Iroman Guru's Quest for the Perfect Tri Bike

Coach Simon on his bike during an Ironman race
December 21, 2021

Simon Butterworth


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A New Bike (spoiler, another Dimond)

I guess deep down in my subconscious I am feeling optimistic about a future with Covid at least under control enough to allow life to go on close to normal.  Otherwise, I would not be buying a new triathlon bike.  I must also be optimistic that I have a few more good years of racing in me despite knees that are getting more wobbly and other body parts are going the way that they do when rolling past 75 years of use.  

I have been having a conversation with a somewhat younger friend who is also thinking of a new bike like mine.  She is reaching an age where comfort is becoming more important and shares some other similar concerns.  It occurred to me that our discussions and my reasoning and thinking about a bike would be of interest to others so I am starting a blog on how things are progressing and will update it until I have the new bike and take it for a spin.  This article will kick off the process as I cover the 'why a new bike now' and some of the considerations behind this.  

For full disclosure, I should say that I am certainly not in the ranks of the top experts on choosing a bicycle but hopefully this will help you find the information you need to make your own decisions.  I have quite a few links to other articles on the topic that should help too. The best single place to go is Slowtwitch, especially their section on bike fitting.   All the links are repeated at the end of the article.  

Triathlon Bikes and Time Trial Bikes

A triathlon bike follows the rules of triathlon and not UCI, the organization that set the rules for most bike racing including the Tour de France.  The big difference in these rules is that UCI tends to limit innovation more, a beam bike like the Dimond is not UCI compliant.  UCI also limits the chord of the aero tubing (that’s the distance from the front to back edge).  However, clever engineers have found ways around the limitations to achieve similar drag numbers.  Time Trial bikes tend to ignore the need to carry stuff.  A TT is usually much shorter than a triathlon and there is no run to worry about afterward.  Perhaps the most important difference is a TT bike geometry is restricted by UCI rules.  This has a significant impact on bike fit as there is a limit to the seat post angle. 

So if you want to race under both UCI and Triathlon rules a Dimond is not for you and you will have to stick with bikes following UCI rules. Not a terrible situation but not the best, IMO, for long-course Triathlon. 

I went looking for some history of bike design and found that TdT has been limiting innovation for a long time.  Here is a quote from the founder of the TdF.  Henri Desgrange once commented, “Isn’t it better to triumph by the strength of your muscles than by the artifice of a derailleur?” He sure thought so: he banned the use of the derailleur in the Tour de France until 1937 - an entire generation after the derailleur had been invented.

Where to Buy and the Process

Choosing which bike to buy is no easy proposition these days.  To start there is a decision to be made as to where to buy your bike.   That decision should be based on how much you already know about bicycles and how much time you can spend researching the details.  If time and knowledge are limited the best thing to do is buy from a local bike shop with access to a bike fitter who has extensive experience fitting triathletes.  The other limited knowledge option is to buy from a custom builder.  It is the most expensive approach and in my humble opinion, not necessary for most people these days.  You can also buy direct from the manufacturer.  This has become increasingly popular over the last few years.  Two of the bikes you will see often in races these days, Quintana Roo and Canyon, are both sold direct.  The bike I am buying is also sold direct.  

Buying direct has gotten easier in the last few years as bike manufacturers have developed tools to help you make the right frame choice.  Some give you a trial period and you can return the bike if it does not fit or suit you.  In some cases, component selection is limited to one brand.  In the case of Dimond, choices are more like that of a custom builder.  In other words, extensive. Dimond has their own brand, Red Crown, selling aero wheels and the cockpit which will be less expensive but you are not limited to their components.   You need to know what you are doing to get the best bike for you buying direct.  

One tip which I think is critical when buying direct:  do not have the bike company cut your steering tube unless you are 101% sure that you will never need to raise your base bar.

