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What is the lead time for a custom bike or frame?
We do not give completion dates until the frame is ready to assemble or ship. ETAs are only estimates. We specialize in building the highest quality, fully custom bicycles and products, and when you get your bike, you will, no doubt, be impressed with the quality, workmanship, fit, and ride quality. Our frames are built to order, one at a time, in the order that deposits were received. The only thing we can guarantee, is that it will be worth the wait. Speed is not our goal (except when riding our bikes). Our number one goal is to build you the perfect bike. We want it to be perfect when you get it, even if it takes extra time. You are welcome to send us an email for updates, questions, component changes, or pay us a visit if you are in the area. Otherwise, we will be in contact with you to discuss component details and then to let you know when the bike is ready. We do NOT give exact ship dates until the frame is finished. At that point we can set an exact date for assembly and shipping. Assembly and shipping usually occur within one week of frame completion unless we are experiencing a back up in assemblies.
Typical lead times: To give you an idea, the typical lead times vary depending on what type of frame you are getting. A titanium or magnesium frame usually takes us around 6-8 weeks to have ready to ride. A steel frame normally takes about 4-8 months. Full Suspension Megabikes and Gigabikes, if not in stock, can take 4-8 months to complete as well. All other full suspension bikes can take anywhere from 6 months to 18 months.
Do I have to be tall to get a Zinn?
No. We build bikes for everyone. No other company in the world can truly outfit a wider range of rider sizes. We can make tiny bikes with 650c wheels, or gigantic bikes for 7 foot tall basketball players. We specialize in building bikes for those who may not be able to find a stock bike with the correct geometry. We have great options for short people, tall people, average sized people, and those with different proportions. We also do a lot of specially designed bikes for cyclists with hip, back, joint, or medical issues that require specific geometry.
What types of bikes does Zinn Cycles make?
All types. We make road bikes, full suspension mountain bikes, hardtail mountain bikes, cyclocross bikes, time trial bikes, triathlon bikes, track bikes, touring bikes, commuter bikes, hybrid bikes, bikes with internal geared hubs, singlespeed bikes, tandem bikes, and most other bikes you can think of. We do not do any bikes with more than 2 wheels. Also, no unicycles.
What materials do you use?
We make road, cross, touring, track, TT, Tri bikes out of titanium, magnesium, or steel. We do full suspension mountain bikes in aluminum or titanium. Hardtail mountain bikes in steel or titanium.
Do I have to come to Boulder to get fitted?
You are more than welcome to make an appointment to come to Boulder for a fitting, but you do NOT need to come to Boulder to get fitted. You can follow the instructions on this page to take your own measurements. Also, click this link to find out all of our fitting options if you decide to come to Boulder for a fitting.
Crank FAQs

Why do you make cranks over such a wide range of sizes?

Because people range so much in size!

When I first got into riding seriously, I got the longest cranks I could (180mm), because it made sense to me that with my 6’6” height I should have the biggest frame, widest handlebar, longest stem and longest crank available. That logic after all held true with clothing, beds, cars, etc., so why not with bikes?

Later, when I got my first really nice racing bike, a Masi equipped with 177.5mm cranks, I noticed that when I switched those cranks to 180mm, I immediately started dropping the guys I’d been climbing evenly with. The next year (1980), when I was first on US National Cycling Team and was having my bike fit checked, Edward Borysewicz (“Eddie B.”), the US head coach at the time, told me I needed considerably longer cranks yet. My quest for cranks longer than 180mm began then and never stopped until I could offer proportional-length cranks for tall (and short) people.

Little kids’ bikes have small wheels and short cranks as well as small frames, stems and handlebars because it works best that way. A small child is so inefficient as a rider that he or she cannot get the bike going if it is not close to optimally efficient for them in terms of sizing. Remember that, besides being new to balancing on a bike, a kid’s bike is much heavier relative to their weight than your is to your weight.

As the child grows, kids’ bikes available to them have increasingly longer cranks and larger wheels, as well as bigger frames, stems and handlebars.

