Subject: You can Ride faster with longer or shorter cranks!

[cnighbor1]

From: Zinn Cycles <sales@zinncycles.com>
To: Charles Nighbor
Sent: Tuesday, May 9, 2017 6:56 AM
Subject: You can Ride faster with longer or shorter cranks!


You can Ride faster with longer or shorter cranks! Improve your cycling with cranks that are proportional to your legs. It will give you more power and

Testimonials from actual customers riding proportional length cranks.

I’d say the proportional length cranks are the single biggest things that have changed my cycling ability. Was a bit of a leap of faith – and I was certainly very worried about stepping outside the cycling norm. But I couldn’t be happier with the result. Climbing is way way better with the proportional cranks. - Adrian in New Zealand

Well I have been using the 200mm cranks now for a few weeks and I love them…I saw immediate improvements in power on the flat and especially in climbing…On my old 180mm cranks I used the traditional 39 / 53 chain-ring combo but I have now changed to 44 / 56 and find that where I used to ride comfortably in the 39 x 15 on my easy days, I now feel like I am using the same effort (and the same cadence) in the 44 x 15…but obviously riding measurably faster

- Steve

read more>>

The major eye-opener for me was the longer cranks. We’re talking about 30mm difference(with 205’s), and I just wasn’t sure how much difference that could really make. Wow was I surprised! On the first ride I could feel the efficiency change and increase in natural leverage that I had which was absent before. I also have no problem spinning at cadences I was spinning at before. I do however notice that I get more power per stroke, which means I’m in slightly different gears when climbing or on flats than I used to me. I have been an athlete all my life certainly appreciate and enjoy when I’m suddenly a bit stronger and faster than I was on my old bike. - Matt
read more>>

The cranks, now there’s another game changer for me. I feel like I’m sitting on top of the bike and can really push down with more power – especially while climbing and on the flats in a big gear. - David

From article on Crank Length:

Here is a very strange fact: athletic humans come in an enormous range of sizes, bicycle frames vary nearly as much, bike riders adjust their seat heights based on their leg lengths, but yet bicycle crank arms are all nearly identical in length, with perhaps 99% of them ranging in length by just half a centimeter. That's less than a quarter of an inch. Why is that??

Dear Charles

Thank you for your interest in Zinn Cycles. Many people ask about crank length, and why we make cranks that are so different in length than what all the big brands offer. We offer the widest range of crank length of any bicycle company in the world. Read this newsletter to find out why we do it, what people think about it, and what the proper crank length is for you.

Thank you,

Zinn Cycles Team

Crank length should be proportional to your leg length for power and efficiency.

The bicycle industry has basically forced riders to commit to a tiny range of crank length designed around the most average sized person. While that is great for the majority of cyclists, there are a lot of people that are shorter or taller than average who can greatly benefit from proportionally shorter or longer crank lengths. It makes sense that a shorter rider should ride shorter cranks and a taller rider should ride longer cranks. Riding a bike with the proper crank length feels more natural because it allows your legs to move with the proper range of motion. This means you will get more power, more effiency, and less fatigue if you ride with a crank length that is proportional to your leg length. We offer cranks from 130mm for very short legs to 220mm for the tallest men in the world. Read more>>

ZIS-3 cranks all sizes in stock now! Click here to order

What is the best crank length for me?

Crank length is definitely dependent on the type of riding.

1. Measure your inseam length using the instructions on this page. Convert your inseam length into millimeters by multiplying by 25.4. Then take that number and multiply by .21 and .216. This will be your ideal range of crank length. Then adjust based on your type of riding and personal preference. Read below for recommendations for each type of riding. You may be surprised at the ideal crank length for you, but we feel confident you will love it!

