Low gears for Campag Veloce

andyealing

My bike has a standard double Campag Veloce chainset. I'm planning to tackle some bigger hills this year and want to lower the gear ratio at an affordable cost. I'd prefer to avoid the costs of changing to compact chainset. Any advice on how to achieve a lower ratio i.e what' the lowest rear sprocket and would this make a difference?

g00se

What's the cassette you currently have? The largest Campag do is a 29 - you'll have to do the capacity calculation to see if you need a longer mech cage.

andyealing

Thanks g00se, unfortunately I'm unsure about the size of the current cassette on the bike. Do you know how I'd find this out? Is it normally written on the cassette itself or do you need to count teeth etc? (Apologises, I'm a bit of a technical novice)

It's good to know that you can get quite a low gear ratio without switching to a compact and having to change all of the drive chain. Has anyone tried switching to a lower ratio on a standard double CC and does it make a difference in the hills? Or would I be best spending more and going for a compact?

rolf_f

The standard '29' Campag cassette is 13-29. I run one of these on a compact setup, short cage, if I'm doing a killer sportive. The difference between the chainrings on a compact is greater than a standard so you should have no trouble running a 13-29 with short cage mech and a couple more chainlinks (depending on what you are already running). This (39-29) gives you a marginally lower gear than the standard compact 34-25 and that does me 95% of the time in hilly West Yorkshire. If that still isn't enough, then you can switch to a compact knowing you haven't wasted any money (as you'd be using that cassette for the hills with the compact).

You may need to tweak the derailleur position to move it away from the big sprocket.

Cassette size - it's probably 25 but count teeth! I tend to put a piece of tissue over one tooth and spin backwards until the tissue reappears which makes it easy!

ant.rocket

Hi. Been looking into this myself. I have 10sp Mirage, 25-12 Veloce Cassette, 39-53 Fsa chainset. Short cage rear mech. My campag manual says for the 29t sprocket you need the medium cage rear mech. I have a 26t sprocket on my training bike and to be honest there is not a lot of difference between that and the 25t on my other bike. So I did think, what about using a smaller chainring as well, 38t, again makes a little more difference but not a lot. Take a look at Sheldon Browns gear ratio charts on his site. I have seen campag compatible BBB and Miche cassettes with 27t sprockets, wether these would work ok with the short cage rear mech, I dont know. The Miche sprockets are for sale individually for £9.99 on Shiny Bikes site.

rolf_f

ant.rocket wrote:

My campag manual says for the 29t sprocket you need the medium cage rear mech.

It does and, on that basis, one (ex) member of this forum kept insisting that my 50-34:13-29 shortcage setup didn't work properly despite the fact that it did - even with crossed chains!

I think there is a theoretical possibility that, depending on frame design, 13-29 won't work in all gears on a short cage mech but I've not heard of anyone on here finding it to be a problem (and if you are on a standard you've got less to worry about). In my case, I'm pretty sure it could have coped with a 30 tooth if Campag made one. I think this is Campag covering their backs.

g00se

I got this info from another post - but can't find it at the moment. Kudos to the original poster...

Whether you can use a short cage with a particular range of rings and sprockets (technically) depends upon the groups 'capacity' and the chain-stay length.

The capacity or 'wrap' is the difference in total teeth between the small/small combination and the big/big combination. So it's a measure (in teeth or chain links) of how much chain the cage has to be able to suck up and still keep perfect tension.

For example, for Rolf's setup 13/29 and 34/50, the capacity is (29-13)+(50-34) = 32.

'Officially', Campag says that the short cage (55mm between jockey axles) can accommodate a wrap of 27.
Medium cage (72.5mm) has a wrap of 36 and
Long (89mm) can take 39

(all modern Campag mechs can take a maximum rear sprocket size of 29 - but note, that's total teeth, not wrap/capacity)

Now, these numbers are very conservative, and it's widely assumed that you can go a couple higher without issue.

So for Rolf, 29 would appear to be the maximum capacity of his setup - though he's running 32 with no problem???

The answer is the actual chain length and how it fits over the teeth...

If you think about what the rear cage is doing, it's taking up slack in the chain. On big/big, it should be at it's full extent - and ideally, this should accommodate the length of the chain. However, you can't exactly shorten the chain to fit this perfect configuration as a chain can only be shortened by one inch at a time (two links). So in worse case, you could end up with a chain with an extra 0.9 of an inch longer than ideal (if you were to remove a couple more links, it would be 0.1 of an inch too short and not fit). So in this worst case - to start with, you've just about lost the capacity of two links before you've even started.

