yngwie

I have a trek 4300 (8 speed)
Im looking up to change cranks and all that are available are 9sp (truvativ-shimano 44-32-22)
>>>so can I just change the crank to 9sp (from a suntour 2sp setup) or should I change the whole drive system / chain /casette?
changing the BB might also be in the mix...

HillRider

Changing the bottom bracket if you change cranks is a given. Shimano 9-speed cranks are Octalink and Truvative are ISIS. Neither will work with your current square-taper type.

A 9-speed crank may not be real comfortable with an 8-speed chain and there may be some chain rub in certain gears. However, a 9-speed chain will work fine with an 8-speed cassette. If your cassette is nearly new, just get the crank, bottom bracket and chain. If it is old and has fairly high miles, get a new cassette too.

You could upgrade the cassette to 9-speed also but then you need to upgrade the shifters and that's where the real money starts.

yngwie

btw...I currently got a suntour crank mod>???
its got 1k on it sais so on the cyclo computer...
so I should get
1.9sp chain
2.crank 9sp
3.bottom bracket (howitzer)

+tools to remove BB

sounds good?
let me know...

tnx hillrider

capwater

So-called 9 speed crank could care less if the are 8 or 9 cogs on the cassette. The 8 speed chain is slightly wider, but the rings will work fine.

yngwie

so 8sp should work then... if not Ill order a 9sp chain just in case of serious rub...tnx

Butterthebean

Hill rider wrote: Changing the bottom bracket if you change cranks is a given. Shimano 9-speed cranks are Octalink and Truvative are ISIS. Neither will work with your current square-taper type.

I'm not sure where this information is coming from, but both Shimano and Truvative make square taper bottom brackets. Universal Cycles has 10 different ones...5 are Shimano and 1 is Truvative. My favorite one is the Sugino. A very nice looking finish and a good price. As long as your chainline still lines up with your new square taper crankset, you will not have to replace the bottom bracket.

https://www.universalcycles.com/shopp...hp?category=64

HillRider

Of course square taper bottom brackets are still available. That wasn't the issue.

The OP wants to use a 9-speed crank. A 9-speed Shimano crank requires an Octalink bottom bracket so the availability of a square taper isn't germain. I believe all of the 9-speed Truvative cranks are ISIS so, again the ability to get a square taper bb is not useful.

Butterthebean

I didn't quite get that from the original post. What I got was that he wanted to just change his crank...that he currently has an 8 speed setup and that all he could find was so called 9 speed cranksets. If I misunderstood, then I apologize.

With all due respect, I believe it is useful, because even if he does want to convert an 8 speed bike to 9 speed, he can still use the so called "8 speed cranks", can he not?

And if not, there are still 5 different Shimano, square taper, "9 speed" cranksets on this page which I had previously linked to.

https://www.universalcycles.com/shopp...hp?category=64

HillRider

I didn't get the idea he wanted to upgrade the entire drivetrain to 9-speed from the OP, just that he wanted to change cranks.

Anyway, your link was very instructive and quite right, there are indeed numerous "9-speed" square taper cranks still available. I had forgotten completely about the Suguinos. Sorry for the mis-information.

That said, it will be a happy coincidence if the OP's current square taper bb is the correct spindle length to match whatever replacement crank he chooses so a new bottom bracket is likely if not a certainty.

yngwie

thanks guys...
I was looking at Pricepoint...and was eyeing the TRUVATIVS ( I like these )...and currently have suntours on the trek 4300...(where can I find SUGINO cranks???) so thats my story...just concerned that the mileage on these tells me "change me now!" >>>they still pedal fine though but might get "optimum" performance with a newer crank set...(crank and chain)