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Discussion Starter · #1 ·
Made a video of how a Shimano Ultegra 6800 52-34 chainset works with a 11-28 cassette. The rear derailleur is a short cage.

The video starts off just shifting up and back down in small ring then big ring to demonstrate how far the derailleur moves. The second half is shifting the front chainring back and forth with the chain in the middle of the cassette, then the high gear, and then the low gear.

https://youtu.be/KR5PuMblY6w

The video below was the original compact 50-34 setup if you want to compare how that performs.

https://youtu.be/V4OiDMkK11A
 

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Made a video of how a Shimano Ultegra 6800 52-34 chainset works with a 11-28 cassette. The rear derailleur is a short cage.

The video starts off just shifting up and back down in small ring then big ring to demonstrate how far the derailleur moves. The second half is shifting the front chainring back and forth with the chain in the middle of the cassette, then the high gear, and then the low gear.

https://youtu.be/KR5PuMblY6w

The video below was the original compact 50-34 setup if you want to compare how that performs.

https://youtu.be/V4OiDMkK11A

Interesting video... what are your thoughts when using it, in terms of smoothness on the road, under load?
 

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Discussion Starter · #3 ·
Asking for trouble if shifting under load. It has a higher chance of dancing on top of the teeth when going from small to big and may fall off the outside or inside. I have only had a chance to pedal lightly around my neighborhood. I will report back after some actual rides, but I definitely need to ease up on the pedal when shifting.

When riding big big there is a little more noise since there is more tension on the chain, but I will be avoiding that combination.

But if you aren't cross chaining much, then it feels the same while pedaling.
 

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My concern about this setup would be the 18-tooth difference between large and small rings. This would make chain drop more likely.
 

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Discussion Starter · #6 ·
I had a chance to finally ride this setup. I will be returning to the compact setup. The slight decrease in shifting performance and gain in top end speed wasnt worth it. Does it work? Yes.. does it work decently well? Yes.. but definitely not as flawless as the recommended sizes.
 

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There are many times you would want a 52-11.. hammering it down any type of descent..
Well, maybe down a false flat with a tail wind, and you'd still be working your ass off. 50-11 is a really big gear. How often do you use it?

On a real downhill, once rider gets up to 30 mph, he'll keep gaining speed by tucking in on the handlebars and stem, and getting aero. That'll increase speed another couple of mph a heck of a lot easier than pedaling. In fact the pedaling movements interrupt the air flow around the bike and rider and slow him down. Think like a bird or fish. That's how they do it.
 

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Well, maybe down a false flat with a tail wind, and you'd still be working your ass off. 50-11 is a really big gear. How often do you use it?

On a real downhill, once rider gets up to 30 mph, he'll keep gaining speed by tucking in on the handlebars and stem, and getting aero. That'll increase speed another couple of mph a heck of a lot easier than pedaling. In fact the pedaling movements interrupt the air flow around the bike and rider and slow him down. Think like a bird or fish. That's how they do it.
Easier but not faster - at least in my experience, maybe you are talking steeper grades that I am - I've always found pedaling until I hit 120ish cadence in top gear is faster downhill, that will get me close to 45mph max.
 

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There really is not much change, 1.6mph @ 120rpm, so I don't see any reason to make a change from standard 50. Now if your going for the land speed record, I would reconsider the whole gearing situation.
 

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On any straight, no-wind, 4-5% downhill most folks will be faster with a 52- 11. Most of us can spin-out on that type of descent but will coast far slower than our spin-out speed.

Further, riding at spin-out cadence only works for a short period of time. If I could practically ride with a 65 tooth on straight 7% downhills I would because a more sustainable cadence would take me to terminal velocity for that gradient faster and more comfortably.
Well, maybe down a false flat with a tail wind, and you'd still be working your ass off. 50-11 is a really big gear. How often do you use it?

On a real downhill, once rider gets up to 30 mph, he'll keep gaining speed by tucking in on the handlebars and stem, and getting aero. That'll increase speed another couple of mph a heck of a lot easier than pedaling. In fact the pedaling movements interrupt the air flow around the bike and rider and slow him down. Think like a bird or fish. That's how they do it.
 

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Easier but not faster - at least in my experience, maybe you are talking steeper grades that I am - I've always found pedaling until I hit 120ish cadence in top gear is faster downhill, that will get me close to 45mph max.
Ok, yes, a relatively shallow grade, sure, pedal away. Do a "speed interval" for the legs; loosen them up. But you won't be delivering much power, and it won't translate all that well on the flats where you might need it.

