|   Do longer legs beget longer cranks? | SDizzle
Nov 13, 2003 12:42 PM | | Or, with the lever advantage of longer legs, is it the other way around? |
| IMO, absofreakinlootly | Sparty
Nov 13, 2003 12:57 PM | | In my case:
Inseam = 36"
Crank lengths of my (non-road) bikes:
Two @ 202mm
Two @ 195mm
A few others barely worth mentioning because their crank lengths are a measly 180mm or less.
Long legs?
Long cranks!
--Sparty |
| Whoa.. Sparty is truly committed. .my inseam is 38" & I'm .... | Padre
Nov 13, 2003 1:53 PM | | running 180mm on my ss and my geared HT. still got the 175mm on my long travel dh bike..... can't imagine bigger than 180mm...for me.... |
| a follow up question or two | SWISS
Nov 13, 2003 1:55 PM | | With such seemingly long crank lengths, do you have any problems with crank arm clearance? Or, are you running these cranks on frames with seriously high BB heights? I don't know if I've ever even seen 200mm crank arms! |
| Yah...those are damn long. | SDizzle
Nov 13, 2003 2:50 PM | | A post below mentioned $35 (!) Truvativ SS cranks, and I figured, for the price, I couldn't do better. I certainly don't need new cranks, but such expensive parts are worth collecting when they come 'round so cheap. Only problem is, they're only available in 170 mm lengths. Ah well, I spose, with a 34" (at least--it's been a while since I was fitted!) inseam, I'd best pass these up! |
| a follow up question or two | Sparty
Nov 13, 2003 4:31 PM | | My 202mm cranks are on:
* commuter '00 Gary Fisher HKEK frame, which I simply won't pedal through corners
* custom CoMotion gearie designed around long cranks
195mm cranks are on:
* custom Vulture SS designed around long cranks
* '01 GF Sugar 1
I smack the ground occasionally with my pedals while riding the Sugar, but it's surprising how little it happens after the first couple of days of riding it (I ride it infrequently). Anyway, in a relatively short time my brain seems to get used to subconsciously being aware of what will cause a pedal strike, then avoiding it.
I can't remember the various BB heights of these bikes, but personally I like a high BB. Contrary to popular belief, my high BB bikes corner just as well (better in a couple of cases) than my low BB bikes. It really depends on a lot of factors including general frame fit, head angle, trail, front center, chainstay length, etc. Can't just say a low BB gives a lower center of gravity and that's that.
--Sparty |
| cornering... | GMF
Nov 13, 2003 5:02 PM | | I bet you have a "normal" CG...
Given two frames with all else equal, where your bottom pedal rests determines where you rest, and therefore pretty much your CG...
However, i do think that bike geometry plays a big part in what length crank you run. I have one bike that doesn't like to be ridden with anything less than 180s (you can feel it climbing), and i have road bikes that are perfectly happy with 170s...
I obviously havn't branched out into the extremes, like some!
-Damon |
| In contrast.............. | Mike T.
Nov 13, 2003 3:28 PM | | .....I just read recently at velonews.com Tech a Q&A where tech editor Lennard Zinn (a big tall fella as I assume you're aware) where, he said, when he did power output tests with cranks of various lengths, he put out the most power on 135s! |
| ...and a short woman tested highest... | shiggy©®
Nov 13, 2003 4:19 PM | | ... very long cranks (195s?). He also found there was very little consistency. Pretty much every test subject was best with a difference length. |
| I dunno............ | Mike T.
Nov 13, 2003 6:27 PM | | .....about that one Shigg. I read the article years ago in VeloNews but, regretfully didn't keep it or committ it all to memory. Zinn referred to it a week or two ago at VN.com. |
| I do remember it | shiggy©®
Nov 13, 2003 7:49 PM | | I also remember that the test subjects did not have time to "learn" to spin the new crank sizes.
It took me 2-3 weeks to adjust to 185s from 180s and 2 months going to 190 from 185. I only need 2-3 miles to go back to the 175s on my road bike. |
| They tested geared bikes on an indoor trainer though, nm | rockdogger
Nov 14, 2003 9:03 AM | | |
| OoooOooo I got it! | Mike T.
Nov 13, 2003 6:32 PM | | Sparty I think I read somewhere that the subconscious choice of crank length was inversely proportional to the length of one's male errr "crank". It's TRUE I tell ya!
