compact versus double whats the difference

[jackthelad]

guys just bought a new frame and was going to fit a new groupset the shimano 5700.I have used 50/34 front and 12/25 at the back on my road bike but was thinking of fitting a double 53/39,was just wondering if anyone could enlighten to the benefits of the bigger crankset.Any help appreciated.


jackthelad

 

[HLaB]

How do you handle hills at the moment, if you handle them well it's probably a good change, increasing your top speed but if you only handle them OK'ish it'll be a negative and you'll have to work hard to get back where you are but eventually it might be better, and if you don't handle hills well its a terrible move and you will only struggle more IMO. IHTH

 

[gbb]

First is to think about where the 50/34 leaves you feeling short ?
How much do you use the 34 and the 50, is your terrain hilly, flat or both ?
How often do you use the 50 and can you maintain good speed on it. If you can cope well on the 50, then the jump to 53 is probably not too much extra....but, if you use and need the 34 because its hilly, the jump to a 39 could be quite a lot.

Personally i like the 50, its kinder on my knees. My commuter with a 53, i tend to spend more time on the 39.
But then the 34 on my compact was useless to me because of the flattish terrain here. Its easy to uprate the inner on a compact to suit your terrain, its hard to reduce the inner on a standard chainset if ithe 39 is too much for any hills.

Its a tortuous explanation In simple terms, i think a compact is more adaptable...if you don't find yourself spinning out on the 50t

 

[jackthelad]

Hlab thanks for the repliy,I practice on massive hills about 3 times a week usually about a 20 mile route with the first ten miles on a constant rise on very steep hills.These hills are so steep that I am on the biggest ring at the back with a 34 front and still find myself to click up a gear and stand on the pedals because of the length of them.But i must admit it has really increased my speed on the flats with the legs building up,but would like to take it one step further with the bigger crankset.I was basically wondering how much of a differnce on the flats.

 

[jackthelad]

gbb thanks for the reply the 34 is usually only used on hills and on the flats I am in my fastest setup 50/12 most of the time

 

[jackthelad]

gbb after reading your reply again I think your right with the 50/34 covering more bases,I am not going up hills at a great speed but i dont let them beat me,I am now thinking maybe I need a bit more time with the 50/34 until the setup becomes a good bit easier
thanks again for the replies guys and allowing me to look at it from a different angle instead of just top speed.

 

[StuAff]

Alternative would be to go for 52/36 rings...bit quicker on the flat, not too much harder for the hills.

 

[gbb]

gbb after reading your reply again I think your right with the 50/34 covering more bases,I am not going up hills at a great speed but i dont let them beat me,I am now thinking maybe I need a bit more time with the 50/34 until the setup becomes a good bit easier
thanks again for the replies guys and allowing me to look at it from a different angle instead of just top speed.

If the hills are that steep, no real surprise you're not going up them fast, nothing wrong with that. It seems to me a 39 would make it impossible.
Why not get a compact 50/36 or fit a 36 to a 50/34, that way you'll be able to revert back easily. Inner chainring would cost circa £20, cheap and readily available. 10 minutes to change tops.

 

[jackthelad]

guys thanks for the replies again,I think the 39 would kill me on the hills,but can you change the big ring and keep the 34,making it a 53/34 or as stu said might have a go at the 52/36

 

[jackthelad]

ok guys just read on the net 53/34 or 52/34 is too big a jump and could cause problems with shifting I guess the manufacturers put out the combinations of 50/34 for a reason seems the 52/36 is ok so might take it into concideration

 

[HLaB]

The maximum I think you could change your big ring to, is a 52 (Ive got one on my compact Kinesis) but 34/52 is an awful big jump I dont know if the mech or you could cope with it, my Kinesis is a 38/52 btw. When my last 12-25 cassette wore out I changed it to a 11-25. In theory changing your cassette to an 11-25 would gain you 2.66mph at 90rpm for no change to your lower gears, that possibly could be an option.

 

[jackthelad]

hlab I am new to the different options I bought a frameset on the net and was thinking of something different from my present road bike setups which are 50/34 12/25,so this was the reason i thought about the 53/39.My present bikes are tiagra 9 speed and on the new frame i was thinking of a different setup with 10 speed .

 

[jackthelad]

I was going to buy a full groupset probably the 5700,with the differnt options would I be better with seperates,I think I will need to change the brakes from a groupset as i need 57mm drop brake calipers

 

[the_mikey]

The problem with big jumps on the front derailleur is caused by the capacity of the rear derailleur to manage the the chain across those differences, if you have 34/50 and change the chainrings you can have 36/50 39/52 36/52 etc, but you can't then have 34/52 because the difference is too large for the rear derrailleur to handle gracefully.

 

[jackthelad]

mikey thanks for explaining I contacted chain reaction and they said that the apex 53/39 with 11/32 works ok.The only problem being I have only ever used shimano.What do you guys think of this setup and what does the apex groupset fell like.I am looking from the point of view of 100 mile sportives across hilly countryside.Any views appreciated

Jackthelad