First, I’m running 8-speed Shimano on all my rigs right now (road and tri). 8-speeds cassettes are becoming kind of rare, so I see myself having to “upgrade” to either 9- or 10-speed soon (ouch! – but the logical choice seems to be 10-speed). So I’m wanting to feel the waters for just how much wallet damage I’ll be looking at…
The first obvious replacements are the cassette and chain. And the STI’s on the roadie.
The tri rigs have bar-end shifters in friction mode, so I know I won’t have to replace those. But if I’m running an 8-speed rear derailleur, would I need to replace that? Or as an alternative, would replacing the stock plastic derailleur pulleys with some narrower aluminum pulleys work as well?
On the front end, would the 8-speed front derailleurs need to be changed?
If I swap to 10-speed chainrings, would those still work with the 10-speed chain on an older 8-speed crank? I’ve got FSA Gossamers on both tri rigs, which I believe are 10-speed compatible (I have NOS 8-speed chainrings on them now), but the roadie has old Ultegra 8-speed (square-taper BB).
According to shimano propaganda, I mean whitepapers, If you switch from 8 to 9 everything has to be switched even your cables (j/k). However what I have seen is that there is quite a bit of wiggle room and that you can get by with a lot less. I would say anything metal that contacts the chain as a bare minimum to upgrade. That would be chain, cassette and chainrings. Other than that you should be fine with your front D. and Probably even your rear D. as well. I would experiment though. sounds like you can take your time with this. I would upgrade as necessary and never just buy the part b/c it says 9sp. Also you should be able to get 8 sp cassettes for a long time still. You wont find them in catalogs like nashbar or performance but any LBS will either “have some in the back” or can get one from QBP or some other parts distributor. Trust me if you can still get a 6 speed freewheel in multiple gear combos you will be able to get 8sp cassettes for awhile.
//The first obvious replacements are the cassette and chain. And the STI’s on the roadie.//
That’s all you “need” to replace. The next place to upgrade would probably be the front DR, since 10spd DR is narrower than 8 speed DR and you can get it adjusted better.
.
I don’t know for sure. It seems to me the 8 speed rear derailluer with friction shifters should still work with a narrower pulley; the STI’s on the road bike will obviously require a new rear derailluer. However, the screws that mount the pulleys thread directly to the derailluer cage in most cases, in which case the narrower pulley would have lateral play and mess up the shifting.
I am betting that the narrower chain on with 10-spd means that if you put 10 speed chainrings on an 8-spd crank that the chain might get stuck between the chain rings; I think that the chainring spacing may have changed, but I don’t know. If you have some callipers, you could measure the parts and figure it out. Or, find someone who knows the answer, which is not me…
However, I recently had to find some 9-spd parts so I knew were to look for the 8-speeds as well.
I just replaced all of my 9 speed 105 stuff with new Ultegra 9 for about $250. You could even do it cheaper with used gear. I put about 30,000 miles on the 105 and figured it was time. In three years I will buy a whole new bike.
Good question! After thinking about this, I am not sure this is true. But I think the cable pull per gear is the same for 9 and 10 speed shimano, but not sure about 8 speed. That is why you can upgrade to 10 speed STI shifters while still running 9 speed drive train. What this means is that the 8 speed derailluer will not have the appropriate lateral movement for each index shift of the STI levers. Another way to think about this is that the cogs are spaced progressively narrower for 8, 9 and 10 speed. So I don’t see how the rear derailluers could be cross compatible.
i bought my first tri bike used, and it came with 9 sp 105 STI shifters … when I transitioned to bar-end shifters i moved the 9sp STI over to my road bike (which was 8sp) … all i changed was the cassette and the chain (more for maintenance than compatability) … so my road bike now runs 105 shifters with RSX (!) everything else. it’s a little heavy and a little sloppy … but it works just fine as my winter bike.
I’m looking at moving my current tri-bike to 10sp … all i’m planning on changing will be the shifters, chain and cassette … ultegra 9sp should be fine for everything else.
On cassette spacing: Width of 8, 9, and 10 speed Shimano cassette is same. I can take 8-spd off my Shimano 8/9 hub and slap on 10-spd. Fits perfectly. (Note this is true only for Shimano, not Campy, and new 10-speed shimano hubs won’t back integrate, i.e. take 8 or 9 speed).
On gear spacing: Since 10-spd cassettes have two extra cogs, they have smaller shift between gears. The indexing, or amount of movement the rear DR makes is controlled by the shifter. Put on 10-spd STI and you’ll get shifts that match 10-spd cassette. For authoritative source, see:
Quoting Sheldon: “Note, also that ***rear derailers do not care how many gears you have. ***You do not need to have a so-called “10-speed” derailer to use a 10-speed cassette. This is true of all Shimano derailers with the exception of 1996 and earlier (pre-9-speed) Dura-Ace units.”
.
HH - You are correct. I was remembering that the cable pull was the same for each shifter, with different lateral motion per cable pull caused by the rear derailleur.
It is in fact the opposite, the shifters all provide different cable pull and the rear derailleurs are all the same, providing 1.7mm of lateral motion per 1mm of cable pull. Here is a link I like (http://www.ctc.org.uk/DesktopDefault.aspx?TabID=3946)
I stand corrected. Use the old 8 speed rear derailleur with the new 10 speed STI’s
