compacts

Rehnquist

can't get my head around compacts v. triple debate.
Going to the Alps and want to know how people have fared on a compact. I know i am on my granny ring on the triple pretty sharpish normally.
Any thoughts / advice gratefully received.

redddraggon

If you already use the small ring of a triple pretty often, I wouldn't get a compact.

I'd stick with a triple from what you've said.

John.T

Agreed. Compacts are good if you are finding a 39 a little hard. If you have a triple and use the granny much I would not contemplate changing. After all it cost nothing to stay as you are and you do not have to use the granny if you don't want to. If looking at a second bike then it is worth considering a compact at this time depending on how you intend to use it.

graham_g

I think it boils down to your usual riding terrain + personal preference to be honest. I fitted a compact because the standard (42/52) chainset just left me dead on hills after I moved to Bristol. Problem is that despite the new found ease on hills, I'm cursing the fact that I just can't get a decent cruising gear on flat or undulating routes. The last parts for my mix and match triple groupset arrived yesterday!

robbarker

If you need low gears get a triple.

Compact chainsets are a PITA as they have a big gap between the chainrings and you are frequently changing at the front, then having to change at the rear too to get an intermediate ratio. They lead to some ridiculous chain lines too.

I've gone back to 53/39 and 12-27 in place fo 50/34 and 12-25 and I haven't looked back.

Compacts are flavour of the month a d fashionable at present, but I predict it will be a fairly short lived fad.

redddraggon

robbarker wrote:

Compact chainsets are a PITA as they have a big gap between the chainrings and you are frequently changing at the front, then having to change at the rear too to get an intermediate ratio. They lead to some ridiculous chain lines too.

Compact works fine for me, although I spend most of my time in the big ring, but when I need the little ring I need it.

Although I have gone for a 53/39 on my latest bike.

itisaboutthebike

Depends on what gear your using at the back when on the granny ring.

if your on 28(F) x 25 (R) a lot then you won't be able to get that using a compact (unless you go for Campag 34 x29 - which will give you a 30.8 gear on 170 cranks as opposed to 29.4 with 28x25).

I'm going with 34x28 bottom gear for this years Marmotte - the 28 if when I'm completely kn*ckered up the last few kms of the Galibier and the Alpe (if I make if that far). Most of the other times I'll be in the 23 or 25 I expect.

I disagree with the poster about compacts being a fad. I used to use a triple previously in the Alps - mainly 'cos you couldn't get a low enough double. This has been solved for the majority of people by compacts.

There aren't may people who can get round the Marmotte or Etape courses (or even one Alpine climb) in 39x25 or 27 (not even Lloydy in last years Marmotte- and yes I know he's 58 now !)

robbarker

I think roadie sportive riders need to overcome the fashion bar to using triples.

They are a much more useable option for very little extra weight.

A 50 tooth big chainwheel is a limiting factor on swooping alpine descents, and big gaps betewwen your gears are a pain in mixed terrain.

Roberto Heras used a triple in the Vuelta a few years ago, as soon as a few other pros do it will become acceptable to the fashion victims / pro wannabees.

itisaboutthebike

Heras only used a triple 'cos compacts weren't available back then.

Pro's don't like using triples (because of the weight penatly) - this was told to me by a well known UK Pro team mechanic recently.

If you're spinning out on 50x12 on an Alpine descent then you need to be riding for a Pro Tour team ! Personally I like to conserve my energy a bit for the next climb.

As someone once somewhere ( I can't remember where) - the 53 ring is really meant for Pro use. How many people use thier 12 and 13 sprockets REGULARLY ?

mrushton

itisaboutthebike wrote:

Heras only used a triple 'cos compacts weren't available back then.

Pro's don't like using triples (because of the weight penatly) - this was told to me by a well known UK Pro team mechanic recently.

If you're spinning out on 50x12 on an Alpine descent then you need to be riding for a Pro Tour team ! Personally I like to conserve my energy a bit for the next climb.

As someone once somewhere ( I can't remember where) - the 53 ring is really meant for Pro use. How many people use thier 12 and 13 sprockets REGULARLY ?

Note that bit 'Pro's don't like triples' most of us on here will v.rarely get to use 50x12 never mind anything bigger and if you are spinning out on an alpine descent on 50x12, you are going at 40mph+ and if you can get down Alpe d'huez or the Aravis etc at those speeds, you should be Pro.

redddraggon

itisaboutthebike wrote:

If you're spinning out on 50x12 on an Alpine descent then you need to be riding for a Pro Tour team ! Personally I like to conserve my energy a bit for the next climb.

