Equinox

I have a Trek 1000 with the Sora drive train. Could I just take the granny gear off and adjust the front derailleur?

Little Darwin

Or just leave it there and don't use it...

Yes you can do it, but your chain line will not be quite as perfect as if you went to a true double. Plus your second chain ring might be a bit larger than if you had a traditional double, so your low gears won't be as low as they might be.

Just out of curiosity, what do you hope to accomplish?

Equinox

save a little weight. just for something to keep myself occupied during this snowy weekend.

BostonFixed

1. Remove leetle chainring.

2. Crank low limit stop on front derailleur down so ya cannot shift to the leetle chainring spot.

HillRider

1. Remove crank fixing bolt

2. Remove drive side crank arm

3.. Remove granny ring.

4. Adjust inner stop on front derailleur

5. Save 30 grams.

sydney

Put in a shorter spindle BB,save a few more grams and the chainline won't blow.

TallRider

Yeah, you should get a new bottom bracket so the crank will be closer to the centerline of the bike. Maybe 5mm shorter bottom bracket?
If you like this and it keeps you busy, have at it. But saving weight is not a meaningful reason to do this, especially given that you're riding a Sora-equipped bike.

DannoXYZ 

Well, 5mm shorter on the right side. This moves the center between the two chainrings roughly into the position of the earlier middle-ring and lines it up in the middle of the cogs in the rear. However, to preserve even pedal-distance from the bike's centerline, you'll have to shorten the left side as well. So 10mm total. It's typically between 8-12mm depending upon how optimal the original chainline was with the triple.

Due to the angular swing of the FD, you'll need to raise it up about 2-3mm as well.

BostonFixed

Why don't you replace the FD to a 'true' double version to save a couple of grams while you're at as well?

sydney

Then ditch the dorky long cage RD and save even more.Then swiss cheze the frame.

cydewaze

Then take a dump and save twice as much as the parts you removed weigh.

oboeguy

Heh, I was thinking the same. In fact, that's what I think whenever my eyes start getting the "upgrade glaze".

Al1943

Save your money for a better bike.

Equinox

I just wanted to have a little fun and feel like an amateur wrench.

capwater

Use one water bottle instead of two and save big weight.

I see where you're going and we've all been there. Don't spend big bucks (or any bucks), just ditch the granny ring and adjust the FD. Any expense will not gain you anything. Now if you wanted to really do it right you'd need a rear der, new cranks, new BB ..... more than it's worth. Better suggestion, just don't shift into your granny and don't look down (you'll never know you're riding a triple!!!

Coyote2

Whenever anyone posts a "I want to convert my triple to a double" question, several people suggest that it is a useless endeavor. After moving from the mtns to the plains, my triple's smallest chainring was totally useless, so for a total of $260 (I shopped very carefully) I converted to a double -- new crankset, BB, FD, RD. My drivetrain is now marginally lighter, has a slightly better Q-factor, and there is far less chain rub than before, and that's worth the money, to me. So if you want to do it, Equinox, I say go ahead.

Goldnblazer

That sentence tells me that it would be worth it. You will learn a lot about the bike and pick up some good skills that can be used later. If you can learn to do a lot of work yourself then you will feel that much more pride in your ride.

It may not be cost effective to do it, but learning new skills and having a little fun with it, makes up for that.
That is just the way I look at it.

Mike