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-   Commuting (https://www.bikeforums.net/commuting/)
-   -   Why 50-34 sucks for commuting (https://www.bikeforums.net/commuting/1059300-why-50-34-sucks-commuting.html)

American Euchre 04-26-16 08:58 PM
When I first got into road riding, my low gear was either 39X23, or 42X23, I don't remember. I remember it being sufficient, although on a few occasions, I wouldn't have minded a lower gear. Every ride had lots of extended climbing, and then gnarly descents.

Getting back into the sport, my low is 34X30. There aren't many long climbs near where I live. Instead, there are lots of short and moderate hills, and rollers. 34X30 is more than sufficient. I am often surprised by how slowly I am grinding up a hill even in 34X21 or 34X24. Around where I live, a 25 would probably, and certainly a 27 or 28 would be sufficient.

I have never touched the 50X12. There aren't many "descents" around here.

Even though the gear range is more than sufficient, both high and low, I still have the feeling that "something isn't right" with compact gearing. On flats, neither the 34 nor 50 seems optimal. In the 50, I'm often using the bottom half of the cassette with larger gaps between gears. That makes it more difficult to find the "optimal" gear. However, in the 34, I use the upper end of the cassette with smaller jumps. However, it's easier to run out of gears with the slightest tailwind or on false flat 'descents.'

Both rings work reasonably well, but in a quirky, non optimal way. I guess I just don't like shifting the front very often. The shifting works well, but I just don't like doing it that often.

I just might welcome a 1X. A 1x13 might be cool...

42 x 10 11 12 13 14 16 18 20 22 24 28 33 38

40 x 10 11 12 13 14 16 18 20 22 24 27 31 36

tarwheel 04-27-16 07:30 AM
Some of you guys are either over-thinking this, or I'm missing out on a whole lot! All of my bikes have 9-speed Shimano groups, with 50-34, 52-39, 52-39-30 and 50-34-24. They all work fine for me. The triples are on my touring bikes on which I might be carrying heavier loads. The compact double is on my cyclocross bike, and I'm about to put another compact on sport touring frame that I recently picked up.

The only gearing combinations that didn't work for me were a single-speed that just about destroyed my knees, and a 1x9 with 42 chainring and 12-27 cassette. On the 1x9, I found that I was actually having to shift more often than with my doubles and triples. There are a lot of hills around here, and I was pretty much using the entire range of the cassette on almost every ride. However, with my doubles or triples, I often can simply shift the big ring on hills without shifting up and down the cogs on the cassette.

alan s 04-27-16 08:59 AM
Originally Posted by tarwheel (Post 18722102)
Some of you guys are either over-thinking this, or I'm missing out on a whole lot! All of my bikes have 9-speed Shimano groups, with 50-34, 52-39, 52-39-30 and 50-34-24. They all work fine for me. The triples are on my touring bikes on which I might be carrying heavier loads. The compact double is on my cyclocross bike, and I'm about to put another compact on sport touring frame that I recently picked up.

The only gearing combinations that didn't work for me were a single-speed that just about destroyed my knees, and a 1x9 with 42 chainring and 12-27 cassette. On the 1x9, I found that I was actually having to shift more often than with my doubles and triples. There are a lot of hills around here, and I was pretty much using the entire range of the cassette on almost every ride. However, with my doubles or triples, I often can simply shift the big ring on hills without shifting up and down the cogs on the cassette.
For me, going from a lifetime of multi-chainrings to a 1x setup requires learning to forget about the front. Still not quite used to the idea of no front shifting, and once in a while think it's time to shift the front. The XT 1x11 drivetrain shifts so smoothly and quickly, with up to 4 cogs (smaller to larger) at a time, that you're always in the right gear. No break in cadence, and shifting under load works great. Having used older generations of trigger shifters, the latest XT stuff requires much less force to shift, so running up and down the cassette is almost effortless.

Darth Lefty 04-27-16 10:20 AM
XT M8000 seems to be a big hit with whoever tries it, in whichever flavor they choose. I wish I could talk SWMBO into a new bike so I could try it!

fietsbob 04-27-16 11:41 AM
Change chainrings ; Paris-Roubaix gears the small is a 46, cyclo cross gearing the Large is a 46.

