Bicycle Mechanics - Upgrading components on Cannondale R600

We have a Cannondale R600 bike with the frame in perfect condition. Would like to change the shimano 600 8 speed cassettes, with the new ultegra sl either 9 or 10 speed, by changing both derailleurs, cassette, chain, and the STI shifters. I would not change the crankset, as I do not know what is involved. Any reason why this would not work?

The older 8-speed crank will work with the newer 9 or 10-speed components. The chainrings are spaced further apart so shifting may cause the narrower chain to get hung up between the rings if you try to shift under load. Shimano used to recommend "shifting while sitting down" as this limited the force on the chain.

You could install a new 9-speed inner chainring as Shimano closed up the gap by offsetting the inner ring's teeth toward the big ring.

The existing rear derailleur should work as well.

I'm pretty sure you can save some cash and buy either 9 or 10speed STIs, a 9/10 speed chain, and an inner chainring and be good to go. If it were me, I would spend the money on a new set of wheels/cassette. ....then again.. i'm a frugal fool.

Thanks folks, any special requirements for the inner chain ring, would most be compatible with the shimano 600 crankset. I really did not want to try to change the entire crankset. I do want to replace the shifters and both derailleurs.

Also, comparing pricing it appears Probikekit has most beat, as long as I can count on the exchange rate being what is listed

Thanks folks, any special requirements for the inner chain ring, would most be compatible with the shimano 600 crankset. I really did not want to try to change the entire crankset. I do want to replace the shifters and both derailleurs.
Any "9-speed" 130 mm bcd inner chainring will work. The most common sizes are 39 and 42T so pick the one you like.

I am still working on this as I can not find the ultegra sti 9sp double available on any website. I replaced the 8 speed cassette with an old 9 speed and it fit. What are the chances of going to a 10 speed. If I can use the 10 speed my options for the STI are better. From the time I have put in researching it would have been better to take it to a lbs.

Thanks for your help - we replaced the STI with new R600s that I found online, 9s ultegra cassette and chain to match. I did buy the 130 mm bcd inner chainring, but could not get the crank assembly off to put it on. So far so good. On this bike and mine own, I used the 12-27 cassette. The lower gear is a big help for old poops like me.

Also, comparing pricing it appears Probikekit has most beat, as long as I can count on the exchange rate being what is listed

I've done a couple of transactions with probikekit. The invoices I received by email are actually in GB pounds. Your credit card company converts this to your local currency (US$, etc.) at the time they receive the charge from Probikekit and that is based on the official rate at that moment. Therefore, the credit card company is responsible for the conversion rate. I have found PBK's conversion rates to be accurate though. If not, I really doubt (based on a lot of foreign credit card experience) it would be inaccurate by more than a very tiny amount, and it could go either way.

This is just like what happens when you use your credit card when traveling.