You can use this with an 8sp setup and it will work pretty good. If you want it to work better then use a 9sp chain, which will work with an 8sp cassette just fine. The only concern with that is that the cassette isn't too worn out and mated to the chain that's currently on there.I also own an old steel frame that I truly love and one thing to consider is that a stiffer crankset will only expose how "soft" the steel has become in your frame. You can check this by standing next to your bike and tilting it away from your body. Put the pedal closest to you in the 6 o'clock position and step on it while looking down at the bottom bracket. Check for flex in the frame or crankset.

Good question. A 172.5mm crankset is usually speced' with frames in the 54 - 56 cm range. The difference is pretty small but bike fitters often suggest different crankarm depending on your body structure. Not knowing how tall you are it's tough to say. If you have a long torso (short leg) you may want the 170, if you are average to longer legged use the 172.5.

Not a dumb question at all. Yes, this will work on your Felt S32.

Should be listed as 53 x 39.

Yes -- there's no major difference between 10 speed and 9 speed chainrings and cranksets.

Item # SHI0164 is the BB that fits with this also, Integrated doesn't necessarily mean "included".

in⋅te⋅grat⋅ed [in-ti-grey-tid] –adjective1. combining or coordinating separate elements so as to provide a harmonious, interrelated whole2. organized or structured so that constituent units function cooperativelyYup, insert bottom bracket and crank somewhere into those definitions. KC

The packages Backcountry has in stock are actually labeled 39x52.

The chainring size listed above is 52x39, which is not right. This is a standard 53x39 crankset.