Creating a wide-range Campag rear cassette

jimwin
jimwin Posts: 208
edited February 2009 in Workshop
Someone posted an idea to mangle 2 Campag 10-speed cassettes to get a wider range of gears. But it didn't take into consideration the need to align the cogs to get decent shifting.

I live in a hilly region between Bodmin and Dartmoor so there are hills-a-plenty and several climbs around here are beyond a standard compact setup (50/34 + 12/25). So I took a careful look at how to get a decent range 10-speed rear cassette of 12~29. This gives a small gear of less than 32" which is good enough for almost every climb up to about 25%.

The gears I wanted to use are 12/13/14/15/17/19/21/23/26/29. At first sight, the 12~15 could be taken from a 12~25 cassette and the 17~29 from a 13~29 cassette. I tried this BUT there was a tendency to jump from 15 to 19 skipping the 17 ring though down-shifting was generally ok. This is because both cassettes use 'A' rings throughout. This was not a reliable solution because the 15-17 jump is used frequently.

I also had a 11~25 cassette to hand and this does the jump from 15 to 17 (11/12/13/14/15/17/.../25). The 17~25 rings in this cassette are 'G' rings which have the correct ramp alignments to ensure good shifting - particularly from 15A to 17G.

So the solution was to use the 12A/13A/14A/15A/17G/19G/21G/23G from the 11~25 cassette and add the 26A/29A from the 13~29 cassette.

There is a misalignment between the 23G and 26A rings, but at this point high up in the cassette, it has no effect at all on the shifting performance. It really works!

The caveats are:
1. The 12A-2 ring from the 11~25 cssette has a built-in spacer so don't add another one.
2. The rear mech might need to be a long-cage variety to take the wider gear range.
3. The cassettes are best as separate rings and not having the last 2 bonded together (Ribble do the separate ring version).

Perhaps others might find this useful.

- JimW

PS - the 15~17 change is 13.3% which is similar to the 23~26 change of 13% and so not a bad jump. Besides, Campag do use this jump in the 11~25 cassette.

Comments

  • Ian.B
    Ian.B Posts: 732
    Jimwin,

    This sounds interesting - but what is the difference between an A ring and a G ring? And how do you tell which is which?

    I'm interested in the possibility of creating a 12-27 Campag cassette (which I think is a standard Shimano cassette option), swapping the 23 and 25 rings on a 12-25 cassette for 24 and 27 rings.

    Ian
  • andrew_s
    andrew_s Posts: 2,511
    How often do you use that 50x12 gear?

    Buying 2 cassettes for every one that you use seems an awfully expensive way of getting an extra tooth over the standard 13-29. It would be cheaper to learn to pedal a bit faster.
  • redddraggon
    redddraggon Posts: 10,862
    Aye 50-13 is plenty, it's not as though you're going to competing in a downhill sprint.
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  • I had an early Campag Veloce 8 spd set up with a bespoke cassette configuration of 30~13 running with a 53/39 chainset. Being keen to get one gear lower (for a forthcoming cross-Scotland trip) I replaced the chainset with a Stronglight Impact compact of 48/34. But I wanted my top gear back for the downhills, so I swapped the 13 for a 12 which I purchased form Chris Bell at Highpath Enginering. In the course of the upgrade I noticed that the 30 and the 20 were worn so purchased replacement for these too. The new sprockets are all Marchisio and Highpath can keep you straight with the right spacers. I'm well pleased with the result (despite the fact that they don't really recommend mixing sprockets). Shifting is fine.

    Highpath have the full range of sprockets for you to make up whatever combination you want. Check out the technical guide at http://www.highpath.net/

    Phil
    Cheers,
    Phil, in Inverurie
  • jimwin
    jimwin Posts: 208
    andrew_s wrote:
    How often do you use that 50x12 gear?

    As much as any other gear - perhaps more than most (for the long descents around here).

    Buying 2 cassettes for every one that you use seems an awfully expensive way of getting an extra tooth over the standard 13-29. It would be cheaper to learn to pedal a bit faster.

    These 2 cassettes are Centaur and around the same price as a single Chorus cassette. But it's actually a bit worse than I said. The 12 ring is a 12A-1 type and not the 12A-2 from the 11~25. I thought I could use the 12A-2 but it doesn't have the serrated edge that keeps the clamp ring from undoing. I had a 12A-1 to hand and used that.

