XxHaimBondxX

I have 2x10 SRAM Apex drivetrain. When chain on smaller chainring and highest gear, it rubs larger chainring, making clanking sound. The only way to get rid of it is by having FD cage sit on the chain, slightly guiding it away. Am I not suppose to ride on smaller chainring and highest gear? This type of set up is new to me, previously I only understood not to ride on larger chainring and low gear.

As soon as I typed this it I found a few threads advising not to ride on small/small combo.

Iride01 

IMO, you can use it for a little bit if you aren't going to be shifting to the big ring soon. But don't ride it in the small/small for a long time. You have a similar gear ratio in the big ring.

You might make sure that crank is providing you the proper chain line for that bike. Did you upgrade a older bike from a group set with less cogs or is this a new 10 speed bike?

XxHaimBondxX

this is how it came from Specialized, I assume and bike has very low miles. I now also reading that small/small is not a good mix...

79pmooney

Riding small-small isn't ideal and with 130 spacing and large chainrings a lot bigger than the small, chain contact with the large chainring typically happens. Narrow spacing with 9, 10, etc chains makes this worse since the chainrings are closer together.

So, small-small is wearing your small cog and stretching the chain quickly which accelerates wear on the other cogs and chainrings. The chain hits the large cog and will do its best to climb up with help of the shifting pins. Using the FD cage to keep it off the large chainring can be done (and I do it) but the chain will wear the cage. This is a matter of choices. If no noise, minimum wear and being strictly "proper" is your goal - quite simple - don't. If you find your ride is better with a better choice of gear ratios and shift options and you can accept that it is costing you a few dollars and a shorter replacement schedule, don't sweat it. (But expect to be told you are doing it wrong.)

Iride01 

Since I've gotten Di2, I've noticed I get better chain life with my 11 speed chains than I ever have. It won't allow me to go into the two smallest cogs when in the small ring. As well I have it set up so I can't shift into the too largest rear cogs when in the big ring. So it doesn't allow the chain to get "bent" sideways as much which probably puts more wear and tear into the pins on the chain pins.

Though I'm not a doom and gloom fearmonger implying that your bike will explode if you do happen to wish to cross chain for a short time in either the small/small or big/big combo. It's perfectly okay for a little bit if needed/desired. The only downside is maybe a few less miles out of your chain. Or wearing out the pads on the inside of your FD cage if it has them. And maybe more cog or ring wear.

choddo

Dayum that’s a clean chainset

Troul 

While it is not good practice to have the chain in that combination, it shouldn't cause immediate issues.
If you find that it's going to be a (bad) habit & are looking for a way to possibly not cause it to scrub the other chain ring, you might be able to address the annoyance by installing a 12speed chain.
Doing so does come with a [metaphorical] price. Such as; Possible delayed/lazy shifting, a slight increase in chain services, gap catching.
IME with a 11sp group set using a 12 sp chain I've not had any of the above issues. YMMV.

alcjphil

This happens all the time and has been happening since I bought my first derailleur equipped bike in 1972. When you shift into the smallest cog and the small chainring your chain falls into the "shadow" area. This is pure geometry. With current compact cranks and 8+speed cassettes, the chain moves over a much wider space than the 5 speed freewheels that were common when I first started riding. The 16 tooth difference between chainring sizes on compact cranks makes the problem worse than the 10 tooth difference on 52/42 cranks common back when I bought my first road bike. If you have a bike with short chain stays, the problem is worse. My advice? It is like the old joke about the patient who tells his doctor "It hurts when I do that" and the doctor replies "well, then don't do that"

smd4

How a properly lubed setup should look.

XxHaimBondxX

I will learn cruising on larger chainring, which should also force me to ride faster. This morning I rode it slower than on hybrid, which defeats the purpose of having a "race" road bike. As well as the clanking noise of chain hitting the rivets or it sliding on FD cage would drive me mental.

XxHaimBondxX

As far as I understand, bike was purchased new in 2012, ridden less than 50 miles, then stored in basement for 10 years. It won't be clean for long.

smd4

You don’t want to mash gears just to stay in the big ring. You want a smooth cadence. Bikes have a variety of gears for a reason, and “forcing” one to ride faster isn’t one of them.

XxHaimBondxX

Of course, I just meant that riding on large chainring will allow me to increase top speed, since I've reached my ceiling on small.

