New answers tagged drivetrain
If you can, find the approximate gradient of hills you want to climb/train on and estimate your power to weight ratio. For 7% climb 34/25 (front/back) is good combination if you have power weight ratio >= 4. With less power, or more weight/load, just get the biggest cassette allowed by the rear derailleur. This way you can maintain about 60 rpm or higher on ...
The difference between 28 and 30 is only about 8%. If you climbed a hill at 70 RPM on a 28, you would only be riding at 75% on a 30, and your force would only go down a little bit.
It's actually kind of tough to say whether or not that's an exact match based on the model numbers alone because Shimano often makes a couple variations of a given model. However, cranksets are more or less universal (at least, more so than things like shifters and derailleurs). There are only a couple of things that you need to watch out for. You need ...
First, about the big steps between gears: you should really go on a test ride to see how you like shifting on a bike with such big steps between gears. For some people it's not a big deal, for others, it's a major annoyance. I don't think anyone else can make that kind of qualitative decision for you. Using Sheldon Brown's Gear Calculator, I calculated some ...
If you're looking to expand into some workout/exercise riding, you don't necessarily need to go as high as 30 or 28. When I run a 50/34 crankset with just a 12-23 cassette, I find that I can still make it up just about any hill, and you probably already put in more miles than I do on your touring bike. So I think you'll find great success with a 12-25.
The large chainring in the picture looks very worn out. Usually by the time teeth on a ring are "shark-toothed"- or very pointed- the chainring is completely shot. However, it's likely that unless you've been replacing your chain regularly that all the other drivetrain components (chain and cassette) have been worn beyond use as well. You should get a chain ...
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