Road, Cyclocross, and Commuting: We recommend in the 20.5-21.5% of inseam range. Bottom bracket should be higher by the crank length difference from standard lengths if racing. If not racing and are careful to not pedal in corners, up to 200mm can be used on a stock frame.
Mountain: I recommend in the 20-21% range, to allow greater ease in varying cadence with terrain changes while also offering good power for climbing and great stability (long distance between the feet for a more stable platform) for descending while standing. For technical riding, the bottom bracket height is very critical to have sufficient pedal clearance. 190mm is usually okay on most stock mountain bikes, except for specific models that have very low bottom bracket heights.
Time Trials/Triathlon: I recommend in the 18-19% range. This is because reduced aerodynamic drag is more important than power output, and having the knees come up higher allows the back to be lower with a more open hip angle and less hamstring and low back tension.

JK Mountain Cranks all sizes in stock now! Click here to order

How did we determine these proportions?

We started offering custom-length cranks in 2002. I had done lots of crank-length testing in the 1990s with a lot of riders for VeloNews; the cranks in the tests varied from 130mm to 220mm. Most riders felt most comfortable on cranks in the 21-21.6% of leg length. I then moved to Italy in 2000-2001 with my family, and I took a bike that had the cranks from the tests that had tested the best for me, namely 203mm. Since I had so many traditionalists shaking their heads at it, I might not have had the intestinal fortitude to leave cranks that much longer than the status quo if I had still been living in Boulder. But as I was stuck in Europe for more than a year with that bike, I just rode it as is. A lot. And I came to love those 203mm cranks so much that there was no way I ever wanted to go back to 175mm or 180mm on my return. So I started getting cranks machined for my self, and other customers who tried my bike loved them, too, so I began selling them and making that a part of the fully custom bike design.

Andel Road Cranks short and long cranks in stock! Click here to order

How does changing crank length affect gear ratios?

People riding cranks longer than they are used to will often find themselves riding in higher gear ratios, and the inverse is true with people using cranks shorter than they have been riding in the past. If you want to remain with the exact same gearing, you can adjust the chain-ring and cog sizes accordingly, but we recommend just getting used to it.

JK Road Cranks all sizes in stock! Click here to order

How to adjust the rest of the bike for a new crank length.

If putting them on an existing bike, the seat height needs to go down with a longer crank by the amount of the crank length difference from the prior crank. The handlebar can generally stay in the same place, in order to not increase hamstring tension.
If instead going to a shorter crank on an existing bike, the seat height needs to go up with a shorter crank by the amount of the crank length difference from the prior crank. The handlebar can generally stay in the same place, as the reduction in hamstring tension will usually allow the use of greater drop from saddle to handlebar. Ideally the seat would come forward for longer cranks and backward for shorter cranks to get your knee over the pedal spindle.

[Gblumenstock]

I have seen this analysis too and am intrigued as a taller rider on 175 mm cranks. What are real world experiences?


Sent from my iPhone using Tapatalk

[Lewis Moon]

This is a topic that makes the rounds about every year.

I'm a proponent...although at 6'4" I only ride 175s now due to the fact that it's SO hard to find, purchase and sell high quality XL cranks. And don't even dream of finding a crank based power meter.

There have been several "scientific" studies where they looked at the difference between the same rider pushing ~170s and then much longer cranks. Those overwhelmingly showed little or no difference. However, I have a big problem with those studies: they didn't give the riders time to adjust and learn how to swing big cranks. When I switched to 190s, it took a couple of months of concerted practice before I could comfortably spin them at 90 - 100 rpm at all times....and I believe that RPM is a key part of the power formula.
The lower seat position and longer crank combine to the point where, in a reasonably aero position, you're bouncing your knees off your chest. Time and practice helps, but gain a bit of pudge around the middle and suddenly your thighs and gut are trying to occupy the same space.
My anecdotal evidence is that they REALLY helped my climbing ability, with the caveat being that you absolutely have to learn to spin the things.

[cmg]

tried to ride 170 mm cranks for 3 seasons, gave up and went back to the 172s that I had been using forever. Felt like I was spinning too much on the 170s. I'm short, 5'6" with a 29" inseam. call me a skeptic.

