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compact cranks
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Dennis 55
Mar 18, 04 10:10
Post #1 of 54 (1125 views)
compact cranks
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What are they and why use them ?
Tom Demerly
Mar 18, 04 10:28
Post #2 of 54 (1110 views)
Re: compact cranks [denewone]
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Compact cranks utilze a reduced diameter crank spider- the portion of the crank upon which the chainrings are bolted- to facilitate lower gears without resorting to a triple chainring and the attendant mechnical and weight limitations of a triple.
On a compact crank you can install a 50/34 combination or even a 46/36 combination of chainrings lowering your gear ratios substantially.
The primary use of compact cranks is cyclocross, and cyclocross frame are often times built specifically to facilitate lower gearing and the attendant reuced diamter chainrings.
Compact cranks appear an attractive alternative to standard cranks with a 130mm (Shimano) or 135 mm (Campagnolo) bolt circle for riders who are concerned about having low enough gears for climbing.
The use of compact cranks may come with its own set of mechanical limitations. Specifically, the distance between the bottom of the front derailleur cage and the top of the big chainring is specified by Shimano as 2mm. With a reduced diameter, 50 tooth ring this relationship may be difficult or impossible to acheive on some frames. Furthermore, the radius of the ring is tighter, and my be inappropriate for use on some frames with a permanently attached, braze-on front derailleur mount.
Additionally, there have been recent (unanswered) concerns about the compatibility of reduced diameter/tooth count chainrings with current 10 speed drive trains such as Shimano Dura-Ace and Campagnolo Record 10. It would appear there are no such concerns with 9 speed drivetrains.
My opinion on compact cranks is that they are a possible solution for a problem that only rarely exists. There are very, very few events around the world that a MOP'er would need to consider compact cranks on: St. Kitts, Lanzarote, St. Croix to name a few. Even at these events, the athlete may need to accept some drivetrain limitations such as poor quality front shifting and an increased incidence of dropped chains. Is it a reasonable trade-off if it is true? That is a decision for the individual athlete. I say it is not worth any potential risk.
I think the jury is still out on the real value of compact cranks, and when they do return their verdict it will be a luke-warm one.
Having said that, there is no denying that compact cranks may potentially add another tool to the bike fitters arsenal of tailoring a bike to a specific application- provided it operates reliably.
Dennis 55
Mar 18, 04 11:00
Post #3 of 54 (1063 views)
Re: compact cranks [Tom Demerly]
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Thanks . I can climb the Ozark Hills which get pretty steep and very long on my 650 wheels 55/42 and 12/25. Most of these climbs seem pretty easy with this gearing. I only run the 12/25 for really hilly courses.
Kenney
Mar 18, 04 11:19
Post #4 of 54 (1041 views)
Re: compact cranks [Tom Demerly]
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Tom do you know anything about there availability? tried my wrench,He was told that FSA is out of the alum,would be shipping more in May,but those would go to major dist. first ect... I wanted to get the alum(can not really afford the 349 for carbon)He told me He"might" be able to get them for me in mid-may. Have you heard anything? Thanks Kenney
ms6073
Mar 18, 04 11:55
Post #5 of 54 (1013 views)
Re: compact cranks [Kenney]
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I have no affiliation with this company but I think Wise Cycles (
http://www.wisecyclebuys.com/id222.htm
) has the FSA Energy Compact cranks in stock priced for $159.00! You can email them at
Sales@WiseCycleBuys.com
but last time I wanted to ask them a question it took a couple days to get a reply - faster to call (800) 362-9588!
Michael
________________________________________
Michael - Cogito Ergo Sum
Why is it after pushing one for English, I still cant understand the person on the other end?
stl_triness
Mar 18, 04 12:58
Post #6 of 54 (990 views)
Re: compact cranks [Tom Demerly]
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Tom,
Thanks for addressing this topic. I have valued the reviews that you have posted on your site and I was interested to see your take on the compact crank debate.
I have 55/42 and 12-23 on my 650 bike and have had no issues at all with the gearing. I live in MO where mostly flat rides are the rule but a few minor hills are a common exception. I have been fine in this setup. I have 53/39 on my 700 bike that I will use for longer rides. I am considering experimenting with a 50/34. Not so much to gain an increase of climbing gears, but for closer gear spacing. I am a reformed masher. I tend to naturally ride with an 80-85 cadence and I am working on making spinning around 95-100 second nature.
