Crank/FD interference question

[Nooch]

I've got a conundrum that I can't seem to make right that I'm hoping you guys can help me sort out.

Here's the setup: PF30 Frame, Wheel's Manufacturing press-in pf30-shimano adapters, Rotor 3d Quarq crank, Sram Red FD.

No matter how I set up the FD, the crank arm is hitting it on the way by. Lightly and not really obstructively, but it's marring the finish on the crank and making a lovely noise. If I trim the FD everything clears. there are no spacers being used on the bb setup, or on the crank spindle.

I figured maybe using a washer would help, but a wrench that I work with mentioned that the issue is more the spacial relationship between the crank arm and the chainrings, since the FD position is dependent on the chainring position -- in essence, adding spacers would give me a larger q-factor, but wouldn't help clear the FD.

The Rotor crankset, for reference, has straight arms with no deviation. Finally, I did not have this issue using all the same parts on my caad9 with the parlee adapters (but boy did they creak!)

Thoughts?

[christian]

Take pictures. It sounds a bit odd. Though judging by photos, the Rotor outside ring does run close to the crank. Perhaps you need a fd with a flatter outside profile?

You're welcome to try my BB30 SI Cannondale SRM crank so see if it fits better with that fd.

[Mark McM]

Have you adjusted the derailleur outer limit stop screw? Turning it in a fraction of a turn should stop it from contacting the crank, if it's just barely rubbing the crank arm now. Also, is the derailleur cage outer plate at an angle with respect to the chainrings (i.e. is one end or the other of the cage pointing outward, toward the crank)?

[josephr]

assuming standard round rings...not the q-rings, right?

[Nooch]

tried adjusting limit screws -- the wrench who's worked on it is good..

it doesn't happen in the stand -- only when being ridden -- maybe there's a wave washer or something that needs to be there, maybe a tiny tiny bit of play? yes, standard round, sram red rings.

not the best pictures:
http://farm8.staticflickr.com/7427/10292353185_d777f45f8b_z.jpg (http://www.flickr.com/photos/54300653@N02/10292353185/)
Untitled (http://www.flickr.com/photos/54300653@N02/10292353185/) by TrickImaging (http://www.flickr.com/people/54300653@N02/), on Flickr
http://farm4.staticflickr.com/3795/10292459813_e6d456fe30_z.jpg (http://www.flickr.com/photos/54300653@N02/10292459813/)
Untitled (http://www.flickr.com/photos/54300653@N02/10292459813/) by TrickImaging (http://www.flickr.com/people/54300653@N02/), on Flickr

[christian]

Something isn't right. As you suspect, I think you're missing something which applies preload and prevents side-to-side movement.

[cmbicycles]

I would loosen the derailleur and rotate the tail end in a bit as that looks to be what is hitting from the picture. Looks like you should be able to just rotate the derailleur in to get some clearance, or put a little "English" on the cage and bend it in a bit on the back end.

*you should be able to remove any play by adjusting the "lock ring" on the ND crank arm. Loosen the set screw and turn ring until play is gone or it feels snug, then tighten set screw and it should be good to go.

[David Kirk]

Can you rotate the derailleur on the seat tube so that the tail is not sticking out as far?...............or does the arm contact the front end of the der. cage too?

dave

[nooneline]

Yeah, I agree that the FD definitely looks a little bit tail out.

[Nooch]

I would loosen the derailleur and rotate the tail end in a bit as that looks to be what is hitting from the picture. Looks like you should be able to just rotate the derailleur in to get some clearance, or put a little "English" on the cage and bend it in a bit on the back end.

*you should be able to remove any play by adjusting the "lock ring" on the ND crank arm.

i'm inclined to say we tried this, but then the chain was rubbing where it shouldn't... but I'll re-assess with another wrench tonight..

[Lewis Moon]

Yeah, I agree that the FD definitely looks a little bit tail out.

Yep.

[oldpotatoe]

tried adjusting limit screws -- the wrench who's worked on it is good..

it doesn't happen in the stand -- only when being ridden -- maybe there's a wave washer or something that needs to be there, maybe a tiny tiny bit of play? yes, standard round, sram red rings.

not the best pictures:
http://farm8.staticflickr.com/7427/10292353185_d777f45f8b_z.jpg (http://www.flickr.com/photos/54300653@N02/10292353185/)
Untitled (http://www.flickr.com/photos/54300653@N02/10292353185/) by TrickImaging (http://www.flickr.com/people/54300653@N02/), on Flickr

http://farm4.staticflickr.com/3795/10292459813_e6d456fe30_z.jpg (http://www.flickr.com/photos/54300653@N02/10292459813/)
Untitled (http://www.flickr.com/photos/54300653@N02/10292459813/) by TrickImaging (http://www.flickr.com/people/54300653@N02/), on Flickrl

Tough from the pix but maybe tail in for the fd a bit, since that's what's hitting the crank arm?