[kingpin75s]

IMHO crank length as a proportion of leg length is a starting point at best.

There are other factors at play and in fact there is a recent thread on here about moving to smaller cranks (170mm I believe) where another member articulated muscle considerations as perhaps a greater factor then leg length. At a minimum that members theory at least starts to address some of the inconsistencies I have seen with strictly using leg length to determine optimal crank length as not all tall riders like them long and not all short like them short.

I prefer 170mm cranks but will run up to 175mm depending on the purpose of the bike and if I feel the need to lower my CG at all.

[kingpin75s]

Here is the thread I was referring to:

http://forums.thepaceline.net/showth...t=170mm+cranks

[bigreen505]

TL;DR they didn't work for me and I went the other direction as advised by a fitter. Long explanation below.

I dipped my toe in this pool a few years ago. I'm 5'10" on a good day (call it a short 5'10") with an 88.5 cm inseam. Zinn's formula puts me on a 191 crank, but 185 could be ok (21%). I spoke with him about it and was told at that length you really need a custom frame designed around the longer crank. I wanted a new frame anyway, and I had wanted one of his since I saw my first one as a teen.

You can't just go on ebay and buy a 191 cm crank, but you can find an occasional 185, so I looked and looked and the ones that came up were not cheap. Then I stumbled across a cheap enough 180. I don't remember what it was, probably Dura Ace, and decided that if a 180 was better than my current cranks I would have a serious talk with Zinn about 191s and probably a frame to hang them on.

As a quick bit of background, I'm mid-cadence rider. I like to keep things in 85-105ish range. All my road bikes have been 172.5 and mountain bikes 175. I was sans road bike for a while (got attacked by a dumptruck) and commuted on my mountain bike with a set of slicks. I noticed that I could spin the 175s on the mountain bike easily, though in hindsight I think this was more about hip angle (pretty open) than crank length. To Zinn's point, that frame was designed for longer cranks, so I could spin them properly.

So my new 180 cranks arrived. I put them on my bike, adjusted saddle position to compensate, and went out in hopes of being enlightened. I don't know what I was riding at the time, but I think it was a stock 56, which honestly doesn't fit me super well. Immediately I didn't love them. They felt fine, but I rode slower, and when I was in the drops my knees would hit my chest. It felt like maintaining my usual pace took more effort. I figured a new crank length meant new muscle groups being used so I left them on all summer. They got better, but never felt great. Any situation where spinning turns more to mashing (steep climbs, even sustained ones) they felt fine, but I always felt slow on flats. I can tell you that my heart rate never got in the upper zones and I could never achieve the speeds on long flats that I knew I was capable of.

How much of this was directly attributable to the crank versus perhaps needing some rest time at the end of a season I couldn't tell you. Someone posted an ad in the forum wanting to trade a 175 crank for a 180 and I jumped on it. After all, I have 175's on my mountain bike and I know I like those. The move to 175 felt immediately better but still not great. I continued to ride them, moving them to a couple different frames.

A few years ago I had some big injuries, and when I was able to return to the bike, I decided I needed a fit from someone who knew how to work around injuries, so I booked an appointment at Boulder Center for Sports Medicine (short version, I don't recommend them). They did the best they could adapting my bike to a multitude of injuries. Near the end of the appointment, the PT fitter (there are two that work together, a body person and a bike person) causally mentioned that I would be better off on a 170 crank and showed me on the spin scan what he was seeing.

I kept that in mind, but didn't want to spend the money on new cranks, and besides, 170 is really short, especially when Mr. Zinn says I need to be on a 191. Due to other injuries, surgeries, family stuff, time constraints (all the usual excuses), but mostly being tired of throwing money at saddles and not finding one that wasn't excruciating, I was off the bike for two years. When I did ride, I rode with a 172.5 triple.

