changing from 12-25 to 13-29 cassette

cookiemonster

Hello

I run compact chainset - 50/34 with a 12-25 cassette. Its fine for steep nasty climbs in the chilterns (25% or so) and was happy spinning my way up Mt Tiede in the canary isles (2100m of non-stop climbing, and 2700m total ascent) and getting up Ventoux at a reasonable pace.

However...

I'm down for the marmotte and the dave lloyd challenge this year (maybe the fred too if i get a place) and i'm toying with the idea of sticking a 13-29 on the back for somewhere to go after 100 miles - a safety net really.

Anyway

If I get myself a 13-29 cassette, is it just a case of adding a couple of links and being careful not to cross chainring and cassette, or am I into the realms of needed a longer cage rear mech from the standard out the box chorus unit?


As an aside - my preference would be 12-27 as anything lower than 34/27 and you're faster walking, but i'm on campag and dont have the option of that size cassette - very annoying and the only thing I prefer about my old ultegra to the current chorus. And, I cant be bothered fitting a triple for the possibility, rather than certainty, that I'll use it for a couple of events over the whole year.

Cheers

Jon

redddraggon

cookiemonster wrote:

As an aside - my preference would be 12-27 as anything lower than 34/27 and you're faster walking,

I doubt you're ever going slower than 3mph with a gear of 34-27

At 80rpm, gearing of 34-29 is 7.3mph, a lot faster than normal walking pace, and definitely faster than pushing the bike up the hill wearing shoes with cleats. You even could always pedal a bit faster......

jpembroke

You will need a medium or long cage rear mech (medium preferably as long cage looks a bit sh*te - Campag do medium mechs). I tried running a 13-29 with a short cage rear mech and it didn't work well, upper jockey wheel interfered with the 29 sprocket no matter how much I fiddled with adjustment screw. Made a right old racket.

a_n_t

medium cage is fine, i run a 29 on the training bike.

cookiemonster

Cheers folks

I'll have to have a think as to what I do - I dont fancy spending a couple of hundred quid on a mech and cassette. Maybe just go with 34/25, maybe look at sticking on centaur or veloce for the marmotte.

mmm

salsarider79

Can I reccommend lots of training?


Bad carpenter etc etc....

rickhotrod

Marchisio cassettes allow you to choose what size sprockets to use. Something like 12-28 made up from one of the following combinations:

12,13,14,15,16,18,20,22,25,28

12,13,14,16,18,20,22,24,26,28

12,13,14,15,17,19,21,23,25,28

With a maximum sprocket of 28, this might allow you to use the short Campagnolo rear derailleur. Just don't use anything smaller than 15t when on the 34 chainring!

Steve928

Duplicate post deleted.

Steve928

You can also mix Campag and Marchisio sprockets to some extent to make custom cassettes i.e. make your desired 12-27.

It's what I do: I bought Marchisio 24 and 26 sprockets plus 28 and 30 last position sprockets, plus the relevant spacers and anti-flex thingies.

Allows me to make a 12-28 or 13-30 using the first 8 Campag sprockets from 12-25 and 13-26 respectively plus the 2 Marchisios. I don't use a compact chainset and it's worked well so far with a short cage mech - though perhaps that depends on the dimensions of your frame's mech hanger. All combinations of 53/39 and 13-30 shift and run smoothly with mine.

Shifting between the C + M sprockets is less good than all Campag, but you only have to be aware of this and use a little care. Fine when it's just a couple of sprockets at the end of the cassette.

kozzo

Miche has separate sprockets
http://www.miche.it/scheda.php?id=460&idCat=247&lang=en

ColinJ

Re the 'Faster walking' comment:

I did the Pendle Pedal a couple of years (hard 100 mile Lancashire sportive) and had some younger guys poke some good-natured fun at my bike and my age (something like "See you've got your granny with you granddad!"). This was at the start of the climb from the crossroads at Quernmore. A few minutes later I caught up with them as they were walking their bikes up the steepest part of the climb. I had a 30/26 bottom gear and it was definitely quicker spinning that than trudging up the hill on foot...

