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Shortening crank length...

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alexaqui

Jul 18, 12 11:45

Post #1 of 46 (2540 views)

Shortening crank length...	Quote \| Reply

Hi all. I've been reading a lot of posts about shortening crank length and the improvements people have experienced, particularly in a tri position. I've also read the plan2peak site, which seems to say crank length, within reason, doesn't really impact power by that much. Currently, I'm riding 175s on both my road and tri bike. As I am contemplating an upgrade of my components, I'm thinking about changing my crank solution. I currently ride a 175 crank with a 53/39 chainring setup. I'm thinking about switching to a 170 with a compact crank 36/50. I'm pretty tall (6'2") with a saddle height of 85.5. Given the cost of the crank, I'm a bit wary of spending $$$ on a solution I may dislike. Given that I like to spin a bit more than push tall gears, is there really any downside to switching? Thanks in advance.

matto

Jul 18, 12 11:52

Post #2 of 46 (2525 views)

Re: Shortening crank length... [alexaqui] [In reply to]	Quote \| Reply

I switched from 175 to 165 when adopting a more aggressive tri position and like it. It definitely makes the position less cramped.

The studies I've seen that showed no power was lost was sprinting power. It's generally assumed that this carries over to power in longer efforts but I don't know of any studies that explicitly showed this.

My advice: buy the cheapest craptastic cranks you can find used and experiment. Once you find the length you like, sell them and buy the crank you really want.

(This post was edited by matto on Jul 18, 12 11:53)

tigerpaws

Jul 18, 12 11:53

Post #3 of 46 (2522 views)

Re: Shortening crank length... [alexaqui] [In reply to]	Quote \| Reply

alexaqui wrote:

I'm pretty tall (6'2") with a saddle height of 85.5.

My gosh I'm 1" shorter and ride 9cm lower saddle.

On point I think you will love shorter cranks if you are having pinching/comfort issues on the tt bike. I ride 165's and love the snot out of 'em. With 175's on road and tt my wattage was ~ 35 less on tt. Went to 165's on tt and shored that up to less than 5 watts difference. Win.

Mind you I could ride 175's on a tt, but no way could I get as low as I wanted. I ride a tt bike to go fast and in order to ride the 175's I had to open up that hip angle so much by getting higher on the front end I may have well just stayed on a road bike.

(This post was edited by tigerpaws on Jul 18, 12 12:07)

alexaqui

Jul 18, 12 12:06

Post #4 of 46 (2500 views)

Re: Shortening crank length... [tigerpaws] [In reply to]	Quote \| Reply

tigerpaws wrote:

alexaqui wrote:

I'm pretty tall (6'2") with a saddle height of 85.5.

I'm seeing about a 20-25 watt drop in my TT position compared to my road bike. When I first started riding, I rode 170's and loved them (15+ years ago). Because I'm so tall, everyone convinced me I should be riding at least 175s. I like to spin, so I am very motivated on getting a compact crank. I'm thinking the 170s should help.

I'll see if I can find a cheap crank to try it and see what happens...

tigerpaws

Jul 18, 12 12:08

Post #5 of 46 (2488 views)

Re: Shortening crank length... [alexaqui] [In reply to]	Quote \| Reply

Dude my 2 cents is just go to 165. I did the 170 thing too and it was better, then 165 and I was in Heaven. If you *think* you might like shorter cranks just go for it I doubt you will be sorry.

(This post was edited by tigerpaws on Jul 18, 12 12:13)

Up2Early

Jul 27, 12 19:13

Post #6 of 46 (2335 views)

Re: Shortening crank length... [tigerpaws] [In reply to]	Quote \| Reply

I'm very interested in going with shorter cranks on my tri bike. I ride a 170cm 50/34 on my road bike. Current tri bike setup is 172.5mm 52/38. My hip angle at the top of the pedal stroke is very acute and a 165 crank arm should be MUCH more comfortable. When you made the change, did you get a sense of the pedals feeling "heavier" because of the increasing gain ratio? Did you find yourself preferring a larger sprocket on the back (i.e. the 17 "feels" better instead of the 16 you preferred in your old setup)?

Thanks.

