I have a compact 50/36 and never use the bigger gear combinations. Would it make sense to convert to a 48/34 or even a 46/34? Would I have to take a link or 2 out of my chain or get a longer rear derailleur hanger if I did this, in particular if I went with a 46/34? Thanks.
downsize to 48/34 or 46/34?
pdxtim
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I have a compact 50/36 and never use the bigger gear combinations. Would it make sense to convert to a 48/34 or even a 46/34? Would I have to take a link or 2 out of my chain or get a longer rear derailleur hanger if I did this, in particular if I went with a 46/34? Thanks.
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8,252 Posts
I ran a 48x34 for a while and it worked fine...and you don't need to take any links out of the chain. With that said, you likely won't see much difference between the 48 and 50 but might with the 46.
The suggestion of a different cog set is a good one for your case...a close ratio cassette that starts with a 14 or 15 tooth cog may be more up your alley.
The suggestion of a different cog set is a good one for your case...a close ratio cassette that starts with a 14 or 15 tooth cog may be more up your alley.
First off you don't have to shorten the chain or change the RD to downsize the larger chainring, but if all the RD take up is used in the 36/smallest combo, you might shorten the chain to accomodate the 34.
As to the effect. Changing the 50 to a 48 is about a 4% change, or less than the difference between a 13 and 14t rear cog. Going to a 46 would be more significant, about 8% or equal to the difference between a 12t and 13t first cog.
So if you never use that first cog dropping 4 teeth on the larger ring would seem about right.
As to the effect. Changing the 50 to a 48 is about a 4% change, or less than the difference between a 13 and 14t rear cog. Going to a 46 would be more significant, about 8% or equal to the difference between a 12t and 13t first cog.
So if you never use that first cog dropping 4 teeth on the larger ring would seem about right.
There's no real reason not to use any chainring combination, except that some outer chainrings have pickup pins located to best phase with particular inners. You'll see timing marks on both, and the outer might be marked with the compatible inner ring size. It's of little significance, and you shouldn't let it keep you from the best combination for your needs.pdxtim said:
The real consideration is the cassette you're matching it with. The two chainrings should work together to give you the best selection of gears for your needs, with a minimum number of duplicated ratios.
By way of example, consider that the typical cassette changes by 6-7% between adjacent cogs in the middle cogs. (I don't worry about the steps at the extreme because I avoid riding crossed over) You therefore would want to avoid chainrings that differ by a multiple of 6-7% sinc that would create duplicated ratios, whereas a difference of, say, 16% would create new ratios in between.
It's your bike so use a gear chart like the one here http://www.sheldonbrown.com/gears/ to work out the combination that produces the nicest selection of gears in the range that you do most of your riding in.
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22,165 Posts
Bigger gears
As others have noted, consider a different cassette. You've not said what your cassette is, but since cassettes are a wear item, the next time you need a new one, get one that gives you useful gear ratios. For some unfathomable reason, people go with a compact crankset and then install a cassette with an 11 or 12t small cog. The reason for a compact is to get lower gears, so use a cassette that gives you those lower gears.pdxtim said:
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1,578 Posts
best of both worlds
The reason (for me anyway) is that I want lower gears for climbing 1000's feet, but high gears 11tx50, which is bigger than a 53x12 for those fast downhills, the ones in the middle with the 50t are for the flats. A compact was 'invented' in the modern sense and designed to be used with an 11t - ala Hamilton in 'that breakaway' a few years ago in the tour. For the same reasons I use one now. more lower and no compromise on top end speed descending. Its the best of both worlds, and much less cross chaining.Kerry Irons said:
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Sorry about that.Kerry Irons said:You should hit the REPLY button on the original post, if that is the one you want to respond to. As it is, you asked me (Kerry Irons) if I have been riding long enough to know if I won't get stronger. The answer is yes
no problem
I formerly ran a lot, knees get sore easily, so I try to be a "spinner" rather than a "masher", and use the lowest (read: easiest) gears possible.
No problem with the question, but I'm on the downhill side of getting strongerksanbon said:
I formerly ran a lot, knees get sore easily, so I try to be a "spinner" rather than a "masher", and use the lowest (read: easiest) gears possible.
Go to the Sheldonbrown.com website and look up his gear calculator. Then look at the gear inches of what you're thinking of doing - changing so that your highest gear would be the ~46 tooth chainring with your current 11 tooth cassette. Then just figure out what cassette you'd need to get that same gear inches with the 50 tooth ring.pdxtim said:
My guess is that you'll find what you need if you look for "junior cassette" which have 14 or 15 tooth smallest sprockets and much smaller jumps up to the largest sprocket. You might also consider trying to find one with a 27 or so largest sprocket while you're at it.
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