Now, to save buying your mech and cassette and finding out you've fallen into this worst case, you can use a chain length calculator to work out what your ideal chain length should be. Park tools 'rigorous' equation is the best - http://www.parktool.com/blog/repair-help/chain-length-sizing and there's a javascript calculator here: http://www.machinehead-software.co.uk/bike/chain_length/chainlengthcalc.html

If the difference between the unrounded result and the recommended chain length is just a small fraction over an inch, then it's assumed you can add a couple more to the capacity (if it's near a whole inch on the other hand, then you're probably not going to be able to).

So assuming Rolf has the perfect length chain stays, he can add a couple more to the his bike's capacity and end up with 31. He's running 32 so my guess is that the mech is running a little tight if he goes big/big but most good cyclists will avoid that

philkeeble

When I had my audax bike built in 1993 it was fitted with a first generation 8-spd Veloce with a 52/39 chainset and a 13-30 bespoke cassette with a short cage deraileur. It was outwith the official spec but it worked faultlessly. 3 years ago I replaced the chainset with a Stronglight Impact compact 48/34 (I'm getting older!) and swapped the 13t for a 12t sprocket to regain my top gear. Again it worked perfectly.

This year my shifter has broken again for the second time so I'm upgrading to 10-spd. I've gone for a medium cage mech this time which has allowed me to up the big ring from 48 to 50. However, I'm gutted that I can't replicate my cassette. I have a Miche 12-29 on order (see other thread) as this is closer to my old cassette than any of the Campag Veloce cassettes.

ant.rocket

Great post g00se. Thanks. Think I'll be going for a 26-13 cassette then.

g00se

I've got a 13/26 with a compact running a short cage centaur - that's a wrap of 29 and it's fine.

rolf_f

ant.rocket wrote:

Great post g00se. Thanks. Think I'll be going for a 26-13 cassette then.

That's not going to give you a particularly low gear.

39-26 = gear ratio 1.5 (= pick your kneecaps up on the way back)

34 - 25 = gear ratio 1.36 (my original compact setup)
34 - 29 = gear ratio 1.17 (my 'hardcore' climbing rig!!)
39 - 29 = gear ratio 1.34 (what you could get without a compact).

Coincidentally, your 39-26 is exactly the same ratio as the 42-28 on my 1980 Raleigh Record Ace. Now that is old school and not the lightest thing in the world. I've got it up Steyning Bostal but it don't 'arf 'urt on the 'ills!!!!

I think something maybe wrong here. 34-29 is, from what I recall of Campags guidance, only just beyond what should be definitely doable. As I said, the mechanism even on 50 - 29 has some remaining movement though it doesn't look pretty! I find it hard to believe that the published range can be 29 if you get that from 50-34, 13/26. Bear in mind that a very common choice is 50-34, 11/25 which gives a wrap of 30.

Note - the Campag 10s rear derailleur manual states that the short cage derailleur is suitable for all 10 speed Campagnolo sprocket sets. http://www.campagnolo.com/repository/do ... illeur.pdf - P20
And I have checked that they still list the 13-29!

Note also that the only medium cage mech Campag now do is Veloce yet they make 13-29s all the way to Super Record.

g00se

Yes - ignore my post, it must be older versions (same vintage as the previous style levers?).

I've just gone through the tech specs on the campag website (need a life...) and for the new style mechs, 10-speed short cage capacity is 32. 11-speed is 33 (that's the new logo 2011/2012 models)

See: http://www.campagnolo.com/repository/documenti/en/2012_COMPONENTS_TECHNICAL_MANUAL_UK.pdf page 75

Looking at the 2010 specs - the short cage mechs had a capacity of 30 (for 10-speed) and 31 (for 11-speed).

Also, the 2011/2012 short cage mechs can accommodate 29 as the biggest sprocket - whereas the previous 2009/2010 short cage mechs would take 26 for 10-speed and 27 for 11-speed.

rolf_f

But the question is - are the pre 2010 mechs really any different? Personally, I take with a pinch of salt anything Campag says - if you look at the catalogues, every step up the groupset ranges, in every component, yields weight savings yet often there is absolutely no difference in quoted spec. And those weight differences might be a gram.

Now, I guess that 2009 may have been the last year of the medium cage mechs - so either they tweaked the short cages for greater range or they realised that the short cages had the range anyway. If I get round to it, I may check as my Look has a 10 speed Record rear mech. In theory, it should fail to cover the range. The bike I use the low gears on is my Ribble from late 2010 so that clearly would be expected to work. And I think it supports my theory that it could actually handle at least another tooth given the appropriate cassette (I suppose I could check it by converting the 13-29 into a 12-29. But I can't be arsed

g00se

The pre and post 2011 mechs are supposedly different. The post 2011 ones use the 11-speed paralelogram. But then, the marketing department is involved....