Bicycle Mechanics - 10 speed/ 8 speed compatibility

Hi, I need a bit of advise about compatibility. I currently have 8 speed Shimano Sora on my bike, but would rather have 10 speed 105. Is it worth my replacing it a bit at a time, as I get parts cheap (I'm a bit broke at the moment), or ill it not work?
I was wondering if I get a new rear derailler, would a 10 speed work OK on my 8 speed block? And will a front derailler for 10 speed work OK with the 8 speed shifters and chainset, or is the spacing different? For that matter, will a 10 speed chainset work with an 8 speed chain and derailler?

If these parts are fairly compatible, I was thinking I could replace it a bit at a time, and get the shifters and 10 speed cassette last of all, when I'm a bit less broke.

You won't need to change derailleurs at all.
What you will need to do is change shifters, cassette and chain at the same time.

Hi, I need a bit of advise about compatibility. I currently have 8 speed Shimano Sora on my bike, but would rather have 10 speed 105. Is it worth my replacing it a bit at a time, as I get parts cheap (I'm a bit broke at the moment), or ill it not work?
I was wondering if I get a new rear derailler, would a 10 speed work OK on my 8 speed block? And will a front derailler for 10 speed work OK with the 8 speed shifters and chainset, or is the spacing different? For that matter, will a 10 speed chainset work with an 8 speed chain and derailler?

If these parts are fairly compatible, I was thinking I could replace it a bit at a time, and get the shifters and 10 speed cassette last of all, when I'm a bit less broke.

You're spending a *lot* of money to gain 2 extra gears - do you really need it?

you're spending a *lot* of money to gain 2 extra gears - do you really need it?

+1

No, I'm not after the gears, that's neither here nor there for me. I think the thing with the gears is like the extra blades on the razors- just marketing.

I want 105 because it seems a much more robust groupset than Sora, and the shifters have much better ergonomics. I've taken to riding stretched out on the hoods a lot, when time trialling or leading along straight roads.

I replaced the brakes already, as the ones that came with the bike were falling to bits, and the 105 ones are SO much better. I was locking the wheels up at first, I'd got so used to gripping like a bear!

The rear derailler is getting quite wobbly, so I was thinking of replacing that soonest- will it work with my 8 speed cassette? Then I have more options later when other parts wear out, to get the rest of the 105 whatnots. I'm starting racing, so I'd like to have a groupset that's a bit more comparable to what everyone else who races is using, I get the impression that Sora isn't really aimed at weekend racers.

if you are starting to race, you are better off riding with your sora until you get better or start riding in a more advanced group. Perhaps I'm being overly cautious, but why would you want to dump money into a bike only to crash it in a beginners race.

On that note, if you really are thinking about doing this, all you need to do is replace the STIs, cassette, and chain.

The biggest disadvantage of Sora is not being able to upshift the rear from the drops. This didn't bother me much at first but has become more and more annoying, especially after a few long rides on my Ultegra 10 equipped bike.

If you wanted to a piece by piece replacement, this is how I'd do it:

1. rear derailler (won't care how many speeds you are running)
2. front derailler and chain (FD cage is more narrow for 10 speed and won't work well with an 8 speed chain)
3. STI's and rear cassette (if you really wanted to break it down you could just buy the right side STI)
4. crankset (unecessary really but might improve front shifting performance)

Thanks for the advise everyone. I doubt I'm going to wreck any parts of the groupset in a crash- most likely the wheels (done that before). I'll keep my old wheels on when I race at the local crit!

Thanks for the advise everyone. I doubt I'm going to wreck any parts of the groupset in a crash- most likely the wheels (done that before). I'll keep my old wheels on when I race at the local crit!

The shifters area common casualty in a racing crash

So does this mean there's no difference in chainring spacing between 10 speed and 8 speed? So you could use a crankset for 10 speed with an 8 speed setup, or vice versa?

I believe you will have to change the inner chain ring of a double to suit the 10 spd chain.

The biggest disadvantage of Sora is not being able to upshift the rear from the drops. This didn't bother me much at first but has become more and more annoying, especially after a few long rides on my Ultegra 10 equipped bike.

I've got Campy on several of my bikes. Their thumb shifters are close to Sora. Even though I have a very small hand, they shift great. Is Sora really that bad?

So does this mean there's no difference in chainring spacing between 10 speed and 8 speed? So you could use a crankset for 10 speed with an 8 speed setup, or vice versa?

The three cranksets currently sitting in my basement, one each of 8, 9, and 10 speed, all have the same chainring spacing (at least within a few tenths of a millimeter). The only difference I have seen when going from 8 to 9 to 10 speed rings is the shape of the ramps. They are significantly more pronounced on 9 and 10 speed rings to pick up the more narrow chain, and also to keep it from going in between the chainrings. As such, the wider 8 speed chain will interfere with these ramps if trying to one with 9 speed rings (personal experience). I do not have any experience running a 9 speed chain on 10 speed specific rings though many rings are labelled for both.

I've got Campy on several of my bikes. Their thumb shifters are close to Sora. Even though I have a very small hand, they shift great. Is Sora really that bad?

I've never used Campy shifters but in discussions with Campy users the difference in thumb buttons is that the Sora button is higher on the brifter putting it out of reach of a normal cyclist's thumb when in the drops. Campy's button is within reach.

Getting another bike is usually cheaper than piece-by-piece, but end of season sales are your friend. Nashbar has an amazing deal on the old Ultegra 10-speed, both brifters for $149. Triple only, though. Matching Ultegra RD is $80. Add in a chain for $50 and shipping and you can upgrade the important bits for a little under $300. Not that bad.

http://nashbar.com/profile.cfm?category=6000104&subcategory=60001194&brand=&sku=13295&storetype=&estoreid=&pagename=

if you use ebay and or nashbar you can go 10speed for relatively cheap. i just went to 10 speed ultegra after my old rx100 stuff died. i replaced the shifter, RD, chain and Cassette for under $300 for practically new stuff.