Given that, doesn’t it seem a bit strange that when we become adults our bikes all have the same wheel size and essentially the same crank length? Are we all suddenly optimally suited to the same crank length and wheel size? Nobody questions that there needs to be a wide range of frame sizes, stem lengths, and handlebar widths to fit everybody. However, you can count on your riding buddies and bike shop salespeople questioning it if you want to ride a crank outside of the given 5mm range from 170-175mm.

Many of the standards in the bike industry are based on traditions that started pre-WWII (even pre-WWI) when people, at least in first-world countries, were smaller on average than they are now. And it also stands to reason that the last thing crank manufacturers, distributors, and bike shops want is the expense in tooling and inventory of as many crank sizes as there are bike frame sizes (or shoe sizes!).

Do you keep cranks in stock, or do I have to wait?

We try to keep our Zinntegrated Cranks in stock, but sometimes we sell them faster than we can make them, and we run out. If we don’t have the crank in stock, you will have to wait. How long depends on the stage of production at the time of your order. We will give an estimate of when the cranks will be ready, but the estimate is not a promised date. We can’t promise delivery dates of anything until it is actually in hand. There are many steps in the process that can cause unexpected delays, so predicting exact completion dates is impossible. what we can guarantee, is that the cranks you order will be of the highest quality in the world, and they will work great and look great on your bike. Zinn square taper cranks are made to order and take from 8-18 weeks to complete.

How do you determine crank length?

For most road riding, we recommend a length between 21% and 21.6% of a rider’s inseam. (Inseam is measured in bare feet from the ground up to the top of a level broomstick pulled up firmly into the crotch.) This is based on seven years of experience of selling custom cranks. A shorter length is often called for on a mountain bike and a cyclocross bike (see below). For most track events, a shorter crank is also advisable.

How will the proportional length cranks affect my cadence?

Riders who already ride lower cadences often find no cadence change when going from, say, 180mm to 205mm; they instead just report a straight increase in speed, and, usually, comfort as well. However, riders who tend to keep a cadence of 90RPM or higher will find that to be unsustainable with a longer crank.
As Jan Ullrich demonstrated when attempting to ride with Armstrong’s cadence, turning, longer, bigger, heavier legs around quickly is actually quite inefficient. With longer cranks moving those legs in a bigger circle, this effect is of course magnified. And the longer crank already provides the reduced peak force and hence reduced lactate buildup that high cadence is intended to do, so you gain efficiency as well as leverage even when pedaling at a lower cadence with the longer crank.

What cranks do you offer?

Currently we make road cranksets with external bearings and an integrated spindle in 185-220mm lengths in standard double, compact double, and triple configurations. They fit SRAM/TruVativ external-bearing bottom brackets.

In our traditional crank design that we’ve been offering since 2001 and that fits on a square-taper bottom bracket spindle, we make all lengths from 130mm to 250mm in road and mountain-bike styles. We offer almost any road spider configuration under the sun, including 110mm, 130mm, 135mm, 130/74mm, 135/74mm, and 110/74mm bolt circle diameter (BCD). Our mountain bike cranks come with a 5-arm 94/58mm BCD spider.

All Zinn cranks come with a bottom bracket included in the price. We of course also sell cranks in standard lengths from Shimano, SRAM, Campagnolo, FSA, and many others.

Do long cranks hurt cause knee pain?

Our customers without a history of pedaling-related knee pain using cranks in the 21-21.6% of inseam length range almost universally report no new knee pain with the longer cranks. We are choosing a length that is in keeping with the length that champion cyclists use relative to their leg length, so your knee and hip angles will be no tighter than theirs, and your percentage of extension and flexion of your muscles will also be no greater. So mechanically, there is no reason you’d have more knee pain.

Lower cadence is often associated with knee pain, but that is without changing crank length. If you pedal at a lower cadence but have more leverage, the peak load can be the same. If you pull a stuck nail out of a board with short claw hammer, you feel more strain in your arm than if you pull it out using the claw on the end of a long crowbar.

What about pedal clearance in corners?

