Noticable difference between 39x29 and 34x29?

rc856

Hi folks.
Heading to the Pyrenees for a wee 4 night stay next year and was looking at changing my gearing.
Currently running Chorus 10sp 53/39 - 12/29 and was going to put a Compact 50/34 on.
I've been in the Alps with this and was ok but this was 5yrs ago and I was fitter. In between times I've been to Ventoux and really suffered.
Will I notice the difference between the two set ups?
The cost of a Centaur compact and BB cups isn't that much so no issue there.
I'd read opinions on if you're not able to do the cols on a 39x29, you won't be able to do them on a 34x29?
The obvious answer is to be better prepared but family/work might not allow this and I thought better to have than not?
Thanks

ColinJ

I'm sure you will get the usual comments about getting fit enough that you wouldn't need the lower gearing. That would be lovely, but if you can't make that happen before your holiday then the least you can do is to fit more sensible gears for the level of fitness you actually have.

Better to have low gears that you don't necessarily need than need lower gears that you don't have!

Even if you get superfit and can normally whiz up the cols in your 39/29, what would you do if you got to the foot of some monster climb and found that you had a 20 mph headwind all the way up?

andyp

In my experience, you can never have too low a gear, especially at the end of a long day.

dodgy

RC856 wrote:

I'd read opinions on if you're not able to do the cols on a 39x29, you won't be able to do them on a 34x29?

i'd like to hear someone convincingly try to argue that point, because it's complete bolleaux.

I'd go for the compact if you think there's a risk you're under geared, it's a holiday after all!

dennisn

andyp wrote:

In my experience, you can never have too low a gear, especially at the end of a long day.

+1...... I can vouch for that. Had more than a few days where I was more than thankful for that 34 tooth on the front. Grinding it out through the mountains in too big a gear is not
anyones idea of a good day.

dennisn

RC856 wrote:

I'd read opinions on if you're not able to do the cols on a 39x29, you won't be able to do them on a 34x29?
The obvious answer is to be better prepared but family/work might not allow this and I thought better to have than not?
Thanks

Forget those morons who talk about being able to push this or that big gear. You're the one who is actually doing the riding. Take all you can get. A 34-29 sounds like a fine choice. Ride your compact and leave the other, so called, big gear pushers to debate it while sitting in their easy chairs.
As for the being in better shape, well, shouldn't we all be, but that doesn't always happen, what with, like you say, work and family. You'll do just fine if you ride in the gears YOU go best in and at a pace YOU can maintain and to hell with everyone else.

greasedscotsman

You could switch over to a compact and then take two cassettes with you, a 13/29 and a 12/25 (or whatever Campagnolo make...) then switch to whichever you feel is the right one when your there. Doesn't have to be a Centaur one, I've quite often switched cassettes for riding in the mountains and dropped down a groupset level. Just a thought, might not be practical as you'll have to take tools as well.

rc856

Thanks folks. Sound advice.
That's all the convincing I need

Monty Dog

Comes down to your fitness and only you can tell - only fit riders would be able to get up the Tourmalet on 39x29 comfortably. Better to have the option of lower gears IMO.

Scrumple

Compact all the way.

Better to have something left to give, than be found wanting.

paul64

From the maths perspective there will be a worthwhile difference. Easy enough to work out a '29' for this graph to show the difference in real terms between the '34' and '39' rings. If I get the time later I'll do that.

Your fitness may not need the 34 but if you are happy enough with the jump between each gear and the top as well then it might be useful to have the emeregency gears