A few weeks ago, someone here posted a PSA about a semi-custom DeSalvo on the bay. After messaging the owner, I grabbed it. It has a thinner diameter seat tube, and the triple FD wouldn't fit, but I had a Campy Record FD in a drawer that would work. Using that meant putting on the 175 crank, so I did. I immediately noticed the difference going to the longer crank. It was subtle, but the feel reminded me of the 180. So, back to the bay looking for a cheap 170 to try as an experiment.

Take this for what it's worth as I've only had one ride on the 170 (I'll have another in a couple hours). I adjusted my saddle to compensate, which kind of messed up the rest of the fit. I got used to it pretty quickly and it felt good. For the first time I could pedal in circles without having to concentrate on doing so. It just happened naturally, and as a result I had easier speed on the flats. I wouldn't say faster, but it took less effort. I've also noticed that I am more comfortable out of the saddle on a shorter crank. Time will tell whether I stay at 170 or go back to 172.

The conclusion I've come to is that we pedal with our muscles, not with our bones. The quads get the glory, but there are other important muscles involved in pedaling (hip flexors being a big one). The 21.6% number makes a lot of sense and has a good bit of data to back it up, but it only takes into account a single variable: leg length. Anyone who is a professional fitter or has been fit to a bike by a good fitter knows that you are adapting an entire system to work together, and crank length is just one piece in a much bigger puzzle. Yes, I get the whole lever length concept, but I don't totally buy into it.

Zinn is is building frames around the crank length, not putting a 200 mm crank on an off the shelf 54 cm frame. I have no way of knowing for sure, but I have to think that makes a difference, and I haven't been up for a $4,000 experiment. If I were closer to 6'5" than 5'6" I would absolutely take the gamble. That said, I don't think anyone here discussing this has tried running long (over 185 length) cranks on a frame specifically designed for them, which makes anything we write here circumstantial because, again, it is a total system that must be considered.

[Mark McM]

Back in the 1990s, a common idea in triathlon (in which the bike leg is a time trial) was that longer cranks gave more leverage for staying on top of a big gear, so long cranks were popular. There were even a few attempts at segmented cranks, which supposed acted like longer cranks on the downstroke and shorter cranks on the upstroke.

In the 2010s, the thinking is now the opposite, that shorter cranks are faster. The idea is that the shorter stroke allows the muscles to stay within their most effective range of motion, but perhaps more importantly, that opening up the hip angle allows for a lower, more aerodynamic upper body position.


The idea that cranks should be proportional to leg length has been floating around for a long time. But there has been little hard evidence supporting it. The controlled tests that have been performed haven't been able to show a strong correlation between leg length and preferred crank length - some riders show a preference to longer crank lengths, and some prefer proportionally shorter crank lengths. But there hasn't been any consistent correlation shown between performance (power, speed, endurance, etc.) and crank length.

[chiasticon]

never had a pro fit done. can they adjust crank length during the fit? because, for me, I can't see just grabbing a different crank and trying it out. all of the sudden my saddle's too high, too far forward, weight is balanced in a different spot, etc. but if you made those adjustments on the fit bike, I could see it working.

[jumphigher]

I borrowed a friend's road bike to ride a century last year - a similar bike to my own. The difference was his had 180mm cranks on it, and I felt a definite difference in leverage. I felt like I developed more power. This was before I even realized I was riding longer cranks.

Back home I thought I might switch to longer cranks on my own bike but never did. I didnt want to deal with the other changes that would be part of switching them out, like less clearance for turns. I'm definitely a believer though that longer cranks can produce more leverage/power. Oh and I'm about 5'10 1/2".

[oldguy00]

Originally Posted by chiasticon

never had a pro fit done. can they adjust crank length during the fit? because, for me, I can't see just grabbing a different crank and trying it out. all of the sudden my saddle's too high, too far forward, weight is balanced in a different spot, etc. but if you made those adjustments on the fit bike, I could see it working.

Yes, some fit bikes have cranks that are adjustable in length via a couple of allen bolts.