Andy_K 04-27-16 01:42 PM
Originally Posted by American Euchre (Post 18721221)
Even though the gear range is more than sufficient, both high and low, I still have the feeling that "something isn't right" with compact gearing.
Bingo! I find the arguments about compact gearing offering the same range to be completely missing the point.

The bike I was referring to when I started this thread has a 34-29 low gear. The day I started the thread I rode it up a hill that peaks at 16% grade. It would get me up an even steeper hill if I needed it to. And the 50-12 top gear is easily enough for my purposes. The range of gears isn't the problem.

As for over-thinking it, it's not as if I put my gears into a calculator, looked at the numbers and said, "Hey, that's a problem." Rather I took it out on the road, concluded that I didn't like the experience and then put the numbers into a calculator to try to understand the problem better. That may still be over thinking it, but I'm pretty sure it's not an imaginary problem.

alan s 04-27-16 02:26 PM
Originally Posted by Andy_K (Post 18723199)
Bingo! I find the arguments about compact gearing offering the same range to be completely missing the point.

The bike I was referring to when I started this thread has a 34-29 low gear. The day I started the thread I rode it up a hill that peaks at 16% grade. It would get me up an even steeper hill if I needed it to. And the 50-12 top gear is easily enough for my purposes. The range of gears isn't the problem.

As for over-thinking it, it's not as if I put my gears into a calculator, looked at the numbers and said, "Hey, that's a problem." Rather I took it out on the road, concluded that I didn't like the experience and then put the numbers into a calculator to try to understand the problem better. That may still be over thinking it, but I'm pretty sure it's not an imaginary problem.
So after you plug in all your numbers and analyze the gearing, based on your riding style, what would be the ideal drivetrain, considering also what is available on the market?

Andy_K 04-27-16 02:57 PM
Originally Posted by alan s (Post 18723306)
So after you plug in all your numbers and analyze the gearing, based on your riding style, what would be the ideal drivetrain, considering also what is available on the market?
Ideal, for my commute, would probably be something like 44-30 with a 12-27 cassette. Sugino makes the crank with a proper road chainline, but it's more expensive than I'm willing to accept.

I started putting together my 1x10 last night. It's going to start with a 39T chainring (because that's what I had on hand) and an 11-36 cassette. If I like it well enough to get a narrow-wide chainring for it I'll probably get a 40T.

The tricky thing about a 1x system on my particular commute is that for 99% of it an 11-25 cassette would be ideal, but for that last 1% I need something around 30 inches. So there are two or three cogs on the 11-36 cassette that I won't use much, meaning I get something like 7-speed gear spacing for most of the ride just to accommodate that one hill. That's probably not too bad though.

American Euchre 04-27-16 03:24 PM
In my case, for road riding, a standard triple would work very well for me. I ride mostly flats as well as routes with lots of rollers. The 39 would be far preferable for flat land spinning compared to a 34. The 50 is fine for descents and for spinning on slight descents and false flats. The 30 would be great as a bailout ring, and for rides in the future which involve a lot of climbing. Shifting would be a bit smoother as well with the smaller jumps between rings.

Unfortunately, as we all know, the road triple has become incredibly unfashionable. A part of me wants to grudgingly accept the possibility that reducing the amount of mechanism might be of slight benefit as well.

The 34 is an attempt to combine and therefore offer SOME of the benefits of both the 39 and 30 rings while not offering the full benefits of either. It's a compromise that just doesn't work out very well.

I suppose a 1X system is inevitable. On the mtb side, 2X systems are increasingly rare in the high and even middle end. On the road side, 3X systems are rare, and doubles are standard. With SRAM's 12 speed cassette, obviously the 1X will be specced with increasing frequency.

So many people complain about 2 tooth jumps, now we're getting 3, 4, 5 tooth jumps with 1X systems and no one is complaining and only singing the praises of losing the front derailleur? It seems like sheep like thinking to me.

alan s 04-27-16 03:30 PM
Originally Posted by American Euchre (Post 18723429)
So many people complain about 2 tooth jumps, now we're getting 3, 4, 5 tooth jumps with 1X systems and no one is complaining and only singing the praises of losing the front derailleur? It seems like sheep like thinking to me.
A better measure is the % change between steps, rather than the number of teeth. This gear calculator makes it easy to compare drivetrains.