A Bike Fit (don’t leave home - or buy -without one)

There is one thing that you should not go cheap on, and that is a professional bike fit (the cost runs over $300 and can be much more if you go to a wind tunnel).  Even if you think you know all the dimensions of a bike that would fit you perfectly, you should get, or have a recent, bike fit.  Doctors, at least smart ones, don’t self-diagnose, neither should cyclists.  A good bike fitter will not only give you the dimensions of a frame but include all the information you need to pick one best suited to you.  With their help, you should be able to identify a complete bike that fits the dimensions closest to you.   Here is a good article on the topic from Slowtwitch

All bike shops will offer some type of bike fitting and it often is included in the cost of the bike, or should be.  However, make sure that the bike fitter has the knowledge to put you on the right bike with the right cockpit, gears, saddle - essentially - everything.  Obviously, a bike fitter associated with a bike shop would prefer you buy your bike from them, but the best do not insist on that.  They will of course give you no discounts for the fit in that case.  Just be sure to maintain a good relationship with your local shop, you will always need them at some time. 

perfect bike for triathlon

Some Background (that will help explain why my choices)

As some reading this know, I have an engineering degree.  Two, actually. An Associate Degree in Aero Engineering and a BS in Industrial Engineering.  The latter goes a long way to explain how I got quickly into the IT world, another story.  The aero stuff goes a long way in explaining why the bike part of triathlon is my favorite.  There is a lot here about my bike decisions over the years. You could jump down to 'My Choices' for the short story, but do come back to this section as it explains 'the why' of those choices.

Friends used to think, I know because they said so, that I was/am anal about making things as aero as possible. Perhaps, but look at the latest so-called superbikes, all wires are internal, fluids are internal (in some cases), some sort of aero storage is provided for food and emergency supplies.  

triathlete cyclist

When I got my first tri bike, one of the original Quintana Roo designs created by Dan Empfield (Slowman the Slowtwitch Editor), I was immediately concerned with all the wires hanging off the bike, the round tubes, and the lack of a place to store stuff that I needed as I rode along the way.  I got creative, the bag hanging off the support for the water bottle cage was my first effort at packing stuff in a semi-aero fashion (later I tucked the wires up under the stem, so they were not dangling in the breeze).  

To race an IM I got concerned about comfort.  The QR was a stiff frame, the choice of tires back then, 19mm at 160psi+, did not help matters.  Softride had just come out with their new model in 2000.  The beam added comfort and the lack of seat stays, sort of, checked off my aero thing.  Wires were still external, and I could not do much about that other than tape them together near the stem.  You can’t see it well but there is a spare tubular tire tucked down the beam with a bit of it sticking out behind me.  There are some other tools strapped in behind the seat.  The swollen elbow is my 9/11 elbow, brought on from leaning on it in my office chair most of the day watching a television off to my left.  

There was also a benefit to the Softride that never got much traction but is being revived by Zipp and other wheel manufacturers.  Reducing unsprung weight in a car, especially race cars, is a performance gain and Softride argued that it applied to riding a bike.  The Softride did this with the suspension built into its beam, the heavy part of the bike/human combo (you) was suspended.  Zipp argues now that designing wheels to allow lower tire pressure has a similar effect, more about that later.  

My Softride died in a bike collision with a car whose owner was in a mad rush to get to his first appointment of the day at a body shop.  He worked for Geico, and the settlement paid for my next bike and then some.  I would have bought another Softride but they had gone out of business.  The next best was a Cervelo P3.  It did not have a beam which I immediately missed, not as comfortable or aero, in my opinion, but a very good bike.  Still no storage but I got to work on that as soon as the bike arrived.  Wires still hung out below the aerobars but disappeared into the frame at the top of the down tube.  

carbon fiber bike

With an all-carbon-fiber bike, I had more to play with.  I moved the shifting wires through the top of the top tube, the small holes I drilled in the top tube did not reduce the strength of the bike, but I am sure it voided the warranty.  This included making a fairing that wrapped around the stem and steering tube running back along the top tube streamlining the bento box.  

Fluid supplies found a new place to hide in a Never Reach Bottle, it held about 48oz. I have since worked out other ways to keep myself hydrated while reducing weight (pick up water, carry powdered sports drink) and ditched the Never Reach. But you will soon read I am back to carrying a bit more fluids on the bike out of T1.   A spare tubular tire was folded up inside the bottle on the downtube along with some tools, more tools were behind the seat taped to the bottle support.  I should note that in the picture to the below I have not yet made the fairing and rerouted the cables, but they are all covered with tape.  You can’t see it, but neither can the wind, there is a race number on my back set up so it stays as close as possible to my back.  

ironman cyclist

Not long after I got the Softride I started to think about how nice it would be to have it made of carbon fiber.  It took another 15 years to have one, the Dimond.  The owner of Dimond Bikes, TJ Tollakson, came to love beam bikes with one made by Zipp (more on that on his site ).  When I read that he was making an improved version I knew it was only a matter of time before I had one.  

