10sp usable gears

I have searched and did not find what I was looking for...

On shimano 10sp systems, how many small cogs are expected to be lost due to chainrub on large chainring when one is using the smaller ring?

I have been told by the LBS to expect to lose 3 cogs, but what good is that if one expects more gears on a 10sp system and then lose 3??? By doing that, one loses the much enjoyed overlap of ratios between the 2 chainrings. Some overlap is really desired, and by losing 3 small cogs, essential overlap is essentially gone. Not good in my book.

Sooo.....how many small cogs are really expected to be lost in a 10sp setup?

In general, two cogs on the bottom (and two cogs on the top), but the reality is that if you're at the extremes in a chain ring/cog combo, you should be in a different gear combo. You can optionally run so you only lose one on top and one on the bottom without too much problem. You can even, for a short time, run the extremes, but it's not good for the life of the chain and cogs.

What's the point of a 10 speed cassette if you lose certain gear combos? You still end up with more useable gear ratios. That's the point.

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I realize the point of more gear ratios, but in my book if I had a 10sp setup and had to double shift all the time it is not only annoying, but time consuming and you lose speed since you have to find the gear again. Maybe I'm not making myself clear, but shifting the fd regularly unless I am riding hills is a "fault" in my opinion. Shld not have to happen so I am trying to figure out how I would avoid that if I lost 2-3cogs due to chainrub.

BTW, how can one even get rid of the chainrub w/out redishing the wheel?? It's not the fd rubbing, but the chainring itself on the bike I tried out.

How to eliminate losing 3 cogs?????? I could see MAYBE 2 cogs, but 3???

The chain doesn't rub the large chainring on a 53/39 setup, but it will touch the front derailleur in the extreme combo. Maybe the frame size (chainstay length) affects this?

I'd say the front der limits can be set so that there is some rub/noise in 2 cogs for one extreme and no cogs in the other, or one cog on each extreme. I occasionally use the 53x28t for short climbs so I don't want rub there, but that does cause rub on the 39x11 & 12 combos (which I almost never use).

Just to make sure I'm tracking, I'm talking about gear combos available without chain rub, rather than gear ratio overlap between large and small rings.

You don't have to double shift all the time, but there is a reason why you can't have all the ratios you need with just one chainring: it's the math of the gear ratios. That's just how it works out. You're not losing nearly as many gears as you think. With 10 speed you should be losing 4 ratios out of 20, but the reality is you only really lose 2 out of twenty. And if you have to, you can for short periods cross chain to the max. The fact is that with a 10 speed, you have more useable gears than you do with 9 or 8 spd.

Redishing won't do anything for you. Not a single bit. That doesn't change where a particular gear ratio is with respect to the ideal chainline.

Any time lost shifting gears is negligible, and any speed loss is equally negligible. If you're losing speed on gear shifts, that means you're shifting too late.

I spend a lot of time riding in the mountains around here, with grades running all the way up to 22%, and I've never found myself limited by losing a tooth or two at the end of a range. I also don't experience any noticeable loss in speed with shifts. After all, a shift takes quite a bit less than a second.

Now, manufacturers have started to reshape their front derailleur cages, saying that you can cross over to the max, but those new FD's don't change the chain wear or cog wear. All they do is reduce the irritation of hearing your chain rubbing on the inside of the FD cage.

The only way to gain more gears is to use a triple, but then the cross over issues are more pronounced.

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frenchyge is right: with shorter chain stays you get more chain rub.

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Yes, I am talking about primarily chainring rub, which in the end affects gearing. If I knew that chainring rub could be "mostly" eliminated, I'd look at it differently. This bike had a 38/52 x 12/23 and the chain rubbed the 52 ring when using the 38x12/13/14 gears. I realize the 38x12 concerns, but the other are what puzzle/bother me in this setup and not sure if I could live w/ that. Interestingly, the 52x23 runs perfect!

Those 38x13/14 are what I would use to spin approaching any hill and then merely dwnshift as needed. However, in this particular case I'd have to use similar gearing w/ the 52 ring and double shift on the hills which is really where one doesn't want to have to fuss w/ shifting lots!