Clearance depends on the crank, the frame, the pedals, the rider’s technique, and the type of event/ride. In the ideal situation, the frame is built to fit both the rider and the crank for the type of riding they do; then the bottom bracket height can be adjusted to provide the desired pedal clearance. At Zinn Cycles, we generally build the bottom bracket on a frame getting a 200mm crank 25mm (one inch) higher than the BB of a frame made for 175s.

However, the majority of our crank customers are not putting their Zinn cranks on frames we or another custom builder has made to fit them. The longest crank we recommend for somebody using a stock frame is 200mm, and only if they are not even thinking of racing criteriums. In a criterium, more power is worthless if you open a gap to the next rider in every corner that you have to close at great expenditure of energy because you had to restart pedaling later to avoid hitting your pedals on the road. I think it inadvisable to race criteriums on a stock bike with a standard (265mm) bottom-bracket height using any longer than a 175mm or 180mm crank.

We do have successful tall masters racers competing on our cranks up to 195mm who must use a stock frame due to sponsor constraints. But they adjust their riding style and choice of events accordingly.

For anybody who has a question about whether they’ll have enough pedaling clearance if they buy a crank from us, we recommend taping a styrofoam block the thickness of the length difference they are considering to the bottom of their pedals and notice if or when they touch it to the road.

What other changes do you make to a custom frame for the crank?

The reason stock big frames have super-shallow seat angles is not because the bike handles better with the rider’s weight cantilevered out over the rear wheel, causing them to pull wheelies on steep climbs, but because the cranks are not proportional in length the length of the rider’s legs. In order to get the knee over the pedal spindle with a crank that is disproportionately short for the rider, you have to have a shallow seat angle to move the saddle further back. If the cranks were proportional to the leg length, the seat angle could be standard. On a custom bike, it would only be based on the ratio of thigh length to lower leg length (longer thigh, shallower angle, shorter thigh, steeper seat angle).

The same holds true for tiny frames with super-steep seat angles, of course. Steep seat angles are used to get the knee over the pedal with a stock crank that is overly long for the rider, and to avoid the toe hitting the front tire. With a proportional-length crank, a small rider could also ride a normal seat angle without having the knee way behind the pedal, and pedal-overlap issues would be reduced as well, hence no need for a steeper seat angle to pull the crank away from front wheel as well. And then their bars would not need to be as high, because their knees would not be coming up so high hitting their chest and tugging on their hamstrings.

Should you use the same length for a road bike and a mountain bike or cyclocross bike?

It depends.

1. Unlike most road riding, which is more steady state with consistent cadence for long periods, thus making full use of the long crank, mountain biking in technical terrain and cyclocross racing involve frequent drastic changes in cadence. Spinning the cranks back up to speed is better accomplished with a shorter crank, while powering up long climbs is best accomplished with a longer one. So I try to strike a balance between those requirements and look for crank length more like 20-21 percent of inseam length for the mountain bike or ‘cross bike (as opposed to 21-21.6 percent of inseam for a road bike).

Of course, a the same crank length as the road bike works well on a mountain bike or ‘cross bike that is used for riding on dirt roads and relatively smooth trails.

2. I designed the bottom bracket height on the Megabike and Gigabike for a 200mm crank. On a custom hardtail or a custom full suspension bike, I can adjust this, but I highly recommend against using any longer than a 205mm on our stock-sized full-suspension 29ers for anyone who rides them in technical terrain, to avoid banging the pedals on rocks frequently.

3. A stock mass-produced mountain bike will probably not have a high enough bottom bracket to ride on technical trails with a crank any longer than 175mm or perhaps 180mm.

Are there any tests showing what length crank is best for a certain rider?

I’ve done a ton of testing of crank lengths, and the fact is that it may not be possible to properly do such a test that gives a blanket result of X length is best for Y rider. Others have tried as well. You can find many papers written on the subject. I have yet to see one that met the criteria of repeatability.

