Compact cranks?

I am no expert, but I was thinking the exact same thing.  I currently have 11/23 with 39/53 it is what the bike came with.  It is ok on the flats and downhill, but too much for the hills.  I ordered a 12/27.  I am going to try that first, then add the compact if necessary.  Makes sense to  me and the bike shop guys I talk too, but I as I say, I am no expert and want to know what the bike types have to say too.

I've been running a compact (FSA and a Shimano) for 6 months.

Couple of comments for what they are worth. Good things: They make a smaller cassette much more usable with closer rations. 53/36*11/23 will give you the equal to a 50/39* 12/27.
Great climbing set up if you go to a 12/25 or a 12/27. I like it but unless you are in a really hilly area the bigger gears are pretty big. The closer ratios of a 11/21 or a 11/23 are nice. I have been doing the local bike races with a 11/21. Gives you plenty of gears for even short climbs and a very close ratio to keep your cadence where you want it. I suspect the 21 gives you something close to a 53/39*12/24. Great if you are training by yourself. I like to spin at 100+rpm and they really help that happen all the time.

Bad things. If you are doing a lot of group rides you'll find the gear ratios off from the pace line. You won't get any stronger riding larger rear gears. I wouldn't have a compact as my only bike. But it is a great option for your road bike/ tri bike combo or second road bike used for climbing or to up your cadence.

Here is a good discussion:
http://www.slowtwitch.com/mainheadings/techctr/gearing.html

After six months I am putting a 53/39 back on one of my road bikes. My tri bike runs a 54/42 normally with a 12/23 in the back. But on my late season IM with lots of hills (7000+ of climbing) I'll put a compact on with 11/27 to keep the spin on for the 18% grade involved.

Good to have options.

The inexpensive FSA compacts are easy to find for $100 or so new on Ebay and worth a try to see what you think. Although my take is the Shimano is a better crank at 1/2 the price of the Mega Expo. The mega Expo is harder to set up as well. (I am currently riding both) Also a Dura Ace 7800 front derailier works the best on either. We tried the FSA as well and went back to a new DA. I went to a compact because of a knee injury this winter. It really helped me get back to riding more quickly. The entire CSC team was using them on the Giro for the harder climbs running a 50/36 up front and a 12/27 in back. So they aren't just for gimps

Hope that helps some. Link is very good to see the actual ratios.

Couple of things I should have added. I have a bunch of really hard climbs around be..20 to 30% beasts. I am not a really strong cyclist and can generally sit down with a compact crank and a 27 in the back on anything up to 20%. I like and search out hills but after a few months the 27 seems to be too much for anything but the most extreme hills (25+) . Nice to have the 27 back there but if I am not using it because I want a better burn and can still keep up a high enough cadence 70/80 I have to wonder about just how useful a 27 is for any thing mortals normally ride up or "reasonable" hills. I have eneded up using parts of two cassettes running a 11 section up front (11/12/13/14/ 15..plus the back 5) and the bigger gears in back to get something more useful than the normal 12/25 or 12/27. My normal cadence of 95+/105 really needs just another gear or two to straighten out the chain line a bit and hiit a gear I can pedal. 36/12 is not enough, 50*12 or 50*13/14 are good. Not great but good on longer rides.
Great grears though for longer rides with lots of climbing.

Again just my experience trying to use the compacts all around and in my terrain.

Edited by Nob 2006-06-01 10:36 PM

Not a big fan of them .........

As triathletes we are not typically going to be doing brutally hilly races, so I don't see a need for the lower ratios. A 53/39 with an 11/23 will get you through 99% of the tri courses just fine. In fact, I just ordered an 11/21 because I miss not having the 18 tooth that is skipped on the 11/23.

I currently never use my 23 to begin with unless it is +10% grade, and then I'm standing up anyways.

There have been a lot of debates about them that you can find online. I personally just see no use for them on a road bike. :shrugs:

I have a compact on my tri bike and I love it.  I put it on last year in advance of the Great Floridian which boasts a killer climb @ mile 40 and 96 (two loops). After the race I debated on changing back to my 53/39 and did some experimenting with the different gearing. I ended up finding out that pushing my 50/11 was plently of gear around here and I even used it for Gulf Coast which is flat as a pancake with no real loss of speed. My advice is if you are a spinner (high cadence) then a compact would probably benefit you,  if you are a masher (low cadence, low gear) then you probably are not going to benefit as much. I bought the Nashbar compact because it was cheap and I figured if I didn't like it then I was only out $79.99, you can always go back to the big crank if you want.

