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Here is an interesting report and study on crank length: http://bicyclecranklength.blogspot.com/
My first clue that the bearings and cranks were going to be far better than my square taper setup was when I set out to put the pedals on the newly installed integrated cranks and ceramic bb. When I gave the cranks a gentle spin to move the crank into position, it spun several times, where I was expecting it to spin less than one full turn. After I put on my pedals and took my bike out for a ride, I was pleasantly surprised that I could feel the difference. I don’t feel any flex from the cranks when I stand up (I’m 225 lbs.). And because they spin more freely, more of my energy is going to power the drive train. I’m looking forward to putting a pair on my other bike.
-Greg
Dear Lennard,By the way I am back doing my indoor bike classes.  So first night back is a time trial – all out for 3 min, 12 min recovery then all out for 20 min.  I averaged 406 watts and 294 watts respectively. Bit disappointed in that as it was a bit off my PB which I thought I should beat due to 8 days killing myself in the Pyrenees.  Custom Cramerotti with 180 cranks.  So I ask to do it again 6 days later – this time on my Zinn.  Result 429 watts and 316 watts and a new PB’s. Now not a perfect comp as the first was on a Saturday morning while the second was last Thursday evening but all the same apparatus.  I felt about the same level of exhaustion in both.  I did not think the cranks and the wider bars and the bike fit would make that much difference.  Same bike coach did both – also a fairly tall guy.  He was more shocked than I was.  So there you have it, not very scientific, but for me very real to me none the less.  Looks like another set or two of cranks and wider bars are required for my Serotta, the Cramarreti and maybe the Guru time trial bike.  All the best and thanks for all you do to help us average sized guys take on the Smurfs!  Cheers
-Martin
Zinn 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.  When my bike was being shipped to NZ – I went out to a local climb and on my old bike – and broke my record for climbing that hill.  A couple of weeks later on my Zinn with 210mm cranks – I broke that record by a whopping 44seconds  – which over a 2km climb is massive.

And that was really before I’d had a chance to get fully accustomed to the proportional cranks.

The thing that surprised my about the cranks however was the difference it made when racing.  I belong to a club and race regularly – and the thing that was immediately noticeable was that the accelerations that used to catch me out – were no longer a problem.  It meant a whole lot of energy saved over a race – as I was no longer struggling after corners or slight rises, to get back onto the peleton.  This meant that within a few weeks of getting the long cranks – I was able to jump a couple of race grades!!  (break 3 to break)

This was a bit of a revelation – and turned a few heads – especially from the people who were sceptical about the whole idea of proportional length cranks.

I’ve had the bike for 18months now and my love affair with the long cranks hasn’t diminished.

I’ve been getting into Time Trialling in the last year – and the long cranks certainly mean I can get on top of a big gear and stay there.  I recently came 6th in the NZ club national champs with a very competitive time (averaging 41.5km/hr over a 25km course).  The cool thing was – I was the only one there on a road bike with clip on aero bars – everyone else in my grade was on TT bikes with all the bling.  So the long cranks effectiveness shone through again – and turned a few heads.  Podium next year…

Can’t recommend proportional length cranks enough – made a massive difference to me.