Briefly:

In the mid 1990s, I did many months of crank length testing at VeloNews that I published in the April 10, 1995 issue, with a followup test in the April 29, 1996 issue. I went so far as to build an ergometer that held the flywheel and apparatus for a Monark ergometer; it was essentially a Monark ergometer (which I was familiar with because that’s what we used at the Olympic Training Center when I was there as part of the National Cycling Team) that took standard parts. (Most ergometers have square seatposts, a seat tube that is not coming off at a standard angle from the center of the BB, a non-standard BB shell, a non-standard stem and bar and no way to mount these things.) Boone (a now defunct crank maker) made us cranks from 100mm to 220mm, and I made a super-long adjustable stem. We tested a range of riders from 4’11″ to 6’6″. All were highly trained cyclists.

Problem is, if you allow the rider to get used to a certain crank, it throws off the test, because you cannot guarantee the same level of conditioning health, etc. on each crank they test. You also can’t do them all at the same time, because the subjects become tired out when you do a step power test as we were doing. And the cadence must be matched to the crank length – you have to pick a cadence for a step test. So if you use 90RPM with a 170mm, then you scale the RPM proportionately up for shorter lengths and proportionately down for longer ones. But changes in cadence and amount of muscle extension/contraction and joint flexion/extension require adaptation for efficiency. But you can’t do that if you have a group of cyclists who are racing and training for events of interest to them. And no test that I’ve ever seen took good cyclists and paid them to maintain a consistent training level over an extended period. We certainly couldn’t do that at VeloNews. Without that, it will never give good results, and even with it, the time frame would become so long that environmental changes also might lead to distorted results.

Our results from those 1995 VeloNews tests without being able to control those things showed that:

All riders, regardless of size, produced more power longer as the crank length increased

All riders regardless of height could ride at low power outputs with a lower heart rate on shorter cranks.

I believe that you would see separation based on rider size if the riders were allowed to get accustomed to each crank length, but it was not possible. The length differences were so vast that their personal bikes could not be adapted to them and give them the same setup. And they all had certain racing goals, so they weren’t willing to ride for weeks on end and do events on some setup they’d been given in the lab. So they just came in and jumped on the ergometer and did tests every couple of days.

And then of course a proper test requires a double-blind procedure, so the test subject does not know what they are testing. That’s not possible with vastly differing crank lengths requiring huge changes in the set and handlebar position on their personal bike.

I did another test for VeloNews around 2002 using a PowerTap and timing riders on a one-mile climb varying from 10 percent to 17 percent. Three well-trained 6’5” riders used 180mm, 185mm, 190mm, and 200mm cranks and went up the climb as fast as they could, using the different cranks in random. Two of the riders had 180mm on their own bikes, and the third had 200mm, but none had the chance to get used to any of the other crank lengths besides the one they’d been using. Every rider was faster on each progressively longer crank, but the time differences were so small over this 8-minute climb, and combined with the inability to control environmental factors as you can in a lab, that I felt it was statistically insignificant, so I never published the results.

I’ve continued to do lots of straight climbing tests with tall riders with lots of crank lengths. This consistently shows an increase in speed with increasing crank length, but again, performed outside, there are too many other variables you can’t control — wind, temperature, barometric pressure, humidity, traffic, etc. to make it ever stand up to scrutiny. So I never was satisfied that I had a test that you could publish in a journal, so I never did.

So, it comes down to the individual to do the testing on themselves and to gather enough data that it smoothes out differences in environment, training, etc. that you can look at long-term trends. Some of our customers have done that and are convinced they are much faster with the longer cranks. There’s one testimonial on our site from a guy (Steve McGrath) who is careful about doing these tests as accurately as possible. With myself, I’ve done that for years on a certain 30-minute climb here to the point that I can say with certainty that on average I’m 2 minutes faster on a 205mm than on a 180mm on that climb. But I’ve done it for so many years that I can’t compare the early tests with the late tests, because I’m well over 50 now, and I started doing them when I was 21. And that 21-year-old speed is not coming back no matter what crank length I use or how much lighter my bike is now or how many more gears it has now or how much easier to shift it is now than in 1979.

Longer cranks = more power; even the arguments against longer cranks say that, but how do you address the issues of reduced ability to spin?