HTML5 Gear Calculator

American Euchre 04-27-16 03:39 PM
Originally Posted by alan s (Post 18723444)
A better measure is the % change between steps, rather than the number of teeth. This gear calculator makes it easy to compare drivetrains.

HTML5 Gear Calculator
Most 1X road systems are being specced with a 40 something ring. Compared to a 34 or 50, there's no point in comparing the percentage. A 3, 4 or 5 tooth jump is still a large jump, whether on a 34, 42 or 50 chainring. Large gaps in gearing are appropriate and necessary in off road riding with large and swift changes in terrain. When spinning on road, not so much.


One con of triples is that at least for me, a dropped chain off the small ring seems far more likely. Chain tension drops a lot more going to a 22, 24 or even 30 ring than to a 34 or 39 small ring.

alan s 04-27-16 03:46 PM
Originally Posted by American Euchre (Post 18723471)
Most 1X road systems are being specced with a 40 something ring. Compared to a 34 or 50, there's no point in comparing the percentage. A 3, 4 or 5 tooth jump is still a large jump, whether on a 34, 42 or 50 chainring. Large gaps in gearing are appropriate and necessary in off road riding with large and swift changes in terrain. When spinning on road, not so much.


One con of triples is that at least for me, a dropped chain off the small ring seems far more likely. Chain tension drops a lot more going to a 22, 24 or even 30 ring than to a 34 or 39 small ring.
Not really. With a 34T chainring, a 5-tooth jump from 35 to 40 is 14% and a 2-tooth jump from 11 to 13 is 18%. If the steps are too small, you end up shifting constantly, and if too large, you may not have the ideal gear at times. Rohloff Speedhub 14 has a 13.6% step between gears across the entire range, and is regarded as "perfect" by many.

American Euchre 04-27-16 04:04 PM
Originally Posted by alan s (Post 18723489)
Not really. With a 34T chainring, a 5-tooth jump from 35 to 40 is 14% and a 2-tooth jump from 11 to 13 is 18%. If the steps are too small, you end up shifting constantly, and if too large, you may not have the ideal gear at times. Rohloff Speedhub 14 has a 13.6% step between gears across the entire range, and is regarded as "perfect" by many.
You're getting lost.

With two rings, say 34 and 50, you can have smaller gaps between gears compared to a single ring since the small ring gives you a lower low and the large ring gives a higher high with smaller gaps on the cassette.


50/34........12X30 gives you 50/12 and 34/30 high/low and max 3 tooth jumps.

44 X 12X30 gives you a lower high, higher low with the same jumps. You must increase the jumps in order to match the high and low, thereby making it more difficult to find the right gear for spinning.

The only alternative is to add cogs, thereby adding weight and negating some of the weight savings of a 1X system. It also increases the angle of the chainline adding noise.

I see 1X systems becoming the norm. It's just that the early adopters will have to suffer through the engineering issues for the next 5 to 10 years.

alan s 04-27-16 04:15 PM
Originally Posted by American Euchre (Post 18723535)
You're getting lost.

With two rings, say 34 and 50, you can have smaller gaps between gears compared to a single ring since the small ring gives you a lower low and the large ring gives a higher high with smaller gaps on the cassette.


50/34........12X30 gives you 50/12 and 34/30 high/low and max 3 tooth jumps.

44 X 12X30 gives you a lower high, higher low with the same jumps. You must increase the jumps in order to match the high and low, thereby making it more difficult to find the right gear for spinning.

The only alternative is to add cogs, thereby adding weight and negating some of the weight savings of a 1X system. It also increases the angle of the chainline adding noise.

I see 1X systems becoming the norm. It's just that the early adopters will have to suffer through the engineering issues for the next 5 to 10 years.
I'm not getting lost. Spend some time on the gear calculator I linked to, and you'll figure out that tooth jumps are not in and of themselves important. In my example above, a 5-tooth jump is actually a smaller step than a 2-tooth jump. Think about a set of stairs. You want steps at the right height and distance for comfortable climbing and descending. You also want them to be even so the next step is about the same as the previous step. Same goes for bike gears.