    Still, I'm happy with it. Someone else suggested a similar idea and this is just a better solution if you need (or want) the wider range cassette. I've been caught out a few times on double chevron hills using a 34/25 setup. So I needed a solution if I was going to use a compact chainset. This does the trick. But then again, I might go back to my triple if it doesn't work out better :)
  • jimwin
    jimwin Posts: 208
    Ian.B wrote:
    Jimwin,

    This sounds interesting - but what is the difference between an A ring and a G ring? And how do you tell which is which?

    I'm interested in the possibility of creating a 12-27 Campag cassette (which I think is a standard Shimano cassette option), swapping the 23 and 25 rings on a 12-25 cassette for 24 and 27 rings.

    Ian

    I don't think Campag does a 27 ring on 10-speed though the new 11-speed does do 12~27 and without missing the 16 ring.

    The only other option is to swap the 25 in a 12~25 for a 26 from the 13~29 cassette. It's an expensive way to get the one extra gear to make a 12~26 (25A can be directly swapped for a 26A).

    BBB do a 12-27 campag replacement cassette. Check out Parkers. The cassette misses the 16 and goes 12/13/14/15/17/19/21/23/25/27. But BBB have mixed reviews.

    The other (and nicer) possibility is to pay a ton and get a Marchisio cassette. I like the 12~28 cassette on this link:
    http://www.bikeradar.com/forums/viewtop ... c&start=43

    JimW
  • jimwin
    jimwin Posts: 208
    Ian.B wrote:
    Jimwin,

    This sounds interesting - but what is the difference between an A ring and a G ring? And how do you tell which is which?

    Ian

    The letters refer to the alignment of the cogs that are indented for the 'hyperglide' changing. The indents need to be in a apecific alignment for shifting to work properly. This is the reason you cannot just mix-and-match cassette rings arbitrarily. The letter is stamped on each cog.

    JimW
  • Thanks for this thread.

    I have a 12-25 Chrous cassette and want to chnage to 13-29. Does anyone know if I can just buy sprockets to combine with the set I have for the 12-25? And, most importantly, which would those be? Is it just about adding a 13, a 27 and 29, and dropping the 12? Would that give me a set that works well?

    Dom
  • mrushton
    mrushton Posts: 5,182
    Just buy a Marchisio cassette in the ratios you want?
    M.Rushton
  • I have about 6 chopped cassettes and make my own ratios up as I want. Anything between 11 and 32, but have never had 22, 27, 29 or 31.

    If you need extra spacers, just ask your LBC for any chuck-away cassettes that they may have.
    AT MY AGE, I SHOULD KNOW BETTER !!!
  • a_n_t
    a_n_t Posts: 2,011
    seems like alot of faffing. I just went with a 13-29 on the winter bike, easy.
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  • jhop
    jhop Posts: 369
    "I have a 12-25 Chrous cassette and want to chnage to 13-29. Does anyone know if I can just buy sprockets to combine with the set I have for the 12-25? "

    I run 10 speed Chorus with the 13-29.

    It comes straight out of the box so rather than trying to mix and match keep the 12 -25 as it is and use the lower set up when required which for me will be on the etape.
  • Chop and change FTW!

    Just strip down a few cassettes and you can make up almost any ratio you need for any set of circumstances. :D Takes just a few minutes with the right tools. :P
    AT MY AGE, I SHOULD KNOW BETTER !!!
  • I confess to my eyes glazing over trying to follow this rigmarole :?

    I'm left wondering , though , why ditch the 11 tooth in the quest toward a 29 t ? On my winter bike - and forcing myself to be cost sensible for a change - I bought a 13 x 29 Centaur block ( no option for anything less than 13 ) and miss the 11t massively from the old Marchisio 11 x 28 I had .

    I still run Marchisio on my best bike and , on reflection , wish I hadn't cheaped-out with the no-option Campag block .

    A lot on this forum will knock the Marchisio as - I suspect - they don't look as funky or hi-tech as the Campag , but , in my experience they function as perfectly as anything out there and is blessed by the rationale : pick n'mix . Wonderful . :D
    "Lick My Decals Off, Baby"