Kilo Juliett

Jul 27, 12 23:50

Post #7 of 46 (2244 views)

Re: Shortening crank length... [alexaqui] [In reply to]	Quote \| Reply

If you have a shimano BB then buy a sora crankset. It's like 60 bucks or something and it is available in 165mm. That's what I did. I went from 175 to 165 and I love it. I couldn't tell the difference at first but when I went back to 175 it felt awful so I put the 165s back on and it was perfect. I'm thinking about going shorter. Rotor makes 155s plus they're quarq compatible.

There isn't really a downside to going shorter except for cost.

2013 Schedule
IM 70.3 Muncie | Ironman Lake Tahoe

tigerpaws

Jul 28, 12 4:21

Post #8 of 46 (2174 views)

Re: Shortening crank length... [Up2Early] [In reply to]	Quote \| Reply

Nope not a single issue it was all unicorns. You might find some setup issues if you make a big jump like I did from 175 to 165. I pushed my saddle back 1cm to keep my 3 o'clock position the same b/c I could definitely feel that aspect. I also used the commensurate saddle height increase to get all the TDC clearance I could.

A lot of guys won't try it due to ego and others due to old adages. The reality is you won't know until you try.

(This post was edited by tigerpaws on Jul 28, 12 4:29)

martinfjuul

Jul 28, 12 4:36

Post #9 of 46 (2163 views)

Re: Shortening crank length... [tigerpaws] [In reply to]	Quote \| Reply

Very much to the pint, it all depends on the individual. I tried going shorter and did not like it at all, felt like I lost speed on the bike and saw no gain on the run. But some people swear by it.

I say try it out and if it doesn't work go back to what you had before.

hoytag

Jul 28, 12 4:57

Post #10 of 46 (2153 views)

Re: Shortening crank length... [matto] [In reply to]	Quote \| Reply

matto wrote:

Agreed. I did this approach and am glad I did.

tigerpaws

Jul 28, 12 5:15

Post #11 of 46 (2144 views)

Re: Shortening crank length... [martinfjuul] [In reply to]	Quote \| Reply

I think that'd be cool if a top flite fitter out there had some data on body morphology that might suggest a success rate. I'm a bit giraffe build, longer legs and femurs and 6' and change barefoot. I have a friend who is about 5'5" and he hated short cranks. Pal in Indy is 6'3" and he went all the way to 160's and it's been gold for him. Wondering if the longer, lankier lends itself more to shorter cranks? Would be an interesting metric to read up on if any fitters read this...thanks!

rpeterson

Jul 28, 12 5:32

Post #12 of 46 (2124 views)

Re: Shortening crank length... [tigerpaws] [In reply to]	Quote \| Reply

I'm 5'7 and love 140s, so no help here.
______________________________________________
Trying out this twitter thing: https://twitter.com/rykpete

tigerpaws

Jul 28, 12 7:07

Post #13 of 46 (2083 views)

Re: Shortening crank length... [rpeterson] [In reply to]	Quote \| Reply

rpeterson wrote:

I'm 5'7 and love 140s, so no help here.

Did you go the Origin8/square taper route? I have a pal who's interested in coming down from 170's and he's quite a bit smaller, figured that might be a good size to try.

o2animal

Jul 28, 12 7:55

Post #14 of 46 (2051 views)

Re: Shortening crank length... [alexaqui] [In reply to]	Quote \| Reply

The majority of the difference in going to a smaller crank has to do with the type of muscle fibers you have built up. The type 1 muscle fiber are less power, but can work for a longer periods of time, whereas the type 2a produce more power, but can't work as long. Taller people tend to like the longer crank lengths due to carrying more weight on a daily basis and therefore building more 2a fibers. However, in your case being you like to spin you would most likely be more comfortable with a smaller crank length. The benefit to the smaller crank length is first, less pressure through the joints and therefore decrease chance of injury; second, more fluid pedaling and therefore more power throughout the revolution and not just on the down stroke; and third, increased use of the type 1 muscle fiber that are more endurance based. Overall, it is definitely something to look into and I really doubt you will be disappointed. Just make sure you give it time to get used to, because more than likely there will be an adjustment period.

