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Discussion Starter · #1 ·
I can feel some flex in the rear of my bike when turning hard or putting the power down. I can hear a bbbrraaaattttt bbrraaatttttt of the rear wheel hitting the chain stay and can see the evidence of the tire rubbing. How can you tell if it is the wheel set or the frame. I ride a Kona kikapu and have mavic crossland wheels. I am also a clyde pushing about 225 geared up. Since I have become aware of the flex it is driving me crazy.

Thanks for the help.
 

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Bike to the Bone...
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rekibtm said:
I can feel some flex in the rear of my bike when turning hard or putting the power down. I can hear a bbbrraaaattttt bbrraaatttttt of the rear wheel hitting the chain stay and can see the evidence of the tire rubbing. How can you tell if it is the wheel set or the frame. I ride a Kona kikapu and have mavic crossland wheels. I am also a clyde pushing about 225 geared up. Since I have become aware of the flex it is driving me crazy.

Thanks for the help.
Oh.. I'm 230, and had the Crosslands on a Titus, and they flexed a lot. I tested the same bike with another wheelset with 32 spokes, Mavic 819 rims and XT hubs and the new wheelset made the bike felt like it was a different bike.

I don't know how flexy or stiff the Kona is, but the Crosslands aren't clyde-worthy, at least in my experience.
 

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Discussion Starter · #3 ·
The Kona seems to be super solid every where else, that is why I am trying to figure out what the culprit is. If a new wheel set will make my bike feel super solid I would be stoked. Much easier to get a new wheel set than a new frame.

The crosslands have stayed relatively true for a solid 2 years of hammering on them. A wheel can stay true yet have a lot of flex?
 

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rekibtm said:
The Kona seems to be super solid every where else, that is why I am trying to figure out what the culprit is. If a new wheel set will make my bike feel super solid I would be stoked. Much easier to get a new wheel set than a new frame.

The crosslands have stayed relatively true for a solid 2 years of hammering on them. A wheel can stay true yet have a lot of flex?
When I tested the wheels on my trackstand, using the eye-o-meter, they seemed true, but I did feel a lot of flex on the trails. Actually, I thought that the bike was flexy, didn't really thought on the wheels.

I was building another bike, and got the wheels earlier than the rest, and just wanted to try them. After the first ride on the new wheelset, I decided to sell the Crosslands. Actually, I sold the Crosslands and ordered a newer wheelset for my ML and kept the XT/819 on the bike they were intended for.
 

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The crosslands have stayed relatively true for a solid 2 years of hammering on them. A wheel can stay true yet have a lot of flex?
Yes, because when any object is flexing, it returns to "normal" after the opposing forces have stopped. Any material will flex but not necessarily bend permanently. I think the phrase I'm looking for is "fatigue strength". As long as you don't go beyond that point, the material will return to normal. Just like most products, cheaper ones are designed with certain compromises. When it comes to wheels, flex can be one of those compromises. I'm sure if you got a more stout wheelset, you would feel less flex but a certain portion of what you're feeling is also coming from the frame. Can't really tell you what part is responsible for what portion of the flex but if you can try out a "higher" grade wheelset and see how much better (or worse) it is.
 

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this is the test, works for forks don't see why it would not work on a frame.

Apply pressure perpendicular to the wheel with it in contact with the ground, that is parallel to the axle, and watch the wheel in reference to the seat stays. If the wheel moves towards the seatstay on the side of applied pressure then the frame is flexing. If it moved towards the side opposite the side you applied pressure the wheel is flexing.

A strong wheel will resist the flex and will stay parallel to the frame thus the frame is flexing. A weak wheel will deflect with the pressure and since one part is stuck to the ground the opposing side will flex in the direction of the pressure.

This also works with forks to see if your fork or wheel is the flexy culprit.

Be warned that you need to put some good pressure on this and it is only somewhat accurate. Swapping wheels to a known stiff wheel set is just as good and more fun in the end really --> you get to ride your bike.
 

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Discussion Starter · #8 ·
Yes I have riden i tpretty hard for a while bike a year and a half and the wheels over two years. I have had the spoke tension checked. I brought it in to see if I had a loose spoke causing the problem. I couldn't feel them being loose and the wrench said that they were all fine. I have checked and tightened my pivot bolts as well. no problems there either.
 
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