I guess a Pro Tour team will be ringing me up to discuss a contract today then.

50x12 @ 80RPM is only 26mph, on the flat I can easily maintain 22mph or so (50x14), as soon as the hill goes down even slightly I'm in the 50-12 and spinning faster than my norm.

Plenty of rubbish being spouted about compacts having higher gears than people need - maybe if you go slowly.

Richard891

Hmmm, I don't quite get the comment about how compacts give you a bad chain line. When I bought my bike last summer it had a triple with 52.42.30t and initially I was very glad of the granny ring. After nearly a year's riding I found I rarely used the granny ring anymore, and I also noticed that most of my riding was being done on the 42t middle ring. After a lot of research, spreadsheets with gear ratios and gear inches and so on I decided to swap the triple out for a 50.36t compact (I've got 12-25 on the back).

The 50.36t compact is a little less common than the usual 50.34t, and if you do the maths the jump in the number of teeth between the rings is 14, the same as on a standard 53.39t double. My lowest gear is 38.9 gear inches, on the triple's granny ring the lowest was 32.4, but as I said I mainly used the middle ring, which had a lowest gear of 45.4. On a 53.39t double the lowest gear (on a 25t sprocket) gives you 45.8. WIth my compact I have two gears lower than this, which is nice, and for me and my usual terrain enough!

I actually find the chain lines with the compact a lot better than with the triple, in fact I'd say that more of my gears are useable and therefore useful on the compact compared to the triple. Oh, and 50x12 seems big enough for me at the moment; don't seem to spin out often and when I do I'm going downhill and plenty fast enough, thanks.

robbarker

itisaboutthebike wrote:

Pro's don't like using triples (because of the weight penatly) - this was told to me by a well known UK Pro team mechanic recently.

Really? Who was that then?

Shimano component weights:

Dura Ace double: 740g
Dura Ace triple: 750g
R700 compact: 760g

graham_g

I think we can chalk this one down as a Marmite decision!

Good point above though about a 36/50 compact - that would've been more sensible for me (I should've paid more attention to the Sheldon Brown gear calculator!).

gavintc

A 50-11 is a higher gear to a 53-12. A compact does not need to be undergeared on descents. A 34-25 is a pretty low gear, albeit not as low as a triple, but for much of the climbs a reasonably fit rider will encounter it should suffice.

I use a compact on my sportive bike as I know I need the lowish gears it provides when I am tired and hit a 20+% gradient. But for my training bike, I use a normal double.

I had a triple and hated it with a passion. I was always in the wrong front ring and found myself bouncing up and down the front rings - a double is so much neater and useful.

robbarker

I use the triple on my audax bike (a Thorn Cyclosportif) as a double, but with the bonus of a additional grovel gear for really steep hills or when I'm particularly knackered, and I don't mind it at all. It's got a better spread of gears for the middling 90% or riding that I do on it.

itisaboutthebike

Oh and the other reason Pro's don't like triples is that they don't give a snapier change as a compact( and short cage rear mech) as it requires a long cage rear mech and longer chain - and also as someone has commented , a marginally better chain line in some gears.

I doubt whether Shimano(or Campag for that matter) would have invested heavily in producing compacts if they weren't going to sell in the first place (and don't give me that rubbish about manufactures creating a demand !).

Twenty years ago I used to train(and race) on 42/23 (not in the Alps admittedly) but now those gears are beyond me and am more than happy using 38x50 and 34x48(in the Alps).

If you want to pedal 53x12 down Alpe D'Huez or the Glandon or any other Alpine col, please be my guest !

markos1963

I am running a 50/34 compact on my bike with a 12/25 cassette. I find that I spend very little time on the small ring. I know living in North Norfolk our hills are no more than bumps to a lot of you let alone the Alps. Hindsite is a wonderfull thing but if I was buying again I would go for a 50/36 set up to give me a better cruising option up long slopes.

robbarker

I agree about snappier changing at the rear with a short cage mech - that's one reason I've gone back to 39/53 and 12/27 as, in Shimano land at least, a compact is supposed to be used with a GS (med) cage mech. (Although most people seem to run them perfectly happily with a short cage)

Front change quality on a compact is clunky though, and I found I was changing it more than I do with a 53/39 or 52/42/30.

As people have said, it's down to personal preference - and I know what I prefer!

jhop

For me as well as a considerable weight saving I have also found changing slicker and a better chain line on the plus side as against a slight loss at each end of the ratios on the minus side.

Aethestically the balance tilts only one way!!