I definitely agree with Brett on this one. I'm a spinner, and living in Maine and racing in New England and New York (Timberman, Mooseman, LP) I am surrounded by hills. With my standard crank I was doing way too much standing on climbs and it was burning me out on long rides. I bought the same crank as Brett and have been very happy with it.

same discussion happening in regards to placid course in the iron distance forum:
http://www.beginnertriathlete.com/discussion/forums/thread-view.asp...

i can see real serious cyclists caring about the skips with a larger cassette, but i don't see any reason not to go with a compact crank. generally it trades your top gear for one more lower gear.

unless you need to hold 90+ cadence at speeds excess of 40mph, the compact should be fine. i don't hit 40mph often and when i do i stop pedaling and tuck.
that doesn't mean everyone should run out and buy one, but if you are in the market for a new crankset anyway, i would go for it.

here is a calculator you can use to estimate how much a different gear combo would help:
http://www.sheldonbrown.com/gears/

the difference is the speed you can hold at that cadence. assuming you are using 700x23 tires, in order to maintain a 95 cadence in your lowest gear (39x23) you have to maintain 12.55mph. that means that if you hit a hill steep enough that you can't go 12.55mph without your hr spiking, your cadence will suffer.
alternatively, if you were to use a compact crank, your new lowest gear (36x23) would allow you to hold your 95 cadence at 11.6mph.
without the lower gears, you either have to mash at a lower cadence or work harder/go faster. some people are strong enough to stay seated and hold that speed on even the toughest hills. someday i might be one of them, but not yet.

It's all just gearing.  The compact is another way of getting easier gears to spin.  You could replace the 11/23 with a 12/25 or 27 instead.  The disadvantage to this is that you have more "skips" in the gearing (which is why Daremo is looking to move to an 11/21).  With the compact, you could keep the 11/23 and still have the advantage of easier climbing gears, though you give up some top end.  For long-distance triathlons in particular, that's probably a fair trade because you'll really appreciate the easier climbing gears and may be recovering on the downhills where you could take advantage of the top end gears anyway.

The slowtwitch article referenced by Nob above is a good summary.

Edited by JohnnyKay 2006-06-02 9:14 AM

Edited by amiine 2006-06-02 9:43 AM

good question. i think it stems from the fact that there are a lot of flat courses out there. also (and maybe more importantly), there are few companies that offered it as an option when people bought the bike. it's tough to run out and spend $170-$400 for an extra gear when you just spent all that $$$ on the bike in the first place.
i think it will become more common as bikes offer a compact as a no cost option.

There are actually several manufacturers that are putting compacts on entry level bikes. I wouldn't catogorize or confuse "weaker" or "inexperienced" cyclist with those who use compacts. Curiously enough when I ride the Gaps or do hill repeats on my road bike I have a 53/39 and 11-23 gear set up that I use with no problems, the caveat to that is that I don't run after those rides. I like having the compact for tri's as it gives me the ability to spin and save my legs for the run. I wish I had had the compact for IMLP in '04. Using a 53/39 and 12-25 I was toast by the climb into town on the second loop.

Good discussion folks. I haven't heard a good reason not to go with a compact on my road bike.  This bike will be used for training, long rides (centuiries and such), and long rides in the montains.  One thing I know for sure is that there were several times last season when my 39/25 just wasn't sufficient. I found myself grinding up moderate hills at <70rpm on several instances.  I NEVER found myself wishing I had a bigger gear to push...but I'm not the type to average 25mph+ over a 56 mile tri course ride anyway...at least not yet.  My tri bike will have Campy Chorus so I can toss on a 29 tooth rear if the course dictates.

It is all just gearing as some one mentioned above. If you coming off the bike split after spinning every where on the course at 100rpm you have no need for a compact. If you are riding every hill locally at 75/80 plus you have no need for a compact.

But as it was also mentioned when guys like all of CSC and Hamilton (and many more in the pro pelathon) are using compacts for specific rides they do have some use on the right terrain. To say other wise is like a roadie saying there is no reason for aero bars or tri specific frames. Nothing really new about the technology just more available now.

A Compact gives up 1.9 mph at 90 rpm at 30+mph seems like a fair trade for what you get back. That would be closer gearing and more gears to climb with. Same reason many high end bikes are now being delivered with compacts already on them.

Unless it is a dead flat course a 11/21 (closer gears and climbs better than a 11/23 w/sc) and 11/23 (closer gears and climbs better than a 12/27 and a higher top speed w/sc) might just be the ultimate casettes (either set up is lighter than "with/standard crank") for a tri bike using a compact crank.

Edited by Nob 2006-06-02 11:52 AM

Now Brett, I know that you can outride me like the wind, but really...killer climb in Florida???
Teasing, just teasing...come to PIttsburgh sometime!

I just see no need for them on a road bike. I do not want to sacrifice top end on downhills (and in sprints) by going smaller than a 53.

And yes, I spin out a 53/11 on decent downhills, and have in sprints as well (okay, I used to, can't say that I can now ).

I can climb everything local with the 39/23, including long climbs. And in my youth I would climb those same hills with a 42/21 (used to run a 53/42 back in the day).

I already maintain 100 - 110 cadence normally and using that with a 53/17 will put me at 25+ mph, which is perfect for flat TT's.

As I said, the majority of the races we do are not in the Alps (regarding the Giro and Tour comments). If for some reason I did want lower gearing, I'd (basically never) opt for an 11 - 25 as my choice. If I ever do the Monaco 70.3, I'll consider using that cassette.

Edited by Daremo 2006-06-02 11:35 AM

For those of you who doubt my Florida comment (ahem Suzanne....)





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