Combined with the right aerobars the wires disappear with the Dimond.  The first iteration of the bike did not have any internal frame storage but there was a fix or at least a partial one, for that.  The downtube has a lot of volume and with a small modification on my part at the top end a spare tubular tire was tucked inside along with some tools and the Di2 battery.  The rest of the emergency spares was tucked behind the seat with a customized bottle cage (you can see a CO2 cartridge in front of the cage.  Some food supplies found a home in the bento box and I made a pillbox that sat behind the stem filling in a gap to allow for different stem types.  

ironman bicyclist racing

Radical Changes in Bike Design and Components

When I got my Softride in 2001, 9-speed gears were the most you could get.  I don’t recall if Disc brakes had made it to the mountain bike world, but they were a long way off for road bikes.  Wheels were thin, tires thin, and high pressure (180psi). Wires, as I have gone on about, were draped around the outside of the frame.  Electronic shifting had been tried without commercial success.  In the last 6 years since I got my first Dimond that has all changed.  

We now have 12 speed (and one 13 speed) gearing.  The changes in gearing over the last 20 years have been amazing.  (If you are interested in some history about gearing check out this information from Wikepedia.)   For some, this has made it possible to ditch the double chainrings, more aero less weight.  But as you will see a bit later this is not suitable for an aging athlete losing measurable power every year.  

Disc brakes are superior in all but flat dry racecourses with few turns.  They also come with through axles which add to the stiffness and handling of the bike.  Hydraulic brakes are a great option with Disc brakes, easier modulation of the braking, easier to hide the cables (AKA tubing).   

As one article I read recently said improvement in wheel aerodynamics is reaching its limits and comfort and rolling resistance are the last areas where “free” speed can be realized.  As a result, as noted earlier, wheels have gotten fatter along with the tires.  What was a bummer for me was when I bought my first Dimond. I met the engineer behind the design, David Morse (he also developed some of the earlier Zipp Wheels), and he told me that my tubular wheels were on the endangered list.  I no longer have them.  They along with Clinchers with tubes are on their way out (expensive change).  Tubeless tires, the hookless type, make for a much better interface with the wheel creating an almost smooth joint and more aero.  If you are switching to disk brakes go with hookless,m tubeless wheels, this is going to be the standard for all wheels in a few years.

With the intro of the Dimond Marquise frame set up for disc brakes and the inclusion of great internal storage in 2017, I knew that another bike was in my future.  Covid, or the prospect of getting over the worst of that, has me buying a new bike.  

My Choices

Frames & Brakes

My choice of bike brand is simple, I have 6 years of experience racing on a Diamond and am extremely happy with it.  I have the first iteration of the bike and Dimond has mad some significant improvement to the bike, all of which I think is important.  They have not changed the geometry of the bike and I have had a fit recently (Ryan Ignatz, Colorado Multisport) making the frame choice very easy. 

I have lumped frame and brakes under one heading as your choice of frame, regardless of brand, dictates the type of brakes or vice versa.  You can’t have disc brakes without through axles.  Dimond’s Marquise comes in traditional rim brake and disc brake versions, you should by now know what I want.  The Marquise also has all Dimond’s storage options and with the right cockpit tucks the hoses and wires almost complexly out of view.  

One easy decision with brakes is mechanical or hydraulic, I am going with the latter.  Modulation is better and with a quick disconnect in the hose lines packing the bike will become even simpler than the present.  With my large frame size, I have to remove the cockpit to get it into a bike bag.  

I had thought going into this that it would be Ultegra brakes and Shifters but there is a favorably reviewed product that would save significant money from TRP, more research.  

tri rig aerobars


Easy choice for me, I am staying with my Tri Rig Aerobars from my old bike.  Dimond’s own cockpit would be my choice if I was looking for the very latest idea, common on many superbikes, a single mono post.

Two weeks ago, I purchased TriRig's latest idea of making pads much longer.  Others, like Vision, also are making more comfortable arm pads.  They even make one with the extensions built-in more aero.  The idea of a longer pad is primarily more comfort and that is certainly the case.  Here is a picture of my current bike with the new pads.  

If the bike you decide to buy is like the Dimond and you have cockpit choices, care is needed, as well as help from your fitter, in order to get the cockpit you will be most comfortable on.  

Wheels & Tires

This is going to be a tough choice and more research is needed.  Zipp’s latest white paper has sold me on the idea of wide tubeless wheels (23 or 25 mm internal width) with matching tires (at least 25 or 28 mm) and hookless.  The question for me is the depth of the rim.  