-Adrian

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…I have not needed bigger than the 21t where I frequently need to bail out to the 25t on steep pitches…as far as power is concerned, on the same hill where I used to struggle to hold 320 watts for 30 mins (3.2 watts/ kilo) I can now hold 410 (4.1 watts / kilo), this is probably the most significant measure of success here…As far as the extra height in the pedal stroke, I actually feel smoother with the long cranks, I practice yoga at least twice a week and I am sure this has an effect on allowing the range of motion of my hips especially to make the transition. The extra 20mm at the bottom of the stroke has taken a little time to adjust, essentially relearning my corner pedaling boundaries, but I have noticed a huge improvement in non-pedaling cornering due to the lower center of gravity. I suspect that this improvement outweighs the loss of pedaling in the tightest of corners…–Steve McGrath
Blog post from Jon Andersen about Zinn Custom Cranks
Hi Lennard,I’ve now had a few weeks to spend riding my new bike. Mostly as expected this has been on commutes (35 miles roundtrip), but I’ve done a few rides for fun as well. With 300 or so miles on the books, I feel I can safely give a fair review of the bike now. Additionally, since it’s Bike To Work Day here in San Diego, I figured today is a very appropriate day for me to pass along my thoughts.The bike fits better than I really knew a bike could fit someone my size. Despite the dropped stem, which I am still deciding on flipping up, I feel a comfort level that just feels “right”. I’m stretched out, but not too stretched out. The bike is comfortable, takes bumps and cracks in the road well, and despite the sturdy build and heavier components I was surprised how nice and quickly the bike can accelerate when I want it to.

The second major eye-opener for me was the longer cranks. I was never a skeptic of the issues I heard many people raise about longer cranks. That they hurt your knees, that you will hit your knees on your chest when you ride, it forces you to mash the pedals, etc. I just wasn’t sure how much I believed that the cranks would feel more natural for a taller rider like myself with longer legs, and that they really could be that much more efficient. 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’m certainly not one of your more performance minded customers as I don’t race or ride in clubs, but I have been an athlete all my life and played volleyball at a Division 1 school, so I certainly appreciate and enjoy when I’m suddenly a bit stronger and faster than I was on my old bike.

The bike works great for my purposes, I’ve got an Ortlieb pannier that I use to carry my stuff to work and back, and the weight hangs low enough that I barely even notice the sway in the back. All in all, it’s really been an eye opener and wonderful experience for me. I know I’ll have this bike for years and years, and I’m confident I made the right decision when I first contacted you.

Thanks again for what you and your guys do, it’s made a huge difference for me!

Cheers,

Matt

Hi Lennard,Wow.  What a big difference this bike makes.  I took the new Dolomite on its inaugural ride yesterday morning to Deep Cove on the North Shore. I went with a training buddy who usually leaves me way behind on the big hills and I was able to stay with him much longer on the climbs.  Afterwards, I actually thought he was dogging it on the ride, but he claims he put in a tough effort.One huge thing for me is that I did not get a sore lower back at all on this first ride.  On a good day on my old bike when my pelvis/lower back was perfectly aligned, I would usually get sore and stiff in my lower back within the first hour.  If all my subsequent rides are like this – it will be worth it just for this.

The ride position is much more upright than I’m used to, especially when riding on the hoods.  Riding in the drops was actually comfortable – imagine that.  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. Standing on the pedals feels very different: you go up much higher.  I had deja-vue  of being about 12 years old riding on my first oversized 10 speed.  I also noticed that my quads were getting much more tired and sore in the upper half.  Ahh, so this is what it’s like to use your entire quad muscle when riding 🙂

So  obviously I did manage to get the crank arm mounted so there was no play across the BB.  I was able to buy a 8mm hex key socket that I used with a 12″ driver I had to get a snug fit.  Whew!  Really wanted to get out on the new machine as soon as possible. Using a combination of your book (thanks again btw for throwing that in!), You Tube, and the component manuals I was able to assemble the head set (never had done that before) and the cranks; the rest of the bike assembly was pretty straight forward.

-David

Over the past week I’ve gotten into a rather intense discussion on a email list with Andy Coggan (and many others) about JC Martin’s study and various other studies on maximal power and crank length. The full discussion is on the “wattage list” here:

http://groups.google.com/group/wattage/browse_thread/thread/a74f988378ab5583/57df679d4b5f8305
The best is on the last couple of pages really.In short there are some conclusions I’ve come to based on my experience and the data.

