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compact crankset or not to compact crankset? that is the question!

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Road Cycling It is by riding a bicycle that you learn the contours of a country best, since you have to sweat up the hills and coast down them. Thus you remember them as they actually are, while in a motor car only a high hill impresses you, and you have no such accurate remembrance of country you have driven through as you gain by riding a bicycle. -- Ernest Hemingway

compact crankset or not to compact crankset? that is the question!

Old 04-26-11, 04:09 PM
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compact crankset or not to compact crankset? that is the question!

hello fellow bf-er's!

here is one of my main questions and i am in need of some serious advise!
i dont want to start any problems with anybody here!

but i just recently did approx 40miles from novato to pt. reyes and back
and it was a beautiful ride, intense but beautiful!

my fellow friend has a compact crankset and he tore up the hills like it was nothing but his down hill was slower than what i thought.

i have a 53/39 set up and he has a 50/34 set up
when i ride usually its around 30-32 miles(cross the city past the ggb and back routine)
and with the city i love the 53/39 but i was wondering should i even go compact?
my friend tells me my race crankset is a phase?

should i even go compact crankset? opinions? triple maybe?

note: i have 3 10speed cassettes to fool around with 11-25 12-27 12-25, but even with the 12-27 cassette it is not even close to compact hill climbs!
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Old 04-26-11, 05:15 PM
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I am switching to a compact, going to give it a shot. If I dont like it I can switch back.
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Old 04-26-11, 05:17 PM
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A compact will help you spin up hills more easily but you'll also go a little more slowly unless you're turning that lower gear over very, very quickly. Are you having trouble on the hills with your standard crank? You said your friend was tearing up the hills. Are you both similar weight/fitness? If he's 40lbs lighter than you are, he's probably going to go up the hills faster regardless of the crank you're each using.

Here's a little info on what a change of crank would get you.

A 53-39 with a 12-27 cassette gives you a decently low gear but not insanely low (39/27=1.44). A compact crank combined with an 11-25 cassette will give you a low gear of 34/25=1.36 and a high gear of 50/11=4.54. This is a higher high gear and a lower low gear than a standard double with a 12-25. A standard double with your 12-25 will give you a low gear of 39/25=1.56 (kinda low but you need to be very fit to tackle really steep grades), and a high gear of 53/12=4.41. Since the problem you're trying to address is hill climbing, here's an example. The low gear of a compact with a 12-25 cassette (34/25=1.36) would be like having a 29t cog on your standard double (39/29=1.34). If when you're using your 12-27 cassette on your standard double you wish you had just one more gear, yet still keep your top end speed, a compact with an 11-25 would do it.

The price you pay for this is that you loose the 16t cog, so there is a gap between your 15t and 17t cogs. This could make it harder to find a comfortable cadence. It depends on how sensitive you are to those kinds of things.

If you need even lower gears, you could go for a compact with an 11-27 or a 12-27 cassette. The price for this, again, is there are larger tooth gaps between cogs.
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Old 04-26-11, 05:20 PM
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Originally Posted by sffred
my fellow friend has a compact crankset and he tore up the hills like it was nothing but his down hill was slower than what i thought.
Would you rather gain speed going up the hills, or down?
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Old 04-26-11, 05:53 PM
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Originally Posted by sffred
my fellow friend has a compact crankset and he tore up the hills like it was nothing but his down hill was slower than what i thought.
He sounds lighter than you. With everything else being equal, heavier riders will descend faster.

What was your cadence and gearing used on the hills where your friend was faster than you? If you had gearing allowing you to pedal at 80 RPM and couldn't keep up he probably just has a higher power/weight ratio and you need to train more.
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Old 04-26-11, 05:53 PM
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Originally Posted by Seattle Forrest
Would you rather gain speed going up the hills, or down?
Well, since you put it that way....

I have a 53/39 (12-25 cassette) on one road bike, and a 50/34 (11-25 cassette) on the other (February of this year). I thought the one with 53/39 was just fine, having ridden it for about two years. But having ridden the compact for a number of rides, I really like it. I think whenever I have to replace the crankset on the 53/39, it will also become a 50/34.

With the compact, I'm finding I don't need lower than the 25t to get up the hills around here. We don't have long ones, but some are fairly steep (up to 18-20%).
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Old 04-26-11, 05:56 PM
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Is your friend lighter than you? That could partially explain the faster uphills and slower downhills. Did you try switching bikes with him to see if you really did go faster up the hills?
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Old 04-26-11, 06:08 PM
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hi there try this little apps ... you can make combination of crank and sprokets ... and looking to the speed at a certain cadense ...

https://www.gear-calculator.com/#
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Old 04-26-11, 06:34 PM
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Originally Posted by Seattle Forrest
Would you rather gain speed going up the hills, or down?
Going UP the hills. Because you spend a lot more time going up than going down.