StanSeven 04-27-16 04:33 PM
Originally Posted by mcours2006 (Post 18705713)
Man, you guys are nerds!;) I have a triple 9 and a compact 10 for my commuters. I am not really fussy about which I like more in terms of the gearing. My commute is not hilly so don't tend to shift a lot. I'm most comfortable pedaling at 95 rpm, but I'm fine anywhere between 80-100.
Most reasonable post in the entire thread in my opinion. I don't see what the issues are. Don't people vary cadences? I think riding along all the time at 90 or whatever is boring. Plus it's not as challenging or beneficial from a training standpoint.

If riders can't get along with 3x9 or 2x10 compact, they're in a rut. Hard to believe people used to get by on 2x5

Andy_K 04-27-16 05:24 PM
Originally Posted by StanSeven (Post 18723602)
Most reasonable post in the entire thread in my opinion.
It's a fool that looks for logic in the chambers of the human heart.

Darth Lefty 04-27-16 05:37 PM
Originally Posted by American Euchre (Post 18723535)
You're getting lost.
No, he's right. These are MTB parts and the shift ratios on MTB's have always been about +-15%. With an 8-speed triple you get two more top ratios with the outer ring, and 3 more bottom ratios with the inner ring. With the 1x system you get the same middle ring ratios you always did, get the 3 granny gears via more cogs on the rear instead of the inner front, and lose the top two. Here's 11x11-40 with a 32 ring, compared to the 8x3 system that came with my Hardrock. The bolded sections are identical, the bottom is similar though not the same.

I don't actually shift it this way, I use the outer ring for the upper three or four and the inner ring for the lower four or five, because the chain rubs. But the ratios would come out similar enough because the cassette ratio spacing is pretty even.

[TABLE="class: grid, width: 579"]
[TR]
[TD]3x8 old Acera
[/TD]
[TD][/TD]
[TD][/TD]
[TD][/TD]
[TD][/TD]
[TD]1x11 XT
[/TD]
[TD][/TD]
[TD][/TD]
[TD][/TD]
[/TR]
[TR]
[TD]ring
[/TD]
[TD]cog[/TD]
[TD]overall ratio[/TD]
[TD]shift ratio[/TD]
[TD][/TD]
[TD]ring[/TD]
[TD]cog[/TD]
[TD]overall ratio[/TD]
[TD]shift ratio[/TD]
[/TR]
[TR]
[TD]42[/TD]
[TD]11[/TD]
[TD]3.82[/TD]
[TD][/TD]
[TD][/TD]
[TD][/TD]
[TD][/TD]
[TD][/TD]
[TD][/TD]
[/TR]
[TR]
[TD]42[/TD]
[TD]13[/TD]
[TD]3.23[/TD]
[TD]1.18[/TD]
[TD][/TD]
[TD][/TD]
[TD][/TD]
[TD][/TD]
[TD][/TD]
[/TR]
[TR]
[TD]32
[/TD]
[TD]11[/TD]
[TD]2.91[/TD]
[TD]1.11[/TD]
[TD][/TD]
[TD]32[/TD]
[TD]11[/TD]
[TD]2.91[/TD]
[TD][/TD]
[/TR]
[TR]
[TD]32
[/TD]
[TD]13[/TD]
[TD]2.46[/TD]
[TD]1.18[/TD]
[TD][/TD]
[TD]32[/TD]
[TD]13[/TD]
[TD]2.46[/TD]
[TD]1.18[/TD]
[/TR]
[TR]
[TD]32
[/TD]
[TD]15[/TD]
[TD]2.13[/TD]
[TD]1.15[/TD]
[TD][/TD]
[TD]32[/TD]
[TD]15[/TD]
[TD]2.13[/TD]
[TD]1.15[/TD]
[/TR]
[TR]
[TD]32
[/TD]
[TD]17[/TD]
[TD]1.88[/TD]
[TD]1.13[/TD]
[TD][/TD]
[TD]32[/TD]
[TD]17[/TD]
[TD]1.88[/TD]
[TD]1.13[/TD]
[/TR]
[TR]
[TD]32
[/TD]
[TD]19[/TD]
[TD]1.68[/TD]
[TD]1.12[/TD]
[TD][/TD]
[TD]32[/TD]
[TD]19[/TD]
[TD]1.68[/TD]
[TD]1.12[/TD]
[/TR]
[TR]
[TD]32
[/TD]
[TD]21[/TD]
[TD]1.52[/TD]
[TD]1.11[/TD]
[TD][/TD]
[TD]32[/TD]
[TD]21[/TD]
[TD]1.52[/TD]
[TD]1.11[/TD]
[/TR]
[TR]
[TD]32
[/TD]
[TD]24[/TD]
[TD]1.33[/TD]
[TD]1.14[/TD]
[TD][/TD]
[TD]32[/TD]
[TD]24[/TD]
[TD]1.33[/TD]
[TD]1.14[/TD]
[/TR]
[TR]
[TD]32
[/TD]
[TD]28[/TD]
[TD]1.14[/TD]
[TD]1.17[/TD]
[TD][/TD]
[TD]32[/TD]
[TD]28[/TD]
[TD]1.14[/TD]
[TD]1.17[/TD]
[/TR]
[TR]
[TD]22[/TD]
[TD]21[/TD]
[TD]1.05[/TD]
[TD]1.09[/TD]
[TD][/TD]
[TD]32[/TD]
[TD]32[/TD]
[TD]1.00[/TD]
[TD]1.14[/TD]
[/TR]
[TR]
[TD]22[/TD]
[TD]24[/TD]
[TD]0.92[/TD]
[TD]1.14[/TD]
[TD][/TD]
[TD]32[/TD]
[TD]36[/TD]
[TD]0.89[/TD]
[TD]1.13[/TD]
[/TR]
[TR]
[TD]22[/TD]
[TD]28[/TD]
[TD]0.79[/TD]
[TD]1.17[/TD]
[TD][/TD]
[TD]32[/TD]
[TD]40[/TD]
[TD]0.80[/TD]
[TD]1.11[/TD]
[/TR]
[/TABLE]

