After reading all the compact etc. stuff it got me looking at my gearing and chain length.
Currently running the standard 53/39 with a 12/25 and have run a 12/27 in the past.
Very hilly where I live but don’t grind too bad with a 39/25 and don’t like the spacing of a 12/27 cassette.
I looked at using a 52/38 with an 11/25 and it seems it would give me a slightly easier gear for climbing than a 39/25 but at the same time give me a bigger gear for the downhill with the 52/11 versus a 53/12.
Do they make 52 and 38 combinations for Shimano 10 speed?
Yes, the question makes sense, and all cyclists should ask it. What is the best gearing for me?
The change from 53/39 with 12/25 to 52/38 with 11/25 would have the following effect: Big increase in your big gear: 53/12 to 52/11 takes your GI from 119.2 to 127.6. This is the major change, you get a much bigger top gear. Small impact on your little gear as you go from 39/25 to 38/25 and change from 42.1 to 41 gear inches. I looked at the Shiman web site, and there does not appear to be a 38 front chainring for either Dura Ace or Ultegra, and they do not make an 11-25 cassette.
How about this suggestion? Change to a compact crank with a setup for 50/34 chainrings and 11-23 cassette. Compared to your 53/39 with 12/25, here is what you will acheive / gain: Moderate increase in your big gear: 53/12 to 50/11 takes your GI from 119.2 to 122.7. So, you still get a bigger gear than you had, which seemed to be one of your goals. Moderately easier lower gear for climbing: 39/25 to 34/23 takes your GI from 42.1 to 39.9, and gives you a little more to spin up hills with. Better gear spacing, which is narrower and not as “jumpy” as the 12/27 that you don’t like.
So, with a compact, you can acheive your goals. If you can climb with a 39/25, then you’ll climb even better with a 34/23, and you’ll have a larger big gear as well. You improve on both ends, and you never need to change your setup (swapping out to 12/25 or 12/27) unless you want to climb steep and long, then you can put on one of the other cassettes if you want that extra “anesthesia” gear.
I have used a 52 on the front for years. Reason - it allows me to make better use of those middle gears on the cassette and keep it in the big ring longer. I run a 39 inner ring and use a 12-25 cassette in the back. Unless it’s a monster, long and steep climb I can usually I am fine with the 39/25 as my smallest gear.
38T and 52T chainrings that will work with 10s Shimano cranksets are available from FSA. I don’t think FSA chainrings shift quite as smoothly as Shimano, but they are good enough.
I looked at the Shiman web site, and there does not appear to be a 38 front chainring for either Dura Ace or Ultegra, and they do not make an 11-25 cassette.
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FSA makes a 38 compatible with shimano. Had no problems using it.
*So, with a compact, you can acheive your goals. If you can climb with a 39/25, then you’ll climb even better with a 34/23, and you’ll have a larger big gear as well. *
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I used a compact and while it was awesome on the hills I positively hated it on the flats. Most of my riding is done at speeds around 28-33 kmh (17-21 mph) and the 50-34 combo results in huge shifts in that speed range.
Thanks, they say it’s doesn’t work with D/A 7800 hubs. I run 10 spd but I don’t think my hubs are D/A - Mavic Kysrium wheels. Don’t know what hub body they have.
That 11-26 SRAM or 12-26 might be the ticket. The SRAM has only a 3 jump on the last cog (21/23/26) and the Shimano has two 3T jumps (21/24/27) and no 3T jumps on a 12-25.
The SRAM 11-26 just drops out the 16. Interesting.