corwin1968

I have a 1995 hybrid that I plan to gradually retro-fit into a nicer bike. The current crankset is a 42/34/24 Alivio. Assuming the chainrings are replaceable, would replacing the 34t ring with a 38 work, given the sizes of the other rings? I don't know if having two so close in size (42/38) would be problematic. I've thought about just replacing the whole crankset but I rarely use the outer ring so I'm not too concerned about it's size and if I can get a 38 on the middle I think I'll be happy.

Also, would most or all Shimano trigger-style shifters work ok? What if I went with a road crankset, like Tiagra. Would Shimano trigger shifters work with it?

Thanks!

HillRider

The 38/44 combination would probably interfere with the inner cage plate of the front derailleur unless you raised it well above the outer chainring. Most newer front derailleurs are designed to work with a difference of about 10 teeth. Yours is only 8-teeth but 4 teeth is likely to be a problem.

corwin1968

I saw the "custom crankset" thread before this one and saw the same info there. I know very little about bicycle mechanics but thought there might be some issues like this involved. I think I may just spring for 50/39/30 crankset and call it good.

Bill Kapaun

I've done something quite similar.
My 2 cranks were 22-32-44 and now are 22-32-36 & 22-32-38.

The FDER has to be set quite high (about 1/2" or so) above the big ring or else it'll hang up on the middle ring.
Everything shifts much better than expected.

Myosmith

Are you sure you have those ring sizes correct? Maybe Alivio comes or once came with with different ring sizes but the two current configurations I've seen are 48-36-26 and 44-32-22. Both are well spaced for most applications. I have the 48 on my touring bike and will be putting the 44 on my trail bike (It came off of my former MTB). Pairing either with a 13-24 cassette will give you a good general purpose setup.

If you really want maximum range of gear choices, pick an 11-28 cassette paired with the 44-32-22 and you'll have road worthy top gears to super low climbing gears. I assume by "hybrid" you mean 700c. According to Sheldon Brown's gear calculator with a 700x38 tire and 44x11 top gear, your speed, at a cadance of 90, would be about 29.2 mph. That's just a hair higher than my road bike which is set up with a 53x13 max gearing for 28.8 mph at 90 cadance. On the bottom end it gives you a 0.78:1 climbing gear that should allow you to just about climb a wall at around 5 mph.

corwin1968

I got the chainring sizes from the 1995 Trek catalog on vintagetrek.com so unless it's a misprint it's correct. My riding is pretty much all done in the middle chainring on mostly level ground. The bike will be used as a fitness bike for spirited sub-1-hour rides on a well maintained multi-use trail. I'm wanting a 38t middle ring because it just feels better to me than a 34 (the 42 is a bit too big for my all-purpose ring). I also plan to use a fairly narrow range cassette so I can fine-tune my cadence without the huge jumps I have now. At the same time, I will ocassionally ride someplace where I need a decent granny ring so I'm wanting to stay with a triple for those occassions. If I could find a decent quality (say Tiagra level or so) 48/38/28 crankset I would be good to go. The only 48/38/28 I've found is a $20 crankset and I want something better for my primary bike.