Zinnsanely long crankarms

Discuss light weight issues concerning road bikes & parts.

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thasle
Posts: 77
Joined: Mon Feb 06, 2006 9:11 pm
Location: Oslo, Norway

by thasle

I am ordering Lightning Cranks for my 2010 Super Six BB30, but I am not sure in which length.
I currently have 180 mm arms on all my bikes, since that has been the longest available high quality option (DA7800 and XTR970).

After deciding for the Lightning Cranks I suddenly have the option of 182.5-185 or even longer. Will the leap from 180-185 be big, and more important will it effect the ground clearance significantly? With the 180 arms I have only hit the crankarms in the tarmac through extreme crit-corners where I did not coast. Nothing dramatic. If the Q-factor are lower on the new crank, that will probably decrease the problem as well?

Anyone know the Q of the Lightning Cranks? I am 200 cm (6'6"), with long femurs. (>50 cm), so according to Zinn I should have something like 200 mm crank arms.
Last edited by thasle on Sun Jan 17, 2010 10:10 pm, edited 1 time in total.

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STARNUT
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Location: Hilly, Hot, and Windy

by STARNUT

Zinn is a bit biased as he's 6'5" or something and has a business building long cranks. It's a solution without a problem. He says I should be on or 185s or 190s. I ride 170s on my TT bike and 172.5 on my road bike. I have very long legs and very long femurs (about 46.5 cm) and big feet. Plus, I still have no clue why he refuses to make foot size a part of his crank length calculation.

Longer crank arms will reduce your cornering clearance and cadence. I personally think you'd be fine with 175s. If you do that you can run the SISL which has a pretty small q-factor. There is not really a reason to go longer unless you're trying to prevent some kind of injury. I, however, can't think of an injury that longer cranks would help prevent.

Starnut
"Don't pedal harder, pedal faster!"
Q-FACTOR IS A RED HERRING

BB30.COM

by Weenie


thasle
Posts: 77
Joined: Mon Feb 06, 2006 9:11 pm
Location: Oslo, Norway

by thasle

The Lightning q-factor was 144 mm compared to 147 for DA7800.

I know that there is a lot of debate whether there is an effect of longer arms, but I believe that it improved both my climbing and TT going 175->180 a few years ago. I am not a spinner, but have no problems keeping high cadence on the 180 arms. I would love to use the SI SL, but I am not planning to go back to 175.

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G20
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Joined: Wed Jan 10, 2007 1:35 am
Location: Glasgow, Scotland

by G20

Thasle, you an anyone else thinking about changing to longer cranks should most definitely check out this thread on the Scottish Braveheart forum
http://www.braveheartcyclingfund.com/Community/topic.asp?TOPIC_ID=1279&whichpage=1&SearchTerms=200mm%2Ccranks%2Carthur
Arthur Doyle (largeheadsmallbrain) is an excellent fellow and a magnificent cyclist who consistently experiments with himself and his bikes in order to extract the most from them.
I find it fascinating that Pantani used 170mm cranks normally but 180mm cranks in the mountains...anyone else tried this?

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STARNUT
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Location: Hilly, Hot, and Windy

by STARNUT

fair enough.

RE: Pantani. He used 180mm in the mountains and never sat down. He was 130lbs and used body weight to climb. Watch old vids, he stands for minutes at a time.

Starnut
"Don't pedal harder, pedal faster!"
Q-FACTOR IS A RED HERRING

BB30.COM

shadwell
Posts: 575
Joined: Fri Oct 16, 2009 1:25 am
Location: Gold Coast Australia

by shadwell

I guess the answer to the question lies around whether or not you feel you existing crank length limits you in any way?
If yes then change, if no then stay at 180 if this is where you find good perfromance.

Alternately get some longer cranks in a budget format for trial purposes only. Then stump up for the lightening units...