Is there any merit to support the idea that on flat terrain, being able to toggle between a greater spread of gears while holding a 90-100 cadence and maintaining close to (if not keeping) the same speed will delay fatigue and be more efficient for 1/2 to full IM conditions?
Thanks much for your thoughts.
Brian
cerveloguy
Mar 18, 04 13:41
Post #7 of 54 (957 views)
Re: compact cranks [denewone]
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Tyler Hamilton used them in last year's TDF including his break away stage win. I think Gerard also posted that a lot of other TDF guys did also. I also think most of the CSC team might have use them. Would have to ask Gerard.
Running an 11/23 with a 50/34 gives a closer gear ratio than a 12/25 with 53/39. Also more bottom end for climbing. I haven't tried mine out yet on the road, but I'm more or less already sold on them, at least for 700c wheels. Will also have to see how they work out on 650c. I'm a spinner, always 95-110 rpm and prefer to spin on hills, so these would be less beneficial for a 75 rpm masher. I'll post a report once the weather changes.
These where discussed in quite some detail on a previous thread a few months ago. It seems you either love them or hate them. Probably depends on your riding style. They have also caught on in Europe much earlier and seem to have more acceptance there than over here.
Lionel
Mar 18, 04 13:56
Post #8 of 54 (939 views)
Re: compact cranks [denewone]
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Ask yourself this : are you really using 53/11, 53/12 or 53/13 in a Tri ? For me the answer was not a whole lot. Actually my previous higher gear was 52/12 and I was using it maybe 1% of the time (700c bike). I have about 300 miles on my compact crank and LOVE it. My highest gear is 50/12 and this is plenty for me. My lowest gear is 34/23 which is useful for long climbs (Wildflower for instance). On a flat course you can go to 11-21, 50/11 is a higher gear that 52/12.
The other benefit that I see is that on rolling courses you stay on the big chainrig without killing yourself.
The other typical issue that people mentioned on compact cranks is that you need to drop 3/4 gears in the back when you shift from the 50 to the 34 in front to go to the next easiest gear. This is not a problem on a tri bike with bar end shifters. Might become a bigger issue on an STI setup.
Tom Demerly
Mar 18, 04 14:02
Post #9 of 54 (937 views)
Re: compact cranks [ms6073]
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I just spoke to Eric at FSA on the phone. He said they (at FSA) are "totally sold out" of compact cranks but that wholesale distributors may have some in stock. That means there are retailers who have them too. It is just a matter of shopping around.
By the way, we took J.C.'s recommendation and machined .010 off the front of some FSA 54 tooth lenticular chainrings and are giving them the test.
Also, Eric said "2 months" on the Visiontech/FSA one peice aerobars.
gerard
Mar 18, 04 14:46
Post #10 of 54 (913 views)
Re: compact cranks [cerveloguy]
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In Reply To:
Tyler Hamilton used them in last year's TDF including his break away stage win. I think Gerard also posted that a lot of other TDF guys did also. I also think most of the CSC team might have use them. Would have to ask Gerard.
______________________________________________________ Well, I guess according to Tom that means Tyler is worse than an MOP'er :-). I am not sure what the cut-off is between an MOP'er and a BOP'er, I think 5h40 for an Ironman bike split should be somewhere in that range and I was happy to have compact cranks at IMC , but I think it depends more on your riding style. If you like to spin and if you like to climb seated, they will come into play much more often than if you are a mashing rider. It all comes down to a sensible combo, and there are many ways to get to that. Somebody posted a combo of 55/42 and 12-23, that makes no sense to me. Why have a bigger chainring and then not use an 11t cog. It gives you the inferior shifting of the bigger ring without the bigger gear. Switching the rear to 11-21 and the front to 50/38 (which can actually be done on a 130mm crank)would make more sense. Anyway, many ways to go about it, but I think the compact crank is a good option for quite a few people. And no, i don't own stock in a compact crank company. Gerard
Gerard
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SimpleS
Mar 18, 04 17:05
Post #11 of 54 (859 views)
Re: compact cranks [gerard]
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Have a very basic question: I ride a P2k with Ultegra, is the BB Octalink?
