Cranksets and gearing.
 

Let's discuss cranksets and gearing - specifically, the pros and cons of compact (50-34), mid-compact (52-36), and what I call oldschool (53-39).

I'm considering going mid-compact or oldschool. It turns out that 34x28 is more than enough for the climbing I do; I pretty much only use that for grades over 12%, and even then, they're short enough that I can grind them out in 34x25 (though it's not much fun). There are also times when I'd like a bit of a higher gear for descents.

So my concern is that with mid-compact or oldschool, I'd want an 11-32 cassette, and might dislike the tighter cluster of 11-28. Those of you who have experience with different configurations: what did you like or dislike about different configurations, and why?

IME a combo which gives you enough top end speed and the closest ratio climbing gearing would be the ideal. That usually means the crankset with the smallest inner ring, resulting in a cassette with a smaller big cog. But that may depend on the gradients on which one rides, i.e. if you'd spin out a 50 X 11 all the time and hate that worse than not having the perfect climbing cog.

I use a compact 50-34 chainring set and an 11-32 cassette on my road bike. I only spin out in high gear going down a fairly steep grade. When everything is working for me a can get a max top speed of about 43mph. Every time I get the feeling that it might be nice to have a higher top end gear for those thrilling descents, I am usually humbled by a tough hill to climb. That always reminds me how nice it is to have that compact setup. I seldom use that 34-32 combination, but it’s there when I need it on long, steep climbs, long days in the saddle, or when I am just having an off day. I wouldn’t want to be without it.

My road bikes are both older, 7-speeds. The steel Ironman (172.5 crank arms) now wears 50/39 chainrings and 13-25 freewheel. The early '90s Trek 5900 (170 cranks) is 52/42 (Biopace -- hey, they're okay with me) and 14-28. On fast downhills I'm often spun out at 130 rpm, where I get a bit wobbly and can hold that cadence for only 15-30 seconds. And on bad days neither has a comfortable granny gear when my legs are dead.

My favorite gearing? My old 8-speed Univega hybrid (175 crank arms) with 50/40/30 triple and 11-32 cassette. I've never spun out on fast downhills (partly because of wind resistance approaching 30 mph with the more upright bike) and always have enough gear for climbs even when my legs are dead. The bike never really feels like its 30 lb weight. In contrast, some days the 20 lb Trek feels like a lead sled, usually the final climbs after a hard (for me) 30 mile workout ride.

Eventually I'll convert the Trek 5900 back to 8-speed, 11-32, and might consider a 52/38 double in 130 BCD, unless I switch to 110. We don't have any long steep climbs so that would be adequate.

Yeah, the crank arm lengths might make some difference. Honestly, I'd need better data over time to be sure it's not just subjective.

50/34. More options especially for the lower gears and you don't need anything bigger than 50-11.

I look at the smallest gear I need and the largest. Say 42-32 and 53-12. Convert those to gear inches. (42/32 X 27 =) 35.4 GI and 119 GI. Now you can look at the chainrings you want to use and see what cassette results or vice versa. Say you really like the spacing on a 11-28 cassette. 119/27 X 11 = 48.5. 35.4/27 X 28 = 36.7 So a 48-36 by 11-28 will be near identical to a 53-42 X 12-32.

Or say you really want a 50-34. So 50 X 27/119 = 11.3 and 34 X 27/35.4 = 25.9 A 50-34 by 11-26 will also get you the same gearing.

Actually, after I decided to go 9-speed years ago, I purchased several different cassettes and a couple of outside cogs so I can have two wheels built up in nearly any combo from 12, 13 or 14 to 23, 25 or 28. (I've used 53-42-28 chainrings for decades.)

Ben

What benefit are you expecting from the mid or standard?

I prefer tight spacing and, like you, I don't have many hills that are both long and steep, so I'm running a compact with a 12-25t. Spinning out on the 50/12 hasn't been a problem for where and how I ride.

I'm specifically looking to avoid spinning out, which happens on descents somewhere around the low to mid 30s (MPH). Most of the hills I ride are only a mile or two - but it's enough to be mildly annoying, especially when trying to get speed back on a straight stretch after hitting a switchback.

Pedal faster.
Also remember that if you are "spun out" at 35mph with a 50-11 that will only increase to 37mph on a 53-11.

Yeah - it's looking like the best solution might be to spend a bit more time training on the fixed gear.

It's so fun to take my bike apart, though!

My bike had a Claris group on it that included a 50-34 crank and 11-32 rear cogs. I did not like some of the big jumps between the gears so I switched to a Shimano 105 group with a 52-36 crank and an 11-30 11 speed cassette and I absolutely love it. There are no more large jumps between gears and I find that I am actually faster on the bike now. My commute is mostly flat with some hills and almost always a headwind in one of the directions so I am rarely in the small ring up front. I have only had the new set for a couple commutes, but I think it will be awhile before I spin out the 52-11 as I have been up to 35 MPH and still had two cogs left on the cassette.

53/39 + 11-32 will give you the same low gear and a slightly higher top gear than 50/34 + 11-28.

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I used to put money and time into modifying my cranks to 52-36.

Now it’s standard in a lot of places. Hooray for me!

Typically run a 12-27 cassette. 52-12 is all the taller I need

Hmmm .... my first derailleur bike was a compact geared 10-speed. 1967. 52-36 X 14-28. Didn't have to modify anything. (And it even used higher math to calculate the number of gears, not this count-on-your-fingers stuff.)

Ben

Eddy raced with a 52-13? Maybe 53-13?

Point being, a mere mortal like myself doesn’t need a taller gear than Eddy.

52/34 works for me and several of my friends.

My favorite set up is a mid compact 52-36 with an 11-30 cassette. But I must admit I love using a 50T from a compact on climbs up to 6%.