I trialled 177.5 from 172.5mm and noticed a difference when cresting hills I felt behind the pedals, and my cadence dropped, which for the enduranc riding i was doing braought on fatigue earlier... Ran like this for a month and never really adapted so i returned to 172.5 and felft alot better.... (so yes 5mm is certainly detectab;e when riding).

All the best.

2 wheels
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Joined: Tue Mar 21, 2006 12:56 am

by 2 wheels

It not relly possible to feel if it limits you or not without trying a longer crank to compare with.
He could buy a cheaper crank in a longer length, but the problem is that most cheap cranks are not available above 175mm.

rabo16
Posts: 68
Joined: Sat Apr 07, 2007 1:57 am

by rabo16

At 195 cm I've tried 180's several times but am back on 175's.
For touring I would choose 170's.

nitropowered
Posts: 1146
Joined: Fri Jul 17, 2009 4:10 am

by nitropowered

Save yourself some money. Get the cranks from HS Cycle http://www.hscycle.com/

Tom makes the cranks for Zinn.

2 wheels
Posts: 4907
Joined: Tue Mar 21, 2006 12:56 am

by 2 wheels

Does High Sierra Cycle Center also make the new Zinn-tegrated crankset too or is this made elsewhere? http://zinncycles.pinnaclecart.com/inde ... g&parent=2
I can only see the old square taper Zinn crankset listed at High Sierra Cycle Center: http://www.hscycle.com/Pages/customcrankset.html

Zinn-tegrated:
Image

Square taper:
Image Image

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Tapeworm
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by Tapeworm

FWIW studies I have seen regarding crank length have shown it makes no difference to power production. So choose whatever you feel comfortable with. I generally aim shorter, especially on a TT bike, helps get the body lower.
"Physiology is all just propaganda and lies... all waiting to be disproven by the next study."
"I'm not a real doctor; But I am a real worm; I am an actual worm." - TMBG

thasle
Posts: 77
Joined: Mon Feb 06, 2006 9:11 pm
Location: Oslo, Norway

by thasle

Thanks! I am more confused now, that's good.

If any of the major alternatives would be available in BB30 180, I would go for that. But since the advice is going down, rather than up, in length maybe I should just get a set of SRAM Red 177,5? That would be half the price. Is the q-factor of the GXP and BB30 versions both 150 mm? I am using q-rings, so the quality of the Red chainrings is not a problem.

Another alternative is buying Wheels Manufacturing BB30 adapter and use the 7800 crakset, still not quite as fun as trying something new.
I have used cannondales threaded inserts on two bikes, that is not an option this time.

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otoman
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Location: Nashville

by otoman

Tapeworm wrote:FWIW studies I have seen regarding crank length have shown it makes no difference to power production. So choose whatever you feel comfortable with. I generally aim shorter, especially on a TT bike, helps get the body lower.


Your saddle position is lower with a longer crank, but the angle of the torso can be lower with shorter crankarms. Just a clarification for those reading.... :thumbup:

I am firmly in the camp of longer is better, to a point. I am 6'3" tall (190.5 cm) and have a 38" (97 cm) inseam - very long legs relative to upper body length. Also size 13 (47) shoes. I found that with 175 cranks, my average cadences were high - 98-105 for most every ride. Given that I don't have the VO2 max of a certain Texan, I have to rely more on leg strength - i.e. lower cadences - for my power. As soon as I switched to 180's, it felt oh so good. There was no adjustment period, no "getting used to it". I love the longer cranks. It also helped me acheive a lower saddle height which reduced my crazy saddle-to-bar drop (long legs) down to about 12 cm and allowed me to run a slightly longer stem, centering my weight over the bike better. That has resulted in better handling and descending. As an aside, my 'cross bike came stock with 172.5 cranks. I felt like I was running a three legged race - could get NO power up. I could spin like a mo-fo, but I felt limited in being able to lay down power in certain sections of the races.

