105 Compact or Double?

JoeAllez11

I live in an area with all the normal hills, not very mountainous. I am upgrading from my Sora to Compact

Also, do I need a new front mech?

lc1981

Impossible to say without knowing how strong a rider you are.

JoeAllez11

Oh okay, fair enough but do I need a new rear mech. Im guessing a compact is easier?

lc1981

A compact will give you lower gearing, so it'll be a bit easier on the hills, at the expense of top-end speed (perhaps, if you tend to use the top gear at present).

jibberjim

Everyone should buy a compact, unless they know they need a double. Changing a compact gearing to a double gearing will cost <30quid, changing a double to a compact will cost a new chainset.

buckmulligan

You don't need new mechs unless you're coming from a triple chainset. If that's the case you'll want a double specific front mech and a short cage rear mech, although you could run the old ones if necessary, they just won't give as nice shifting.

JoeAllez11

Okay thanks very much Is there a huge difference between the compact or double? I am nearly always in the large chainring on the front.

jibberjim

JoeAllez11 wrote:

I am nearly always in the large chainring on the front.

Everyone in the UK is - but when you need to go up steep hills, you won't be. And even though you're in the big ring at the front, you're not also in the 11.

JoeAllez11

Okay fair enough.

herb71

I have just changed to a compact. I have always had my road bike on 53/39 at the front and 11/23 on the rear and that's always been fine for the mild undulations around my locale. I never used the highest gearing much, so after finding out what real hills are during a recent Pennines sportive, I have changed to 50/34 front and 13/26 rear in preparation for next year.

I am quicker up the mild hills round here as I can spin a bit more and I can climb everything seated now, unless I really want to attack a given hill. I still have a high enough gear for most stuff, although I can spin out on the steeper descents. I run out of revs at about 38 mph and am coasting from there on.

I would say a compact is a useful change for all but the strongest riders for regular road riding / training. I wish I had changed years ago. No change to either mech was required.

JoeAllez11

Thanks for that I have an 11/25 on the back so I think a compact on the front is a good idea There's only been a couple of descents when ive got over 40 anyway

centimani

jibberjim wrote:

Everyone should buy a compact, unless they know they need a double. Changing a compact gearing to a double gearing will cost <30quid, changing a double to a compact will cost a new chainset.

Best advice....
Yes you lose a bit on the top end (running a 50 instead of a 53), but you gain so so much versatility on the small chainrings by spending circa £15 on a 36, 38, 39 or 40, the options are easy and cheap. Top that with the fact you can switch small chainrings in 15 minutes, so if you want a day 'in the mountains' you can swap easily.
Chainlength isnt really an issue, whenever i buy a compact 50/34, i immediately change the 34 for a 40...no change in anything else required.

JoeAllez11

Thanks very much. I think im going to get the Shimano 105 Compact Crankset and am considering new brakes and a new front mech.