Just bought myself a new Cannondale Quick Speed 2, which has Shimano Sora derailleurs (3x9; 27 gears). Pretty happy with the Cannondale. However, is it acceptable that certain gears, those that run "cross" sprocket, front to back or vice versa, will result in scraping of the chain against the device that moves the chain from sprocket to sprocket? I understand how this can happen and that it would stress the derailleurs. But it seems kinda silly to this layman to load 27 gear ratios on a gear system and have certain gears removed from the mix because it stresses the system and makes a scraping noise.

Maybe I'm just venting against the laws of physics; but would appreciate any comments from the members.

Yes in extreme cross chaining it happens so don't use those combinations. You may have 27 gears but there are only about 15 or so different ratios. The same ratios are available using other combinations that run more in line.

Congratulations!!!!!

Yeah. It's called cross-chaining. And bicycles aren't immune from the same user-operator harm as nearly every other machine.

All machines need to be handled/operated properly. You ain't got 27 useable speeds! There.... someone posted it. But don't worry... you got plenty of gears there. I remember when we were thrilled to have five cogs in the back and two gears in front.

I remember having that same thought once years ago when a shop told me they weren't able to dial out the scraping when I was cross-chained.

In theory, I believe Shimano intends for the derailleur cages to always clear the chain. In practice, on different bikes, that doesn't always work out.

I've gotten to the point where I don't obsess so much if the rubbing is only in the extreme two cross-chain positions. Because then it serves as a subtle reminder to me that I should maybe think about shifting again when I'm able.

Congrats on the new bike, btw. And don't worry too much about cross-chaining every now and then. Most of us probably do for short periods. Those gears are not really "removed" per se. It's just that using them leads to some additional wear on the chain and some additional risk of breaking it under load. But for that matter, so does any gear combination that doesn't result in a perfectly straight chain. And pedaling results in additional wear over non-pedaling! So where does it end?

If you find yourself cross-chained, just make a mental note to shift into a straighter chain line when it's convenient to do so. That's all, and no harm done. IMHO.

Thanks to all who replied. Message heard, lesson learned.

I have a Specialized Secteur with a 11-32 compact double. I also have a Sora setup but being a double, it either is leveraging the lack of a third as a trim or just has a trim feature that will partially kick the cage a bit to prevent it from rubbing on the chain. That doesn't mean they want you to use all the gears in all combinations but I think it allows the 50T to use the full cassette. they still do warn of using the 34 -11 combination even though the trim will not make it rub.

I think Sora changed since either 2013 or 2014 so only if you have newer does this apply. My Secteur is 2014. The change is that they improved the setup and got rid og the thumb buttons and went to 2 lever brifters. I think there are other changes too but this is the most visible.

Does a triple have Trim??

One quick correction.

Crosschaining should not cause rubbing of the chain against the FD. It causes the chain to rub against the next bigger crank gear.

You use the trim of the brifter/FD to keep the chain from rubbing the FD.

On my bike with Tiagra (10-spd), I'll get chain rub on the FD that I need to use the trim (one way or another) on the top/bottom 3-4 gears. The middle few gears can normally handle the trim being in either setting.

GH

I've never had a triple with a trim feature, nor have I ever needed one.

My compact double, on the other hand, definitely does need a trim feature. Do higher end triples have trim?

Well, my main point was that rubbing against the derailleur is not cross-chaining.

I'm not sure if a triple has a trim feature or not.

If the chain is rubbing against the FD, then, if your bike has a trim feature use it. Otherwise adjust the FD, or don't use the gears that cause the rubbing against the FD. Or get used to a little rubbing.

GH

The new 9/10/11s chains are supposed to be more flexible than the old 5s chains. And, adding one more front sprocket only adds about 1/4" of additional twisting of the chain, or about one sprocket in the rear, so even with perfect shifting... you're only saving about one extra shift.

Trim the derailleur so it doesn't rub as above.

It doesn't hurt to double check your chain adjustment at home before taking it on the road. Your derailleur should have enough adjustment so that it is safe to do Big Front --> Big Rear without tearing off the derailleur, as well as Small Front --> Small rear without the chain dragging across the derailleur.