One benefit of spinning is spreading the load over the work cycle so that the peak power on each downstroke is reduced while maintaining a given power output. This is the entire reason behind the Lance Armstrong/Chris Carmichael high-cadence adaptation. You will notice, though, that Jan Ullrich, try as he might in the offseasons to develop the same kind of spin rate for the same reasons (a) could not do it (b) could not be efficient at it, (c) found it uncomfortable, and (d) for the above 3 reasons did not see the benefit of reduced heart rate and lower lactate concentrations at the same power output that Armstrong did. The reason cited was that it was inefficient to move his legs, which were so much, longer, bigger, and heavier than Armstrong’s, around and around at such a high cadence. He was more efficient at a lower cadence, and I have generally found that taller riders, especially heavily muscled ones, tend to be gear mashers (low-cadence riders).

Now, with longer cranks, you get the same benefit as you do with spinning, but at a lower cadence. For the same reason that it is harder to pull a stuck nail out with a claw hammer than it is with a crowbar, you can reduce the peak load on each downstroke at a given power output by increasing the leverage, which is what a longer crank does. And if cadence decreases proportionally with crank length, linear foot speed along the circle remains constant; there are some who cite this as critical, since it determines the speed of muscle contraction.

Furthermore, one would have to assume that the crank length that, say, a Lance Armstrong wins 7 Tours on is a pretty efficient length for him. And that the range of knee and hip angles (flexion and extension) he uses is optimal. Same with the range of extension and contraction of his individual leg muscle fibers and entire muscles themselves. So what makes us think that a long-legged rider working like a sewing machine with a short little crank (for them) or a short-legged rider working through a huge crank circle (for them) is going to be efficient? Should we tell them that’s the way it’s supposed to be simply because the range of available cranks is essentially not a range at all?

But if the crank length is in the same proportion to the taller or shorter rider’s leg length as Armstrong’s is to his legs, then all three of them will move through the same joint angles and muscle extension and contraction rates.

What about reduced ability to accelerate?

In events where acceleration is at a premium, probably a shorter crank is a benefit. That is my guess and seemingly my experience, but I’ve also not seen compelling data on it, for the same reasons cited above. Magnus Bäckstedt, a recently-retired (from the Garmin-Slipstream team) ProTour sprinter and former Paris-Roubaix winner, was happy on a 190mm crank I made for him. He and Garmin-Slipstream biomechanist Allen Lim determined that he was more efficient, he knew he was more comfortable, and, in combination with his Rotor rings, he felt that his jump (initial acceleration) was faster and felt more able to continue ramping up the speed. The problem was gearing. At the 75kph speeds of ProTour sprints, he could simply not turn the 190mm fast enough. He has to turn a 53 X 11 at 124RPM to go 75kph. To go 75kph at 110RPM, he would need a 59 X 11 gear, which is not only hard to find, it shifts terribly. And while a proportionately larger wheel and tire size would eliminate the problem and allow him to use the same gears as everyone else, we all know that no tire or rim manufacturer is clamoring to change standards for racing bikes. So he abandoned the idea. But it does help explain why taller riders lover 29er mountain bike wheels, or even 650B ones.

Won’t you produce the most power with the cranks you train on?

You will perform relatively better on a crank you’re accustomed to than on one you are not. All riders still produce more power on longer cranks. It’s just that, were they as accustomed to them as they were to the ones they usually use, one would expect to see yet more of an increase due to adaptation.

 Q:What do fast racers experience with a proportional crank?
Kieran Cox, a very fast 6’4″, 212-pound sprinter on both the road and track who is using 200mm Zinn cranks on his Zinn road and track bikes, has done considerable research into the effects of proportional-length cranks. His 200mm crank is 21.5% of his inseam length. He rides with a power meter and studies its output diligently. Here is what he has to say about it:
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 nowhere 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 any case, 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 with the 200mm crank vs. the 175mm crank. 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 leverage 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, i.e. 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.
If it’s true, it means Jim’s (Martin’s) study (and Andy (Coggin’s study)) 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 percentage power increase I’m observing during shorter anaerobic bursts against a high resistive/inertial load (such as 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 average
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

zinn crank power output graph kieran cox

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