Mike (170mm cranks on my mtb) T. |
| If that's true... | Sparty
Nov 13, 2003 6:46 PM | | ...you should be running 120mm cranks. At least that was the rumor going around Barbie Camp last month every time your name came up (which was very, very frequently!)
Next year you need to attend so as to prove/disprove the speculation.
Besides, Justin could use the competition in the Ugly Dress & Skimpy Lingerie Contest.
--Short Crank Sparty |
| I thought it was shoe size that was related to "crank size" <eom | SoloWithOthers
Nov 13, 2003 3:51 PM | | Hehe.. |
| Crank Sizing has nothing to do with.... | rogueturtle
Nov 13, 2003 5:38 PM | | inseam actually. The important things to look at are your upper to lower leg ratio as well as positioning visa vie the crank center.
If you have a very long lower leg(knee to foot), a longer crank will put your knee to upper leg angle in a weaker position than someone with the opposite ratio given the same frame geometry and positioning visa vie the crank center.
Longer inseams however can compensate for longer lower leg ratios as well as frame geometry+positioning on the crank center which must be payed attention to as you run longer cranks. |
| re: Do longer legs beget longer cranks? | JerseyDevil
Nov 14, 2003 6:13 AM | | My inseam is 34 inches. For years I rode 180s on my geared and SS MTBs. Then I bought a 'cross bike and put 175s on it. I didn't notice any difference really. Then I got a fixie which came with 170s. After a couple rides on it, my pedal stroke improved, and somehow I developed smoother spin, higher cadence, and more power. Now I switch between all 3 sizes and just notice a slight leverage advantage with the 180s, but better spinability (is that a word?) on the 175s and 170s. I don't get any discomfort or pain switching between the lengths, and it only takes a few revolutions to adjust to each length.
I really don't know if 5 mm is a big deal at all. |
| My experience on this | rockdogger
Nov 14, 2003 8:58 AM | | My reading and experience on the subject lends me to beleive that flexibility and femur length have alot to do with it.
but here's my take. There's 2 issues we're dealing with. Leverage and spin.
Leverage first. The longer the crank arm the more leverage and the lower the gear the more leverage. Pretty simple. And for us SSer's, who don't have gears to help with this so we have to pick the best combo once.
According to sheldon Brown's (www.sheldonbrown.com)gain ration theory, a ss bike with 2:1 gearing with 175 cranks will "feel" like a 1:9 ratio with 180 cranks. So theoretically, you are getting the same speed etc of 2:1 gearing with the effort of 1:9.
The same is true from 170's to 175" etc etc. Sheldon has a great article on his site about this. (zinncycles.com is another great site for long legged persons- 210 cranks there)
This bring up the second issue, spin. It seams that most of the people arguing the length doesn't make any difference must have long legs. And this is were I think the biggest issue lies.
I'm 5'6" with a 30" inseam. I ride road, CX and SS and have a few bikes and ridden many with various size cranks.
With a 30 inseam I cannot spin 180 cranks. Sure I can ride a bike with them on but I lose more than I gain. I have huge flat spots in my spin from 7:00 to the 1:00 position. I can stay in the saddle longer on hills but I can't rev up more than 60 rpm. My top and my average speed are down, and I have no snap when I try to accelerate.
I ride 175's on my ss and I can spin pretty good (120+ rpm). But if I pedal with with just one foot, it's still difficult to spin a full revolution with out hitting a bad dead spot. When I ride the same bike fixed, I don't notice it at all because the momentum carries me through. I need/like the extra leverage of the 175's so I deal with it.
172.5's on the road give me a great spin and still a decent amount of leverage (gears help here as well).
170's or smaller spin like a humming bird but noticeably less leverage on hills.
So here's my opinion, on an SS with no gearing to help you out, pick the longest crank you can that allows you to spin comfortably.
Stretch well and warm up, then hit a trainer or ride on flat road. Pedal with one leg (alternate), use the longest crank you can till you start feeling a really bad (almost can't pedal through) dead spot on the up stroke. You've found the magic number.
If you've got longer legs, take advantage of them and get long cranks. It may take a while to get used to them but when you do, it will be worth it.
For us with shorter legs, you might find like I did that we might lose a little in the leverage dept, being able to spin those cranks easier keeps the speed up and is far more comfortable.
Don't listen to the masses, fit what works best for you. Try different sizes till you get it right. |
| |
