View Full Version : Gearing question
Biker Jo
01-02-2011, 03:53 PM
I brought my bike into my LBS today and talked with the mechanic about swapping components to get some lower gearing. I currently have a 34-50 compact crank and 12-26 nine-speed cassette. He said replacing the crank with a triple would be cheaper and easier to do than changing the cassette and rear derailleur. In looking at Sheldon Brown's gear calculator, the setup with the triple would lower my lowest gear from 31.8 inches to 28.1 inches. Is that really a significant enough difference to justify the cost of changing components?
JennK13
01-02-2011, 04:21 PM
I brought my bike into my LBS today and talked with the mechanic about swapping components to get some lower gearing. I currently have a 34-50 compact crank and 12-26 nine-speed cassette. He said replacing the crank with a triple would be cheaper and easier to do than changing the cassette and rear derailleur. In looking at Sheldon Brown's gear calculator, the setup with the triple would lower my lowest gear from 31.8 inches to 28.1 inches. Is that really a significant enough difference to justify the cost of changing components?
What is he suggesting to put on up front? I changed my cassette from 12-25 to 11-28 and did NOT have to change my rear derailleur. I also have a compact double up front. I guess it depends on how much gearing you want to add. If I went any bigger than 28 on the back, I would think about changing my RD, but as long as I don't cross chain, I've got plenty of room.
indysteel
01-02-2011, 05:10 PM
The worth of making that change depends, at least in my mind, on how often you find yourself wishing you had a smaller gear(s). How long have you been riding and what kind of climbing do you do?
Like Jenn, I'm a little surprised that you LBS thinks it needs to change out the r/d for at least a slightly wider cassette. I would think it could accomodate at least a 12-27/28. Of course, that comes with a tradeoff in that you will have eveń wider jumps between some gears.
pumpkinpony
01-02-2011, 05:59 PM
I think that's odd too. I had a similar situation but with a double up front. I wanted a triple, and the bike store suggested replacing the cassette as an easier/cheaper option. I ended up with a $100 Campy Centaur 13-29, replacing an 11-23. I think it took them about 5-10 minutes to swap the cassettes and adjust the RD. And yes, it makes a noticeable difference on the hills. Occasionally I run out of gears on the other end, but I'd rather have that problem!
I'll third the odd.... if you want to go from a double to a triple usually you have to change the cranks the front derailleur and the shifters... that's much more expensive than getting a different cassette for the rear, which unless you are going for an very large one won't require a different derailleur...
OakLeaf
01-02-2011, 07:40 PM
I'm surprised a crankset change (meaning a shifter change also) would cost less than a cassette and RD. Especially considering that a cassette is a wear item. Basically I'd only compare the cost of crankset + shifter + FD vs. the cost of a RD, because the chain and cassette are going to be replaced periodically anyway.
If you don't mind large jumps between the gears, I think the mountain gearing will give you more bang for your buck. I do agree that one more tooth on the rear probably won't be enough to make much of a difference.
Here's what you might do, if you don't mind a bit of a wait: fish around for someone with a cassette that's got a 28T bottom gear (or whatever's the biggest that your current RD will handle). Ask if you can have it when they've worn it out. Then when you wear out your current cassette, put on their old one. If your new chain needs to be one link longer to accommodate the larger gear, you can always re-cut it after you've tried it. Ride it a few times (100 miles or less - not enough for the old cassette to put excess wear on your new chain, but should be enough for you to know if it's going to make a difference). If you like it, then get a new cassette with the same gearing; if it's not enough, then try one of the other options.
Biker Jo
01-02-2011, 07:52 PM
Thanks, everyone, for the responses.
Indysteel, I've been riding for years. I had a Trek road bike with a triple for nine years, but two and a half years ago, I got a Cannondale with the compact crank. It's fine for most of the riding I do (I live in Chicago, where it's flat as a pancake), but on the occasions when I've ridden in Wisconsin, I wished I had lower gears. The more I've been thinking about it, though, the more I think I'm just going to stay with my current configuration.
featuretile
01-03-2011, 12:28 PM
I also had a similar setup to you (compact double with 12-25). I bought a 12-32 IRD 10 speed rear cassette and a medium cage 105 rear derailleur for about $160 + $25 install. With the 32 teeth, I did need to change from a small cage derailleur. I don't know if you would get enough lower gears out of one with 28 teeth to make it worth it. Now my bike has similar gearing to a triple (they have one lower gear). It greatly helped because it is very hilly where I live. I don't find the jumps between gears to be too big.
indysteel
01-03-2011, 01:07 PM
Thanks, everyone, for the responses.
Indysteel, I've been riding for years. I had a Trek road bike with a triple for nine years, but two and a half years ago, I got a Cannondale with the compact crank. It's fine for most of the riding I do (I live in Chicago, where it's flat as a pancake), but on the occasions when I've ridden in Wisconsin, I wished I had lower gears. The more I've been thinking about it, though, the more I think I'm just going to stay with my current configuration.
I went from a 53-42-30 triple with a 12-25 cassette to a 54-30 compact with a 13-26 cassette. Both ten speed. I'm an okay/good climber, but the hills of southern Indiana can get the best of me. So far, I've survived with the compact. Do I wish I had a smaller gear or two some times? Sure, but given that I ride on the flats most of the time, it's an okay compromise.
I, personally, wouldn't like mountain gearing with a compact set up, because I don't really like big jumps between gears, which is primarily why I liked having a triple in the first place. With wind being my bigger limiter than hills, I like to make small gearing adjustments to find "that perfect gear."
But that's just me. I agree with the ladies who indicated that you may have more choices than your LBS is suggesting. With some digging, you should be able to determine the widest cassette that your current r/d can handle from Shimano (or SRAM's) website. Given that cassettes are wear items, as Oakleaf has indicated, you could just replace it when the time comes with a 12-27. I know that may not seem like a big change, but one extra small gear is sometimes all you need.
OakLeaf
01-03-2011, 02:17 PM
A 54/30 compact? What brand? I've never heard of such a large difference.
indysteel
01-03-2011, 02:27 PM
Oops. I woke up at 3:30 this morning and was half asleep by mid-afternoon. I meant a 50-34.
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