4

I followed the Park Tools guide to set up my gears. The rear derailleur was a success but I can't manage to adjust the front derailleur so that the chain stops grinding on the guard. There's no more give left in the H adjustment so I can't bring it forward. Any ideas?

As you can see by the paint damage, the chain has hit my frame many times in the 6 months I've owned the bike. The chain has never come off though.

One suspicion I have for the chain pushing against the derailleur cage is that the chainring is not fitted correctly, or has shifted. The photos show that it's on an angle. Is this cause for concern?

Thanks in advance.

For the images below, the chainring is set to the top and the casette is set to the bottom:

enter image description here

enter image description here

enter image description here

enter image description here

4
  • 2
    Based on that variable width gap between the bottom bracket shell of the bike and the drive side crank, I wonder if your spindle is bent or there is odd bearing wear on the drive side. This will need to be determined and corrected first before figuring out the derailleur. – Jeff Feb 11 at 4:34
  • 2
    Also, when you've run out of adjustment with your limit screw of the front derailleur (the H-limit is wound all the way out, or the end of the screw is out far enough that it no longer is touching the derailleur stop) you can manipulate the inner cable tension with the barrell adjuster (typically at the shifter or at the first cable stop on the frame). Loosening the adjuster will increase tension on the inner cable, which will make the derailleur move more outside, at least until it hits the H-stop which we have wound out. – Jeff Feb 11 at 4:45
  • 1
    Side note: your drivetrain looks pretty dang clean for six months of ownership. Nice work! – MaplePanda Feb 11 at 4:47
  • 2
    Are you sure the band-on strap clamp has not moved a little over time? FDs have a lot of different motions so a little tweak might be all it takes. Photos look fine, but they distort too. Perhaps the rear of the cage could kick out to the right a tiny amount to make it parallel to the chain ? – Criggie Feb 11 at 10:28
5

Are you trying to bring the derailleur farther outwards? If so, you need to add cable tension. Screwing out the H limit screw won’t help if there isn’t enough tension to get to the limit anyways.

To check for chainring problems, derail the chain from the chainrings entirely and give the cranks a spin. If you see the chainrings wiggle side to side, then you know there’s an issue. I suspect your chainrings are permanently riveted to the crankarms, so your only solution would be to replace the entire right crank assembly if there indeed is a problem.

The paint damage on the chainstay is caused by chain slap, where the chain flies up and down as you ride over bumps and subsequently knocks off bits of paint. Although it shouldn’t be a structural issue on a bike of this caliber, it may be best to install a chainstay protector to protect the remaining paint and eliminate all those slapping noises. I find the best solution is a piece of old road bike tire, but if you don’t have one then anything from adhesive vinyl wrapping film to neoprene sleeves to molded rubber guards are available commercially.

The scratches, gouges, and chips directly beside the middle and small chainrings are more mysterious. I’m not sure what causes them (frame flex?), and I have experienced these symptoms on both of my bikes even though their drivetrains are set up very well.

5
  • 2
    I’m guessing the chips next to the chainrings are from the chain jamming in there after falling off to the inside. – Andrew Feb 11 at 11:54
  • That's definitely what it's from. This shouldn't be as much of an issue now the front deraileur is set up as good as it can get. Although the chain feels slacker than it should. It stays on though. – Luke Allison Feb 12 at 11:19
  • 1
    Thanks maplepanda. There was definitely a slight wobble no the chainring but not enough to justify a replacement yet. I'll punish it some more first! After hours of tweaking, it's perfect. Funnily, straight after I took the rear wheel off and set my bike on a direct-drive trainer. It has the same cassette as my bike but requires adjustment, which I'm just not willing to do after all my efforts. I'd rather keep it set up for the bike. – Luke Allison Feb 12 at 11:22
  • 1
    @Luke Allison You’re not going to get much chain tension with these cheaper derailleurs. You’d have to switch to a higher end clutched derailleur, which will really help eliminate chain drops. – MaplePanda Feb 12 at 19:16
  • 1
    @Andrew Yea, that definitely looks to be the case here. Strangely, on my bike the scratches are concentric with the small chainring, hence why I’m unsure. – MaplePanda Feb 12 at 19:18
6

There's more to front derailleur adjustment than limit screws and cable tension. Both the angle of the derailleur and the height need to be set properly.

The angle of the derailleur being off can cause chain rub against the cage. If the rear of the cage is angled too far outward, the chain can rub against the inside of the cage when the chain is on the largest cogs. If the derailleur is angled so the the rear of the cage is too close, the chain can rub against the outside of the cage in gear combinations where the chain is on the small cogs.

The derailleur looks to be canted slightly inwards towards the rear.

When looking down on it, I'd say it needs to be rotated counterclockwise to move the rear of the cage just a bit farther from the frame.

And that will likely affect the limit screw and cable tension settings.

2
  • 2
    that's the first thing I saw too: viewed from the top, the derailleur seems to be rotated too far clockwise on the seat tube. – mac Feb 11 at 15:50
  • You were spot on. It took me a few attempts (more than a few) of adjusting the H, L and cable tension to realize two things - 1. I needed to take up the slack in the cable at the deraileur and 2) The deraileur needed to drop a touch and adjust the angle as you said. Now it's perfect with the exception of alternate extremes on the front and rear gears causing rubbing on the cage. But this is three speed and 9 speed so I think that's normal. Thanks for the advice – Luke Allison Feb 12 at 11:18

Your Answer

By clicking “Post Your Answer”, you agree to our terms of service, privacy policy and cookie policy

Not the answer you're looking for? Browse other questions tagged or ask your own question.