Advantages of compact chainset? oh and help picking one :D

rossbarney2003

I'm buying a new road bike this week. I'm going for a Specialized Tarmac Comp '08 and i'm getting it from Edinburgh bicycle coop.

A friend of mine said that at some point I should get a compact chainset for it, but what are the advantages of them?

Oh and at the moment in the bike shop, you are getting 10% back in vouchers when buying a bike, so thought I might as well pick up a compact chainset from the shop. What is the best compact chainset that edinburgh bicycle coop offers?

Here is the link to the page

Click Me



Thanks in advance

aussie70

The advantage of a compact chainset is that for most riders, it offers a more usable set of gears than a standard 53/39 setup. The chainrings on a compact are typically 50/34 which means that with something like a 12/25 cassette, you have a decent high gear, and no big jumps between the gears, and yet you still have a low enough gears for most UK climbs, using the 34 chainring.

Nearly all modern chainsets are good quality and it normally comes down to personal preference, so here's mine. Go for the Shimano FCR700 it's good quality, and absolute doddle to fit and set up, and very slick changing.

rossbarney2003

aussie70 wrote:

The advantage of a compact chainset is that for most riders, it offers a more usable set of gears than a standard 53/39 setup. The chainrings on a compact are typically 50/34 which means that with something like a 12/25 cassette, you have a decent high gear, and no big jumps between the gears, and yet you still have a low enough gears for most UK climbs, using the 34 chainring.

Nearly all modern chainsets are good quality and it normally comes down to personal preference, so here's mine. Go for the Shimano FCR700 it's good quality, and absolute doddle to fit and set up, and very slick changing.

Thanks for your help.

I'll probably pick that up as well when I go to get my bike.

robbarker

In my experience you'd be better off getting a 12-27 rear cassette.

It'll be cheaper, offers roughly the same bottom gear as 34/25, a higher top gear and is nicer to use as you are not constantly changing front chainrings as you'd find you would with a compact.

Also if you have a shimano drivetrain, you are supposed to run a medium cage rear mech with a compact so that would really need changing too, although a lot of people do use short cage mechs with compact chainsets and get away with it.

I ran an R700 compact last season but I've gone back to a 53/39 with 12-27 now.

redddraggon

Rob is right, 50-34 jump is too big, and 53-39 is better with a wider ranging cassette.

Personally I'm finding it easier to climb with 39-25 as my smallest gear over 34-25. Compacts aren't that good IMO, I really wish I'd got my Carbon Centaur in a proper 53-39.

I think Compacts really are for people who need a triple, but want to look like theyare good enough to run a double.

Van_Heerden

Sorry to jump on this post, but just picking up on something Rob said.

"Also if you have a shimano drivetrain, you are supposed to run a medium cage rear mech with a compact so that would really need changing too, although a lot of people do use short cage mechs with compact chainsets and get away with it."

I was always under the impression that the SS (short cage) was designed to go with a compact double?

Am I wrong in this as it was a parts website I got this from (can't remeber which one off hand) or can you use SS provided the front difference isn't greater than 16T?

Van_Heerden

Also, just so the details are there, I am running a 36/50 and 12-26 cassette.

dennisn

I run a 50-34 and a 11-21 on the back. I live and ride in an area that is about as flat as it
gets, so this suits me. Although I am considering going to a 35 or 36 small ring as the
34 is a bit to low for me but not that big of deal. When I travel to the hills or mountains
I switch out to a 50-33 and a 12-27. I use a Shimano crank - no problems. Easy to work
on.

Dennis Noward

topdude

As you have not even ridden the bike yet i think you should make this decision after a few hundred miles, you will have a better idea what you need rather than what everyone else thinks you should have.
By the way i have a 34-50 compact chainset on mine and a 12-27 cassette and i suits me fine but my riding is for pleasure not racing.

John.T

Shimano 50/34 with 12/27 works fine with a short mech. It needs carefull chain length adjustment but that is all. I just change to a 12/23 for racing and use 12/27 for everything else. I don't use the 27 much but am glad it is there at times with Yorkshire hills and old legs. I also do not seem to make any more ring changes than I did with 53/39. I do use the big ring a bit more though.

FSR_XC

I got my first road bike less than 2 months ago. I was concerned about the Compact / Standard differences. Especially as I like speed, but live in quite a hilly area.

In the end I stayed with the 53/39 - 12/27 that the bike came with.

I am very glad I did. The 27 is a godsend on some of the hills, but I haven't yet needed anything lower.

IMHO keep the vouchers for a month or so, get out and ride the bike as it is and then you'll be in a position to know what you need to change - if anything.

robbarker

V-H - the Tarmac Comp comes with an Ultegra rear mech:

http://www.evanscycles.com/product.jsp?style=86020

And the spec says max front difference 14t:

http://cycle.shimano-eu.com/catalog/cyc ... 1227619934

So to be within Mr Shimano's recommendation a 50/36 would be OK but not a 50/34.

In practice though people do it and I haven't heard of anyone experiencing a nasty as a result, althought he spec will be there for a reason!

neeb

It's rolling terrain where I am, lots of ups and downs but very few long ascents, and I find 50/34 with 11-23 suits me very well. This gives pretty much the same range of gears as a 53/39 12-25 (effectively the same highest gear at the top and one extra low gear at the bottom) the jumps between the rear sprockets are nicely spaced and if I want to go to the alps I just need to stick a wider-range cassette on the back.

nicer to use as you are not constantly changing front chainrings as you'd find you would with a compact.

I think this depends on terrain and riding style; I'm finding I'm in the "big" ring 95% of the time unless I'm really tired or on a long, steep hill. I think if I had a 53/39 I might even be changing more often at the front unless I had a really wide-range cassette, as it's possible to blast up the small hills in 50/23 (OK I know it's a bad chain line) but a 53/25 might have me needing to change down to the small ring a little more often.

The jump between the 50 and the 34 is a little annoying at first, but it soon becomes second nature to go up a couple of gears at the back before dropping to the small ring to avoid that unpleasant spinning sensation you get if you change at the front without changing at the back first.

Van_Heerden

Rob

Thanks for clearing that up for me. I've done a bit more reading around this and I now understand the concept of the front teeth differences and how to work it all out. Lets hope Mr Shimano's components remain as reliable as they have been

Van

John.T

VH. Don't worry about that 14 tooth max. Shimano have not updated all their info sheets yet. This is from the info sheet for the FC-R700 chainset.
"Shimano Compact cranks get inner chainrings with tooth profiles that specifically address the greater shifting demands imposed by Compact's 16 tooth difference in chainring size. This special profile is designed to prevent the chain from falling off when shifting down to the inner ring. Combined with other Shimano advances in shifting technology, these rings enable the use of a standard front derailleur with compact cranks.
Compact specific chainrings mean that you don't need to worry about compact specific front derailleurs! "

I am running 50/34 and 12/27 with a Sora 8sp front mech on one bike and the same with an Ultegra 9sp one on another with no trouble at all. Both bikes have non Shimano chainsets.

hodsgod

redddraggon wrote:

Rob is right, 50-34 jump is too big, and 53-39 is better with a wider ranging cassette.

Personally I'm finding it easier to climb with 39-25 as my smallest gear over 34-25. Compacts aren't that good IMO, I really wish I'd got my Carbon Centaur in a proper 53-39.

I think Compacts really are for people who need a triple, but want to look like theyare good enough to run a double.

I think you are right in many ways, but not 100% I run a triple because I like the flexibility 52/42/30 suits me. I have never really come across a time when I am looking for a gear I don't have. It has nothing to do with looking good or not. Then again I am 48 these days and don't worry about such things.