Gearing question

[ny biker]

My road bike (2010 Madone WSD 4.7) has this gearing:

Crank: SRAM Rival 50/34
Cassette: SRAM PG-1070 11-28, 10 speed

I rarely use the big chain ring, because it tends to make my knee hurt (I've had problems with a patella tracking problem in the past. It usually does not hurt now, but riding in too hard a gear will cause problems.) When I do use the big ring, it's usually with one of the larger cogs. I also tend to use the small ring with the smaller cogs when I want a harder gear. So I am cross-chaining.

Whenever I mention this to a fellow cyclist, and I say I want to get a smaller chain ring, they always say no, you need a different cassette. I don't understand this. To me it just makes sense to make the harder gears less difficult by making the large ring a bit smaller.

I'm taking the bike in for its annual clean-and-tune service tomorrow, and I think they might tell me the cassette is worn and ready to be replaced. So this may be my chance to change things. But, I am confused about how to change things.

Does anyone out there understand this?

BTW, the current gearing is good for hills. I cannot afford to lose my lowest gears, regardless of whatever other changes I make.

Thanks!!!!

[Becky]

What cassette would they suggest that you put on? With a 28T low gear, and assuming a short- or mid- cage rear derailleur, there's not much lower you can go. You could add a long-cage mountain rear derailleur and something like a 12-34 mountain cassette, but that's more money, I think. (Also, I don't know off the top of my head what the compatiability issues with SRAM road vs. mountain might be. Don't quote my ramblings as gospel and please feel free to correct them.)

If you want a 46T or 48T big ring, why not? Cross double cranksets are often 46-36. You wouldn't have to change anything else- just shorten the chain a touch. Have you consulted with your shop?

[OakLeaf]

I agree it makes sense to put on a smaller big ring if it'll fit. Maybe people's objection is that it'll cost you the same as a cassette when it might not be worn out yet?

But the other thing is that with your current gearing, your bottom five gears in your big ring overlap the top seven gears in your small ring. So you're not cross-chaining because you need to. Practice shifting the FD more....

[lph]

Yup, you might be shifting too much in the rear because it's both quicker and gives smaller steps, causing you to be in the right gear for the terrain faster. The front shifter may take a little longer to shift properly, at least mine does, at which point I've either picked up speed or lost more speed, plus the step between shifts is larger. I compensate by shifting the rear a bit the other way at the same time.

[ny biker]

I agree it makes sense to put on a smaller big ring if it'll fit. Maybe people's objection is that it'll cost you the same as a cassette when it might not be worn out yet?

But the other thing is that with your current gearing, your bottom five gears in your big ring overlap the top seven gears in your small ring. So you're not cross-chaining because you need to. Practice shifting the FD more....

Just so I understand this correctly -- you're saying the (big ring with the five largest cogs, the ones closest to frame) overlap with the (small ring and seven smallest cogs, the ones farther away from the frame)?

I don't spend much time riding in the small ring/smallest cog combinations. I do tend to ride more in the small ring/middle cogs.

The jump between big ring and small ring does seem jarring to me, which is the other reason I don't use the big ring much. I'd be switching between the two too often.

I will talk to the LBS guys about changing the big ring. The former manager was one of the people who recommended getting a different cassette last year, but I wasn't able to ask him for details on what he meant at the time, and he has since moved on to greener pastures.

Thanks!!!

[OakLeaf]

Normally when you upshift in front, you then immediately backshift the rear once or twice to get a manageable effect on your cadence, and vice versa. So yeah, it's a pain to be doing it all the time. But when you'll be staying in the taller gear range for a while, use the big ring.

You can run a comparison with the gear calculator on Sheldon Brown's page. http://sheldonbrown.com/gears/

[Crankin]

I find I shift my compact a lot more than my triple. It does feel annoying and while I am good with it now, sometimes it doesn't feel like I can ever find my sweet spot. It felt like all of the time in the beginning, but I guess I got stronger, because I always am in the the slightly harder cog. And, I do have the 12-34 mountain cassette on the rear. It's awesome on those +12% climbs. I have an 11-28 on the triple, so there's really not much difference, but you get used to what you have!

[Becky]

But the other thing is that with your current gearing, your bottom five gears in your big ring overlap the top seven gears in your small ring. So you're not cross-chaining because you need to. Practice shifting the FD more....

+1. I missed the cross-chaining part earlier....

[pll]

You can switch rings. I am doing it with my cross bike, where I ran a set of Wick Werks 44/34 with an 11-28 cassette. I am swapping to 50/34 compact rings for two events. Go for it.

[Chile Pepper]

My DH switched from a standard double to a compact a few years ago, and he has often said that while the compact is easier for climbing (and at our age, that's a big plus), it makes it harder to keep up with the guys. That sort of logic may be why people object to the idea of switching to a smaller big chainring--you'll limit your speed on the upper end. But if that isn't a problem and if it will give you more gearing options, then I don't see why it wouldn't work.

[Seajay]

46T will work just fine as a large chainring. Cyclocross riders do it all the time and lots of people use them on winter bikes when we have no business using a 53 anyway.

it makes it harder to keep up with the guys.

Well, technically the issue isn't that the gears aren't tall enough. As said above, the typical 50x11 top gear of compact is actually a higher gear than the typical 53x12 of standard gearing.
What is more likely happening is that at a fast pace you have fewer high gear options because the 50T gets you into "midrange" sooner. For normal people this is a good thing. For peloton riders it can be an issue.

50x 53x
11 122 ----
12 112 12 119
13 104 13 110
14 96 14 102
15 92 15 95