Another example: There was a big cyclocross event in Centre Vale Park, Todmorden about 10 years ago (I'm fairly sure it was the national championships). There was a savage little climb up one side of the woods, near a church. On the first lap, virtually everybody rode it. Gradually as the event went on it got more and more muddy and riders were tiring so more and more got off and ran. A few laps on, they were walking. The guys who kept riding were using low gears and overtaking everybody else.

PS (1) Just noticed - they had a cyclocross event there yesterday and I missed it - damn!

PS (2) Ooh - the national cyclocross championships take place at Peel Park, Bradford next week. Might well nip over to watch!

jpembroke

Whilst I have Campag on my road bike (and I'm very fond of it) I do see the benefit of having Shimano. I have a 105 equipped 'cross bike that has a 48/34 chainset and either a shimano 12-25 or a SRAM 11-28 cassette. If I wanted to go even bigger for any reason I could easily stick on large (and cheap!) MTB cassette and a £20 Deore rear mech. Could even whack on an MTB triple, too. All readily available and cheap as chips, unlike Campag.

FWIW, my road bike has a standard 53/39 double and a 13-26 and that's been fine for big days out in the alps so I'm not too bothered.

dennisn

I've said this a few times before but here it goes again. T-A Specialities makes a 33 tooth
compact front chain ring if that will help. I use one when I head for the big mountains. No problems and I use it with a 12-27 or 12-25. Don't have to switch rear mech's.

Dennis Noward

cookiemonster

Hi

Cheers for this folks - the sprocket approach sounds exactly what I'm after, i'll look at swapping the 23 and 25 with 24/27 similar to the shimano 12-27 for the event(s)

The 33 chainring sounds good, but (and this may sound ridiculous) I tend to shy away from messing around with the UT bottom bracket - once its been fitted nicely its fine forever, but messing around with it can cause problems (yes, I know, ridiculous, sorry)

Suprised no one has come up with most obvious solution - swap out my 10 speed chorus for 11 speed...

jon

dennisn

cookiemonster wrote:

Hi

Cheers for this folks - the sprocket approach sounds exactly what I'm after, i'll look at swapping the 23 and 25 with 24/27 similar to the shimano 12-27 for the event(s)

The 33 chainring sounds good, but (and this may sound ridiculous) I tend to shy away from messing around with the UT bottom bracket - once its been fitted nicely its fine forever, but messing around with it can cause problems (yes, I know, ridiculous, sorry)

Suprised no one has come up with most obvious solution - swap out my 10 speed chorus for 11 speed...

jon

Is the bolt circle on Campy compacts 110 or something else?

Dennis Noward

cookiemonster

Mr Brown suggests its 135 BCD (and Shimano 130) - the mtb stuff is 110 PCD

http://www.sheldonbrown.com/harris/chainrings.html

dennisn

cookiemonster wrote:

Mr Brown suggests its 135 BCD (and Shimano 130) - the mtb stuff is 110 PCD

http://www.sheldonbrown.com/harris/chainrings.html

That's the BCD on standard cranks. I'm wondering about Campy compact.

Dennis Noward

nickwill

It's 110, but just to be awkward, one of the bolts is offset. Only Campag or Campag compatible rings can be fitted!

stevekosky

I have Campag 13 - 29 with 50/40/30 and it seems to work well for me.

I need all the help I can get

dennisn

Nickwill wrote:

It's 110, but just to be awkward, one of the bolts is offset. Only Campag or Campag compatible rings can be fitted!

I kind of thought so. Odd that they do that or maybe not so odd. Makes people have to buy their chainrings because hardly any aftermarket ones are made. Or are they?

Dennis Noward

redddraggon

dennisn wrote:

Makes people have to buy their chainrings because hardly any aftermarket ones are made.

