i have a 89 cannondale s600 and i was wondering if i can put on a new crankset with out replacing everything else

What is "everything else"? If you stck with the same number of rings, shifter and FD should be fine. BB is determined by crankset so, unless you find a crankset that has the same interface and same spindle length, you'll need a new BB.

byt everything else i mean derailer's and cas...i just wanna replace the crankset inculding the bb clearly,...so basicly everything everything stays what i have but the crankset and bb

As long as you are staying near the dimensions of what you have. Are you going from a double to a triple?

what do you mean?the number of sprckets on the crank?

Yes, that's what he means (I'm pretty sure, feel free to correct me if I'm wrong.) As long as you replace the crankset with the same number of rings you have now all should be fine with a few notable exceptions:

- If you try putting a 9, 10, or 11 speed crank on your bike your 7/8 speed chain will probably be too wide and it won't work well.
- If the outer ring is a lot larger or smaller than what's on there now the FD might not shift as well as it used to.
- You need to make sure whatever you get doesn't screw up your chainline. https://sheldonbrown.com/chainline.html

Finally, typing with at least some clarity helps us so we don't have to decipher what you've written...

sorry,i was posting from my phone earlier.
ok imma check my tooth count tonight on my outer ring to make sure it will work and if the chain is 2 wide would i be able to just get a newer chain?

You could get a crankset of the same vintage as your current one ... ie, NOT 8-9-10 speed crank.
That is the simplest solution and eliminates all the guessing about various compatibility options.

I have not tried a new narrow crank on an older drivetrain, so not sure if the old chain will work. If you go with a narrow chain too, I guess it would work with your freewheel. However, if your freewheel is old and worn, the chain may skip, so you'll need a new freewheel too.

Edit: Could be a cassette as Jeff pointed out below.

You need to add more details- exactly which Cannondale are you working on, for instance? I looked at the 1989 Cannondale catalog: https://66.147.244.179/%7evintagm8/year/1989/1989.pdf , and there's a "SM600" mountain bike, a "ST600" touring bike, and a "SR600" racing bike. Telling us which one you have will allow us to zero in on an answer quickly.

All of those bikes used Shimano cranksets, bolted to standard square-taper bottom brackets. All have 7-speed rear cassettes, so you should probably pick an "8-speed" crankset to insure compatibility. You could install a "9-speed" or "10-speed" compatible crankset and have it work fine, but crankset compatibility can be fuzzy.

Why are you replacing it? Cranks from that era were quite good, and are highly prized by some folks. I wouldn't replace it just for the sake of replacing it.

Agreed. If it just needs new chain rings, replacement rings should be readily available.

its an 3.0 sr600,it has suntour cranks not shimano and they are ugly as hell

OK... Ugly cranks aren't a deal breaker. Your Suntour cranks* are square-taper, so you don't necessarily have to replace the bottom bracket. However, it would be a good idea to do so since there are other issues with bottom bracket length that need to be dealt with.

Back to your original question: yes, you can replace your Suntour crank and bottom bracket with a more modern crank and BB and not change anything else. You will want to buy a road double crank with a 52 or 53 tooth large chainring, 8-speed compatible and matching English thread bottom bracket. Sell your old cranks and BB on Ebay.

*The Cannondale catalog says a 1989 SR 600 had a Shimano 105 crankset. By 1989, Suntour had all but disappeared. I think your bike is from a year or two earlier.

If you really don't like the look, feel free to send it my way. I'll take it off your hands.

it is for sure an 89 i think the cranks were swaped out,i got the bike used.
these are what i wanted to swap to
https://www.nashbar.com/bikes/Product...0052_514570_-1

That's definitely a 10 speed crankset, so I have no idea if your current chain would work with it, or if a 10 speed chain would work with your cassette/freewheel. You could, however, swap some older chainrings onto that crankset and be 100% set.

if that would for sure work,id be happy with that...would i replace both chain rings or just the big dog?

Usually it's the smaller chainring that's changed to move the teeth closer together. Change it instead.

My opinion about cranksets: many of the them from the late '80's/early '90's are much prettier than newer ones. The current two-piece type strike me as very clunky and chunky, but they might look OK on your large-tube Cannondale. I don't like black cranks- they are too easily scuffed and scratched. At least silver cranks hide the scratches more better.

ok will do,i agree with you to some extent but i find the more sleeker and dark look of black parts esp with a white frame

That crank should work just fine. I made a similar change to a mid 80's 7 speed Trek. In my case I wanted to change gearing and decided to put a modern 10 speed compact crank on the bike. I changed nothing else except lowering the front deraileur to match the smaller crank. I had no issues at all with chain suck or shifting. In fact, because of the ramps and pins, front shifting as vastly improved over the old cranks with flat chain rings.

Go for it!

8spd cranks are the same dimensions as 5spd ones IIRC. 9, 10, 11 are the narrower ones.