chain ring is a chain ring? double vs triple
 

can't get a straight answer from the mechanics so i shall post it here..

i'm looking to put a 36t middle ring on my rain bike's triple 50-44-28 at the moment but want a bit more useful middle gear

it is 110 bcd so it is a standard compact size but i wondered if it mattered what you put on the inside ring of a triple. front der. is friction shifting if that matters.

I think the reason you are having trouble getting a straight answer is because nobody knows.

I certainly don't know for sure. If I were to guess I'd say you will have difficulty getting it to shift from the 28 to the 36 because the 36 will be in the "shadow" of the 50. I'm thinking you might have to shift up onto the 50 and back down to the 36.

Not a clear queestion to begin with. Are you asking about the drop or pickup from a 36 to a 50, or are you asking about a 9 speed crank with an 8 speed ring and chain type question?

BTW, what is standard compact size? I thought standard was different pattern from compact, maybe I am just unclear of the way you worded it.:D

As long as the BCDs match I don't see a problem. Lots of compact cranks are 50-34, which is a bigger jump for the chain to make. Do double check on the BCDs, though.

It certainly should work. The jump up from your 28 to a 36 will be easier than your current 28 to 44. Going from the 50 down to the 36 should be no problem either. I've run a 50/36 for years on a 110 BCD crank, and it's worked fine with either a road or mountain front derailleur (friction shifting). If anything, I'd expect that your shifting will be even better than now.

edit: I'm not sure what the "double vs triple" part of the question is, in your title?

ok now i get 2 responses that i wasnt expecting and am now confused :) how does putting a smaller middle ring make it easier to mistakenly jump from the 28 to the 50. especially with a bar end friction shifter that i control the distance the FD moves..

i'll try to clear up the set up.. mtn bike/touring triple deore 50-44-28 7 speed rear cassette, bar end friction front, indexed rear.

mostly worried that the spacing between the rings will be correct. width wise.. and that as long as it doesn't have any funky ramps (which the sugino one doesnt have) it should be fine.

http://img.photobucket.com/albums/v1...0118002127.jpg

Edit: Simplify that is what i am hoping. The double vs triple part is some chain rings are labled as double 9/10 speed blah blah i was just trying to figure out if there was a major difference

I've easily gone from an 8 to a 9, and on another bike a new 10 speed crank (chainrings) that works perfectly fine with the 9 speed setup. No problem there.

What Retro Grouch is describing is that as the front derailleur pushes the chain to the right to go up from the 28 to the 36 the chain is coming in to the 28 at an angle. If all goes well, teeth from the 36 encounter the chain, hook it, and your chain is transferred over to the 36. With some front derailleurs it's possible that the chain encounters a tooth from the 50 first and up you go into high gear instead of the desired middle gear. This is more likely to happen when the small to middle ring tooth difference is small compared to the middle to large ring tooth difference. In your case 28-36-50 means 8 versus 14 which certainly has the potential for this problem.

Having the gaps reversed, large jump from small to middle and small jump from middle to large, does not have this problem and is used by the once popular half-step plus granny setup.

Have you tried asking in the mechanics area?

I get what he's describing.. i just don't understand how it shifts perfectly from 28 to 44 to 50 up and down on friction shifters and making the middle ring further from the top ring would make it easier to double shift. that would mean a larger throw while using a smaller movement.

anyway.. i think it will work and ride a lot more comfortably

Edit:

aight.. we're going for it. I got a Vuelta 36T 110bcd no ramps or crap ring and i'm smart enough to get the Park chainring tool so i'm not stuck going why the hell won't these bolts come out! :D i'll try to remember to post up on how it goes :)