my wheel is just one that has lower tension than it should have.
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Re: How do I figure out what's flexing. Flos or bike? [exxxviii] [ In reply to ]
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exxxviii wrote:
Here's a great article that explains stiffness: http://www.slowtwitch.com/..._Stiffness_3449.html

Maybe your spoke tension is low. Or, it could be a problem with the frame. You have a perfect storm with wide carbon wheels and the brake on the seat stay.

Ummm...unless the tension is SO low that some of the spokes go completely slack, wheel lateral stiffness is NOT a function of spoke tension.



http://bikeblather.blogspot.com/
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Re: How do I figure out what's flexing. Flos or bike? [Benv] [ In reply to ]
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Benv wrote:
Obviously that could be the case, that my wheel is just one that has lower tension than it should have.
j



Could be overly stiff causing frame to flex?
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Re: How do I figure out what's flexing. Flos or bike? [Fishbum] [ In reply to ]
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And my superstiff training wheels do not because... ???
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Re: How do I figure out what's flexing. Flos or bike? [Tom A.] [ In reply to ]
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If spoke tension is low, then wouldn't deflection on one side of a stiff rim would result in greater deflection on the other side of the rim. In general, wouldn't low spoke tension generally allow greater lateral deflection overall?
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Re: How do I figure out what's flexing. Flos or bike? [exxxviii] [ In reply to ]
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exxxviii wrote:
If spoke tension is low, then wouldn't deflection on one side of a stiff rim would result in greater deflection on the other side of the rim. In general, wouldn't low spoke tension generally allow greater lateral deflection overall?


I'm confused!
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Re: How do I figure out what's flexing. Flos or bike? [Fishbum] [ In reply to ]
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I'll ask maybe a stupid question: skewer properly tightened down?

As a poster asked above also make sure the wheel is "squared" in the dropouts, meaning both sides of the axle seated in the same spot on each dropout.

Not uncommon for a qr axle to move in horizontal dropouts a little bit under heavy (standing) effort or hard braking. Espcially if the qr isn't tight or seated evenly side to side.

Good luck!
Last edited by: talking head: Aug 6, 17 16:01
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