8 speed campy cassette guru?

[bikenut2010]

I have 2 Campag 8 speed cassettes:
12-21 and 13-26

I'm using a 50/34 compact

I need the 26 for climbing , but the 13 only gives me a 103 inch high gear, 12 is more realistic 112 inch

Can I make up a cassette that gives both? The 13-26 doesn't seem to have the modern shifting ramps either.
I understand that the cogs must be oriented a certain way ( letter codes aligned? )

Anyone able to plug the knowledge void for me?

 

[foz]

You shouldn't have any problem... You might get a larger than usual (2 teeth not 1) jump somewhere though.

 

[bikenut2010]

found this: viewtopic.php?t=64390

so how does the chart read?

 

[Toff]

Unless you are using the old pre-ExaDrive cassettes, then you don't need to worry about that chart. On later 8-speed cassettes (including the ones you can buy today) they don't use that lettering. The spline pattern on the freehub body will only allow you to place each sprocket in one orientation as you slide it on. If you have one of the older pre-ExaDrive hubs, then you simply align up all the rhombus symbols on the sprockets as you stack them on.

In my experience, it's not critical to worry about lining up the rhombuses anyway. The concept of seamless shifting was created more as a marketing one than a practical advantage. And even then, the advantage was not important unless you were riding on the edge (such as racing).

You can recombine the sprockets from the two cassettes to make two new cassettes, and both will work just fine. I would still recommend changing only the sprockets you need to change though, and keeping the bulk of the cassette unchanged. This will maintain whatever shifting advantage the original cassettes had.

 

[bikenut2010]

OK thanks very much, in that case how would you recommend arriving at a working cassette without too large a jump?
13-26 (13-14-15-17-19-21-23-26)
12-23 (12-13-14-15-17-19-21-23)

In both instances all I can see is 12-13-14-15-17-19-23-26 using the 12-23 and replacing the last 2
or 12-13-15-17-19-21-23-26 using the 13-26, adding the 12 and removing the 14.

Appreciate your experience!

 

[Toff]

So, after my last post, I realised that some people might want the technical information to build the best cassette possible. I pulled out my old ExaDrive sheet...

When using ExaDrive cassettes, there is a letter assigned to each sprocket next to the number of teeth. This is not the same as the letters on the pre-ExaDrive cassettes, so you need to be aware of what cassette you are installing.

For optimal shifting, you want to stick to the table, but it will still work, even if you don't follow the table.

In the case of a 12-26, it's interesting to note that Campagnolo have never produced this combination. I would suggest running the desired cassette combo through Sheldon's gear calculator just to make sure you choose sprockets with a good range and no overlap...

 

[bikenut2010]

So, after my last post, I realised that some people might want the technical information to build the best cassette possible. I pulled out my old ExaDrive sheet...

When using ExaDrive cassettes, there is a letter assigned to each sprocket next to the number of teeth. This is not the same as the letters on the pre-ExaDrive cassettes, so you need to be aware of what cassette you are installing.

For optimal shifting, you want to stick to the table, but it will still work, even if you don't follow the table.

In the case of a 12-26, it's interesting to note that Campagnolo have never produced this combination. I would suggest running the desired cassette combo through Sheldon's gear calculator just to make sure you choose sprockets with a good range and no overlap...

Cool, so my guess at the 12-26 combo is identical to campy 12-25 bar the last cog; btw, mine are pre-exadrive, ( I think? ) no keyed spline, they are all the same.

 

[Iwasgoodonce]

I run an 8 speed set up. I don't remember lining stuff up but did try to keep everything the same. Having said that mine was only ever going to work in friction mode anyway. I think I have the same config as your 13 - 26.

I was worried about larger jumps in the gears but I found this to be less noticeable than I feared. I built the bike to have a lower gear than my other bikes so I went with 38/53 up front. I don't really have climbs round here that have warranted lower than the 38/23 yet. I even managed Daj's evil last climb with that gear on Sunday.

I too am thinking of trying a 50 tooth chainring to try and encourage me to use the big ring more often. I like a high cadence so will probably be OK with the 13 sprocket.

 

[daccordimark]

OK thanks very much, in that case how would you recommend arriving at a working cassette without too large a jump?
13-26 (13-14-15-17-19-21-23-26)
12-23 (12-13-14-15-17-19-21-23)

In both instances all I can see is 12-13-14-15-17-19-23-26 using the 12-23 and replacing the last 2
or 12-13-15-17-19-21-23-26 using the 13-26, adding the 12 and removing the 14.

Appreciate your experience!

I would avoid that 19-23 jump personally. Best bet is to use the 13-26 but take the 12 and 13 from the 12-23 to replace the 13 and 14. You can't move the 13 from the 13-26 up a position because it has the serrations for the lock ring in it.

I assume your hub is pre Exa-drive otherwise the old cassette won't fit.

Mark.

 

[bikenut2010]

OK thanks very much, in that case how would you recommend arriving at a working cassette without too large a jump?
13-26 (13-14-15-17-19-21-23-26)
12-23 (12-13-14-15-17-19-21-23)

In both instances all I can see is 12-13-14-15-17-19-23-26 using the 12-23 and replacing the last 2
or 12-13-15-17-19-21-23-26 using the 13-26, adding the 12 and removing the 14.

Appreciate your experience!

I would avoid that 19-23 jump personally. Best bet is to use the 13-26 but take the 12 and 13 from the 12-23 to replace the 13 and 14. You can't move the 13 from the 13-26 up a position because it has the serrations for the lock ring in it.

I assume your hub is pre Exa-drive otherwise the old cassette won't fit.

Mark.

Thanks Mark, that makes perfect sense.