Lets talk gears!
 

I have a GF Tiburon, with a stock gear set Crank 48/38/28, and a cassette with the 13-34 7 speed. Now that I have road my son’s road bike I was thinking that this may not be the best gear combination for me. I like the seating position of the Tiburon, but I like the gears of the Trek

I usually start out in the 2nd sprocket, and go up from there. I never use the #1 sprocket, nor do I use the 34gear on the cassette. This is making me wonder if I would be able to upgrade to a 30/42/52 crank, and a 13-24 7 speed cassette.

What would be the problems I would get into, and what benefits would I gain by doing this?

Why not just try the cassette swap first? I'm not sure what a GF Tiburon is by the way. I thought a Tiburon was a Korean (fake) sportscar. Anyway, if you have the 13-24 7 speed cassette, go ahead and put that on and try it out. You may have your problem solved right there if you're satisfied with a 48X13 top gear which I think is the main limitation for road use. Do you attack downhills? Which brand 7 speed cassette do you need? You may be able to get one with a 12 tooth small sprocket, the 48X12 is just a little better. The gear inches are a little steeper if you have 700c: a 48x13 = 99.7, or a 48x12=108.0 gear inches. If you are talking 26" wheels the gear inches would be slightly lower.

Agreed. A 48/12 combination gives you the same gear ratio as the 52/13. Changing cassettes is pretty trivial. Changing cranks is less so, especially since you'd have to move the front derailer up to accommodate the larger chainring. I'd suggest a 12-27 instead of the 12-24 however. It's nice to have a low gear when you need it, even if you don't need it all the time.

If you want you can run all kinds of gear ratios at Sheldon Brown's site. Calculate to your heart's content:D

I am on the band wagon for doing a cassette swap to get some higher gearing. Swapping cranks could get more expensive and there may be some trouble with your FD.

That sure makes a lot of scence, but is there a 12-27, or 12-24 in a 7speed? I only looked at Nashbar, and the best they had was the 13-24. Plus what is involved in doing something like this?

The GF Tiburon is a Garry Fisher Tiburon S. I have upgraded the tires to a 700-28 at 90lbs.

I will be working on upgrading my web page this weekend, and I will put some cool pictures of it on there.

Harris Cyclery sells a 12-28 for $30. Loose Screw sells the same one for $25. Bikeman sells one (and list a whole bunch of others ranges) for $27.

Here's a step by step guide to removal and replacement of the cassette. Pretty simple actually.

Hope this helps.

Sweet! Gary Fisher sounds much cooler than a Hyundai.
I am assuming that your cassette is a Hyperglide 7 speed. If you type "7 cassette" into ebay you'll find some that might fit your requirements. I didn't see any 12-24's or 12-23's though. If you check a couple of times a week, within a week or 2 you'll find what you need, and usually pretty cheap. Don't know your brand of crank, but if you find out the bolt circle you could get a compatible big chainring and increase the teeth slightly.

The 12-21 from bikeman sounds sweet. The tighter cog spacing is better for road applications. With a 28 tooth small chainring in the front you've still got a 28x21 climbing "granny" gear. This is 36.0 gear inches which is pretty darn low, in my area this will be sufficient for even the steepest climbs. You might need lower for towing a trailer or loaded bike camping.

The closer ratio cassette will give much slicker shifting and you will probably find it easier to get the right gear for your comfort. With the small ring you will still enough low gears for little hills and monster headwinds, when you are totally exhausted

I think I am starting to understand. I will change the cassatte first, and see how that does.