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-   -   derailleur hitting spokes (https://www.bikeforums.net/bicycle-mechanics/909892-derailleur-hitting-spokes.html)

unterhausen 08-28-13 11:19 AM

derailleur hitting spokes
 
I have an ultegra hub from the 9 speed era and a DT swiss 700c rim. I use SRAM 9 speed cassettes. In first gear, the derailleur hits the spokes, not enough to rip it off the frame, but enough to make me worry about it. I need to check the alignment of the hangar, but it still seems like the derailleur is awfully close to the spokes. Does this sound normal? I bought the hub used, I suppose that the spacing could be off.

miamijim 08-28-13 11:28 AM

Unless someone replaced the freehub body it is what it is.

Do SRAM cassettes sit further back on the hub? Is the wheel over dished?

FBinNY 08-28-13 11:30 AM

Close is normal, close enough to touch or nearly touch isn't.

Odds favor a bent hanger, and you can probably confirm this by shifting to a gear combination where the cage is nearly vertical, then looking from behind the bike.

The cage should be vertical, and not have the bottom pointing in toward the wheel. If you're not sure, place a yardstick vertically against the wheel (tire on is fine) as a frame of reference. The cage should be parallel.

copswithguns 08-28-13 11:35 AM


Originally Posted by FBinNY (Post 16007563)
Close is normal, close enough to touch or nearly touch isn't.

Odds favor a bent hanger, and you can probably confirm this by shifting to a gear combination where the cage is nearly vertical, then looking from behind the bike.

The cage should be vertical, and not have the bottom pointing in toward the wheel. If you're not sure, place a yardstick vertically against the wheel (tire on is fine) as a frame of reference. The cage should be parallel.

Had this happen once as well. Spent a good amount of time adjusting the front derailleur and got very frustrated when it wouldn't adjust properly. Then found the culprit.

FBinNY 08-28-13 11:41 AM

Also note that if you changed the wheel, your limit settings may be off. There's some variation in the exact cassette location wheel to wheel. So it's possible that your RD is inboard more than it should be in low. This would be confirmed if you had to adjust the trim (cable tension) after changing the wheel.

Even before checking the hanger alignment, check the trim adjustment, confirming that it's restrictive enough to allow crisp shifting to low and no more. Confirm by pushing in the lower body with your hand while pedaling.

dsbrantjr 08-28-13 11:58 AM

It sounds like you have a new/different wheel. You should expect to have to make minor derailleur adjustments whenever you change a wheel, even like for like, due to manufacturing tolerances.

After ensuring that the derailleur and hanger are not bent, I would suggest following this procedure from the beginning, as if it is a new installation: http://www.parktool.com/blog/repair-...nts-derailleur

Retro Grouch 08-28-13 11:58 AM


Originally Posted by FBinNY (Post 16007563)
Odds favor a bent hanger, and you can probably confirm this by shifting to a gear combination where the cage is nearly vertical, then looking from behind the bike.

9-speed era says 10 years old (give or take). If your hanger is still straight after that much time you should buy a lottery ticket.

FBinNY 08-28-13 12:02 PM


Originally Posted by Retro Grouch (Post 16007690)
9-speed era says 10 years old (give or take). If your hanger is still straight after that much time you should buy a lottery ticket.

The hanger on both my 1967 Frejus, and 1990 Prisms are both straight after 10s of thousands of miles. What numbers should I play?

Seriously, the bent hanger is the most likely possibility, and easy enough to confirm at home.

Retro Grouch 08-28-13 12:08 PM


Originally Posted by FBinNY (Post 16007711)
What numbers should I play?

If I knew what numbers to play, I'd play them.

FBinNY 08-28-13 12:11 PM


Originally Posted by Retro Grouch (Post 16007738)
If I knew what numbers to play, I'd play them.

But you don' have an old bike with a straight hanger.

Retro Grouch 08-28-13 12:14 PM

1 Attachment(s)
http://bikeforums.net/attachment.php...hmentid=337333

Originally Posted by FBinNY (Post 16007760)
But you don' have an old bike with a straight hanger.

Pretty old. It's a '92 (or so). It's been reworked a couple of times though.

joejack951 08-28-13 12:41 PM

Check your drive side spoke tension. I had a very loose leading spoke on the drive side of a wheel that would go slack enough to contact the derailler cage under high torque. After the wheel was properly tensioned (found numerous other low tension spokes too that no doubt contributed to the problem) the noise went away. I encountered the same thing a few years later on a friend's almost new bike with Mavic wheels.

techsensei 08-28-13 12:55 PM


Originally Posted by joejack951 (Post 16007878)
Check your drive side spoke tension. I had a very loose leading spoke on the drive side of a wheel that would go slack enough to contact the derailler cage under high torque.

That's one reason why I like to build my wheels with the pulling spokes on the inside of the flange; tension pulls the drive-side spokes further away from the cage.

joejack951 08-28-13 01:02 PM


Originally Posted by techsensei (Post 16007929)
That's one reason why I like to build my wheels with the pulling spokes on the inside of the flange; tension pulls the drive-side spokes further away from the cage.