Suggestions?

Like frenchyge said, you can tune the FD to prevent chainrub at one end or the other, but you give up something in doing that.

Again, unless you can somehow restructure the Universe so that physical laws apply differently, you'll have limits. As I said earlier, you shouldn't lose any speed or time shifting. It's not a time consuming thing and it doesn't bleed off energy. By shifting the way your shifting, you're actually missing ratios you could be using. In simple terms, you're shifting wrongly.

You've been given all of the solutions available. You can call customer service for the manufacturer of your gruppo to see what they advise. That's it.

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I appreciate your answers, but, as I stated above, it is NOT front der rub....it's chainring rub I am investigating.

It is not about shifting "right"; it is shifting "less". And, with one-tooth increments, it's not about missing ratios. Approaching an incline/hill is not the time to be playing games w/ cog choosing...unless you like to shift both der while standing up on a hill...why would one choose that when I've experienced the ability to approach & climb the hill while using just the rear der??????

I'd like to know reasoning in desiring to shift both der instead of just the rear....there are times when you must, but choosing to do that??????.

Hey, I've tried logic and giving the facts of how the systems operate. You don't want to understand or believe, so I can't help you with that. I will say that it seems the majority of the riding public doesn't have the issue with changing gears that you do. Again, it's a process that takes all of a few bits of a second, and doesn't cost you ANYTHING.

Maybe you should look elsewhere for advice or be less rigid about the answer you want.

Have a wonderful day.

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It appears you don't understand my question. Sorry.

One last time. Changing your chainline won't help. It'll just move your problem. FYI, chain rub comes from the same thing. Spec chainline for a double is 43.5 mm. Drivetrains are designed to operate with that spec. It's a very simple concept. In other words, I understand your question perfectly. You have the problem because you don't understand the answer, and you seem to insist that the answer conform to your notions. Sorry. The physical world doesn't operate that way.

Someone with a competitive spirit will be in the right gear and understand that an event that lasts less than a second will not impact his or her "race." Again, it's a simple concept.

I guess at this juncture, I'm supposed to revere you for your highly competitive nature and marvel at how you know exactly how I ride without ever having pedaled a meter with me. You've got skillz.

It's your problem if you don't get the extremely simple geometry that makes up the drivetrain and rear triangle of a bike. You know I can just as easily talk to a wall in my office.

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WOW, how a simple question becomes a pride issue w/ you. Because I have ridden for years and rarely shift the fd, I'm not understanding how a bike works?? Hah!
There are things I don't know, but, SORRY, you are wrong in that shifting the hub on the axle WILL alter chainring rub....shifting it...to give more gears w/ the 38ring and fewer w/ the 52ring...WHY? you do the research, but it, well, changes the hub location...which CHANGES the cassette location! Marvel at that!

Go ahead..You figure out how you can double shift under load and not lose a hair of time or rythm. Aint gonna happen. Meanwhile, I know for fact that shifting less is better. WOW! (and that is bad to most bike riders?)

One more who needs to learn that less is more.

That sounds very odd. What size was the frame? 700c wheels or 650c? The fd wasn't pushing the chain outward into the side of the big ring, right? (That'd be an adjustment issue again)

*My* Shimano 10sp does not do that, so I'm guessing it's a bike issue rather than a general issue for the group. Did you compare to some other bikes in the store?

It's not pride. It's just the idiocy displayed when people refuse to understand the simple answers or can't come to grips with how a 10 spd works.

Moving the hub will change access to one end of the gear range or the other? No kidding. Gee. That sounds a lot like what was said by both frenchyge and me. Still, it doesn't improve things on both ends. You take one or the other.

I'll bow to your massive climbing skills and the decades you've spent mastering the art of shifting a bike. Clearly you must be a master, because you say that you are.

Enjoy your rub.....or learn how to phrase a question...or both if you've got time in your busy day.

__________________
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Pain is Fun
I cut my fingers off
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