Ratio change advice

2_tyred_itai

Hi, here's my current set up:
Primato 10sp 12-25T (I'm assuming this is Miche)
Campy Xenon Rear Derailleur
Campy Xenon Brake Shift Levers
Fas Team Issue 10sp, 110 link chain

I'm thinkning of widening the range of rear ratios, say to 12-30 (maybe even 11-30?). I have found these that appear to match what I have:
http://www.miche.it/en/catalogo/catalogo-miche/pignoni/pignoni-primato-10-ca-2
Details: http://www.miche.it/uploads/pdf/schede-tecniche/cassette_Primato_tech-2015.pdf

I have also seen this document about general Campy cassettes, which states what combinations I can use, but I'm not sure if it is relevant to my cassette because the cassette is Miche, however intended to be Campy compatible.
http://www.campagnolo.com/media/files/035_39_Technical%20manual%20-%20sprocket%20pack%20-%20Campagnolo_REV00__09_14.pdf

My questions are:
Would the Campagnolo cassette document be relevant?
Can you just purchase the missing sprockets and make up the combinations that are suggested?
Is it really important to stick to recommended combinations or not?

I will try and count the teeth on all my sprockets, but if they are as suggested in the Campy document, then that will be:
12, 13, 14, 15, 16, 17, 19, 21, 23-25

So I could change it to:
12, 13, 14, 15, 17, 19, 21, 24, 27, 30
by taking out the 16 and 23-25 and fitting 24, 27 and 30

Does anyone see any problems/things to look out for with this?
I assume the rear derailleur and shifters won't have a problem with this, since it would remain 10sp, but would I potentially need a longer chain to cope with the larger 30 sprocket?

I might think about making the 1st ratio an 11, but not sure what best combo of ten sprockets would keep the shift smooth, perhaps 11, 12, 13, 15, 17, 19, 21, 24, 27, 30

Any advice greatly appreciated.

ai_1

I'm not familiar with Campy but just a couple of thoughts to consider which would be true of any system:
- If you buy a complete cassette you can easily swap back and forth later should you wish to do so depending on the terrain you're riding. If you only swap specific sprockets only then you'll probably end up with big differences in wear between sprockets if you swap around later (or if the existing cassette has significant wear as it is).
- You don't mention what chainrings you have but I'll assume it's a compact double. It's rare that you'll gain much by having an 11 tooth sprocket available. 12 tooth is usually sufficient - I've done 80km/h on a 50/12 ratio albeit with a very high cadence. If I was looking for a 30 tooth top end I'd rather have a 12 at the bottom to keep the increments between gears that bit smaller. If you have a standard double or a triple with 50+ teeth on the big chainring this is even more true.

2_tyred_itai

Thanks for that! Yes it's a standard compact 50/34

g00se

Your Xenon rear mech - is it short or medium cage? If it's short, it's 'officially' not going to have the capacity for such as wide-ranging cassette on a compact chainset (the cage can't suck-up enough slack chain). Also, any mech (small, mediaum or long) from that era is not going to 'officially' have the scope to take a 30 (the older shape mechs like the Xenon are down as accommodating a max sprocket of 26).

Saying that, you may get away with it - I do with the older shape short cage Centaur mech which has the same limits (biggest cog being 29). However, I do recall someone saying that even though these mechs can take a 29 or 30, doing so stresses the mech's spring and can cause premature failures.

To be safe, you could get a 2011-onwards new-shape 10-speed mech (Veloce or Centaur).

2_tyred_itai

Thanks g00se, I've checked and alas, it's short cage specified for up to 27t.

Mind you it came on a 2014 bike so I guess it's current but not mentioned as a range on the Campy website. I digress.

So what I'm looking at is a new dérailleur, probably longer chain taking on board Ai_1's comments (advice on length for 12-30?) the required cassette/sprockets and the campy tool, right?

I assume a Veloce or Centaur RD will be perfectly compatible with my Campagnolo Xenon QS/Escape 10s Ergopower shifting levers?

