53/39 or Compact

garetjax

I'm interested in buying a new bike, but many increasingly have the compact gear ratios of 50,34; 12-27. I currently ride a bike with 53,39; 12-25.

I am a strong climber and I can always muscle my way up even the steepest of hills on 39-25 combo, but I admit I do sometimes think it would be useful to have an easier gear, if only to protect the knees a little - and I do do alot of steep hills as I enjoy them!
Maybe sticking with 53,39 but adding a 12-27 on the back would be just as good as a compact?
Any disadvantage to compact? I do the odd fast club run and I also stick tri-bars onto my bike for time trials..would Compact limit me there?

Wappygixer

I recently changed to a compact from a triple.
I do think the compact is making me a stronger rider.I now ride more on the bigger ring powering slightly bigger gears which is building me up in strength.The 34 is great for the hills but useless on the flats as you run out of steam all to quickly.
I do run a smaller cassette though at 11-23 and these gears get me up everything I've tried so far around the Peak district.
In time I may go back to a 39-53 and maybe up to a 12-25 cassette but for the time being a compact is working well for me.

If you are already riding fine with 39-53 I'd stick with it especially if you do TT'ing.
You could buy and 12-27 for the hills and keep your 12-25 for TT.

baxterstrikesback

39 - 53 All the way. Compact chainsets are not great unless you want to spin at 110rpm all day or push your highest gear all day long. If you need a shorter gear you could use a 12-27 like you said. Compacts are useful to beginners or on really hilly sportive courses for example, but if you are able for the 39-53 now it would be a step back for you, esp for the TT's.

Smokin Joe

Gears are a personal thing and if the 53/39 suits you then stick with it. Don't worry about your knees either, that load of old tosh is just a myth constantly repeated by the type of people who ride triples and shout at everyone who doesn't. Those of us who spent our youth riding round on 52/42 with a five speed block and a granny sprocket of 23t are all still here and walking and riding without problems.

maddog 2

50-12 @ 110 rpm is 37mph

Should be okay for most people. 8)

I think gears are a personal thing too. If you do a lot of miles on hilly terrain then they make a lot of sense. Just make the decision rationally, based on the terrain and type of riding you do, without falling into the macho trap that many bikers try to set...

disgruntledgoat

maddog 2 wrote:

50-12 @ 110 rpm is 37mph

Show your workings!

How heavy a rider is that based on and what kind of resistance?

Never used a compact, by the way, I remember seeing a clubmate try and sprint at the end of a road race on one once... legs going like the clappers, going nowhere.

redddraggon

disgruntledgoat wrote:

maddog 2 wrote:

50-12 @ 110 rpm is 37mph

Show your workings!

How heavy a rider is that based on and what kind of resistance?

No matter how fat, thin, skinny, stupid, tall, short you are, if you pedalling a certain RPM in a certain gear, with a certain tyre size, you are going at the same speed.

agnello

redddraggon wrote:

disgruntledgoat wrote:

maddog 2 wrote:

50-12 @ 110 rpm is 37mph

Show your workings!

How heavy a rider is that based on and what kind of resistance?

No matter how fat, thin, skinny, stupid, tall, short you are, if you pedalling a certain RPM in a certain gear, with a certain tyre size, you are going at the same speed.

disgruntledgoat

You know what I love? is when I ask an innocent question and get patronised in return.

Maybe I am but a poor misguided fool i don't understand how it can be that, assuming all other things are equal, a rider weighing 75kg turning, par example, a 53x16 at 90rpm will generate exactly the same speed as a rider weighing 110kg turning the same gear at the same rpm. I can understand the same amount of force is required to turn both gears, but surely one of them is moving a much greater mass for that force and will, as such, be slower.

Eat My Dust

I run a 52/34 12/25. I just changed the 50t on the compact for the 52t. I asked at the LBS before doing so and the mechanic said it shouldn't be a problem (which it isn't) I'm really enjoying the bigger ring and I've noticed the difference in top speed. I get the best of both worlds.

***ducks for cover***

redddraggon

The force won't be the same, the bigger guy will need to create more power at the same RPM in the same gear, but he will be going the same speed.

(All the above is assuming everything else is constant)

Hudster

Surely 'compact' just refers to the BCD size of the chainring. So with the smaller BCD of a compact, you can get less than a 38T inner. A 34T inner would generally be too small for me, but I like having a 36 and can up this to a 38 if I want. If I really want, I can run something like 52/38 on a compact, but personally I don't really need any more than a 50.

