KtownScott

I was going to switch my 8speed rear cassette to a 9 speed. I know I have to change my shifters to 9 spd but do I have to change any of my rear derailleur?

frantik

i think if you have indexed shifting you might have to change how that is set up.. i have grip shifters and they only support 7 gears. if you just have friction shifters it shouldn't matter, but i'm sure someone more knowledgeable than i will sort you out if i'm wrong

badger1

Shouldn't be an issue; the indexing is in the shifter, not the r/d mechanism. So long as that has a long enough cage to take up the chain (depends on front/rear gearing combination), and you ensure the high/low stops and (then) cable tension are set correctly, you're good to go.

AdelaaR

You cannot simply change one thing in your drivetrain to more gears and assume it'll be fine.
The cassette and shifter can be changed and it will kind of work ...
BUT:

-your chain will be too wide for your cassette and so you'll need a new 9 speed chain.
-your front chainwheels will be too wide for your new chain and so they will possibly start damaging it.
-your front derailleur will have a cage that isn't suited for your specific chain anymore and so it might not shift smoothly anymore.
-your rear derailleur will also not be made for your new chain and possibly have issues.

Bottom line: a drivetrain should consist of parts specifically designed for a certain amount of gears on the cassette ... you shouldn't interchange between the various systems.

oban_kobi

Just curious why you want to do this. What will one extra gear gain you?

Burton

I really have to agree with this post. You can pretty much go from a 5 speed to a 6 speed to a 7 speed to an 8 speed without issues because the chain with is the same for all of them. Unfortunately as soon as you start talking 9 speed the chain size is different and all components in the drive system are designed accordingly. So your rear derailleur for example, would have the throw to handle the extra cog, but the idler cogs wouldn`t interface well with the narrower chain.

Not sure what you hope to gain. This is a situation where the conversion would be expensive (probably more expensive than a new 9 speed bicycle) and the advantages questionable. All those 9 speed components are more expensive, built to closer tolerances, more fragile and have a shorter life expectancy.

Personally if I was on the market for a `new` bike I`d be looking second hand so I could buy an 8 speed or 7 speed and avoid the 9 and 10 speed complications. But I guess thats just me.

oban_kobi

^ That. You don't need nine gears anyway. If you want to go faster, buy a smaller 8 speed, or a larger crankset. If you're in ridiculous hills, do the opposite. Way cheaper, and more effective.

KtownScott

Thanks for all the great info. I had no idea that there was that much to it. The reason I was considering the change was I ride with a guy that has a mendota and he seems to pull from me on hills and his has a 9spd rear cassette. I just was browsing ebay and saw I could pick up the very same one for a little bit of nothing. Just tring to do a little upgrading but if it's all that I will pass.

Sirrus Rider

If he's pulling away then his motor is more effective than the one your running on your bike..

KtownScott

No that is not the issue. After I posted eariler I knew I was going to get that response.
I left the door wide open. I will just stick with the 8spd and live with it.

qmsdc15

Is the gap between your gears too great? One gear is too easy, but the next one is too hard? Shift your front derailleur. Your biggest cog paired with your middle chainring is probably a little bigger gear than your small ring and the second biggest cog. Your small ring and third biggest cog is probably a little bigger gear than the middle ring/biggest cog combo.

So there are gears on your other rings that fit between the gaps in your middle ring, but honestly, an eight speed cogset has lots of choices, with small gaps between the choices even without shifting the front derailleur. It might not be the engine, but it's certainly not the extra gear that allows your friend to pull away on the climbs.

AdelaaR

Other option: get a close range 8 speed road cassette to have more usable gears on hills.

khutch

I think the difficulties of the switch have been somewhat overstated. It is not a plug and play swap but it certainly could be done if you are determined. Getting an 8 speed cassette with a gear range more suited to what you are trying to do (as has been suggested above) would be a plug and play swap and may solve your problem. I would not discount the possibility that your riding buddy is a better hill climber than you however. We never like to admit such things but it is possible. That's between you and yourself so if you want to try to keep up with him by re-gearing then you need to find out what gears are available on his bike and what gears he is using when he pulls away from you. Then you can adjust the gearing on your bike by swapping out gears on either the cassette or chainring(s) to give you the same gear range he has. He will have a slightly finer jump between the available gears in that range, you should be able to match the overall range pretty closely. This assumes that you both have the same number of chainrings, if he has three and you have two then matching his range will be harder and his gear spacing could be considerably finer than yours. If you both are running the same sized wheels then all you need to do is to match the range in tooth counts that he has (assuming your derailleur has the chain wrap capacity necessary). If you are running on different sized wheels then you need to calculate his gear-inch range and match that on your bike.

Ken