tigerpaws

Jul 28, 12 8:09

Post #15 of 46 (2041 views)

Re: Shortening crank length... [o2animal] [In reply to]	Quote \| Reply

Please don't mistake my inquiry here as one of those ST pissing matches 'prove it to me with a scientific study!'. I'm genuinely interested in knowing how the shorter lever recruits slow vs fast twitch. Anything else I can read on this or where did you learn about it? I think in the back of my head I realized it *could* be something other than just reducing the pinch at TDC with shorter cranks. My body loved the short crank experiment. Thanks

rruff

Jul 28, 12 9:00

Post #16 of 46 (2018 views)

Re: Shortening crank length... [o2animal] [In reply to]	Quote \| Reply

less pressure through the joints and therefore decrease chance of injury

No, there will typically be slightly higher pressure applied at a slightly higher cadence, just less range of motion.

more fluid pedaling and therefore more power throughout the revolution and not just on the down stroke

Maybe.

increased use of the type 1 muscle fiber that are more endurance based

Since you are applying a higher force, this will not be the case.

The benefit of short cranks is reducing the range of motion, which specifically benefits blood flow and muscle recruitment in an aero position. If you do not have an issue with that now, then shorter cranks will likely not be an improvement.

The_Aesthete

Jul 28, 12 9:44

Post #17 of 46 (1990 views)

Re: Shortening crank length... [tigerpaws] [In reply to]	Quote \| Reply

I've wandered around the internet for hours reading various "SHORT CRANKS ARE DA' BOM" or "SHORT CRANKS WILL KILL YOU DEAD" posts, and as far as I can tell, it is entirely personal preference. I haven't been able to find any hard data at all.

That being said, my experience (just under 6'1", 146 lbs) is mixed. I just moved from 175mm 53/39 to 170 50/34. Now that I'm used to spinning a little bit more to sustain speed with a more efficient pedal stroke rather than mash, I've started to see some benefits, but it seems that it is terrain-specific. That is, I'm fairly sure that I'm faster on the flats and downhill, but feel like I'm a little bit slower on the hills. There is an obvious difference in the amount of force I feel like I'm applying � a good bit more, assuming the same gearing.

Has anyone else noticed a terrain-specific difference?

____________________________
"you gotta undo the doing to do the suffering of doing so you can do what you shouldn't think about doing while doing it."
� Mr. Tibbs channeling Mr. Fitzgerald

rpeterson

Jul 28, 12 9:53

Post #18 of 46 (1983 views)

Re: Shortening crank length... [The_Aesthete] [In reply to]	Quote \| Reply

I had to swap my 11-23 for an 11-28 when I went from 170s to 140s. I just wasn't comfortable mashing up hills at 60rpm anymore, I had to keep my cadence up or I was a lot more uncomfortable and a lot slower. I also went shorter so I could get a much lower and forward position, so that probably did a little damage to my climbing as well.
______________________________________________
Trying out this twitter thing: https://twitter.com/rykpete

knewbike

Jul 28, 12 9:59

Post #19 of 46 (1977 views)

Re: Shortening crank length... [alexaqui] [In reply to]	Quote \| Reply

I went from 172.5 straight to 155 and have loved it so far. Cadence is a bit faster, I have no power meter. I no longer feel cramped in aero. A little sad to give up my red crankset for it but in reality it makes no difference in performance. The only major change is I changed to a 50t big ring so I can stay in it for races. I used a origin8 triple and left off the small ring with a square taper BB. Kept the small at 39t. Cassette is 26-12. Scored the fastest bike split at a local tri last weekend, so it didn't hurt me none.

The_Aesthete

Jul 28, 12 10:11

Post #20 of 46 (1967 views)

Re: Shortening crank length... [rpeterson] [In reply to]	Quote \| Reply

rpeterson wrote:

Yes, the extra teeth on back were necessary for me with the change too. My first ride after changing my cranks was with two guys (including last year's Tour of the Catskills KOM winner and podium finisher) doing a hard training ride for Tour of the Catskills. We did about 125 miles with 9k vertical. I went with 50/34 up front and hadn't changed the cassette (12-25). Thankfully our support vehicle had a spare wheel with 12-28. If I didn't have those extra teeth I never would have made it up Devil's Kitchen (which we hit at mile 115 - http://app.strava.com/rides/14211196).