Campagnolo 06 Centaur Carb 10 Spd Chainset
Weight: 558g

Campagnolo 06 Record Triple 10 Spd Chainset
Weight: 737g.

itisaboutthebike

Really? Who was that then?
]

I don't want to mention any names on the forum - but he,s been a very highly regarded Pro Tour team mechanic for the last umpteen years.[/quote]

daniel_b

robbarker wrote:

I've gone back to 53/39 and 12-27 in place fo 50/34

Chaps,

my Felt has a double running a 53/42, with a 12/24.

I was considering changing the rear cassette for an Ultegra 12/27, and initially didn't want to change my front cranks, but now I see some of you are running 53/39 as above, so, dumbass question, can I buy a smaller inner ring, ie 39 teeth, and unbolt my 42, and replace it with the 39?

Cheers

Dan

robbarker

You should be able to provided the bolt circle diameter (how wide the bolts are apart that fix the inner chaainring to the outer) is . What is the chainset?

Are you absoulutely sure it's a 42? That's quite unusual nowadays. 39 is the normal inner ring size.

daniel_b

Hi Rob,

I'm pretty sure it's a 42, as I counted them manually a while back, but I will double check when I get home.

The spec for the bike is an FSA Gossamer crankset, however the spec also says it is a triple, and mine is a double, but it is defo an FSA.

I bought it 2nd hand, so perhaps the previous owner specced it as such from new, or changed it post purchase.

Cheers

Dan

musto_skiff

Can you run a 50/34 with 12-27 with a standard rear mech (Ultegra)?

I belive this is pushing the set up a bit - what are the possible issues?

itisaboutthebike

Yes most people riding Alpine (and other ) sportives run 34x50 with a 12-27 rear with no problems (altho I doubt whether you'll be able to get the mech change into the 27 sprocket on the big chainring !!)

dennisn

musto_skiff wrote:

Can you run a 50/34 with 12-27 with a standard rear mech (Ultegra)?

I belive this is pushing the set up a bit - what are the possible issues?

Yes. I have run a 50-33 and a 50-34 with a 12-27 with a Dura-Ace rear(which has the same capacity as Ultegra. Chain length is the critical thing if you want ALL gears to work.
Although if you try to run a 34 front ring to a 12 or 13 rear cog you will proably get
a bit of chain "dink" because the chain line is at a bad angle and brings it to close to the 50 ring causing it to hit slightly, hence "dink". Also using the 50 front ring with the 27 rear
is just about the limit of chain takeup on the rear mech if the chain is set up to work
through the complete range of gears.

Dennis Noward

musto_skiff

itisaboutthebike wrote:

Yes most people riding Alpine (and other ) sportives run 34x50 with a 12-27 rear with no problems (altho I doubt whether you'll be able to get the mech change into the 27 sprocket on the big chainring !!)

I wouldn't usually cross chain like that but if you did would it all jam up and break or would it just not go?

dennisn

musto_skiff wrote:

itisaboutthebike wrote:

Yes most people riding Alpine (and other ) sportives run 34x50 with a 12-27 rear with no problems (altho I doubt whether you'll be able to get the mech change into the 27 sprocket on the big chainring !!)

I wouldn't usually cross chain like that but if you did would it all jam up and break or would it just not go?

With a combo of 50-33 or 34 and 12-27 you are definetly at the limit of a Dura-Ace or
Ultegra rear mech to either let out enough or take in enough chain slack to stay working
in all gears but I have done it for years at the Bicycle tour of Colorado and not had any problems. Once again proper chain length is critical.

Dennis Noward

daniel_b

Daniel B wrote:

Hi Rob,

I'm pretty sure it's a 42, as I counted them manually a while back, but I will double check when I get home.

The spec for the bike is an FSA Gossamer crankset, however the spec also says it is a triple, and mine is a double, but it is defo an FSA.

I bought it 2nd hand, so perhaps the previous owner specced it as such from new, or changed it post purchase.

Cheers

Dan

I've just counted them again, and yes the inner ring is defo a 42.

Do I have to buy an FSA one to change it, or is there a standard bolt pattern that's used?

Dan

pneumatic

I've ridden the Alps on both.

The triple (48/36/26 x 11/34) was very reassuring, but I found myself plunging down the gears to a place that was almost certainly lower than I needed to be, which slowed me down on ascents as I tended to twiddle away in my comfort zone.

The compact (50/34 x 12/27) was also fine, even on long steep ascents. Having nowhere to go below 34x27 was a good discipline and didn't have me grinding to a halt.

Frame weight makes a difference, too, though. As does rider weight and fitness (high and low respectively in my case!)