BTW I love riding and more importantly racing my P2k. I recommended Cervelo to buddy who is in his late 50s and he ended buying a Dual through a local tri store. He took it out last weekend for the first time he had a huge smile on his face for the entire 100km, he just loved it. At the end of the ride he said he never gone faster on a bike nor had he ever been more comfortable on a bike!
__________________________________________________
Simple Simon
Where's the Fried Chicken??
Lionel
Mar 18, 04 17:16
Post #12 of 54 (851 views)
Re: compact cranks [SimpleS]
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FSA compact crank exist in both Octalink and Isis.
fredly
Mar 18, 04 21:40
Post #13 of 54 (809 views)
Re: compact cranks [Tom Demerly]
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Hi Tom,
One quibble: compact cranks are almost never used in cyclocross, except very recently in the US, and with the notable exception that Danielle Pontoni used them when he won his world championship (he ran Middleburn CNC mountain cranks with two rings mounted.)
Cyclocross bikes are definately not designed with compact chainrings in mind, at least traditionally.
The vast majority of pro 'cross riders run a 46 or 48x42 or 39, with a 12-25 or 11-28 rear cluster, with many riders using a single 42 or 44 front chainring.
All of the FSA sponsored European pros ran standard size cranks this season, as did Mark Gullickson and Todd Wells, Mark with a single 42 and Todd with a single 44.
FSA brought a compact cross crankset to market primarily as a result of input from Tim Rutledge, formerly of Redline, who saw Pontoni at Munich and thought he had a great idea, that idea being that using a 46/36 crank one could use a 12 or 11x23 cluster and get a gear range nearly identical to a traditional cross setup, which really isn't that small if you crunch the gear inch numbers.
MH
Formerly of FSA, 7th at cross nats this year
MH
Blah.
"...Popeye and Jesus both said 'I am what I am'.... but always bet on the guy with the bigger forearms..."
- Guillermo DelToro
Dennis 55
Mar 19, 04 5:27
Post #14 of 54 (774 views)
Re: compact cranks [gerard]
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This is not meant to be a smarta_ _ reply but how is useing a 55/42 12/23 on a 650 bike in hilly country different than using a 53/39 12/ 23 on a 700 bike? It's cheaper to change in back than change in front.I go from a 11/21 12/23 12/25. Now you might not agree with me but I see some very good riders riding these set-ups. It's just my opinion that unless I was in the mountains a compact crank would wear me out becouse of my riding style.
I'm also the dumba_ _ that said he was going to buy a carbon seatpost just because I liked the looks (P3). You made the comment that that was a decision you could not understand. Spending the money for looks. I didn't buy it, Good sells tactic : )
Indytrekracer
Mar 19, 04 5:48
Post #15 of 54 (760 views)
Re: compact cranks [fredly]
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Do not assume that some with a compact cranks is running a 50/34. I am pretty sure that Tyler was running a large chain ring that was much bigger than a 50. My guess is that Tyler was running a 53 or 54 big ring and a 34 or 36 small ring. He has personal mechanics and is probably a very skilled riders, so they could over come the issues such a large chain ring tooth differential causes. So while his bike may not have shifted as smoothly, having the small ring for the climbs and the big ring for the descents was worth it.
I have a FSA carbon crank set on order and plan to run a 52/36 chain ring option for most road race coursed. The big advantage to the compact cranks is that when I go to North Carolina to ride in the mountains, I can swap back to the 50/34 setup. I may even see if I can get a 52/34 setup to work.
Of course to take advantage of the chain ring options you need to be able to pull your cranks, swap chain rings and readjust derailleurs on your own, or have enough cash to have your shop work on your bike a lot.
gerard
Mar 19, 04 6:57
Post #16 of 54 (738 views)
Re: compact cranks [SimpleS]
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Ultegra has Octolink
Gerard
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gerard
Mar 19, 04 7:00
Post #17 of 54 (733 views)
Re: compact cranks [denewone]
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The difference between a 55/42 and a 53/39, aside from obviously slightly different gear ratios, is that the bigger 55t chainring hurts the shifting a bit. You'll get better shifting performance out of a "smaller big" ring.