Kontact

I think you might be misunderstanding the gearing design. The combination of small chainring and smallest cassette cog is the same as the large chainring and one of the medium low cassette cogs. There is considerable overlap in the gearing, and that is by design. On a 22 speed road bike, you really have maybe 16 non-duplicated gear ratios.

https://www.bikecalc.com/gear_inches
Try putting your gearing into this calculator. "Gear inches" are just arbitrary numbers for comparison.

FBinNY 

First of all, let's understand WHY this happens.

Imagine 2 buildings across the street from each other, with the taller one to the east. You're standing on the roof of the short one. As the sun rises the shorter building is in the shadow of the taller one, and stays there until the sun rises enough to clear the taller building and shine on you. The difference in height determines how long you'll stay in the shade. If it's small you'll get sun early, if it's big you'll be waiting until noon.

Same thing with the chain and chainrings. They're close together, and when the chain comes from the outside it will pass close to or touch the outer ring. There are two ways to avoid this, a smaller difference in chainring size, or increasing the gap between them. Both are problematic, either limiting your gear range, or causing shifting issues by allowing the chain to fall between rings.

That's WHY your bike is this way, and the truth is what others are telling you, namely that the "missing" gear combos are (approximately) duplicated elsewhere. Also, even if there was no rub, the increased angle causes more chain wear than better aligned combinations, so experienced riders would avoid them anyway.

Long story short. You don't have a problem, and aren't losing anything.

AndreyT

Mine does the same thing. Also 2x10 SRAM drivetrain on a Specialized bicycle. This is normal for small-small combination.

As always, the intensity of this effect will depend on chainline parameters and chainstay length. But even longer chainstay bicycles often show this effect.

choddo

Exactly (although gear inches are more useful comparing between bikes because of the added complexity of crank length, wheel sizes etc and for one bike you only really need to calculate tooth ratios) - you only really need to use the easiest 4-5 gears with the small ring xXHaimBondXx - the rest of the ratios are ~duplicated on the large ring & bigger half of the cassette (though large/large also isn’t great) and in my experience also feel nicer. Placebo probably, based on knowing the bike looks better in the big ring

wheelreason

The big ring somewhere in the middle of the cluster is going to be just about the same gear as the small ring on the smallest cog...

grumpus

Gear inches aren't arbitrary - they show the equivalent "ordinary" (high wheeler) wheel diameter (an ordinary typically had about a 50 inch wheel, limited by the leg length of the rider). The other common expression of gear ratio, "development" or the distance travelled in one rotation of the crank (in metres), can be calculated from gear inches using the conversion constant 0.0254 * π.

XxHaimBondxX

Thanks everyone, I think I got it, although not all the technical details. I got accustomed to middle chainring on my other bike, while going through all the rear gears, which was sufficient for my area. I'll have to learn using both shifters now for steep hills.

choddo

One of the joys.

And shifting early enough into the small ring before you’re putting too much torque down.

Kontact

That is arbitrary, because you, me and the OP aren't riding highwheelers. I was trying to keep things clear and straightforward for the OP, rather than post more distracting explanations in a thread that is a little much already for someone new to gearing systems.

andrewclaus

Have you tried any adjustments? I would tinker with it a little. Start by tightening the low limit screw, a quarter turn or so. First check clearance while in the large rear cog. Make sure it doesn't affect a crisp downshift. I'd also try toeing out the cage a fraction of a mm. See the Park Tools video if needed.

Also, does the shifter have a trim position? Some allow trimming in both chain rings.

I agree with not cross-chaining, and a little noise while doing it accidentally is a good wake-up call. But most modern bikes will allow you to do it without actually grinding.

XxHaimBondxX

I did try adjusting it before I posted and learned this is normal operation. I don't want to wear out components prematurely, since this bike most likely will be sold next year. I'll try to mess a bit more to make FD shift easier. It takes two taps to drop to small chainring, while it should take one like on RD. Also, much harder to go up. I expected better from expensive drivetrain.

andrewclaus

My cheap Sora front shifter has a trim position in the large chain ring only, and also takes two taps to shift to low. But I have it adjusted so I never need the trim position. One full movement of the lever will bypass the unneeded trim position on my shifter.

The difficult upshift could be friction in the cable. Since it's essentially new, and apparently stored well, it's doubtful there's any corrosion. But I would check for excess length or bends in the housing, and/or try replacing it if you're serious about it.