I'm not sure I understand why there are different options available. I ride a P2K outfitted with the standard 53/39 Ultegra. Wouldn't such a drastic difference in gear teeth mean you would need an equally drastic cassette ratios?? I am putting preliminary "must have" things on paper for my next bike and I wanted to research the FSA options. Thanks.

---

Doug in Michigan

No need to do much with the rear cassette from what I have read, i.e., I have not tried this yet myself. It would let most people get by with a "tighter" rear cassette, like an 11-23 instead of 12-27, so that you have smaller "jumps" between the gears. Bottom line is that most people can't use about 1/2 of the rear cassette on a 53 unless they are using a lower cadence than most people recommend for tris.

I have a spreadsheet set up to show speeds at 90 rpm for 700c bike at various gear ratios. Message me with an email if you want a copy of it.

I'm getting pretty intrigrued with this idea myself. I'm curious to get some feedback from you early adapters on whether the "fipple" thing that TNT was posting about as a big negative of this setup seems like a problem to you.

I run an 11-23 cassette and the shifting seems to be fine on the trainer. I think one could run a 12-25, or 12-27 with this combo, however I dont plan on trying to climb up the Grand Canyon. With the 50/34 on the front and the 11-23 cassette, I think I can spin up just about anything no problem. I will keep you posted on how this FSA Compact works in the real world on the road.

---

"You're guaranteed to miss 100% of the shots you never take" - Wayne Gretzky

believe me i'm no ludite, but why would someone want one of these , if my avg. cadence is 100-105 and at the top of yellow lake, they say"good cadence,good circles"?????

---

i think there, 4 am

Well my avg. cadence is about 100 - 105, and I love to spin my way up the hills. I sure a heck want a set of those. I have a 38/50 on there now and I would love that 34.

 sure who wouldn't like a 34 on the pass, but you'll wind it out on the down hill. Mr. 55/39 with a 12-25 (thats me for now)will come flying by, If i can hold a better than avg. cadence up the hills ,why shouldnt I push the 55 dinner plate. As long as i'm not mashing ive gotta be faster than a 50/34 racer? don't I ?

---

i think there, 4 am

Well lets see. At 100 rpm, Mr 55/12 makes 35.8 mph while Mr. 50/11 piddles along at 35.5 mph. Yup, you'll go flying by.

don't get me wrong i'm not trying to sound like captain quads, i just can't believe it would'nt be faster.

---

i think there, 4 am

Hey, more power to you if you can use a 55 dinner plate, I can't so I'm going to keep wanting a 50/34. I don't know about you but I am not a big fan of racing downhills anyways, even if I did, I spin out around 140 going down hill, that puts me at ~49mph with a 50-11, if you fly by me I'm sure a heck not going to get in your way.

Like I said, I spin a 50/38 now anyways, why not go for the much more useful 34 w/ a tighter cassette?

I'm not much of a mechanic, can someone confirm that this is a similar product to the FSA compact cranks?
http://www.xxcycle.com/cgi-bin/shop.pl?Screen=detail&REF=2835&FROM=bestwebbuys

It is labelled "Stronglight Compact crankset. Triple combination with double crankset advantages"

They advertise that it comes with either a 50/36 or 48/34.

Your speed is determined by your pedaling cadence and the gear ratio. Your cadence is what it is so lets look at the ratios. 55/12=4.58, 50/11=4.55; less than 1% difference. So at a given cadence, the speed for the two combinations will differ by less than 1%. to put it differently, to match your speed with the 55/12 at 100 rpm, you have to pedal the 50/11 at 101 rpm.

This is what makes the idea of the 50/34 intriguing. For those of us who don't need an 11 with a 53 or greater chainring, going to a 50/11 costs us nothing (in fact a 50/11 is a bigger gear than a 53/12) but gives us a lower low gear plus the added benefit of closer spacing.