My first Zipp wheels came with my Softride, 303 in the front and 404 in the back.  I survived the worst wind conditions in Kona on that setup - 55 mph gusts and a steady 25 mph headwind going up the climb to Hawi.  With improvements to the cross-wind handling of the Zipp wheels and my handling skills, I have managed with 404 up front and 808 in the back for 15 years.  I upgraded the 404/808 tubulars 5 years ago to the very expensive 454 and 858 clinchers, a huge improvement in crosswinds. But the days of deep rim wheels for me are over or will be soon.  I feel a lot less secure on them now.  

The articles I have reviewed about Zipp’s latest offerings suggest that in hairy conditions as I have experienced in Kona, or any windy race venue, a 303/343 wheel up front would be my best choice with either the same or a 404/454 in back.  Experience has taught me that you can go a lot deeper in the back even in wild conditions but at present, no one makes a wide rim bigger than the 404, and I want that comfort.  I am leaning towards the 303 front and back with the idea that if a race is coming up where I think I can ride a deeper wheel I can rent it.  

Dimond’s Red Crown wheels are a less expensive option with, I suspect, very comparable performance to Zipp’s latest.  More research on that is needed.  


One decision is made with gearing, 12 speed.  I did consider a 13-speed offering from Rotor and Sram.  Rotor’s system is hydraulic.  It seems to me that electric is a simpler approach to shifting so I will be sticking with that.  I also looked at eliminating the inner chainring.  Sram offers this with their 1x13 setup.  More aero for sure but the compromise with this setup is either a limited range of gearing or wide spacing between each gear, neither of which would work for me anymore.  10 years ago perhaps yes.  

Di2 or Sram is still an open decision.  The difference between them as far as actual gearing is very comparable.  Sram batteries do not last as long as Di2 but to charge them you take them off the bike.  So, you can have spares and always have a fully charged one.  

The decision may come down to availability.  The Di2 12 speed is very new, and supplies are still limited.  

Summary of Open Questions

tri bike racing

The To-Do list is as follows.  

  • Brakes and Shifters: Shimano or TRP
  • Wheels:  Which rim size, Dimond or Zipp.
  • Di2 or Sram and which initial cog set.  
  • Paint design and color.  I have not talked about this before; it will be a difficult decision for someone who is partially color blind.  One idea in the works is adding a sketch of my two close friends on the beam, Ingrid and Rita.

Articles that I have been reading that helped my decision making 


Article on the recent history of gearing through 2014 and an explanation.

History from Wikipedia about the Number and Width of Sprockets (look specifically at that section)

Bike Fitting Articles

Reasonable Bike Fit Expectations (Slowtwitch

What to Expect in a Bike Fit (Bikefit Blog)


Most of these articles are about Zipp’s latest wheels.  There is a reason for this, they are my primary focus, and they get more press than most other brands.

Slowtwitch’s take on the latest from Zipp

Zipps White paper on their wheels

A view of the Zipp wheels from across the pond (Europe)

A look at wheels other than Zipp

Articles that include discussion of bike features that are of interst to me

I would be considering this bike if I was not already sold on the Dimond.  It has all the things I think are important in a superbike and this review of a new trek speed concept and aerodynamics.

Here are some other bikes that Triathlete ranks as the best of 2021, I am always a bit suspect of articles like this as they never seem to include bikes that don’t advertise in their magazine. 

Coach Simon Butterworth has 15 Ironman Kona World Championships to celebrate ... and he knows bikes. His philosophy about coaching notes that the key ingredients in a good coach/athlete relationship are regular and open communication, mutual respect, and keeping it fun for the athlete and their family. My training programs are developed with those ideas in the forefront. I work with athletes to develop both short term and long term objectives that work well within the context of the other things they have going on in their life.

Coach Simon Butterworth has an experienced philosophy about coaching.  The key ingredients in a good coach/athlete relationship are regular and open communication, mutual respect, and keeping it fun for the athlete and their family.  His training programs are developed with those ideas at the forefront. He works with athletes to develop both short-term and long-term objectives that work well within the context of the other things they have going on in their life.

Coach Simon is a 2X World Ironman Champion and has 16 Ironman World Championships races to his credit. He has finihsed on the podium 7x.  He is a USAT Certified Coach, USMS Swim Coach, FIST Certified Bike Fitter and Training Peaks Certified Coach.

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