2_tyred_itai

Just looked at campy dérailleurs. Even the medium and long cage versions are officially only suitable for max cog size 29t despite larger cogs being available for campy groupsets. They are however supposed to suit chain wrap values exceeding that of my desired 50/34 & 12-30 set up.

Does anyone have experience of what is more important out of max cog size and chain wrap in real world terms?

I understand the difference between the two in definition, just not sure how strictly I should follow the mfr specs

g00se

I think the 29-speed limit is a bit of a bum steer. They only made one 10-speed 12-30 cassette - and that was for the Centaur group. For 2015, they've discontinued the Centaur group (leaving Veloce as the only 10 speed setup). With Centaur, has gone the 30 cassette - Veloce cassettes only went up to 29. I think the new limit just refers to the biggest 10 speed sprocket they now do.

If you look at the tech specs, all 10 speed rear mechs have 30 as their maximum:

http://www.campagnolo.com/media/files/0 ... _07_13.pdf

This is the 2013 version - but it's presented as 'current'

2_tyred_itai

So you reckon it should be alright?

2_tyred_itai

g00se, I've just come across your excellent posts on this thread: http://www.bikeradar.com/forums/viewtopic.php?t=12836231&p=17444209

So you think the new short cage RDs may even match the capacity of the old mediums?

I might still try and get a Veloce medium length cage so that I'm more than covered in terms of capacity and so that I'm only going over the max cog size by 1 (29>30)

g00se

Considering a replacement mech: Don't worry about the 29/30 thing for the post 2011 rear mechs - the specs says ALL the 10 speed mechs will take a max sprocket of 30. See the PDF link above.

Officially, you'll need a medium cage for 11-30 or 12-30 cassettes - as the short's capacity of 32 will only take a 13-29 cassette with a compact front. it woudln't surprise me if you can get away with it though.

Regarding the campag docs on available cassette sprocket combinations: the limitations are because the sprockets are ramped and profiled (like chainrings) to aid shifting - but each specifically sized sprocket has ramps/profiles to match up against those particular to adjacent sprockets. So one size sprocket will only work properly against one it is designed to. Miche don't do this, so you can mix and match combinations.


As for that previous thread - and using the old Xenon mech: One thing I didn't take into account - and was later informed on another thread by Velotech - is that chain capacity isn't the most important consideration - the biggest sprocket is.

First, the derailleur hanger has to be long enough to allow the mech to get over the biggest sprocket. Some may be out of specification to do this.

Second, it will put a strain on the main spring - which it isn't designed to take. Velotech has seen quite a few failures because of this. As I was putting a 29 on the bike to help with doing the Cheshire Cat (the Mow Cop climb is a mile long and hits over 20% for the last bit) I thought it's a risk worth taking with a 2010 mech that only went up to 26. Most of my riding is around Norfolk so I normally use a closer cassette. If I was to use the 29 more often, I would have considered getting a more modern rear mech.

2_tyred_itai

Ok thanks for that g00se, some great info.

So here is what I'll do (maybe after my wallet has recovered from Xmas):
- Replace the Xenon 10sp short length cage derailleur with a Veloce 10sp medium (this in itself will be a nice upgrade)
- Buy a campy cassette tool (ouch)
- Buy a chain whip
- Buy 24, 27 and 30 toothed Miche sprockets and take out the 16 and 23-25 (not sure if I need spacers though)

As for the chain, the parktool.coom calculation suggests that the chain length needed for the new set up would need to be 53" therefore 106 links, however the bike spec (I've not counted links on my chain, will do tonight) states I have a 110 link chain, so I assume I should keep it as it is!?

g00se

Don't get a campag cassette tool: If you've got a big socket set or adjustable spanner - just get a cheap Cyclo one for a couple of quid. Or if you want one with an arm, you can get a BBB or similar for a tenner.

2_tyred_itai

Found them, cheers