Standard double to compact chainset options...

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amnesia

Free-wheeling into oblivion...
Hi all,

I have a Specialized Tarmac Comp with Shimano 5700 105 groupset, 11-28 rear cassette, and 39/53 chainset.
I really don't get on with it on hills as I like to spin at 90+rpm and I just can't do this at the moment. I know I should MTFU and just get on with it, but it's making me avoid hills altogether on rides which is stopping me from enjoying riding.
angry.gif


Sooo, what are my options for changing to a compact ?

If I get the compact version of the 5700 or the SRAM Rival chainset would I need to fit a shorter chain (or could I remove links from the one I have) ?



Any thoughts ?


Cheers,
Daniel.
 

aberal

Veteran
Location
Midlothian
If you replace a chainset you should technically replace both the rear cassette and the chain as the wear on the chain can theoretically increase wear on the new chainset. In reality, I'm not sure what real difference it makes, but the very least you should do when you put a compact on is replace the chain and lengthen it to suit.
 
OP
OP
amnesia

amnesia

Free-wheeling into oblivion...
If you replace a chainset you should technically replace both the rear cassette and the chain as the wear on the chain can theoretically increase wear on the new chainset. In reality, I'm not sure what real difference it makes, but the very least you should do when you put a compact on is replace the chain and lengthen it to suit.

Cheers... the bike only has about 750 miles on it, but will replace the chain anyway if I put on a compact.
 

brockers

Senior Member
If you replace a chainset you should technically replace both the rear cassette and the chain as the wear on the chain can theoretically increase wear on the new chainset. In reality, I'm not sure what real difference it makes, but the very least you should do when you put a compact on is replace the chain and lengthen it to suit.

If you fit a compact, you might find that you'll need to fit a longer cage rear derailleur to take up extra slack as well. Starts to get expensive. I'm no expert on Shimano mind, so I might be wrong. You've already got a 28 on the back though. Exactly how steep are the hills around Bournemouth? ;)

A cheaper way is to undergo some sort of regime of shorter, intensive hill reps (not exactly M'ingTFU, but close!), and recovering properly, and then tackling those long drags with a bit more power in your legs!
 

MacB

Lover of things that come in 3's
if the rear mech has the capacity it should be fine, it might work anyway...the capacity is the teeth difference at front and rear added together, so currently you have:-

53 - 39 = 14
28 - 11 = 17

14 + 17 = 31 and that's the capacity your rear derailler is coping with.

according to the Shimano tech specs then the 105 shirt cage rear derailleur has an overall 33t capacity and the medium/GS has 39t.

By my reckoning that would mean that, regardless of which version of the rear derailler you have, you can go with a 50/34 compact chainset as your actual capacity would be 33t then, and I guess there's a bit of leeway in there. I don't know if the front derailleur would be ok, but I'd have thought it would be the same one for compact or double.
 

al78

Guru
Location
Horsham
if the rear mech has the capacity it should be fine, it might work anyway...the capacity is the teeth difference at front and rear added together, so currently you have:-

53 - 39 = 14
28 - 11 = 17

14 + 17 = 31 and that's the capacity your rear derailler is coping with.

according to the Shimano tech specs then the 105 shirt cage rear derailleur has an overall 33t capacity and the medium/GS has 39t.

By my reckoning that would mean that, regardless of which version of the rear derailler you have, you can go with a 50/34 compact chainset as your actual capacity would be 33t then, and I guess there's a bit of leeway in there. I don't know if the front derailleur would be ok, but I'd have thought it would be the same one for compact or double.

Yes a 50-34, 11-28 compact setup will work with a short cage derailleur as this is what I currently have on my road bike.
 
OP
OP
amnesia

amnesia

Free-wheeling into oblivion...
Thanks chaps...

The Purbecks and North Dorset are surprisingly lumpy - there are a few 16%+ drags and a couple of 25% killers about, although nothing like you guys have Oop North ;)

I will do some Googling for hill training techniques and just get on with it for now...
whistling.gif


Cheers,
Daniel.
 
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