[Nooch]

think I may have figured it out -- it's not actually the crank arm, but the fact that the chainring is 'wavy' for lack of a better word -- out of true (that seems better)... the sound I'm most hearing is the chain rubbing the inside of the derailluer on that spot in the pedal stroke where the chainring is fluctuating toward the crankarm/cage.

guess it's time for new rings, but I have no idea how that could have happened!

[christian]

You can straigthen chainrings. Big-old adjustable wrench while they're on the bike. Or mallet/dead-blow hammer on a flat surface.

[David Kirk]

think I may have figured it out -- it's not actually the crank arm, but the fact that the chainring is 'wavy' for lack of a better word -- out of true (that seems better)... the sound I'm most hearing is the chain rubbing the inside of the derailluer on that spot in the pedal stroke where the chainring is fluctuating toward the crankarm/cage.

guess it's time for new rings, but I have no idea how that could have happened!

I think what you are describing is called 'runout'. Do both of the rings have the same runout? It's easiest to see if the chain is pulled off the rings and dropped onto the BB so you can spin the crank without it getting in the way.

Spin the crank and watch the rings - if just the outer ring has runout then replacing the ring should help...........if both rings have the same runout then I doubt spending money on rings will help as it is most likely the crank that is the problem. The spider would be the issue and it has the runout and it is making the rings waver back and forth.

dave

[Nooch]

I think what you are describing is called 'runout'. Do both of the rings have the same runout? It's easiest to see if the chain is pulled off the rings and dropped onto the BB so you can spin the crank without it getting in the way.

Spin the crank and watch the rings - if just the outer ring has runout then replacing the ring should help...........if both rings have the same runout then I doubt spending money on rings will help as it is most likely the crank that is the problem. The spider would be the issue and it has the runout and it is making the rings waver back and forth.

dave

i'll have to check tonight -- I'm hopefull it's just the outer ring -- the spider is a quarq...

[David Kirk]

i'll have to check tonight -- I'm hopefull it's just the outer ring -- the spider is a quarq...

I want to prepare you for this - I doubt it is just the other ring........it seldom is. But it's worth checking.


Dave

[Nooch]

I want to prepare you for this - I doubt it is just the other ring........it seldom is. But it's worth checking.


Dave

well i suppose the alternative is to just deal with the sound, lol.

[SPOKE]

well i suppose the alternative is to just deal with the sound, lol.

Just have Dave build you a new bike!........problem solved.

[David Kirk]

Just have Dave build you a new bike!........problem solved.

As long as he puts a new crank on the new frameset I can almost guarantee there will be no rub!

dave

[Nooch]

now there's a though, a kirk, a bedford, and a serotta in the same house...

[Peter P.]

I think it's the poor design of the Rotor crank arms. You'll find the major manufacturers provide greater clearance between the crankarm and the large ring. Sure; it's a wider Q-factor but it's necessary with today's shaped front derailleurs and wider cassettes/more cogs. There should be at least a little tolerance for runout of the large ring.

You could try installing the Parlee adapters with the other parts just to prove out the bearings as the possible cause.

[Ralph]

The tail of the FD sticks out too much. Adjust the FD properly and you don't have a problem. Run out or not. Make the inner cage of FD roughly parallel with small ring. If necessary, you can even kick the FD tail in a tad more, but be careful or you'll throw a chain. If it rubs on top of a ring, inner or outer, move the FD up some. But otherise position FD roughly 1-2 mm above big ring as a starting point. If still rubs....is the stop setting allowing the FD to go "out" too far. Chain only needs to barely clear the side of cage in big front to small rear. Assuming the FD travel is proper for this frame down tube size and crankset, can't imagine not being able to get it adjusted to work well.

[SPOKE]

now there's a though, a kirk, a bedford, and a serotta in the same house...

Works for me very well Nooch! Give it a try....:)

[Nooch]

yeah, I'm going to tear it all down this weekend and set the crank and FD back up. while I'm at it I might just throw my rival FD on too..

[Nooch]

does anyone know if any of the spacers (wavy or otherwise) are required in this setup?

sram pf30 bb, wheels manufacturing 24mm (for shimano) adapters, rotor 3d crankset.

[Nooch]

alright. swapped the front derailleur, swapped the chainring, still getting rub. i put a call into quarq and they recommended that maybe the bottom bracket wasn't sitting completely flush -- before i tear it all apart, is that a reasonable consideration? otherwise, next step is to send it back to quarq and see what's up!

[Nooch]

Figured I'd update this thread with hopeful resolution.

Sent the crankset back to quarq, they checked it out yesterday and called me up. Turns out the spider lockring was broken, which they're saying is the likely culprit of the wobble.

Should have it back sometime next week to see if we're back in business!