That and on any decently-steep descent your crankset doesn't matter because you're going too fast anyway.
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Old 04-26-11, 06:37 PM
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i live in the mountains, and at least two other member on BF live near me and have recently purchased compact sets. My next one (hopefully this summer) will be a compact rival or force set. Only way to go around here.
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Old 04-26-11, 06:39 PM
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i have a conpact, and i dont even end up using the 34/23 up any climb that im trying to actually climb semi fast. i really want to switch out to a 52/39 because i've maybe used the 34/25 once of twice in a year of having a compact.
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Old 04-26-11, 07:14 PM
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my fellow friend has a compact crankset and he tore up the hills like it was nothing but his down hill was slower than what i thought.

i have a 53/39 set up and he has a 50/34 set up
That would be expected if he weighs less than you. Less weight means he goes faster up-hill at the same power but means decreased cross-sectional density so his terminal velocity is lower.

A 50-34 compact crank makes the rings act as if your cogs were one step smaller than the traditional 53-39. 34x23 is like 39x26 and 50x12 like 53x13. That changes the point at which you need to get off and walk and may make your life more pleasant before that point but won't make the difference between being slow and rocketing up hill - you need a good power to weight ratio (Watts/Kilogram) for that.

should i even go compact crankset?
How much do you weigh, what's your mean maximal power curve look like, how steep are the hills near you, how long are the hills you ride, what's your preferred cadence range, what happens to you (get dropped, too much fatigue to ride hard tomorrow) when you aren't riding in that range, and how fast can you spin?

We need answers to all those questions before making a reasonable recommendation.

triple maybe?
That would be my choice in your situation.

I wouldn't choose to ride a double crank if I wasn't strong enough to have one tooth jumps up to the 19 with my required low gear and desired starting gear, especially with a 34 ring that means spending more time on the big ring where the cogs are farther apart. In the 10 speed era that means needing a big cog more than 21 with an 11 starting, 23 with a 12 cog, and 26 with a 13. You're not there yet and could use a triple.

In the 8 speed era I rode 50-40-30x13-14-15-16-17-18-19-21 instead of 53-39x13-14-15-17-19-21-23-26 living in Boulder, CO so I had perfect gearing for the Rocky Mountains west and plains east without switching cassettes. It was lovely.

After wearing out parts I ended up with 50-34x13-14-15-16-17-18-19-21-23 9 speed which has the same range and gear spacing but has only gear of overlap (50x21 and 34x14) leading to excessive double shifting in the wrong hill/wind/fatigue or rest day situations and more chain noise when using one of the extreme gears compared to 40x17 in the middle of the cassette. I'd have bought another triple instead if I knew those things.

People (perhaps parroting bike company bean-counters who are much happier with fewer SKUs) say that a compact does everything a triple does but gloss over the gear spacing and neglect to comment on your options if you're willing to buy a new small ring which might cost 1/3 what a cassette does.

For example, assuming you need a low gear like 34x32 and want a high gear like 53x12 your options are

53-39-24 x 12-13-14-15-16-17-18-19-21-23
or
50-34 x 11-13-15-17-19-21-23-25-28-32

obviously the former is nicer on flat rides.

And if you really need it, the triple can provide low gear 30% lower which is like having another 3+ cog choices. To match 24x34 with a 33 on a double (the smallest which will fit on a 110mm BCD) you'd need a 47 cog.

note: i have 3 10speed cassettes to fool around with 11-25 12-27 12-25, but even with the 12-27 cassette it is not even close to compact hill climbs!
It's the rider not the crank.

Last edited by Drew Eckhardt; 04-26-11 at 07:31 PM.
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Old 04-26-11, 07:27 PM
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Originally Posted by jsutkeepspining
i have a conpact, and i dont even end up using the 34/23 up any climb that im trying to actually climb semi fast. i really want to switch out to a 52/39 because i've maybe used the 34/25 once of twice in a year of having a compact.
They make cassettes which end in 21 and 23 ( SRAM doesn't make an 18 cog or have 11-21/12-23 10 speed cassettes but Shimano and Campagnolo do so you're covered regardless of what flavor derailleurs and freehubs you're running) and provided you stay away from cassettes with too much titanium and aluminum those costs less than new cranks and won't require chain replacement to handle the increased wrap from big/big.
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Old 04-26-11, 07:28 PM
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i am 10 pounds heavier, about the same height.
its usually during the steep city streets i can take him thru the hills, but for some reason i was considering the compact crankset because when we rode thru the mountains at steeper elevation it was easier for him to pace hill, initially we rode thru more than half way to the top with me taking a considerate lead, but here he comes saying "to your left!" as he passes by me pedaling at a slight bit faster pace which i believe it would be a tooth or two more in the cassette.

or maybe i should have bought a triple group (ride everywhere and be done).
a triple set up cost more but it will be heavier... but it is not what components or weight behind the bicycle, it is all in the motor!

sorry for wasting your time u guys i just think i might be going crazy!
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Old 04-26-11, 09:24 PM
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Originally Posted by Drew Eckhardt
They make cassettes which end in 21 and 23 ( SRAM doesn't make an 18 cog or have 11-21/12-23 10 speed cassettes but Shimano and Campagnolo do so you're covered regardless of what flavor derailleurs and freehubs you're running) and provided you stay away from cassettes with too much titanium and aluminum those costs less than new cranks and won't require chain replacement to handle the increased wrap from big/big.
yeah, i wanted to change to a 52/39 so i can have the biggest gear possible 52/14 in races, because i'm a junior and a 50/14 is a lot smaller than a 52/14.
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