Gerard
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Cullen Watkins
Mar 19, 04 7:01
Post #18 of 54 (729 views)
Re: compact cranks [Indytrekracer]
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There a lot of problems that you will encounter with a 20 tooth difference.I am not an expert but the shifting ramps won't line up,you would need a MTB. rear to take up slack in chain?? Just a thought.
Cullen
Slowman
Mar 19, 04 7:17
Post #19 of 54 (713 views)
Re: compact cranks [Tom Demerly]
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"There are very, very few events around the world that a MOP'er would need to consider compact cranks on"
i think if you raced out here in the west you'd find a lot more courses for which 34t chainrings make sense. and during training as well. just considering the ride several of us did in san diego a couple of days ago, a 34t would've made sense for a lot of people.
i think this sort of gearing is a pretty relevant option considering the need (IMHO) for a triathlete in particular to keep cadence high and effort levels even throughout the race. i can think of 7000 triathletes who, right off the bat, would benefit from a 34t chainring, namely everyone who enters any of wildflower's races.
as i said, tho, this is perhaps more of a west coast thing.
Dan Empfield
aka Slowman
Dennis 55
Mar 19, 04 7:56
Post #20 of 54 (690 views)
Re: compact cranks [gerard]
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Sorry one more question. My front shifts great, so there is very little difference between a 55/42 12/23 650 bike and a 53/39 12/23 700 bike ? I see that most/many road bikes come with a 53/39 12/23 . So why did you say my set up didn't make sense? I just tried to match what I saw and it seemed to work ? What do your 700 road bikes come with "standard" ?
It seems that many agree with a 700 53/39 12/23 but don't like the 650 55/42 12/23 . Why? I mean if it shifts ok up front. The gear ratios are sooo close.
gerard
Mar 19, 04 8:14
Post #21 of 54 (678 views)
Re: compact cranks [denewone]
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I didn't say it didn't make sense, it just makes little sense to ME. If it shifts OK, then no worries, but it usually gets harder and harder to get the front to shift crisply as the chainring size increases. That's all, and therefore my suggestion of a combo that offers the same gearing while using smaller rings.
Gerard
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amy
Mar 19, 04 8:26
Post #22 of 54 (666 views)
Re: compact cranks [gerard]
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Just to verify... I am considering a FSA energy Compact or perhaps the Ritchey compact crank for my '02 Soloist. With the braze on FD hanger, I shouldn't have a problem with the 2mm FD/big chainring clearance, right?
gerard
Mar 19, 04 8:29
Post #23 of 54 (659 views)
Re: compact cranks [amy]
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That depends, as the Soloist and our TT bikes have front derailleur hanger positions to accomodate larger chainrings (although I don't like them, they are a reality). So a P3 for example will accomodate a 58t chainring (for Bjorn :-), but it is sometimes a bit tricky to set up a compact crank (but it works fine for me). So just have your LBS check if they can get it to shift properly or not.
Gerard
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mr. mike
Mar 19, 04 8:47
Post #24 of 54 (645 views)
Re: compact cranks [Slowman]
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I don't think it's just a western thing. No doubt you have longer climbs, but we have some steep little mothers here in the southeast.
As alluded to above by someone though, the reason I have opted to try the 50/34 is not to make climbs easier, but to get tighter gear spacing. I was running a 53/39 with a 12-27. That allowed me to get up the hills, but I had big jumps on my big ring and felt like I was spending too much time x-chained on harder efforts (for me). My average speed in races has always been between 20 (hilly half IM) and 23.4 (rolling 16 mile bike leg).
At 90 rpms, here are my options on the big ring 15--25.5mph, 17--22.5mph, 19--20.2mph, 21--18.2 mph. I felt that didn't give me enough gearing options in the range where I spend an awful lot of my "racing time" without a pretty dramatic variance in cadence.
I'm running the 50-34 with a 12-25 10 speed, so my easiest gear (34-25) is barely easier than the 39-27 combo I had below. So, I'm trying the compacts more for the flat to rolling terrrain where I can stay on the big ring than for the climbs.
I've only done 3 outside rides, and I expect the benefit to come at racing speeds (low 20's) more than training speed (17-19), so ll let you know how it works out for me in a few months.
SuperDave
Mar 20, 04 17:25
Post #25 of 54 (594 views)
Re: compact cranks [gerard]
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Tyler didn't use a 50t or a 34t however.
-SD
http://feltbicycles.blogspot.com/
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