I'm curious about your suggestion that a "lower and forward position" hurts climbing. Is sitting further back on the saddle often suggested for a more efficient/stronger climbing position?

____________________________
"you gotta undo the doing to do the suffering of doing so you can do what you shouldn't think about doing while doing it."
� Mr. Tibbs channeling Mr. Fitzgerald

rpeterson

Jul 28, 12 10:32

Post #21 of 46 (1935 views)

Re: Shortening crank length... [The_Aesthete] [In reply to]	Quote \| Reply

It put way more weight on my hands and shoulders, so being on the basebar got really uncomfortable really fast and the discomfort hurt my climbing.
______________________________________________
Trying out this twitter thing: https://twitter.com/rykpete

manofthewoods

Jul 28, 12 10:57

Post #22 of 46 (1917 views)

Re: Shortening crank length... [alexaqui] [In reply to]	Quote \| Reply

this has been the year of short crank experimenting for me. I'm 5'11'' ~170 (heavier than I want). USAT AA guy.

Been on 175 forever (I'm 50). My carbon 175's were defective so I had to replace them anyway.

Went the cheapo route got Tiagra 165's, had some Octalink Ultgra's shortened to 154 and some 105's shortened to 149. for the last few months I've been using the 165's on my race bike and 154's on the training bike. I just didn't like the 149's. I live and like to ride hills/mountains and even the 154's are iffy.

I have power on the training bike and I don't notice much difference from last year. But more important...

Racing. My times on the same exact races (I've been doing a summer series of 3 races for a few years - Tri For Real near Sacramento) are also about the same. That said, I did a race (Lifetime fitness in MN) and hadn't done it since '09 - I had the split in my AG both years. What is significant is that the course is also the exact same distance and my time this year was over two minutes faster. That is huge; being 3 years older.

The reason I changed the cranks in the first place was to help my run and make my knees feel better. Neither has happend. My run is about the same and knees usually feel better, but have had some issues lately - perhaps unrelated to anything with my crank's (actually l think my track w/o's are the villian - maybe).

My bottom line. Glad I used cheapo cranks. So far I'll stick with my current set-up. Though I actually believe I'll try some cheapo 170's and If I can find 167.5's

Would I have been the same on 175's? I wonder. To many variables to know for sure.

Enjoy your journey

All the above said
I could break the course record - theoretically, Bishop Pickering - from the movie "Caddyshack"

alexaqui

Jul 28, 12 13:12

Post #23 of 46 (1865 views)

Re: Shortening crank length... [alexaqui] [In reply to]	Quote \| Reply

I'm amazed that so many of you have opted for pretty extreme sized cranks. 150's is short! Didn't the study find that there was little differences within a certain crank length range and then there were dropoffs on the top and low end? I believe the range was something like 160-180s or so.

In my case, I'm thinking 170s and a compact; a reduction from 175s and a standard 53/39. I'm more of a spinner so I'm hoping the compact crank and shorter crank arms will let me spin up hills more easily. Since I ride Campy, finding a "cheap" crank isn't as easy as for those who ride Shimano.

The_Aesthete

Jul 28, 12 13:35

Post #24 of 46 (1848 views)

Re: Shortening crank length... [alexaqui] [In reply to]	Quote \| Reply

alexaqui wrote:

Didn't the study find that there was little differences within a certain crank length range and then there were dropoffs on the top and low end? I believe the range was something like 160-180s or so.

What study?

I'm a similar situation � 175s and 53/39 and moved to compact 170s, but I haven't yet figured out how to spin up hills more easily. Maybe its just a matter of changing shifting habits.

____________________________
"you gotta undo the doing to do the suffering of doing so you can do what you shouldn't think about doing while doing it."
� Mr. Tibbs channeling Mr. Fitzgerald

rruff

Jul 28, 12 14:01

Post #25 of 46 (1835 views)

Re: Shortening crank length... [alexaqui] [In reply to]	Quote \| Reply

Jim Martin did the study and 145-195mm was the "good" range, with some drop off at 120 and 220mm.

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