Wednesday, 7 May 2014

Campagnolo 12-30 Cassette Review

I live in a flat part of the country but I'm a frequent visitor to the Buttermere area of the Lake District. As a result, I often find myself climbing Honister Pass from the Buttermere side. To me, Honister is one of the hardest climbs in the area. The climb finishes with a stretch of 1 in 4 (25%) and it really pays to save your legs and ignore the temptation to get out of the saddle too soon. You can get a rider's eye view from the picture on the visit cumbria website. If you prefer, you can watch ITV news coverage of the 2013 Tour of Britain climbing it too.

Why buy the 12-30 Cassette?

Last time I went up Honister I was riding my lowest 36x25 gear on my Cinelli/Centaur home build with 165mm cranks. That's as low as I want to go when riding around the area where I live and I thought it would be good enough to get up Honister but as I rounded the penultimate bend I didn't have the strength left to turn the bike into the wind and I was driven in to the left hand wall by a super strong gust funnelling through the gap. I grabbed the wall to steady myself and clasped the front brake but on that gradient the front wheel was never going to hold, I started sliding backwards and had to put my foot down. Defeated I vowed to come back with a lower gear.

Realistically it is difficult to make significant changes to the gearing on a bike routinely, you are likely to need to change the length of the chain and perhaps even the derailleur and if you are switching between a double and a triple you've got a major job on your hands. I decided to rejuvenate my old Tifosi alloy frame instead, I looked at the costs of getting a Veloce triple but decided I could almost get the same lowest gear with a Centaur compact double (50/34) and the new 10-speed 12-30 Cassette. I bought the whole groupset from Ribble - they've got a handy groupset builder which flagged the need for a medium cage derailleur rather than a short cage.


Installation was pretty simple. There are no special considerations as far as the wheel or hub is concerned. My Tifosi frame has a very short chain stay and that is the only thing that proved a challenge. Firstly, the Campy 'longest chain that can possible work' method of chain sizing left me choosing between a chain that was too short (by their method) or one that slightly too long. The tension was very low in the small-small combination and the chain was only just hanging below the cage. Still, better a little too long than too short.

With such a big cog you are going to need to adjust the 'H' screw to increase the gap between the sprockets and the guide pulley of the derailleur by unscrewing it (in my case, pretty much to the limit). This is the most confusing thing to me because the Campy instructions label the adjustment screws in a different way to most internet articles:

B screw
Lower limit
G screw
Upper limit
H screw
Cage spring tension

These instructions also don't specifically say which way to turn the 'H' screw to achieve the desired effect and, unlike the limit screws, you can't easily see the change. There is a better explanation on the the Park Tools site, but bear in mind that they use the letters 'L', 'H' and 'B' where Campagnolo use 'B', 'G' and 'H' respectively! Scroll down to the Campy specific para and you'll see a clear explanation of the rack-and-pinion style adjustment of the cage:

In this system, the upper spring is fixed. Increasing cage tension (turning screw clockwise) will bring the upper pulley closer to the cog. Decreasing cage tension (turning screw counter-clockwise) will increase the distance between upper pulley and cog.

Thank you Park Tools!


As you might expect from a brand new groupset the shift is precise and the chain runs in that silky smooth way that I've now got used to with the Centaur equipment. The chain hops up to the 30T sprocket without any fuss or extra noise.

I set my bike up with a standard 50/34 compact crankset. The 34T chainring is smaller than my regular 36T but even if you are already riding a 34T compact you'll have two extra gears below what you get on a standard 12-25 cassette. It is worth noting that the first seven sprockets in the 12-27 and 12-30 cassettes are the same, it's only the last three hill-climbing gears that are different, changing from a 23-25-27 to a 24-27-30 combination. This means that when you are running on the big ring you won't really notice any difference between the two options. If you are changing from a 12-25 cassette you're swapping the 16T sprocket (which sits at #5) for a lot of extra leverage.

The day after finishing the build I took the bike for a test drive up Honister. I'm happy to report that, with the benefit of the 34x30 gear, I got up comfortably despite the brisk head wind and being a bit older and a bit less fit than I was last time. I stopped briefly at the top to take this picture for posterity.


With the top riders now choosing to climb in lower gear ratios for more efficiency it is no longer considered clever to thrash up these steep climbs in a big gear. Also, with 10 sprockets you can surely afford to keep a few back for use on high-days and holidays. In conclusion, one of my better purchases, I can now dream of tackling Hardknott and Wrynose.

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