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Discussion Starter · #1 ·
on the stand and on flat road (low loading) riding in the lowest gear is perfect but when climbing (high loading) my rear dérailleur hanger is hitting the spokes. i believe that my limit setting for the rear dérailleur is correct thus my guess is that the spokes are bending.

are these correct assumptions? what is the fix? is it to add more tension on the spokes?

tia
 

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A wheelist
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SAIG said:
......when climbing (high loading) my rear dérailleur hanger is hitting the spokes. i believe that my limit setting for the rear dérailleur is correct thus my guess is that the spokes are bending.
are these correct assumptions? what is the fix? is it to add more tension on the spokes?
Good questions! If you look at the final spoke crossing of the drive side of your rear wheel you'll probably find that the "pulling" spokes (backwards radiating ones) are laced inside the non-pullers. So when you apply torque, the pulling spokes tend to straighten (they take a slight bend as they pass the other spoke) and they pull the spoke cross towards the derailer cage. The fix for this is, of course, to re-spoke the rear wheel drive side with the pullers "heads out" (and non pullers "heads in") which will place them on the outside of the cross and pull the cross away from the derailer.

You mention spoke tension. Of course the looser the spokes the more likely this is to happen and the more likely that wheel flex will be making the problem worse.

You also mention the rear derailer adjustment. It could still be set a bit too far in and here's the test - shift into the big rear sprocket. With your fingertips of the left hand hooked behind the top of the derailer, push the lower derailer pivot inwards with your thumbs with all your might while turning the cranks. If the chain derails over the top of the cog or even tries to, the derailer stop needs tightening to restrict its movement.
 

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Discussion Starter · #3 ·
mike,

thanks for the response. i'll try looking at the rear dérailleur adjustment as you mentioned tonight.

"Good questions! If you look at the final spoke crossing of the drive side of your rear wheel you'll probably find that the "pulling" spokes (backwards radiating ones) are laced inside the non-pullers. So when you apply torque, the pulling spokes tend to straighten (they take a slight bend as they pass the other spoke) and they pull the spoke cross towards the derailer cage. The fix for this is, of course, to re-spoke the rear wheel drive side with the pullers "heads out" (and non pullers "heads in") which will place them on the outside of the cross and pull the cross away from the derailer."

even though i built the wheel myself the above answer is flying above my head. i built the wheel following the late great sheldon brown's website. knowing this, does my wheel have the pullers "heads out" or the wrong way?

tia
 

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A wheelist
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SAIG said:
even though i built the wheel myself the above answer is flying above my head. i built the wheel following the late great sheldon brown's website. knowing this, does my wheel have the pullers "heads out" or the wrong way?
Even though I link Sheldon's site from my wheelbuilding info I don't remember how he tells to build them and I'm too lazy to go look. Lots of wheelbuilders consciously build with the "pullers" on the inside of the final cross for their own reasons (their reason is that it makes the elbows of the pullers not vulnerable to chains derailed over the cassette). So there is no wrong or right way. The fact is that the pullers laced heads-out (meaning: heads facing out in the hub flange) will tend to pull the final spoke cross away from the derailer a very slight amount. Some builders want to pull this cross away and others want to safeguard the puller elbows. Ya can't have both. Me, I'd rather adjust my derailer to the n'th degree (details in my 1st post!) so the chain won't go over the top. Either one is fine, nit-picky stuff.

If all this is over your head then with it in mind, take a long & good look at the drive side of your rear wheel. The spokes that transmit drive from cog to rim radiate backwards. These are the pulling spokes in question. See whether they're inside or outside the final spoke cross. If they're outside, then when you apply torque, as they try to straighten, they will pull the final cross (and both spokes) towards the center plane of the wheel and away from the derailer cage.
 

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Not to try and point out the obvious...but is your derailluer hanger aligned properly?

Even a slight misalignment could be enough to cause your derailluer to contact you spokes under load.

BTW-I've build a many wheels (former mechanic) and I prefer the pulling spokes heads in...this has never caused any of my bikes (or customer bikes) rear derailluers to contact the spokes.
 
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