very novice part swapping question...

[abejita]

Ok, I've only been cycling since last summer and this is my first attempt at minor upgrades on my bike and would like advice.

I have a friend who upgraded his cassette and crank and gave me the parts he replaced. I have all 105 components on my bike except for a FSA crank. I would like to swap out his cassette with mine because it would give me an extra gear to help on the hills. His cassette is 12-27T and mine is 11-25T. They are both 105 cassettes so I don't forsee and issues with this.

My question really more concerns my husband's bike. He has sora/tiagra mix on his bike. He wants to put my 105 11-25T cassette on his bike and a FSA Gossamer crank on his bike. The problem is that his bike is 9 speed. I am not sure that these new parts are compatible and if there will even be increased performance from these parts if he can use them. Any opinions?

[OakLeaf]

Shimano steel freehubs are compatible with 8-, 9- and 10-speed cassettes, so that shouldn't be a problem.

The reason for that is that the cogs are different widths. So a 10-speed cassette requires a 10-speed chain and a 10-speed shifter. I'm not 100% sure whether chainrings are also different widths.

When you swap your cassettes, you may have to adjust the B-tension screw on your RD to keep the jockey wheel from contacting the 27T cog. (I did when I made the same swap.) Shimano has service and adjustment instructions for all their components on their website.

[abejita]

Ah, ok...so hubs will not be able to use the 10 sp cassette because he has 9 sp shifters?

[Cataboo]

the 9 speed shifters won't work with the 10 speed cassette - he can use the gossamer cranks no problem

[abejita]

When you swap your cassettes, you may have to adjust the B-tension screw on your RD to keep the jockey wheel from contacting the 27T cog. (I did when I made the same swap.)

Did you notice a difference when you went from you 25T to the 27T cog? Is it worth swapping them?

[OakLeaf]

Those two teeth make all the difference in the world to me when the grade is over 15% or so.

And he CAN use the hub, he CAN'T use 9-speed shifters with a 10-speed cassette.

[abejita]

And he CAN use the hub, he CAN'T use 9-speed shifters with a 10-speed cassette.

LOL, I always call my husband 'hubs'...there is not a new bike hub in the equation...sorry!

[lph]

You can put an 8, 9 or 10-speed cassette on the same hub (wheel). They're the same width. But to fit more sprockets on the same width, each sprocket gets narrower and the distance between them gets less as you go from 8 to 9 to 10. Therefore you will need a specific 8, 9 or 10 speed chain to fit the sprockets.

The rear derailleur doesn't care how many sprockets you have, it just moves as much as the shifter on the bars tells it to. The rear shifter, on your bars, does care. It's indexed to 8, 9 or 10, and if you want to swap your cassette to one with more sprockets you also have to swap your shifter.

With my limited experience of road bikes, and if I have understood Sheldon Brown and my LBS correctly.

[ridebikeme]

Great advice everyone!;)

If indeed you make the swap, the one thing that could also pop up is the wear on the new cassette vs your chain. If either have a fair amount of wear on them, you could get skipping/poor shifting as a result. So, if you find this happens, it easy to fix with a new chain.:D