And for a more modern take with slightly lower gears for 29ers, here's 11-42 compared to the current Acera 3x9 system

[TABLE="class: grid, width: 579"]
[TR]
[TD]3x9 Acera[/TD]
[TD][/TD]
[TD][/TD]
[TD][/TD]
[TD][/TD]
[TD]1x11 XT[/TD]
[TD][/TD]
[TD][/TD]
[TD][/TD]
[/TR]
[TR]
[TD]ring[/TD]
[TD]cog[/TD]
[TD]overall ratio[/TD]
[TD]shift ratio[/TD]
[TD][/TD]
[TD]ring[/TD]
[TD]cog[/TD]
[TD]overall ratio[/TD]
[TD]shift ratio[/TD]
[/TR]
[TR]
[TD]40[/TD]
[TD]11[/TD]
[TD]3.64[/TD]
[TD][/TD]
[TD][/TD]
[TD][/TD]
[TD][/TD]
[TD][/TD]
[TD][/TD]
[/TR]
[TR]
[TD]40[/TD]
[TD]13[/TD]
[TD]3.08[/TD]
[TD]1.18[/TD]
[TD][/TD]
[TD][/TD]
[TD][/TD]
[TD][/TD]
[TD][/TD]
[/TR]
[TR]
[TD]30
[/TD]
[TD]11[/TD]
[TD]2.73[/TD]
[TD]1.13[/TD]
[TD][/TD]
[TD]30[/TD]
[TD]11[/TD]
[TD]2.73[/TD]
[TD][/TD]
[/TR]
[TR]
[TD]30[/TD]
[TD]13[/TD]
[TD]2.31[/TD]
[TD]1.18[/TD]
[TD][/TD]
[TD]30[/TD]
[TD]13[/TD]
[TD]2.31[/TD]
[TD]1.18[/TD]
[/TR]
[TR]
[TD]30[/TD]
[TD]15[/TD]
[TD]2.00[/TD]
[TD]1.15[/TD]
[TD][/TD]
[TD]30[/TD]
[TD]15[/TD]
[TD]2.00[/TD]
[TD]1.15[/TD]
[/TR]
[TR]
[TD]30[/TD]
[TD]17[/TD]
[TD]1.76[/TD]
[TD]1.13[/TD]
[TD][/TD]
[TD]30[/TD]
[TD]17[/TD]
[TD]1.76[/TD]
[TD]1.13[/TD]
[/TR]
[TR]
[TD]30[/TD]
[TD]19[/TD]
[TD]1.58[/TD]
[TD]1.12[/TD]
[TD][/TD]
[TD]30[/TD]
[TD]19[/TD]
[TD]1.58[/TD]
[TD]1.12[/TD]
[/TR]
[TR]
[TD]30[/TD]
[TD]21[/TD]
[TD]1.43[/TD]
[TD]1.11[/TD]
[TD][/TD]
[TD]30[/TD]
[TD]21[/TD]
[TD]1.43[/TD]
[TD]1.11[/TD]
[/TR]
[TR]
[TD]30[/TD]
[TD]24[/TD]
[TD]1.25[/TD]
[TD]1.14[/TD]
[TD][/TD]
[TD]30[/TD]
[TD]24[/TD]
[TD]1.25[/TD]
[TD]1.14[/TD]
[/TR]
[TR]
[TD]30[/TD]
[TD]28[/TD]
[TD]1.07[/TD]
[TD]1.17[/TD]
[TD][/TD]
[TD]30[/TD]
[TD]28[/TD]
[TD]1.07[/TD]
[TD]1.17[/TD]
[/TR]
[TR]
[TD]30[/TD]
[TD]32[/TD]
[TD]0.94[/TD]
[TD]1.14[/TD]
[TD][/TD]
[TD]30[/TD]
[TD]32[/TD]
[TD]0.94[/TD]
[TD]1.14[/TD]
[/TR]
[TR]
[TD]22[/TD]
[TD]28[/TD]
[TD]0.79[/TD]
[TD]1.19[/TD]
[TD][/TD]
[TD]30[/TD]
[TD]37[/TD]
[TD]0.81[/TD]
[TD]1.16[/TD]
[/TR]
[TR]
[TD]22[/TD]
[TD]32[/TD]
[TD]0.69[/TD]
[TD]1.14[/TD]
[TD][/TD]
[TD]30[/TD]
[TD]42[/TD]
[TD]0.71[/TD]
[TD]1.14[/TD]
[/TR]
[/TABLE]