I say longer to a point, because I have the subtle feeling that if I went any longer, I would start to really increase the dead spot at the top of the pedal stroke. As it is now, I can acheive a fluid spin in the low 90's cadence average. I only occaisionally do single leg drills but ride the rollers a lot to keep things smooth. I agree with the above poster's though, gotta try them to know for sure.
Age and treachery shall overcome youth and skill

wilmar13
Posts: 348
Joined: Wed Aug 10, 2005 12:50 am
Location: Union of Socialist Americans

by wilmar13

For road bike, I am going to be the contrarian and say 180 or longer.

Longer cranks = lower gearing, but if your legs are long enough you can handle the extra foot speed and maintain a normal cadence.

I started out riding 172.5's and had a old masters guy tell me I needed 180's because I had long femurs, I scraped together what I could as a poor college student running some leftover Sugino/XT with generic ring mismatch (literally two different left and right crank arms), and I sure did ride faster, even with that hack setup. Placebo or not it doesn't really matter.

I tried 177.5's for a while several years later, but went back to 180's and they just feel so much better. I sprint seated at 140rpm and have no problem with 180's, so don't let the whole "spin short arms/grind long arms" hogwash mess with your head.

I have been riding a track bike on rollers for several weeks (with 170's) and today I headed out on the road bike. At first the longer stroke made it feel like I was riding a tractor but after literally only 5 mintues I was back to spinning at 100rpm and it felt great.

I am 6'3.5" (192cm) with a 36.5" (93cm) inseam and size 13 (48) feet if that matters. Really it comes down to what you feel comfortable on, but all else equal at your size, I know I would be trying the 185's for everything but TTing. The downside is if they don't work well, you have a limited market to sell them in. But whatever you do only go shorter if it is for position (TT), if you are already comfortable on 180's. :thumbup:

by Weenie


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by User Name

STARNUT wrote:Zinn is a bit biased as he's 6'5" or something and has a business building long cranks. It's a solution without a problem. He says I should be on or 185s or 190s.

Exactly! That "21.6% of inseam" thing is totally crazy, and based on nothing more that his opinion, and that of the other tall, biased guy on the net, Kirby Palm. According to this "formula", I'd be 193mm cranks, and I'm 'only' 182cm! 193mm cranks: unblievable. Even his 'conservative' forumula of 21% of inseam would still have me on 188mm cranks.

This is just about the only topic these days that still gets me riled enough to get on forums to post anything longer than one sentence. :)

----------------

Zinn, and the other two main advocates on the net of longer cranks, are all tall guys who were frustrated in the old days at the lack of availability of cranks longer than 175mm. Zinn, Kirby Palm, and Andrew Bradley (the "thanks to my cranks" guy) all tell the same story about "being tall, and I always felt somewhat restricted on 175mm cranks, then, one day, I got some 180s, and I immediately felt stronger and less restricted. I proceded to try longer cranks and felt even better", etc. This gets me a bit 'cranky', especially the Kirby Palm stuff, which is just rubbish -- at least Andrew Bradley is more flexible in his views.

The bottom line is, no top pro in the world, over about 5ft8", uses cranks which are relatively that long (and the short guys that do use relatively long cranks only do so because they grew up on tiny bikes that probably incorrectly came with 170mm or 172.5mm cranks), yet they’re still the fastest riders on the planet. Pantani apparently used 180s for some mountain stages, but, as the other guy said (and thank god someone else remembers this), he spent heaps of time climbing off the saddle. Ullrich used 177.5s, but he's 183cm, so I doubt that would even exceed 20% of his inseam; same with Boonen (6'4", and 177.5s), Backstedt (same as Boonen), and, of course, Indurain, who's 6ft2", and used 180s and 190s for some time trails. Being 6'2", I'd be surprised if those cranks exceeded 21.6% of Indurain's inside leg; even if it did, he's one of the most powerful riders we've ever seen, so maybe he shouldn't even come into the discussion :)

I have a theory that short guys tend to be weaker flat-road riders, not because they're less powerful, but because they use 170mm or 172.5mm cranks (just because that's what they've always used), when they should be on shorter cranks. I'm 182cm and use 172.5s, and I dunno how the hell the 5'4" guys i know can use the same length!!

