Sure, but this is what the OP was asking about.

If top speed on long descents is the main reason for the swap, it's probably not going to make a big difference(about 1.5mph)

Oh, yeah. Definitely go for it. Sounds to me like you're holding yourself back with that compact.

If I could gain 1.5 mph on the bike while descending, you're darn skippy I'd make the swap. (which I have on one of my road bikes). Seriously, a 1.5 mph gain is a big deal. It takes me a good 3 months of training to gain that on my average speed. JMHO - YMMV

The GI change between a compact and semi compact is the same

power is power, its not free. To go 1.5mph faster with the 52x11 at say 90rpm compared to the 50x11 @90rpm, you'd have to put out more watts. Alternatively you can just spin the 50x11 at a faster rpm at the higher power output.

http://www.pbase.com/jhuddle/image/163817821.jpg

Here's your solution. Wickwerks 53/34 setup. Works just fine with a normal FD. In fact, these really are my best shifting set of chain rings by far.

I rode the bike these are on again last night and near the end I just played around with shifting the front just to enjoy how easily and quickly it jumps from the 34 to the 53.

Now in all honesty it's not a practical setup for most of my climbing routes. But on the shallower 20 miler down Monte Cristo it is great because you speed a lot of it in the zone between spinning out and needing to tuck. I can carry a better avg speed through that section with the setup.


This is the bike they are on.

http://www.pbase.com/jhuddle/image/163817826.jpg

even in a race, on a descent where you can go 40mph plus, the preferred technique is bust it hard over the top, get to speed quickly, once you're in the 40's then tuck, recover, and take advantage of the momentum.

Spinning like a banshee to raise your speed maybe a mile an hour will take a huge amount of energy and ends up costing you way more than it's worth.

FWIW, I've raced in the mountains of Colorado, California, the Appalchias and other mountain terrain on a 50x11 and never felt limited by my gearing.

But it's not that simple. As pointed out by others, the 1.5 mph speed increase takes a lot of watts regardless of the gear.

And because wind resistance is a squared function of speed, going from 40 mph to 41.5 mph takes a huge power increase compared to say 23 to 24.5. So you're getting comparitively little return for that power out put, as opposed to the much bigger return you'd get recovering and saving those extra watts for the flats, or the next hill, where the payback is much greater.

Additionally, the better way to get that extra speed on the descent is go hard at the top of the clmb. The speed and momentum you get at the top adds more speed as you descent. So instead of trying to pedal your way down the mountain in a bigger at 1.5 mph faster, go hard at the top spin up the biggest gear to 120-130, then tuck . That extra speed at the top multiplies down Athe mountain, and is faster than trying to pedal a big gear all the way down steadily. And the energy cost is much less ( and therefore more energy for later in the race.)

To put numbers to this, trying to raise your speed from 40 to 41.5mph on a 6 percent descent takes an additional 106 watts for an average size rider.

going from 23 to 24.5 on the flats takes only 48 watts.

And more importantly the 41.5mph takes 464 watts total, which for virtually everyone short of the pro tour ( and even most of them) puts you above threshold and burning a match for very little return.

Another way to look at this, if the slope will give 40mph plus, tucking, then the cost of going to 41.5mph is not an additional 106 watts, its 464 watts, compared to zero watts coasting.

If the hill is steep enough that your spinning out a 50x11 (and you can spin 120 or so) it is almost always better to tuck and cost after you get up to that sort of speed/rpm

OMG.... I know you've been at this a lot longer than I, but I can't believe you don't see the issue. Purposefully spinning on a descent? SMH..... And regardless, given the same smallest cog, max rpm with a smaller chain ring is never going to get you going as fast as the same rpm on a bigger chain ring. I can't believe you're missing that.

Yes, absolutely, maximizing the power output at the top of the descent is always the way to go. The thing is, I've found that when heading downhill, getting those watts to the wheels works a LOT better at lower cadences - by downright mashing. Heck, I've started getting on the rivet at the beginning of descents, and it's like night and day. The delightful thing is, it's not even hard, it's a piece of cake. I used to be the one getting left behind on descents, now it's the other way around.