gregf83 04-27-16 09:14 PM
Originally Posted by StanSeven (Post 18723602)
Most reasonable post in the entire thread in my opinion. I don't see what the issues are. Don't people vary cadences? I think riding along all the time at 90 or whatever is boring. Plus it's not as challenging or beneficial from a training standpoint.

If riders can't get along with 3x9 or 2x10 compact, they're in a rut. Hard to believe people used to get by on 2x5
+1. I climb a 3 min hill on the way to work at anywhere from 55 to 100RPM. If I'm transitioning from the flats to a hill I'll often start in the big ring and just wait until my cadence drops to about 70 and then switch from the 50 to the 34 up front. No need for complicated shift patterns just a little variation in cadence. Studies have shown there isn't much change in efficiency over a broad range of cadence.

McBTC 04-27-16 09:49 PM
Originally Posted by gregf83 (Post 18724168)
+1. I climb a 3 min hill on the way to work at anywhere from 55 to 100RPM. If I'm transitioning from the flats to a hill I'll often start in the big ring and just wait until my cadence drops to about 70 and then switch from the 50 to the 34 up front. No need for complicated shift patterns just a little variation in cadence. Studies have shown there isn't much change in efficiency over a broad range of cadence.
That's got to be true... which is why the 175mm crank arm paradigm really is nothing more than a rule that has been accepted based only on unquestioning adhereance to prior practices. The conventional thinking that has grown up around what, as it turns out, is just an arbitrary length is that going to a shorter crank reduces leverage and consequently would have a negative impact on performance. However, when tested objectively, actual experiences even for longer legged riders has shown that crank lengths even less than 165 (which is about as low as is readily obtainable in the mass market) may actually help riders produce more power on the road, allowing riders to increase gear inches with no greater increase in perceived effort.

cyccommute 04-28-16 08:23 AM
Originally Posted by Andy_K (Post 18723199)
Bingo! I find the arguments about compact gearing offering the same range to be completely missing the point.

The bike I was referring to when I started this thread has a 34-29 low gear. The day I started the thread I rode it up a hill that peaks at 16% grade. It would get me up an even steeper hill if I needed it to. And the 50-12 top gear is easily enough for my purposes. The range of gears isn't the problem.

As for over-thinking it, it's not as if I put my gears into a calculator, looked at the numbers and said, "Hey, that's a problem." Rather I took it out on the road, concluded that I didn't like the experience and then put the numbers into a calculator to try to understand the problem better. That may still be over thinking it, but I'm pretty sure it's not an imaginary problem.