I wish you could get these Campag chainrings.......but I can only find TA and Stronglight rings that are compatible - they aren't cheap though.

nickwill

Thecompatible rings seem to be more or less the same price as the Campag ones. I was looking for some Campag rings a few weeks back and couldn't find any.

wildmoustache

cookiemonster - you should try and avoid having 50x13 as your biggest gear for the marmotte at least. from the lauteret down to the base of alpe d'huez is an exceptionally long, fast, relatively shallow descent where you'd benefit from a bigger gear (assuming you are comfortable descending at speeds of around 40mph).

I wouldn't want to go into that one with anything smaller than 50x12, and i'm actually planning on doing it with an 11-25 cassette but we are all different. 12-27 with 50-34 sounds like a good option if you can build it.

jpembroke

dennisn wrote:

cookiemonster wrote:

Mr Brown suggests its 135 BCD (and Shimano 130) - the mtb stuff is 110 PCD

http://www.sheldonbrown.com/harris/chainrings.html

That's the BCD on standard cranks. I'm wondering about Campy compact.

Dennis Noward

Yes, Campag Compact chainsets have 110mm BCD, same as Shimano. It's just their standard chainsets that differ (135mm instead of 130mm).

nickwill

jpembroke wrote:

dennisn wrote:

cookiemonster wrote:

Mr Brown suggests its 135 BCD (and Shimano 130) - the mtb stuff is 110 PCD

http://www.sheldonbrown.com/harris/chainrings.html

That's the BCD on standard cranks. I'm wondering about Campy compact.

Dennis Noward

Yes, Campag Compact chainsets have 110mm BCD, same as Shimano. It's just their standard chainsets that differ (135mm instead of 130mm).

Yes... apart from the offset bolt, which means it isn't compatible!

redddraggon

Nickwill wrote:

jpembroke wrote:

dennisn wrote:

cookiemonster wrote:

Mr Brown suggests its 135 BCD (and Shimano 130) - the mtb stuff is 110 PCD

http://www.sheldonbrown.com/harris/chainrings.html

That's the BCD on standard cranks. I'm wondering about Campy compact.

Dennis Noward

Yes, Campag Compact chainsets have 110mm BCD, same as Shimano. It's just their standard chainsets that differ (135mm instead of 130mm).

Yes... apart from the offset bolt, which means it isn't compatible!

Only with the Ultra Torque Compacts. The older square taper Campag compacts are normal 110bcd

nickwill

redddraggon wrote:

Nickwill wrote:

jpembroke wrote:

dennisn wrote:

cookiemonster wrote:

Mr Brown suggests its 135 BCD (and Shimano 130) - the mtb stuff is 110 PCD

http://www.sheldonbrown.com/harris/chainrings.html

That's the BCD on standard cranks. I'm wondering about Campy compact.

Dennis Noward

Yes, Campag Compact chainsets have 110mm BCD, same as Shimano. It's just their standard chainsets that differ (135mm instead of 130mm).

Yes... apart from the offset bolt, which means it isn't compatible!

Only with the Ultra Torque Compacts. The older square taper Campag compacts are normal 110bcd

Serves me right for following the latest fashion! :evil:

jpembroke

The offset bolt? Is that what designers call 'a feature'?

jpembroke

I do seem to recall reading that original Campag chainrings won't fit on new UT chainsets but I assumed that was a myth. Assume they were talking about compact chainsets then. How odd.

redddraggon

jpembroke wrote:

The offset bolt? Is that what designers call 'a feature'?

Ultra Torque chainsets have one of the smallest Q-factors for an external bearings setup - the hidden bolt had to be offset slightly on the compact to allow such a low Q-factor (apparantly)

Steve928

redddraggon wrote:

Only with the Ultra Torque Compacts. The older square taper Campag compacts are normal 110bcd

The sqaure taper carbon compacts have the offset bolt too, in fact the offset exists because of something to do with the manufacturing process of the carbon cranks.. Only square taper + all alloy cranks are standard/uniform 110 bolt circle.

P.S. standard 110 rings can be fitted to offset-bolt cranks quite easily by elongating the bolt hole in the ring with a file.. The difference is only 1mm.