I may have made a mistake with SRAM. I have a 10 speed Rival group on my cx bike, and wish I could find a larger cogset. I do not plan on cx racing, just going up and down hills in the woods. I already have a 34 chainring, and I wish I had a 32 or 34 cog in the rear. My current 11- 28 is not enough. I don't believe I can buy a larger cassette from SRAM, right?

Please help.

you can use shimano cogsets.

Nope. Shimano doesn't make those either, for road bikes! Nor Campy.

If you can get a custom 10-speed cassette built for Shimano, though, that will work with SRAM too. I know people do this by taking apart MTB cassettes or something, but I don't recall where they get 'em.

You want 1 to 1 on a cx bike? Can't you just run up it?

I'm curious. What percentage in grade are the hills you are trying to climb where a 34x28 isn't cutting it? How would you rate your fitness level?

SRAM doesn't make an 11-28 10 speed cassette so I,ll assume you have an 11-26 which is the largest big cog they make in 10 speed but any shimano splined 10's cassette will work with your rival group, miche make cogs from 11t to 30t for 10 speed so 26t to 30t would be a big jump from your current cassette and would make a big difference on those killer hills, I'm about to order one myself for my road bike to get a more usefull gear selection I currently have 12-27, 50-34 rings & going to 11-27, 48-33 rings. 11-13-15-16-17-18-20-22-24-27. Hope this helps and you figure out what you need.

I may have made a mistake with SRAM. I have a 10 speed Rival group on my cx bike, and wish I could find a larger cogset. I do not plan on cx racing, just going up and down hills in the woods. I already have a 34 chainring, and I wish I had a 32 or 34 cog in the rear. My current 11- 28 is not enough. I don't believe I can buy a larger cassette from SRAM, right?

Please help.

For off road you may indeed need more than that. What kind of bike is it? You may have to go with a mountain bike cassette (then check that your dérailleurs will handle the new gearing.) For what it's worth, I've got 30-34 low on my mountain bike, and you have to spin pretty fast to attain walking speed. It's great for steep dirt trails- by the time you're having trouble spinning the front wheel is starting to bounce around and it's getting ready to go over backwards, so it's out of the saddle or bail time anyway.

Edit: Wait, do they even make ten speed mountain bikes? I wonder if you can go custom? It might be easier to just swap over to nine speed and put the Rival on a road bike.

To answer some ?'s, my fitness level is very good, the bike is a tricross, and the dirt road sections that I will need this gearing on is very steep, and SRAM does make a 11-28 10 speed cassette. The others that I ride with use 46x34 with a mtn bike 9 speed cassette with 34 as their largest cog.

I think I will use California L33's suggestion and move the SRAM to the road bike, and my road bike's 9 speed ultegra to mt cx bike, then buy a mtn bike cassette.

Thanks for the help.