Bicycle Mechanics - Changing gear ratio

I have been riding a bike with a triple 52-30 chainring and 9 sp. 12-26 cassette. I just purchased a new bike with a Dura-Ace double 53-39 chainring and 10sp. 12-23 cassette.
I love the new bike but, my problem is that the new bike does not have a low enough ratio for some of my climbs (for me).
Changing to DA triple would be pretty expensive (considering a new crankset, BB and shifter) so I am considering changing the 12-23 cassette to a 12-27.
If I make this change, will I have to add links to the stock chain and/or change out the rear der to a longer reach?

I realize this isn't the question you asked but I've got to point out that 39 - 27 is 1.444 no where near the 30 - 26 1.1538. Will this do what you want?

Joe

The current rear derailleur will work fine. The chain will have to be lengthened by two "half-links" (1") if it is at the minimum for the 23T cog. You could use the existing chain and studiously avoid the big-big (53x27) combination but you would have to be VERY careful not to use it inadvertently or the resulting damage could be pretty expensive.

There is the possibility your current chain may have been left long enough so I'd fit the 12x27 cassette and very carefully try to shift to the 53x27 combination on a repair stand. Stop if there is any sign of resistance and add the extra chain or take your chances with a too short chain.

I would think that the chain is long enough, but as HillRider points out carefully try shifting into the 53-27 combination, with no rider on the bike. If in the big to big combination the derailleur doesn't "bottom out" you should be OK. No need to change derailleurs. You could also replace the 39 inner ring with a 38. It's also possible to make or buy a custom cassette with a larger big cog, like a 13-28, or even a 14-30, but it may take some tweaking to get the D-A rear derailleur to work with a 30 cog.

Al

39-27 may not be low enough for you even with the cassette swap. Your other alternative is to go compact.

I realize this isn't the question you asked but I've got to point out that 39 - 27 is 1.444 no where near the 30 - 26 1.1538. Will this do what you want?

Joe

I am hoping that it will do what I need. Recently, I have used the 30-26 less and less.
The 39-23 is 1.696 and I am hoping that the 1.44 will be enough of an improvement.

My recommendation would be the new Shimano R700 compact. Very easy to set up. Just pull the D/A off, slap R700 on, lower fr. der and your in. This would provide you w/ 50-34. In gear inches, that would give you w/ 23t cog (38.66), 25t(35.57), 27t (32.94).
Then you sell your slightly used D/A to pay for the compact.

It's also possible to make or buy a custom cassette with a larger big cog, like a 13-28, or even a 14-30, but it may take some tweaking to get the D-A rear derailleur to work with a 30 cog.

Where can you buy a custom 14-30 10sp? Recently, I have seen 11-32 and 11-34 but not a 30. My understanding is that the last cog is very different.

The difference between 23T and 27T is VERY noticeable. If you are willing to stand on the cranks occasionally, 39/27 = 39" may be an adequate low gear for you. Otherwise, as others have already suggested, consider replacing the 53/39 combination with something like 48/34.

Where can you buy a custom 14-30 10sp? Recently, I have seen 11-32 and 11-34 but not a 30. My understanding is that the last cog is very different.
Are you sure the 11x32 and 11x34 cassettes are 10-speed? I believe they are 9-speed since ratios this wide are generally intended for MTB use. There are no 10-speed MTB components from any maker I know of.

Are you sure the 11x32 and 11x34 cassettes are 10-speed? I believe they are 9-speed since ratios this wide are generally intended for MTB use. There are no 10-speed MTB components from any maker I know of.

+1............11 x 32, 11 x 34 are mtb cassettes, nine speed max (so far, anyway).

Where can you buy a custom 14-30 10sp? Recently, I have seen 11-32 and 11-34 but not a 30. My understanding is that the last cog is very different.