I build my wheels that way too now, per Sheldon Brown's advice. This particular wheel was a pre-built wheel that I purchased before I started desiring odd combinations of wheel components that could only be had (for a price I was willing to pay) by building the wheel myself.

unterhausen 08-28-13 01:14 PM

I forgot to mention that I replaced the freehub body, but I'm pretty sure it was identical to the old, broken one. I don't know if that's when this problem started or not.

I have a hanger alignment tool, I'll probably just check it. I'm pretty careful to keep the drive side away from anything, but I suppose it could have taken a hit.
The derailleur has been adjusted.

davidad 08-28-13 01:14 PM


Originally Posted by techsensei (Post 16007929)
That's one reason why I like to build my wheels with the pulling spokes on the inside of the flange; tension pulls the drive-side spokes further away from the cage.

Mavic says the out board running pulling spokes make for a stronger wheel.

davidad 08-28-13 01:15 PM


Originally Posted by unterhausen (Post 16008012)
I forgot to mention that I replaced the freehub body, but I'm pretty sure it was identical to the old, broken one. I don't know if that's when this problem started or not.

I have a hanger alignment tool, I'll probably just check it. I'm pretty careful to keep the drive side away from anything, but I suppose it could have taken a hit.
The derailleur has been adjusted.

If the bike fell to the right that could bend the hanger.

techsensei 08-28-13 01:22 PM


Originally Posted by davidad (Post 16008014)
Mavic says the out board running pulling spokes make for a stronger wheel.

Maybe it does; I dunno. I'd like to know their reasons or to see the tests. Stronger in what way? Higher load bearing? More lateral stiffness? Better resistance to fatigue?

joejack951 08-28-13 01:42 PM


Originally Posted by unterhausen (Post 16008012)
I forgot to mention that I replaced the freehub body, but I'm pretty sure it was identical to the old, broken one. I don't know if that's when this problem started or not.

I don't think the freehub would work properly without it but make sure you didn't forget the spacer that goes behind the freehub between it and the hub shell. Without that spacer the freehub willl sit further inboard than it should and could result in the derailler hitting the spokes. I seem to recall that leaving out that spacer binds up the freehub but I could be wrong. It's been a little while since I did all my Shimano freehub experiments (one hub which I used was a 9 speed-era Ultegra too).

A quick way to check to see if you forgot the spacer is to measure over the locknuts. If it's less than 130mm, you goofed somewhere.

FBinNY 08-28-13 01:48 PM


Originally Posted by techsensei (Post 16008051)
Maybe it does; I dunno. I'd like to know their reasons or to see the tests. Stronger in what way? Higher load bearing? More lateral stiffness? Better resistance to fatigue?

Europeans have been building pulling elbow out forever. I also do so because IME, the contact with the rim of the flange provides more stability, hence resistance to fatigue, the free unsupported inboard spoke. This is a marginal difference, but can't hurt.

OTOH Jobst Brandt always held that building the other way reduces the chance of snagging the derailleur, since tension change ubnder load would move the point of cross in, and for the last 30 years or so many (most?) USA builders build that way.

I continue to build pulling elbow out, for a different reason entirely. Having the outboard spokes fan counter-clockwise means that the overrunning wheel will tend to lift an overshifted chain out, rather than sucking it down toward the hub as a clockwise turbine would.

So ther you have it, 3 theories, three reasons. Pick whichever you feel is more important and build accordingly.

unterhausen 08-28-13 04:26 PM

Is there really supposed to be a spacer behind the freehub body on this hub? It didn't have one when I replaced it, and so it doesn't have one now

I always did pulling spokes on the outside because that was the way it was done when I was learning. Funny that one person seems to have changed that for the U.S. The previous incarnations of this wheel were built with pulling spokes on the inside, so I kept it that way when I put the most recent rim on it

FBinNY 08-28-13 04:32 PM


Originally Posted by unterhausen (Post 16008643)
Is there really supposed to be a spacer behind the freehub body on this hub? It didn't have one when I replaced it, and so it doesn't have one now

I don't know about a spacer behind the freehub, but suspect that the person who mentiond it might have meant a spacer behind the cassette to push it out so it overhangs the freehub body and the lockring works to compress it without bottoming.

squirtdad 08-28-13 05:03 PM


Originally Posted by unterhausen (Post 16008012)
I forgot to mention that I replaced the freehub body, but I'm pretty sure it was identical to the old, broken one. I don't know if that's when this problem started or not.

I have a hanger alignment tool, I'll probably just check it. I'm pretty careful to keep the drive side away from anything, but I suppose it could have taken a hit.
The derailleur has been adjusted.

good excuse to use a really cool tool.... this is what i was the only time I ran into the derailler into spoke thing...but I was doing fixes for a charity and the bikes were "well used"

joejack951 08-28-13 07:41 PM


Originally Posted by FBinNY (Post 16008671)
I don't know about a spacer behind the freehub, but suspect that the person who mentiond it might have meant a spacer behind the cassette to push it out so it overhangs the freehub body and the lockring works to compress it without bottoming.

Nope, I meant what I said. See here: http://techdocs.shimano.com/media/te...9830611839.pdf

If the OP had mentioned a 10 speed cassette vs. 9 my first question would have been about the Shimano 10 speed cassette spacer though.


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