Say what you will about the value of spinning and mashing generally, but for accelerations on hills, I've found that the way to go is to spin when going up and to mash when going down. When riding down and up a bowl, start mashing at the top, and don't stop until you've run out of cogs, then spin until there's no more acceleration, but keep spinning as you approach the other side. As it starts heading up, just step up to bigger cogs, one at a time, still spinning just as fast, and sometimes you can get all the way back up without it ever seeming like any effort. Approaching the top again, it's super rewarding to be relaxing ones cadence while blowing past guys out of their saddles trying to hammer their way to the top. Better yet - coast your way past at the top - dzzzzzzzzzzzz!. :D

I'll simplify. There's a point where gravity takes over and pedaling becomes counterproductive. If you have a decent spin you can exceed that point with a 50x11. Going to 52x11 is not going to give a meaningful advantage in the vast majority of circumstances.

As for missing it, I obviously understand that for a given rpm, 52x11 is faster than 50x11.

What you're not considering is the additional watts to turn the bigger gear, and the fact that pedaling becomes counterproductive on a descent as you hit higher speeds.

nothing about that would be limited by a 50x11 compared to a 52x11. The difference in acceleration and mashing force at lower rpms is small between the two, it's simple physics and gearing.

I hope this was said in jest.

Sadly, I think he's serious.

Yep... I have a pair of 53/34 Stronglight rings on my Campy cranks, they seem to shift well without chainsuck (although I should install a chain catcher for the downshift).

I like them. With the wider range cassettes, there is no reason to have a tight range for the cranks... I do find myself frequently double shifting, but that means less overlap.

I've hit 50 MPH a couple of times.

My current goal is 55 MPH... I managed to hit 54 MPH max... just a little faster spinning.. :giver:

https://www.bikeforums.net/attachmen...hmentid=609504

And, I'm still not even in the top 10 for the king of the downhill. :mad:

I hit 58 several times when I live in Summit County Co, but after a wreck at 48, I rarely charge the DHs anymore.

I guess it all depends on what gives a ride meaning. Also, some of us are happy to use the watts. . :) One can stop pedaling once it gets counterproductive on any setup, but dismissing the 1-1.5mph advantage of the bigger chain ring seems to indicate a lack of appreciation for speed and an absence of competitive spirit. If one rides solo most of the time, I can understand the lack of interest in these "small" numbers, but I don't think a rider has to be particularly competitive to appreciate the difference between 23.5 mph and 25, between overtaking and being dropped or being the first or last to reach a certain point, or to find that these things, although they occur only during the smallest fraction of any ride, can be enough to establish the character or absolutely define a ride over an ordinary course. When people just look at numbers and say "it's such a small number, it's not worth the bother," I have to take exception. Little struggles and little pushovers add up fast.

The context of my post was in response to the implication that you would need more than a 50x11 to race. I totally stand by my assertion based on experience (racing in P 1/2/3 races with a 50x11), and the simple physics outlined above, that 50x11 is perfectly adequate for the vast majority of circumstances road racing.

The higher gear ratio doesn't magically give you 1-1.5mph. And the cost of pedaling on a downhill beyond a point where 50x11 is spun out will in most cases make you overall slower, i.e. less likely to win the race.

So if your goal is to see how fast you can bomb a single descent, go ahead and put a 56x11 on the bike. If you have excellent 5 minute power (i.e. 500-600 watts) you may be a tiny bit faster. Even then I bet I'm down the hill first with a 50x11 sitting on the top tube, ahead of someone with a 52x11, a 56x11, or even a 58x11 pedaling in the drops.

if your goal is to win road races, 50x11 is going to be more than adequate for the vast majority of cricumstances.

OK, I'll buy that. But it gets us back to the question of whether a recreational rider is truly "spinning out." Riders who are well disciplined may be able to spin up to max after a slog of a climb or sitting in the middle of a bunch for half an hour, but many of us who CAN spin up to 140 FEEL like we've spun out before we even get to 110 after grinding up a hill or sitting lazily in the middle of a bunch just doing 80 during the boring bits. It's not all about being smart. Sometimes it's just about being fun.

Yep! I can get there going to Trappers Loop in my Utah Valley. Of course, I'm using "heavy" steel and have enough,ummmm.... extra weight... to help it along. :o

For sure Powder Mt descent too but...that one may literally kill you. Up to a 20% grade and bikes/cars wreck coming down quite regularly.

+1 :thumb:

Yup, sure am! :rolleyes: