nexus hubs
 

so what is the difference between the nexus 3 and the other nexus hubs? is the high gear and the low gear the same in all of them, with more gears in between? that is what the nexus rep told me. thanks for any info.

No. The more gears, the more range. An 8 speed Nexus has a little less than double the ratio range of a 3 speed.

Not true, Nexus 8 has both lower and higher gear ratios than 7 speed. 2010 Tech manual.

ok the tech at nexus told me. compairing the nexus 3 to the nexus 7. gear one is the same on both hubs, gears 3 and 7 are also be the same, and gears 2 and 4 would be the same as a single speed bike. so the difference is that there is less of a dramatic change in gears with the nexus 7. also that the best way to get to a higher or lower gear is changing the front sprocket.

Well, the numbers might sound like they are close, but the difference is substantial. A Nexus 3 speed has a low gear of .732, direct in second and a high gear of 1.36. The 7 speed has a low gear of .632, a high gear of 1.545, and no actual direct gear,although 4th is very close to direct. The 8 speed has an even wider spread.
It's enough to make a lot of difference if you ride any hills.
It's cheaper and easier to change the rear sprocket than the front.