New bike tune up

[Supermau]

Went and got my new Trek FX tweaked after the first 100 miles yesterday and last night noticed some chain rub on the front derailer when I was in the 2nd chain ring and the small cog in the back. I spend a lot of time in the 2nd chainring and hadn’t noticed any rub prior to the tuneup.

The mechanic told me it’s cross chaining, but in this gear the chain is nearly straight front to back, certainly not your typical definition of cross chaining. He basically called it an annoyance and said it wouldn’t do any harm but didn’t take another look at it.

I’m still a bit intimidated by screwinging around with derailers as I’m just learning. What I did do was loosen the front just enough to give it a tiny twist away from the chain and tighten it down again. Seems good to go and no more rub. Shifting seems good.

Any thoughts on this? Do you think my mechanic was just being lazy? I’ve really got to get some hands-on experience and get over my derailer phobia.

PS – I know I’ve spelled derailer incorrectly, my iPad is doing the spelling.

Topic

[Supermau]

[QUOTE=Harry Meatmotor;94032…

One thing you can do on most modern indexed shifters is to do a double-shift or triple-shift in the rear and a single shift in the front, at the same time. So, if you find yourself in getting near the small end of the cassette, try and get used to doing a double-shift down in the rear while at the same time doing a single shift up to the big ring. In most gearing combos, this will put you in just about the same number of gear-inches. You can do the same if you find yourself in the big-big combo, only in reverse.

One final rant – some newer front derailleurs (SRAM’s Yaw technology, Shimano’s Di2 system) will allow cross chaining with no rub on the FDer cage – but in my experience the chain, cassette, and chainrings still make a huge racket even when perfectly adjusted.

Thanks for the input. I just started riding again this spring after at least ten years away, and even ten years ago I knew little about the nuances of shifting. I corrected all that on my last ride. I had a solid 25 miles to practice with. I did double shift and spent more time going between the big ring and the middle and I definitely learned a lot.

I must say though, my bikes make no huge racket unless I’m shifting under stress, which I try to avoid. They generally shift pretty smooth and quietly. Unless our definitions of “racket” just aren’t the same.

[Harry Meatmotor]

@Supermau 94038 wrote:

Thanks for the input. I just started riding again this spring after at least ten years away, and even ten years ago I knew little about the nuances of shifting. I corrected all that on my last ride. I had a solid 25 miles to practice with. I did double shift and spent more time going between the big ring and the middle and I definitely learned a lot.

I must say though, my bikes make no huge racket unless I’m shifting under stress, which I try to avoid. They generally shift pretty smooth and quietly. Unless our definitions of “racket” just aren’t the same.

a small addendum to the SRAM & Shimano 22 speed stuff is noisy complaint: the noise is from the chain and chainrings – i think we’re getting to the limits of drivetrain offset in terms of cassette width, tho not necessarily the number of speeds. I did see Phil Wood’s tweet of a picture of a 13 speed cassette and I can’t imagine how much that tweaks the driveline if you were to run that as a 1×13 setup.

[dkel]

@Harry Meatmotor 94329 wrote:

I did see Phil Wood’s tweet of a picture of a 13 speed cassette and I can’t imagine how much that tweaks the driveline if you were to run that as a 1×13 setup.

I was wondering about the single chainring option with regard to this thread. If I ran a 1×10 (which I have considered), would that create additional chain wear from cross-chaining at both ends of the cassette? Obviously there would be no FD to rub, but it would be a wide range for the chain to navigate without relief of switching rings.

[nsfnsfdave]

I’ve been riding many years and have built all my own bikes from frames with a variety of components, from 3×7 to 3×10 and many 2×9 and 2×10 setups. Cross-chaining should only result in slightly faster wear on all the components, in my opinion not enough to worry about. It should never result in excess noise. If both derailleurs are adjusted properly you should never get rubbing on the front derailleur no matter what the gear combination. And if you use good chain lube and keep everything else clean, you should hear little or no noise. I currently ride a 1996 trek with 53/39 and 11/28. I rarely get off the big ring and I frequently ride 53-28 on hills. This is cross-chaining at its worst, and I don’t have any rubbing, chain noise, or other issues.