A 50x12 is a bit like losing one top gear off your current setup, although having a 50x11 would mean having a very slightly longer gear. Use a gear calculator and see how the numbers compare.

will3

Eat My Dust wrote:

I run a 52/34 12/25. I just changed the 50t on the compact for the 52t. I asked at the LBS before doing so and the mechanic said it shouldn't be a problem (which it isn't) I'm really enjoying the bigger ring and I've noticed the difference in top speed. I get the best of both worlds.

***ducks for cover***

You must have a huge jump in gearing between rings! I find 50/34 quite annoying as if you are to avoid cross chaining, there's a certain speed range around 15mph where you'll be constantly having to muck about with the front mech, which in turn requires a large shift accross the cassette to give a sensible change of ratios.

maddog 2

think about it this way

the speed of a car doing 4000 rpm in third gear will be the same speed regardless of the weight of the driver.

most front mechs on a compact setup are usually only rated to allow a 16 tooth gap, such a 34t to 50t. A bigger gap may be possible in reality but shifting will clearly deteriorat the bigger you go, and may exceed the mechs capabilities (in all gears).

Hudster

Another way of thinking about it, is speed is how fast the wheel turns round, no matter what weight the rider is. The cranks are directly connected to the wheel by the chain, so how fast those cranks are turning is directly connected to speed. The gears mean the two revolutions are different, but there is a direct connection between pedal revolutions and speed irrespective of the weight of the rider.

A bigger rider may well have to work harder and put more power in to make those cranks turn faster and therefore to go faster than a more areodynamic rider.

50x12 is probably fast enough for most people, especially if you can spin the pedals quickly.

chriskempton

Compact with a 36T inner is great IMO. Only problem is the only one I could find (for 110BCD Shimano compact) was a low grade TA one. My front changes ended with chain falling between the two rings. I suspect it's a shifting ramp incompatability thing. Anyone know where I can get a 36T ring that'll work well with a Shimano compact?

redddraggon

It won't be the inner ring that's creating any difficulty - the chain either drops onto the inner ring while shifting down, and while shifting up the big ring has pins and sometimes groove type things to facilitate shifting.

FSA, TA and stronglight all do 36T inners.

http://www.wiggle.co.uk/p/cycle/7/FSA_1 ... 360031665/

(need "ordering" though)

mrushton

chriskempton wrote:

Compact with a 36T inner is great IMO. Only problem is the only one I could find (for 110BCD Shimano compact) was a low grade TA one. My front changes ended with chain falling between the two rings. I suspect it's a shifting ramp incompatability thing. Anyone know where I can get a 36T ring that'll work well with a Shimano compact?

Do shimano/TA/Stronglight not make one. Try this link but I'm not sure of the bolt circle measurements

http://www.chickencycles.co.uk/index.php?cat=32&ord=2

I use a 50/36 Campag compact with either 13-26 or 12-25 and life is so much easier. i have considered dropping to 48/36 with 12-27 as I very rarely get to 50x13 or 50x12.

eh

50-12 @ 110 rpm is 37mph

If you race this it too slow. However, if you just ride for fun etc. it should be more than fine.

In an ideal world you'd change your gear ratios depending on ride, race, course, etc., but most of us can't be bothered with the fuss and so have to compromise.

maddog 2

Middleburn do a 36t compact too.

see http://www.chainreactioncycles.com/Mode ... delID=3324

or ebay 110376243877 and 220395552907

[I'm currently running 36/48 on a 12-27]

fnegroni

eh wrote:

50-12 @ 110 rpm is 37mph

If you race this it too slow. However, if you just ride for fun etc. it should be more than fine.

In an ideal world you'd change your gear ratios depending on ride, race, course, etc., but most of us can't be bothered with the fuss and so have to compromise.

53 x 12 @ 120rpm = 41.4
50 x 12 @ 120rpm = 39.1

Is it really that big a difference?

Or is it really just down to something a bit more relevant, i.e. cadence?

If your ideal cadence is 120rpm and you are asked to push a higher gear at lower rpm, you will find it harder; which I guess is great for training, but I am not sure it would be for racing. I am asking the racers here for their opinion.

Surely you choose your gears based on ideal cadence and torque generated by your legs.

I wonder if this dislike for compact chainsets comes down to lower rpms being preferred over higher rpms by those who prefer 'race' chainsets.

Also, a chainset is way more difficult to change than a cassette by the side of the road.

Moreover, with 10 cogs at the back, a small gap between chainrings just increases the overlap between them, so it makes sense to me that if you have more cogs at the back, the more gap should be between the front chainrings.

A pro might have a different view.

eh

53 x 12 @ 120rpm = 41.4
50 x 12 @ 120rpm = 39.1

Is it really that big a difference?