I don't think it's an imaginary problem at all. Perhaps other people aren't bothered by lots of cadence variation but I've worked a very long time to maintain a steady cadence while I ride. I've never even been tempted by a compact double system because I'm not a huge fan of the way a "normal" road triple shifts and the effect it has on cadence.. Going to a system where there are huge gaps and huge differences in cadence just never appealed to me. This is my current commuter gearing, a 50/39/30 crank and an 11-34 cassette. If, for example, I'm riding in the 50/17 combination and I have to downshift to the middle ring, it doesn't feel "natural" since I have shifted a gear that requires a higher cadence (90 to 120 to maintain the same speed) to keep up with the speed or, on the other hand, I have to wait for the bike to slow down to that speed at the same cadence. Yes, cadence varies but it always feels better to me to have a fairly steady cadence rather than letting it vary all over.

If I compare a 50/34 compact with the same range to my current gearing the problem is even worse. The same shift would require me to increase my cadence from 90 to over 130 rpm to maintain the same speed.

Perhaps it's not that much of an issue for people who live where the terrain is much flatter. But looking at a terrain map of Beaverton and knowing what I do about the terrain here along the Front Range of Colorado, I'd say that it makes quite a difference for us. I've noticed this for the past 35+ years. Given what is outside my door, I can't help but be a bit nerdy about gearing.

gsa103 04-28-16 10:36 AM
Originally Posted by cyccommute (Post 18724812)
If I compare a 50/34 compact with the same range to my current gearing the problem is even worse. The same shift would require me to increase my cadence from 90 to over 130 rpm to maintain the same speed.
Except that's not how you shift on a compact. You almost always move the rear 1-2 gears in the opposite direction. So going from a 34-17 you shift the front and back to a 50-23, taking you from 55 gr-in to 60 gr-in. The new Shimano Di2 XTR even does this automatically.

The whole way a compact works is that you adjust the front ring to suit broad terrain, and the rear to handle small changes. Going uphill, 34 ring, get to the top, 50 ring. With a triple, you'd do the same thing, except you have a 39t ring that you need to skip over.

trailangel 04-28-16 10:42 AM
^^ I don't buy any of that.

Andy_K 04-28-16 12:57 PM
Originally Posted by gsa103 (Post 18725244)
The whole way a compact works is that you adjust the front ring to suit broad terrain, and the rear to handle small changes. Going uphill, 34 ring, get to the top, 50 ring. With a triple, you'd do the same thing, except you have a 39t ring that you need to skip over.
So going back to my original post, I suppose I could have summed it up by saying that I don't think 50T is a good ring size for commuting.

When I'm using a 50-39-30 for commuting, I don't "skip over" the 39T gear. I use it for almost everything, including moderate climbs. When commuting I pretty much only use the 50T if I'm feeling energetic and really want to get up and go. That is to say, 39T is a good ring size for commuting, though it does cut off a bit at the top end. I only use the 30T gear for really steep hills.

What I gather from the responses that have supported compact gearing is that most people use the big ring all the time and use the small ring as a climbing gear. That makes perfect sense to me for open road situations. For urban/suburban riding, not so much.

ThermionicScott 04-28-16 01:11 PM
Originally Posted by Andy_K (Post 18725635)
So going back to my original post, I suppose I could have summed it up by saying that I don't think 50T is a good ring size for commuting.
I thought you did a good job laying out why 50/34 specifically wasn't great for commuting, allowing that a smaller big ring would obviate most of the problems.

Skipping between the big and granny rings of a triple would be an unbelievably stupid way to use it unless your riding consisted entirely of 15%+ undulations. That would be a pretty ideal scenario for a 50/34 compact, really.

Banzai 04-28-16 02:33 PM
I can achieve nearly identical gear RANGE with both a triple and a compact. However, a triple allows that same range with every cog spaced at 9% or less on the jumps. Nothing in double digits, if I recall.

That being said, 11 speed has all but eliminated that advantage. I've run the numbers, and that 11th cog tightens up an ugly jump in the middle of nearly every 10 speed 11-27 or 28 cassette.

Since I'm running 10 speed, I like my triple. 52-39-30 triple. A triple with a big ring of 50 is just dumb and redundant.


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