UKH

I am currently riding a standard chain ring (52/39) with 11/25 cassette which is fine for where I live but brutal when I go to the hills. 

For about £80 I can replace my short cage for a medium cage rear derailleur and a 13/29 cassette (possibly need new chain as well). 29 is the max size the medium will accommodate.

My rather vague question is , will those four teeth make much of a difference on the hills? I'm pretty sure I am going to do it anyway but am curious if people think it will be a big help or just a little. Plan is to do some cycling trips to Lakes and Cairngorms and have more chance of saving my knees

Yes. 

In rough terms what is currently gear 1, will be gear 3. So you'll have the feel of going two gears lower than your current set up.  

You'll feel up to 16% stronger. I'd notice that.

jk

16% stronger for £80....bargain

Another way to look at is you'll feel 16% lighter. To test this you could load up 16% extra weight in a backpack and try one of your regular rides, if this doesn't make it feel brutal you may need even lower gears.

Yes, I think you'll notice a big difference.

Or 16% more disappointed when you look at the back wheel and realise you are in the lowest gear and still blowing out of your ar.....  

Prophetic!

The other option is to change the chain set to a compact 50/34. I am assuming this would have slightly more effect (5 teeth less on the smaller ring)  but it costs £125 rather than £80

or do both and spin like a lunatic doing 5mph

Check to see how often you are in the smallest two gears at the back at the moment (and really pushing rather than costing along).  If the answer is not often, then a compact may be the way to go.

A larger cassette would make life a lot easier, but not as much as a compact

i have some local hills which I will be out of the saddle for in lowest gears, but they are short and punchy rather than long. So you would spend the extra and change the chain set rather than rear cassette and derailleur?

I'd do this. Then in a few years when you're even older and fatter you can eventually go for 34-29 or even lower. Worked for me

E

I suppose one advantage is I keep the closer ratios on the 11/25 

the ratios on the the 13:29 are actually closer, 223% range rather than 227% range on the 11:25

What groupset do you have - more modern groupsets can handle bigger cassettes I think the 105 short cage can go up to 30 teeth,

As a general principle I think the modern fashion is to keep a high cadence where ever possible so bigger rear cassette and compact up front would be great if you're going to do steep long hills.   My bike had a compact and 28t rear - for a trip to the Alps a couple of years ago I put a 30 rear cassette on and was glad of the extra gear when doing 8-10% sections 10k into a climb.

"What groupset do you have?"

Campag Veloce 10 speed

Spend some time on here I think! https://www.sheldonbrown.com/gear-calc.html

Ha, shows what I know lol... glad i started this thread...have learned a lot!

Come join the MTB fraternity and enjoy the delights of a 52t cassette!  

a cassette change must be cheapest option. seems the short cage will work so don't get the RD until you try it out..

https://forums.roadbikereview.com/campagnolo/13-29-short-cage-derailleur-13...

or get bike n+1 with a sensible gear range

34 front/25 rear is actually a slightly higher gear than 39 front/29 rear: 1.36 vs 1.34.  Not a lot, but it suggests that simple maths can have a bit of an edge over guesswork sometimes...

interesting link...thx, maybe just a cassette after all.

I don't really agree withe comments here. Increasing your largest sprocket from 25T to 29T won't make nearly as much difference as you might imagine. If you increased your 11T to 15T you'd feel a huge difference. It's not the difference in number of teeth which matters, it's the ratio. Being the age I am I always go for calculating gears in inches. This is found by multiplying chainring T by wheel diameter in inches and dividing by sprocket size. So your plan would change your bottom gear from 41" to 35.6", not a huge difference. 

I'd suggest another ploy. If you search through the ads in cycling mags you might find an adapter which enables you to mount your rear mech slightly further from the wheel spindle. This might enable you to use a cassette with a bigger sprocket like 32T or 34T. You'd really notice the difference then, as your lowest gear would then be 30". If you're interested I could probably find the ad for the adapter.

Edit:

Spa Cycles, search for Sunrace extender link

why not just stick a smaller chainwheel on the front (switch out the 39) and ease all the gearing ?

How?

E

The BCD might be different on the crankset to just swap chainrings. I guess you could get a new crankset quite cheap though if you're not bothered about Ultegra level componants. £63.99 on CRC for a 50/34 compact Tiagra chainset. 

I'm running Campag Veloce as well.  As i take my road bike on tours and i want to preserve my knees, i kept my compact chainrings and changed to a long cage derailleur with a Miche 13-30 cassette.  I swapped sprockets to make it 14-32 and it'll now get me up short sections of 20% (with 8kg) of bike bags at 5mph.

The only downside is that i can't pedal beyond 35mph on a downhill. But as I don't race, that really doesn't matter!

In the past, I swapped out an 11-25 (I think) cassette on my road bike for an 11-32 MTB cassette for a hilly ride in the Alps. Worked fine with the short-cage mech, just twiddled the B screw a bit so there wasn't any rubbing.

The downside with a bigger cassette is bigger jumps between the gears.

buy a 34 tooth chainring, a 5mm allen key, and a flat blade screwdriver and replace the 39t ring with the 34t to ease all the ratios - a wee daub of blue Loctite on the chainring bolt threads when tightening up

https://www.condorcycles.com/products/campagnolo-veloce-10-speed-chainring

Bet you can't.

E

why not - whats the hitch ?

You standard 53/39 Campagnolo chainset will have a BCD of 135mm - the smallest chainring you can fit will be 39 teeth - you need a 110mm BCD crankset to fit a 34 chainring. By all means change the cassette to a 13-29 but you'll probably need to replace the chain as it's likely worn / skip on the new cassette.

I bit the bullet and bought a compact chainset and I also got shorter crank length (I was using 175mm and bought 170mm) I’m hoping this helps me in the drops as I’m only 5’8’’ and found my knees punching me in the chest with the longer cranks. 

Also bought a medium cage derailleur. But will see how I go first with the new chainset before fitting a bigger cassette and the derailleur. Will be handy to have to put on if and when I get to the alps anyway so pleased I bought it  

Thx for all the advice chaps