When I wrote this I was thinking Sheldon Brown for a custom cassette, and I had forgotten that you have a 10-speed. Still I think it would be possible to build a 13-30 10-speed by adding a 10-speed spacer and a single 30 cog to the backside of the 10-speed 12-27. You would need to remove the 12 and 13 and add a 13 first position cog with built-in spacer. If you can't find a single 10-speed first position 13 you could use an 8-speed or 9-speed first position 13 and grinde down the built-in spacer so that the thickness of the cog plus built-in spacer would equal the thickness of the 10-speed 12 cog with built-in spacer. The spacer removed from between the 13 and 14 could be used between the 27 and 30. Then all of the cogs would be spaced properly for 10-speed. If the 30 cog is too thick that could be dealt with.
I've put together several custom 9-speed cassettes but have not yet tried a custom 10-speed. Making the rear derailleur work with a 30 cog might take some tweaking with a longer "B" screw.
Necessity is the mother of invention.

Al

+1............11 x 32, 11 x 34 are mtb cassettes, nine speed max (so far, anyway).

Here's the link for the 11-32 and 11-34 10sp cassettes:

http://www.interlocracing.com/cassettes_steel.html

They are available now at IRD's store but they are fairly expensive ($169).

As I said before, the last cog on a 10sp (for Shimano) is different from the other cogs, so you can't just put a 30 on the last position. You have to wait until someone makes a special cog.

Here's the link for the 11-32 and 11-34 10sp cassettes:

http://www.interlocracing.com/cassettes_steel.html

They are available now at IRD's store but they are fairly expensive ($169).

As I said before, the last cog on a 10sp (for Shimano) is different from the other cogs, so you can't just put a 30 on the last position. You have to wait until someone makes a special cog.

I stand corrected. Learn something everyday on this forum, thanks-:)

The current rear derailleur will work fine. The chain will have to be lengthened by two "half-links" (1") if it is at the minimum for the 23T cog. You could use the existing chain and studiously avoid the big-big (53x27) combination but you would have to be VERY careful not to use it inadvertently or the resulting damage could be pretty expensive.

There is the possibility your current chain may have been left long enough so I'd fit the 12x27 cassette and very carefully try to shift to the 53x27 combination on a repair stand. Stop if there is any sign of resistance and add the extra chain or take your chances with a too short chain.

+1. Don't guess. Check out the chain length and be sure.

As I said before, the last cog on a 10sp (for Shimano) is different from the other cogs, so you can't just put a 30 on the last position. You have to wait until someone makes a special cog.

How is it different? The splining is the same, the spacing is the same. Most cassettes have the largest 3 cogs on a common carrier but that doesn't mean you can't put a bigger one behind it. I don't know, maybe I'm missing something.

Al

How is it different? The splining is the same, the spacing is the same. Most cassettes have the largest 3 cogs on a common carrier but that doesn't mean you can't put a bigger one behind it. I don't know, maybe I'm missing something.

Al

If you look at the back of the last cog on a 9 speed cassette it is perfectly flat. The last cog on a 10 speed cassette has a ridge and it takes a washer that is not needed on the 9 speed.

If you look at the back of the last cog on a 9 speed cassette it is perfectly flat. The last cog on a 10 speed cassette has a ridge and it takes a washer that is not needed on the 9 speed.

Ok, this wouldn't be a bigginner's job but all you'd need to do is get the spacing right. The washer probably depends on the hub. My 10-speed isn't like that.

Ok, this wouldn't be a bigginner's job but all you'd need to do is get the spacing right. The washer probably depends on the hub. My 10-speed isn't like that.

I'm not sure what that ridge does on a 10sp. It may be that it lets the cassette fit closer to the spokes than a 9sp cassette. The washer/spacer is very thin metal.

Where can you buy a custom 14-30 10sp?

There is a similar new thread at the Roadbike Review Component forum. Someone posted that Cycling Dynamics now offers 10-speed cassettes with optional cogs larger than 27. But their 10-speed cassettes are not listed on the websites yet.

Al