Very true. And if you are afraid Mr. 55/12 will come flying by because of his 1% advantage, just go with the 52/36 combo on the compact cranks. Then you can fly by Mr. 55/12 on the descents AND school him on the climbs. Or as we compact crank users like to say, you can tyler him into oblivion.

And we haven't even gone into the weight savings of the smaller rings, or the smaller frontal area :-)

---

Gerard Vroomen
3T.bike
OPEN cycle

 wow, maybe i'm changing my mind
thanks.

---

i think there, 4 am

Gerard,

Do you run an 11/23 cassette with your FSA Compact?

---

"You're guaranteed to miss 100% of the shots you never take" - Wayne Gretzky

I used an 11-23 at IMC, but I also have a 12-27 (got that before I had the compact crank). I would have no trouble using the 12-27 in combination with the compact crank in some situations though (like a Paris-Roubaix Challenge type of ride and maybe in the Pyrenees). I like to spin so I appreciate some small gears. At the same time I don't need the big gears on the descents as there is too much traffic to bomb down the mountain at 70mph anyway. In a race it's a bit different, and at IMC I used both the 23 and the 11 regularly, but without any need for a bigger cog or serious needs for a smaller cog.

---

Gerard Vroomen
3T.bike
OPEN cycle

Could someone tell me an online dealer who sells these compact cranks or how much they cost?

Does it work with a splined shimano bottom bracket or does it need it's own brand?

Any idea of what is the smallest chain rings you can put on a statndard crankset?

Thanks

38 is the smallest you can spin on a standard crank.

Thanks, I think I need to get my big in a smaller size. I don't have the $$ to get a new crank or rings right now. I guess I'll just have to get my file and take a few teeth off the rings I have. ;-)

What about high speed descending with these ratios? What goes up must come down. A look at the ratios convinces me these are viable for flatlanders, but what about when the roads go up and then down. I like to be able to get on top of a gear during high speed descents over 40mph, but without spinning myself into oblivion. What is the answer there?

I seem to recall having read several times that at any speed above ~30mph in a descent, it's actually more efficient to tuck in and coast- both from an aero vs power perspective and from a recovery perspective. This would negate the need for gearing for this type of application. I don't know if there is any science behind this claim or if it's just one of those things that's been repeated often enough that people assume it's true. At least from the recovery standpoint, I'd rather tuck and give my legs a break for a few seconds or minutes and then be fresher for the next hill. Pedalling vs coasting at that speed is only worth a handful of seconds, and I think the recovery could easily outweigh that.

So if I understand this right, a 34-23 would be equivilant to a 39-27 for climbing. And a 50-11 would be equivilant to a 55-12 for decents. The main advantage would be avoiding the 3 tooth gear changes in the 27 tooth cassette.

Does this sound right? If this is correct, it seems to me like it would be worthy of trying. I use a 25 now because I don't like the 3 tooth differences on the 27. I really feel the need for another gear when climbing with my 700C bike.



Dennis

Try www.bestbikebuys.com type FSA compact crank into the search. I think you'll find that they cost around $250. I found a stronglight compact crankset that looks very similar in that it will get you some small gears, but I'm not sure that this crankset is compatible with our BB and shfting. See my earlier post in this thread if you are enough of a gear head to know if this crank is Ultegra compatible. The stronglight compact crankset is $107.

How about double shifting? Without studying the gearing charts my question is whether there is more double shifting required with this combo? Or is it actually the other way around, with LESS double shifting required? Too busy at work to find the answer myself.

Answering 2 questions at once here:

1. The 34/23 is almost as "easy" as the 39/27. The gear ratio at 34/23 is 1.48, the 39/27 is 1.44. That's awfully close. For reference purposes, the 39/24, which I believe is the next easiest gear on that 12-27 cassette, has a gear ratio of 1.63.

2. From just looking at the charts, I think there would likely be more double shifting with the 50/34. I think that's the tradeoff in exchange for the tighter jumps between gears and the ability to get something on the back you can spin up steeper hills. I'm trying to decide whether it's worth it.