Thats over 2mph which in racing is a big difference, especially as a lot of people after 120rpm are quite rev limited. But as I say for normal riding its no difference at all.

Eat My Dust

will3 wrote:

You must have a huge jump in gearing between rings! I find 50/34 quite annoying as if you are to avoid cross chaining, there's a certain speed range around 15mph where you'll be constantly having to muck about with the front mech, which in turn requires a large shift accross the cassette to give a sensible change of ratios.

I don't really use the 34. The 50t was worn out and I wasn't happy with it but the 34 was in good condition so I just left it. I will probably stick something bigger on it when the time comes tp replace it.

tenor

If you find 53/39 ok for most of your riding you may chose to try a 50/36 combination with either a 12-25 or 12-27 cassette, assumimg you are using Shimano.This will give a more useable range on the inner ring.
Sastre, used a 52/36 ratio for most stages of last years Tour.
You will find many folk on this Forum insist that 50 - 11 is the minimum top ratio needed for reasonable progress - this is a higher gear that Merckx used, by the way so you can imagine how fir these contributers must be..!

marksteven

it makes me laugh all the sunday racers who struggle to the cafe on sunday using 53/42 chainsets & mostly using the 3 biggest sprockets at the back & struggle to keep 20mph when you suggest a compact which would use more of there cassette hence making it last longer you might as well ask them to tounge there mums ive used compacts for a few years now i used to be a 22 min 10 time trialer so could push a bit but find a compact much more flexable & hardly ever need the 50 /12 gear only the pros really need full size chiainsets all the rest of us are just kidding our selves

juggler

Why would using a compact lead to using more of the cassette? A straight swap from 53/39 to 50/34 will give you one extra climbing gear for the hardest hills.... Most riding around here 39/25 or 39/27 is fine. Granted 53/12 or 53/11 stays unused for most of us, but seems to me that this debate always concentrates discussion on the relative use of the highest and lowest gears on the cassette when the majority of riding is done somewhere in the middle. Front shifting for a standard chainset is superior to a compact and may need less associated shifting of the cassette as the gears are closer together.

Eat My Dust

marksteven wrote:

hardly ever need the 50 /12 gear only the pros really need full size chiainsets all the rest of us are just kidding our selves

I wouldn't agree with that. I use 52/12 twice a day and that's just on my commute.

juggler

Eat My Dust wrote:

marksteven wrote:

hardly ever need the 50 /12 gear only the pros really need full size chiainsets all the rest of us are just kidding our selves

I wouldn't agree with that. I use 52/12 twice a day and that's just on my commute.

likewise exercised the 53/12 on the way to work today, but maybe that was me trying to prove a point..... mostly a nice long gradual slope for the final couple of kms, turning the gear nicely and getting well over 50 kph... the other side of the hill before that is a different story ... but no need to go near the big cogs, 39 and somewhere near the middle of the cassette is fine...

italiaandyf

I run a 30/42/53 triple, after changing from a 34/50 compact, and would never change back to a compact. (I run a 12/25 or 13/26 on the back).
The triple gives the best of all worlds, high gears for powering along the flats and decents, low gears for spining up steep hills, and the 42 ring is just a fantastic ring, giving a good range for general terrain. The other plus for the 42-53 change is that allows smoother accelaration and ability to maintain a given cadence, the 16 tooth jump of the compact was too big, and required shifting too many sprockets on the cassette to achieve the same smoothness.

juggler

andyfaden wrote:

I run a 30/42/53 triple, after changing from a 34/50 compact, and would never change back to a compact. (I run a 12/25 or 13/26 on the back).
The triple gives the best of all worlds, high gears for powering along the flats and decents, low gears for spining up steep hills, and the 42 ring is just a fantastic ring, giving a good range for general terrain. The other plus for the 42-53 change is that allows smoother accelaration and ability to maintain a given cadence, the 16 tooth jump of the compact was too big, and required shifting too many sprockets on the cassette to achieve the same smoothness.

Andy - hear what you say and it makes sense, unfortunately i could never do it and get a triple... aside from the expense and hassle of changing all the gearing etc.... just couldn't.... :oops: :oops: on this one it's image over practicality for me

ellieb

What OP needs to do is look at a gear inch calculator like this one:
http://www.panix.com/~jbarrm/cycal/cycal.30f.html

Have a look at the mph difference with different gearing at his likely cadence and then decide if he needs a compact. Haveing got a compact & a 39/53 I personally prefer the compact, but that is just me, the way I ride and the terrain I travel over. In addition, my knees can occasionally get a little dodgy & there is no doubt that using a lower gear helps.