How well does that front shifting work? Sounds like it would be a nightmare without some really good chainrings.

If I'm in any doubt about running out of gears, I'll just put on a triple and forget about it. Plus, that lets you use a reasonable middle ring, like a 38 or a 40, so that you won't always be running on your small cogs with a crossed-up chain during times you're out of the big ring.

I would go Compact. I have never needed to go faster, but I have needed better climbing gears but I have an old bike with 52/42 biopace up front and 13 - 28 in back. 42x28 doesn't cut it for steep hills at all. I doubt 42x31 would cut it either. I'd rather have the flexibility for more hill climbs, than a few more MPH down hills.

I guess it depends on the terrane. On my main road bike I have a somewhat unconventional combination of a 53/39 and a 12-27 in back. This works for me in Minnesota and isn't bad when I go ride the hills of Wisconsin. On the other hand, when I did some serious climbs in California last year, I was dearly wishing for some easier gears. On my second road bike I have a compact 50/34 and also a 12-27. That's better for climbing, but if I really want acceleration down a hill, I wish I had an 11 in back. I keep thinking I should make a change, but I haven't yet.

If I were shopping for a new bike, I might think hard about a 52/36. That seems like a great compromise.

I have three road bikes. One is the traditional 53/39 10 sp. w/ 12x28, one is 50/34 10 SP. w/12x28 and the latest (CAAD 12) is 11 sp. 52/36 w/ 11X30. The standard crank is a bit much for me at this point in the season. The other two are pretty similar except the mid-compact gives me a bit more flexibility and a higher top end. The bottom end is similar and the top is a bit, but not that much more.

I use 52/34 with a 11-28 cassette. I do a lot of mountain rides events I really like the 52 on the descents. I could do a 52/36 with a 11-32 cassette to get the same results, but I like the 11-28 much better for rolling hill routes. I just like the 34 in case I burn all my matches before the last climb in a century.

In all honesty, I really only use the small ring in the mountains & generally it's one chainring shift at the base of each climb and one and the crest of each climb. I've never really had any problems with the front shifting.

I run Etap on one bike and Red mechanical on another. No issues with either. I've got friends on mechanical Ultegra and Ultegra Di-2 as well as Etap. We do maintain our bikes - change the chains when needed and don't run worn chainrings.

when calculating and comparing GI why bother with wheel diameter it's a constant between them, only if you're considering different wheel sizes does it make sense

Lets say in back you have an 11-cog cassette. And in front you have a double. Common choices are the 11-35t, 11-28t, 11-30t, 11-32t, and 11-34t.

With a 50/34 in front, and an 11-25 in back, your lowest gear ratio will be 1.36:1. Highest will be 4.55:1
With a 52/36 in front and an 11-25 in back, your lowest gear ratio will be 1.44:1. Highest will be 4.73:1
With a 53/39 in front and an 11-25 in back, your lowest gear ratio will be 1.56:1. Highest will be 4.82:1

Now lets do the same exercise with an 11-34t in back:
With a 50/34 in front and an 11-34 in back, your lowest gear ratio will be 1:1. Highest will be 4.55:1.
With a 52/36 in front and an 11-34 in back, your lowest gear ratio will be 1.06:1. Highest will be 4.73:1.
With a 53/39 in front an d an 11-34 in back your lowest gear ratio will be 1.15:1. Highest will be 4.82:1.

So why wouldn't everyone want the broadest range of gears possible? Because the spacing between gears in the 11-25 cassette is much closer than in the 11-34 cassette, making it a lot easier on the narrowly-spaced cassette to fine tune your cadence to fall within the best power/cadence balance when riding in less hilly terrain. A broadly spaced cassette will leave you wishing you had a gear between the gear steps when you ride at speed down a long flat or slightly inclined/declined road.

But that 11-25 cassette is going to suck for climbing steep grades. The best cassette for you is the one that provides the low end you need, and the spacing you need. The front end plays into this as well, of course. So the whole thing is a series of trade-offs and optimizations that have to be configured to meet the individual rider's needs given the terrain this rider encounters.

It's unfortunate that triple cranksets have gotten such a bad rap in recent years. Sure, if all you ever tried in the triple-crankset world is low end stuff, it's going to be kind of lousy. Higher end stuff will perform better, but is becoming harder to find. On my Cannondale Synapse, with 105 components I have a 50/39/30 in front, and in back a 10sp 12-30 cassette. With this I get reasonable spacing between gears for good power-band efficiency, while still getting some good low gears (as low as 1:1) for climbing Little Cottonwood and Big Cottonwood canyons near my home. To get this range in a compact double I would need a 34t rear cassette, and in a 10sp setup that's going to leave some big gaps. So I would have to swap out my rear mech including shifters for an 11sp setup to get to an 11-34t cassette, which would still have more gaps than I have in my 10sp 12-30 cassette.

My bike originally came with that 50/39/30 in front, and a 12-25 in back. It was fine living in LA, but not the right cassette for where I ride now that I've moved to the Southeast corner of the Salt Lake valley. I swapped to an 11-28, and later to 12-30, and am not ashamed that the 12-30 is a great cassette for long, steep, sustained climbs.

Not that I disagree. I would just like to add that many forget the one tooth jumps are often in a gear range they may not use for most of their rides. Especially if they ride alone.

For instance the first 1t jump on a 50/11-28 is 15t to 14t or about 90" to 96" gear inches, or about 23 to 24 mph. Fairly fast. On a 50/11-34 there are no 1t jups, but the gearing is more useful in the 50" to 90" gear inch range, that I believe many solo riders tend to use a lot. For that reason the 11-34 is in fact more useful for me than the 11-28 and the 11-25.

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