1. JC Martin’s study is correct, but only pertaining to his test environment. As such his “one size fits all” conclusion is incorrect. The problem with his test environment (among many) is his purely inertial load is no where even close to reality. In real world cycling you experience inertial AND resistive loads varying continuously depending on a number of variables. As such his test to full power with a purely inertial load is suspect.
In anycase, my experience is that the maximum power is in fact unaffected by me riding 200mm crank arms versus 175mm cranks arms.

*however*

I have experienced a roughly 10% average power increase in hill climbing and during accelerations in general. Which completely disagrees with the study and makes everyone upset when I share that. This is not the 14.28% increase I would assume it to be due to the 14.28% increase in power going from a 175mm crank arm to a 200mm crank arm.

2. I have noticed I prefer a *higher* rpm in the hills and a *lower* rpm at full speed/power on the 200s than with the 175s. This has puzzled me for a long time. However a Phil Martin (who is CC’d on this email) has finally shed some light on this with the following attached two graphs which he extrapolated from McDaniel (2002) “Determinants of metabolic cost during submaximal cycling”

He goes on to say the following about graph one:
“The graph attached may help explain the relationship of crank length, sunmaximal VO2 and PO. I used data from McDaniel (2002) “Determinants of metabolic cost during submaximal cycling” and converted the metabolic cost (watts) to VO2 as the VO2-power relationship is generally well understood. I used the data from figure 4. showing the metabolic cost of unloaded cycling and delta efficiency vs pedal speed.
I have used the two extreme measurements cited in the study.
Notice that longer cranks do reduce the slope of the relationship (12.9 ml O2/watt vs 10.7 ml O2/watt, 195mm, 100rpm vs 145mm, 40rpm respectively). However, the oxygen cost of cycling with no load increases with increasing crank length and cadence (i.e. the y-intercept). In this example the O2 cost of 0W cycling is ~4 times greater with longer cranks. Hence the linear relationships are quite similar. The lines start to splay apart at either end of the power output spectrum at around 0W and 500W which are both unrealistic for submaximal steady state cycling performance.”

**************
He goes on to say the following about graph 2:

“This graph may be more pertinant to the discussion.

It uses the same McDaniel (2002) data except that I have extrapolated it for 200mm and 170mm cranks.
It compares two crank lengths (170mm vs 200mm) and two cadences (60rpm vs 120rpm) usually the lower and upper limits for most riders when cycling at a submaximal steady state effort.
There is a clear difference between cadences with the O2 cost of no load cycling about double for the higher cadence. However there is no difference between crank lengths as the slope of the lines are similar. Therefore 170mm cranks pedaled at a certain cadence over a range of 60-120rpm and power outputs has the same O2 cost as pedaling 200mm cranks over the same range. ”

This is the most revealing piece of information I’ve seen to date on the situation, and has led me to the following conclusion:

“I’m probably selecting the rpm that I feel the most efficient at for a given power output.
With a purely resistive load from a grade I’m more efficient at a
higher rpm on the 200s than the 175s, with a mostly resistive load
from wind ie 40mph, the opposite is true.
The chart would suggest I’m selecting the rpm efficiency based on the
O2 cost.  That’s the best description of the situation I’ve ever seen.
It it’s true it means Jim’s study (and Andy) are in error saying the
length does not really matter. Though it would seem they are correct
in saying the maximum power generated will always be similar. It also
means they are in error in suggesting gearing alone can make up for
crank arm length differences.
It also means my assumption of the power increase from mechanical
advantage is also in error, but my observation of average power
increase with higher or varying loads is correct. So the % increase
I’m observing at steady state is from improved efficiency, not mechanical (ergo the same max power).

The % increase I’m observing during shorter anaerobic bursts against a high resistive/inertial load

(such at the first 125m of a standing start sprint) is purely mechanical as I’m able to accelerate faster with the same strength.

So we could conclude the following:
Maximum power will remain unchanged. However, there will be an avg
power increase from more efficient use of strength and O2 with a
proportional crank arm. Short anerobic accelerations will be faster due to the mechanical advantage as well.

Cheers,
Kieran

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