"but given that on a flat road with the wind behind me I run out of legs long before I run out of gears why shouldn't I go compact?"

You should go to the weight room to get stronger, not go compact =P

Freestyle, no one runs out of legs because their legs are weak and need more muscle power. It is about the engine and accumulating too much lactate.

Personally, this year I will be running a 48/34 in the front with a 13-26 in the rear for training and 12-23 for racing. For reference purposes, I have split sub 60 min in Olympic tri, 2:25 in half Ironman and 5:17 in Ironman, with 50 tooth and rarely used my top gear (50x12). Usually, if I am going faster than 60 kph in a tri, I choose to coast. This is more valuable over the course of the race (see reference above to "running out of legs")

For the life of me, I can't understand why bikes are spec'd with a 53/39 with a 12-23 for your average guy. This is what pro cyclists need, not your run of the mill local age group poser.

aww thanks!

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"Are you sure we're going fast enough?" - Emil Zatopek

"Why not go compact?"

Because I spin out a 55/11 on the downhills, and 54/12 on the flats with a tailwind.

but that's the weird thing - I take your point on the downhill scenario (though if I'm going too fast to pedal with a 55/11 and going downhill I'd just be concentrating on staying alive - I am a wimp), in your second scenario a 54/12 would give you exactly 4.5 revs on your back wheel per revolution of the crank whereas a 50/11 would give you 4.54 revs. and you'd be lighter (a bit). As I said maths isn't my strong point but I'd love to know if I'm getting this wrong.

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"Are you sure we're going fast enough?" - Emil Zatopek

do compact cranks just have a shorter crank arm?

56-50 is this compact? ;-)

Don't think so - I think you can have any crank length you want it justb refers to using smaller cogs at the front which can be coupled with a smaller cassette at the back. First I heard of them was that ludicrous Tyler hamilton TdF stage win when he won with a massive solo break despite having a broken collarbone.

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"Are you sure we're going fast enough?" - Emil Zatopek

Downhill is usually a small portion of the ride. Most of it is flat or uphill. That's where you spend most of your time and that's where you should have gears that work with your style of riding. For most, they'd be better off with compacts. OTOH, two of the fastest people I know (and one is 50) use 56 front and 11-?? in the rear. It's less than 21, it looks lke half of a small pinecone. Both these guys seem to have cadence in the teens, yet they also run very fast.

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Proud member of FISHTWITCH: doing a bit more than fish exercise now.

I'm currently on a 52/42/30 with a 12-25. I can spin up to 45mph on a downhill in the 52/12. My next set of cranks will probably be a 50/36 or even 46/34 with an 11-23. I'm fairly strong by triathletes standards, so you'd probably be happy with a compact set. Give it a try if it interests you.

"Because I spin out a 55/11 on the downhills, and 54/12 on the flats with a tailwind. "



If you're spinning a 55 X 11 on downhills you're better off to tuck aero and coast because you'll go just as fast and conserve a bit of energy.

I just went on analytic cycling and calculated that 100 rpm on 54 X12 will give you 57.17 kph but 100 rpm on 50 X 11 will give you 57.75 kph. Check it out for yourself:

http://www.analyticcycling.com/...eedCadence_Page.html

in windy areas...it can be worse...saturday, with a tailwind on columbus road NM (no trees, just desert) I was going 64-65km/h with at 140bpm...
(don't ask the speed on the way back...)

Hello,

Its really a minor point. Compact does give up some top end, no matter how you slice it you have a low gear, a high gear, and the steps in between. You can get a lower low, a higher high, or closer spcing, etc but not everything.

The main "problem" with compact is that the smaller the cog and the bigger the chain angle the worse the mechanical efficiency. So if your highest gear you actually ride in is 50 x 11, then you are better off with a 59 x 13. Assuming the 13 is not the smallest cog the chainline is better and the bigger cog is more effiecient. If you ride both hilly and flat races, you should have a variety of chainrings and cog sets.



Styrrell

I used a compact for much of my base miles, it did help keep my watts in the right range on sustained climbs. I did swap the 34/50 for a 38/53 in race season as I found that often it seemed I was stuck at a speed halfway between the two chainrings. I did put the 34/50 back on for some races super steep climbs (10%+ sustained). I us a 54/42 for time trials with an 11-21 as the ones I do are flat and fairly short.

I do agree that far to many riders are riding the same gearing as pro riders when they dont have pro rider strength. Sometimes I think that it is an ego thing, I once saw an agegrouper at Memphis in May with a 58 chainring on a 700C wheel bike. I passed him into the wind while he struggled to turn that sucker over.

I love mine! I have a 50-36 (sometimes a 50-34) with either an 11-21 or 11-23 10sp in the back.

I have yet to run out of gear except on the longest of steep downhills. I have been riding them for just over a year and have yet found a reason to go back. Just before IMAZ I did a long ride and averaged just over 28 on the way out (and just under 15 on the way back) and still had enough running gear. When I installed the compact setup (from Campy Record Crank/BB & 12-25 Chorus cassette) I dropped almost 1 pound off my bike (FSA Carbon Compact/BB & 11-21 Record Cassette).

Now, Like I've said before Compact aren't for everyone. I am comfortable spinning at 95+ and don't ride like lance. I dunno if I would be as hooked on compacts if I could ride like I did before I stopped racing in '95 or wasn't focusing on ultra tris and rides. I have found it is perfect for me, and I believe that a good majority of riders would benefit from a compact setup also.

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"The nation which forgets its defenders will be itself forgotten." - (John) Calvin Coolidge

I hear ya. Last year I did a short triathlon (19 mile bike leg) on a flat to gently rolling course. I have 53x39 and 700C wheels and went with a 12-23 cassette instead of 11-23 figuring the tighter gearing would be more useful than a taller gear. But the wind picked up by the time the race started and I ended up pedaling 100+ rpm in the 53/12 on the tailwind leg wishin' I had that 11T.