Why compact chainsets?

[Chrisz]

What is the rationale behind compact chainsets?

 

[John the Monkey]

The thinking is, I reckon, that "most" riders don't use a racng double *really*. I.e., they won't go to the top of the range on the big ring, and might want a bit more down the low end.

For whatever reason, they don't want to rub a triple, so the compact (50/34, 50/39) as opposed, to say, 52/42 gives a more usable range of gears for Joe Average, without the weight penalty and fashion faux pas that would come from using a triple.

 

[Will1985]

Marmite.

Personally I prefer compacts. More gears at the bottom end, sacrificing one at the top, or roughly the same range but with smaller gaps inbetween. Sure there is less crossover between rings, but with two hands it isn't too hard to shift between chainrings and up/down the cassette.

 

[John the Monkey]

Personally, I roll with a triple, and in the week I fit SPD pedals.

That's why they chucked me out of the roadie club

 

[gavintc]

I have a normal chainset on my commuter and a compact on my good bike. I find for most riding the normal chainset suffices and I like the narrower gap between 53 - 39. A quick change of front ring does not demand necessarily a change up at the back. My good bike was specced for sportives and when I was less fit. I have pondered changing to a normal chainset, but find that every so often I need the lower gears 34-25 when grinding out a steep hill. I have raced the compact and not been bothered by the lower gearing but find myself not using the bottom range of 34 for most riding.

In conclusion, I think I need the bottom gears when doing sportives. But, I like the less sharp change between 53 and 39. So, I will probably stick with the current option.

 

[yello]

Part of it is roadie ID; it's not really the done thing for a serious roadie to be riding a triple. I don't say that critically, fashion plays a part in all walks of life.

A compact will have a weight advantage over a triple for a similar gear spread. People will testify to there practical & everyday usability (as they have here) but I personally would need convincing.

 

[Breedon]

Triple for me and glad i went with it, not botherd what other roadies think of my triple.
I like the gearing options.

 

[Big John]

I did a gearing spreadsheet in Excel and discovered my compact of 50/34 gave me one more climbing gear at the loss of one racing gear, compared to a 53/39. I bought it because I was doing a hilly event and couldn't afford to go triple. A couple of weeks later I did a race and realised you can't race on a compact 50/34 as you do miss that top gear. I changed back to 53/39 and haven't missed the compact. The jury is still out on whether they're useful or not. Let's put it this way - you'd have to be a strong rider to go up the alps with a compact as opposed to a triple.

 

[MacB]

I think you really need to cover all the bases, fitting a Rohloff hub, 11 speed cassette and triple chainrings should give you about the right range

 

[HLaB]

I have a normal chainset on my commuter and a compact on my good bike. I find for most riding the normal chainset suffices and I like the narrower gap between 53 - 39. A quick change of front ring does not demand necessarily a change up at the back. My good bike was specced for sportives and when I was less fit. I have pondered changing to a normal chainset, but find that every so often I need the lower gears 34-25 when grinding out a steep hill. I have raced the compact and not been bothered by the lower gearing but find myself not using the bottom range of 34 for most riding.

In conclusion, I think I need the bottom gears when doing sportives. But, I like the less sharp change between 53 and 39. So, I will probably stick with the current option.

I've done similar with my bikes I got BBils to fit a 39/53 to the kinesis and my Bianchi has the compact (36/50). My Sirrus is a 30/42/52 and once a year I'm in the granny and to be honest I like to use the 42/52 more than the compact; 36 for me is too low to cruise on the club run and I sometimes spin out in the 50. So hopefully the 39/53 will suit me and if I find myself struggling on hills I'll change the cassette for a 12-27 or something.

 

[Steve Austin]

There has also been a change in how we are supposed to pedal. Its common belief that spinning is better for your knees, energy levels, climbing and its what Lance does. Its a bit hard to spin a 53 chainring, so it makes sense to use a double.
As someone who rides a mtb, a double gives me a much more similar range of gear ratios that allow me to pedal the same sort of cadence as a mtb.

 

[stephec]

Re the debate about the wide spread between 50/34 as opposed to 53/39 - why not have a 50/36 as a compact then?

Same 14 tooth gap at the front, and with a 12-25 on the back a nice spread of useable gears for most situations.

 

[Dan B]

With handlebar-mounted gear levers it really is no hardship to upshift twice on the back when downshifting on the front - even while standing on the pedals. I suspect that the "wide spread" arguments carried more weight in the days of downtube shifters

 

[MajorMantra]

Re the debate about the wide spread between 50/34 as opposed to 53/39 - why not have a 50/36 as a compact then?

Or a 34-48 with an 11-? cassette, or indeed any of numerous other options? Simply talking about compact vs. double is a bit meaningless unless you specify the cassette you're using. Some people with standard doubles have a smaller top gear than some with compacts.

My hi-ten monster has a 52/42 which I've ridden up and down fairly steep hills (up to 15 or even 20% in places) which makes me sound hard until I admit that it has a 14-28 block which gives a low gear that's pretty typical at just over 39". I do think it's slightly impressive that I've hit over 50 on it since the top gear is under 98".

I agonised a bit when choosing the hearing for the new Ribble but in the end decided that the run of the mill 53/39 and 12-25 should work for me, and so far it has. And yes, I use the full range of gears including the 53/12. Not sure I'd use a 53/11 if I had one, but maybe...

Matthew

 

[Sittingduck]

I did a race and realised you can't race on a compact 50/34 as you do miss that top gear.

Not that I race but surely this depends upon the particular rider and natural cadence etc?