I'm 182cm, with an 89.5cm inseam and size 43 feet.. I got right into the long crank thing about 8 years ago, after accidentally putting myself in a 'blind, long crank test'. At the time, I was doing all my riding on a couple of crappy commuter bikes with 170mm cranks, then, one sunny day, I dusted off one of my old racing bikes on which to do my commute. When I got to my regular short, but steep-ish hills, I got off the saddle, and flew up these hills noticeably quicker than normal. I couldn't work out why I was climbing much better. I thought I might've eaten something different. :) I got off the bike to check the teeth numbers, to make sure I was using the same gears; I was. As I was flying up the next hill, I realized that the bike I was on had 175mm cranks! Well, that was it! I thought I was onto a secret weapon.

So, I put cheap 175s on as many of my bikes as I could afford. I went well for about a month, then I naturally started thiking: "what if I went longer?" The next thing I knew I'd bought two sets of 180mm Dura-Ace cranks for my two best bikes! At first, I thought they were unbelievable, especially for off-the-saddle efforts on hills, at low/moderate revs. After about 7 or 8 months, I started to notice how low and not "over the pedals" I felt. After a few tough rides one week, which seemed to strain my hammies a bit more than usual, I found myself lowering the saddle bit by bit. It eventually felt that I was riding with my knees in my chin, but I persisted with the 180s for another 4 or 5 months. Feeling very low on the bike, I was always getting off the saddle at the frustration of not being able to really stomp the pedal when seated.

Eventually, after experiencing some moderate medial knee pain in both legs for a couple of weeks, I hopped on one of my other bikes which had 175mm cranks, just with the thought of alleviating some of the discomfort. Well, the first time I got back on the 175s, I rode like Superman! I couldn’t believe how powerful I felt, because I was much higher over the pedals and could pound the crap out of them. After feeling so great with the 175s, I switched between these and the 180s for a couple of months. I felt better (when seated) on the 175s, so I abandoned my ~12-month 180mm experiment.

I wanted some new 10sp DA cranks, and my local shop had a good deal on some 172.5s, so I bought them. I felt even better on the 172.5s than I did on the 175s, so, that was it – the 180s were gone! I sold both of my pairs of 180s, and started looking for shorter cranks for all my bikes. I found that 172.5s were more readily available than 170s, so I settled on 172.5s. I’ve since been very happy on 172.5s, and probably would’ve been just as satisfied with 170s.

So, in my opinion, the main impact that longer cranks have is on position, rather than revs, which is what most people talk about (although, pure sprinters have more concern about spin and revs). Basically, longer cranks have more leverage, but having to lower the saddle for the extra reach, coupled with the extra length, the rider is in a relatively much lower position through most of the down-stroke. In other words, long cranks may provide more torque, but being in a lower/weaker position, they’re harder to push. When I went from 180s to 172.5s, I was approximately 15mm higher over the pedal at the top of the stroke (with the 7.5mm length difference, plus rasing the saddle approx the same amount for the shorter reach at the bottom of the stroke)! That’s a lot!

The issue gets a little more complicated, with muscle torque and force, which Arnie Baker explains in this article:

http://www.arniebakercycling.com/pubs/F ... Length.pdf

The only time I missed the long cranks was when ‘levering’ off the saddle over short hills, so I now have 177.5s on one bike, with which I’m still experimenting. I like the 177.5s for off-the-saddle efforts, but after about 45mins on grinding along on flat roads, the old problems come back: feeling low and not being able to “get on top of” the pedals. I rarely use the 177.5s; only for some hilly rides, and some early-season crits, when I suspect my fitness might be down a bit, coz I know I can get off the saddle to lever my way out of trouble when coming out of slow corners or bridging gaps.

One of the traps of longer cranks is that they are addicitive, because you feel the extra leverage (especially off the saddle), and will try everything to make them work. :)

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