We see TDF riders pedaling down the grades to keep their legs "supple." But they're wasting their energy if exerting much power. But ok, at a certain point, the grade becomes steep enough, gravity takes over; by now rider is probably spinning out at 40 mph, and if you can pedal 120 rpm, at 45 mph, you're right.

So yes, I'm talking about steeper grades than you're encountering. As the grade gets steeper, there's a certain point where gravity takes over, pedaling spins out, and rider is better off tucking aero to cut through that wall of air hitting him at 35-45 mph. Also, how long can you sustain those 120 rpm descents? I always say, "Screw it," stop pedaling, and just go into the tuck, usually discovering I haven't lost any speed and can now rest the legs.
 

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On any straight, no-wind, 4-5% downhill most folks will be faster with a 52- 11. Most of us can spin-out on that type of descent but will coast far slower than our spin-out speed.

Further, riding at spin-out cadence only works for a short period of time. If I could practically ride with a 65 tooth on straight 7% downhills I would because a more sustainable cadence would take me to terminal velocity for that gradient faster and more comfortably.
Alright, so it really depends on the grade what rider can get away with. Yep, I put on a 50 one summer. It was nice solo, but in a competitive group I kept spinning out on those 4-5% grades as the others were pulling away. The 53 developed a bit more torque on the 13 and I could punch out another couple of mph for a few seconds. Like you say, few riders can sustain above 120+ cadence for very long.

Many times, I've passed riders pedaling, me in a full tuck. Then again, they were usually pedaling 90-95 rpm, not spinning out like mad, so there's that. :D

I always ask myself, "Is it worth it?" What do I get for frantically pedaling as fast as I can just to cheat out another 1 mph going 40 mph? by 25 mph, that wall of air becomes the primary resistance to forward momentum. If I can increase speed by 1 mph in a full tuck, why pedal? If the grade is steep enough, pedaling has actually slowed me down. I've experimented with this at 30-35 mph, more typical of the descent speeds attainable around here, and found my speed could drop 1 mph if I start pedaling like mad. The cost of overcoming the wall of air for that minimal gain, when I could be resting the legs, aren't worth it.

So keep those 50 t. chain rings. They'll give rider at least one more usable gear on the flats than the 52. :D
 

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Discussion Starter · #15 · (Edited)
People have different riding styles and different terrain. Some like to smash it with a group of friends even downhill even if it's just for a minute. Some crit racers prefer a 52. I would personally like to be closer to my average cadence than spinning out my max if able to. A 53T, 52T, and 50T exists for a reason.

I had already stated I will return to the compact 50-34 setup since the decrease in shifting performance wasn't worth the extra top end - for me.
 

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People have different riding styles and different terrain. Some like to smash it with a group of friends even downhill even if it's just for a minute. Some crit racers prefer a 52. I would personally like to be closer to my average cadence than spinning out my max if able to. A 53T, 52T, and 50T exists for a reason.

I had already stated I will return to the compact 50-34 setup since the decrease in shifting performance wasn't worth the extra top end - for me.
Yep. And let's not forget 50-11 is about the same as 53-13. Haven't used that gear in years! :D
 

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Like you say, few riders can sustain above 120+ cadence for very long.

I always ask myself, "Is it worth it?" What do I get for frantically pedaling as fast as I can just to cheat out another 1 mph going 40 mph?

So keep those 50 t. chain rings. They'll give rider at least one more usable gear on the flats than the 52. :D
The use for 53/11 gearing is pretty limited for me admittedly. We have a couple of downhill sprints to city limit signs on group weekend rides that tall gearing makes the difference on - I don't need to spin for long finish first or second (mostly first) - 6 or 7 seconds at 120 rpm making 600 to 700 watts and I'm not getting passed often.

53 front ring with close spacing on an 11/23 cassette gives plenty of gears for all of my rides around here. Going to areas with lots of climbing I'd much prefer the compact.
 

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The use for 53/11 gearing is pretty limited for me admittedly. We have a couple of downhill sprints to city limit signs on group weekend rides that tall gearing makes the difference on - I don't need to spin for long finish first or second (mostly first) - 6 or 7 seconds at 120 rpm making 600 to 700 watts and I'm not getting passed often.

53 front ring with close spacing on an 11/23 cassette gives plenty of gears for all of my rides around here. Going to areas with lots of climbing I'd much prefer the compact.
Awesome! That's how its done. Kudos! :thumbsup:

Would also guess you've got a 39 inner ring on there. 39-23 will handle anything most places, even those mountain passes out west.
 
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