Take it back and have them adjust it properly. The front derailleur on a triple has very little room for error. It must be adjusted to a precise setting with the cable length and stops and more important, the alignment of the derailleur to the chainrings (rotating it on the seatpost) is very critical. But if the shop does it correctly, you should not have it rub in any gear combination.

[hozn]

@nsfnsfdave 94343 wrote:

If both derailleurs are adjusted properly you should never get rubbing on the front derailleur no matter what the gear combination.

This depends on the frame geometry and the groupset. I cannot adjust my 10sp Sram Force FD on my 135mm rear spacing & 410mm chainstays road bike so that the chain doesn’t rub the FD when cross chaining in the small ring. Unlike Shimano, Sram (this version, anyway) has no trim for the small ring. Doesn’t matter, because I don’t need to cross chain and spend most of my time in the big (50t or 52t) ring, but it’s certainly not a universal truth that there will be no rub if the FD is correctly adjusted.

It sounds like this case, though, is one where some adjustment will fix the problem — particularly since it used to be noise-free.

[Harry Meatmotor]

@dkel 94337 wrote:

I was wondering about the single chainring option with regard to this thread. If I ran a 1×10 (which I have considered), would that create additional chain wear from cross-chaining at both ends of the cassette? Obviously there would be no FD to rub, but it would be a wide range for the chain to navigate without relief of switching rings.

IMHO the jury is still out on this from a more or less typical 700c-wheeled commuter bike perspective. I can’t think of any bikes out there aside from some very new race-inspired cyclocross bikes running a 1×11 setup. The 1×10 groups seem to be holding up pretty well, but again, they’re usually 26″ or 29″ or fatbikes that see a bit different kind of abuse than a commuter. I’m interested to see how the 1×11 setup penetrates the gravel bike market – in fact, i think it was Wolf Tooth that introduced a 50T narrow-wide chainring at inter bike this week that when coupled with an 11-38 or 11-40 (or even 11-42) cassette could net you the same gear ratios as a compact (34-50) with an 11-28 cassette. The murmurs on the forums are that the narrow-wide chainrings work really well, but tend to wear out a little faster than normal chainrings. again, that’s in the dirt on MTBs, not on commuter bikes or road bikes.

[dkel]

@Harry Meatmotor 94345 wrote:

IMHO the jury is still out on this from a more or less typical 700c-wheeled commuter bike perspective. I can’t think of any bikes out there aside from some very new race-inspired cyclocross bikes running a 1×11 setup.

I saw the 1×10 on the Civilian Vive le roi when I was shopping for my Straggler, which is what got me thinking about it. Admittedly the Civilian is not really a commuter, but I’m pretty sure I could do my whole commute in my big ring (46T) except for the effects of cross-chaining the big cogs on climbs.

[Harry Meatmotor]

@nsfnsfdave 94343 wrote:

If both derailleurs are adjusted properly you should never get rubbing on the front derailleur no matter what the gear combination.

I’m sorry, but that’s simply not true. There’s much more that affects the chainline on a bike that proper adjustment can’t make up for in every single case on any bike with any mix of components. I don’t disagree that on your bikes it hasn’t been a problem, perhaps ever, but I’ve certainly seen combinations of BB width, crank design/chainring offset, seat tube dimensions/shape, rear axle spacing, and chainstay length that net noisy crosschaining that’s not at all related the mechanic’s ability to properly adjust a front derailleur.

[DismalScientist]

I just checked the Deore front shifter pod (M-440) on my hybrid. The front derailleur is not fully indexed. While a major pull will shift gears, a minor pull will move the derailleur slightly to eliminate chain rub in cross chaining situations.

[mstone]

That’s the trim function. You usually get a bit more adjustability with higher end gear than lower end, but I think all indexed front shifters have some trim adjust.

[Author]

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