Tri Bike Fitting – part 2

by | Mar 18, 2019 | Bike, Gear

I (Eric) went in to The Energy Lab for a bike fitting session to optimize my position on my Giant Trinity Advanced.  I felt like my position was pretty good but I knew that there was room for improvement. 

Just like Tara’s fitting session Marc started by taking measurements from my current position.  I then hopped on the bike on the trainer and Marc captured some video of me on the bike to set my current fit coordinates.
From the initial video Marc is able to determine things like whether your seat height needs to be adjusted, your hip angle, the angle of your arms relative to your aerobars, and the angle of your back.  
Marc determined that my seat height needed to go up and that my hip angle was pretty tight.  The angle of my back was a bit high (meaning I was pushing my frontal surface area against the wind) and that my arms were in a pretty good position.  I felt fairly comfortable in that position so it was going to be a matter of staying comfortable while trying to find some gains in a new position.

Next step was for Marc to program my current position into the Vertex and for me to hop on.  The position felt familiar of course.  From there we started with seat height.  I’ve been running approximately the same seat height on my road bikes and tri bikes for a loooong time, like maybe 30 years.  Marc raised the seat height on the Vertex (that happened while I was pedaling – one of the coolest things about the Vertex) and it felt weird at first.  Again, my body was very used to my old seat height so any change was going to feel odd.  In my case we determined that my seat had to go up by 3cm(!)  Next was swinging the cranks/bottom bracket relative to the seat position.  This change determines seat fore/aft position and relative seat angle.  To get to a relative seat angle in the 79/80 degree range my saddle would need to come forward by 3cm.  At this point the new position felt good.  Those changes resulted in my hip angle opening up a bunch (9 degrees) and I felt like the relative dead spot at the top of my pedal stroke was gone.  Hip angle is super important here.  Watch this video from TT Bike Fit for more on hip angle and its importance to triathletes and cyclists doing time trials. 

With my seat height and fore & aft set we moved on to the front end of the bike. For me the differences here were a little harder to feel. This is another place where the Vertex is super cool. Marc was able to move the stack and reach independently and a little at a time until we arrived at a position that was both comfortable and more aerodynamic. Marc swung both parts of my front end position to relative extremes then back to what felt good. It’s pretty cool to be able to run through a range and go, “nope that feels unstable…yup that feels good…nope I feel like I’m reaching too much…Ok, that’s good but let’s try just a tiny bit back” etc. Looking at my before & after pictures you can clearly see that I was pretty scrunched up and my shoulders were just about in my ears. The after has me more stretched out and my back is a a good deal flatter at 15 degrees vs. 23 when I came in.

The last thing we played with was crank length.  The is another thing that’s super easy for Marc to adjust on the Vertex.  Something I’ve KNOWN for a long time is “the longer the cranks, the faster you go”.  Couple that with the fact that a tall guy like me should use longer cranks.  It turns this knowledge isn’t exactly right when it comes to a triathlon or time trial bike.  

Marc set the cranks at 165mm.  (My bike has 172.5mm cranks.)  This instantly felt easier.  Marc set the wattage at 200w without me knowing it.  I pedaled for a bit and said “that feels good, nice and easy” and Marc then told me that I was at 200w.  It sure didn’t feel like 200w!  From there he bumped me up to 250w (just under my FTP).  Again, it felt easier than 250w.  This piece is completely counter to what I’ve known to be true but maybe switching to 165mm cranks is the way to go.  Check out this article on for a good explainer on crank length. 

Ultimately we arrived at position that has my back a good deal flatter and more aerodynamic.  To transfer the new cockpit measurements to my bike will require some new aerobar elbow cups as the cups on the Giant are essentially one position cups with no fore/aft adjustment.  Marc ordered what I need plus some J bend aerobars.  While playing with Vertex Marc had me ride with J bend bars to see what I thought.  They definitely felt better than my current S bend bars.  

Once the cups and bars are in we’ll finish adjusting the bike to my new position.  I’m looking forward to getting the bike set up and getting out for some longer road rides to see how the new position feels for a longer time in the saddle.  

Marc’s notes from the session:

  • We raised your saddle height by 3cm from 79 to 82cm.
  • Saddle moves forward 3.5cm to steepen your effective seat angle and open hip angle
  • Need new armrests with more adjustability (to lengthen reach since saddle is moving forward) and new extensions to provide a more natural hand position.
  • Drop increased from 7cm to 13cm (since saddle height increased by 3cm, only 3cm of aerobar spaces need to be removed.  You don’t need to remove all 3cm at once if you want to start off a bit higher.

So, what does this cost?  About the cost of a new helmet.  Marc’s pre-buy fits are $175.  A portion of this is refundable if you buy a bike through Marc.  He has access to bikes from Argon 18, Blue, Fuji, Kestrel, Look, Louis Garneau, Ventum, Quintana Roo, Litespeed, Open, Orbea, and Premier.  
If you’re getting your current bike fit to you the cost is $225.  This cost is a bit higher but will include adjusting your current bike’s fit after determining things on the Vertex.

In the course of a year of triathlons we all spend a ton of money on race entries, travel, nutrition, new gear, etc.  $200-ish is a pretty small price to pay to make sure that you’re getting the most out of your bike and body.  If you’re within a reasonable driving distance from Bucks County PA go see Marc.  If you’re in New England go see TTBikeFIt.  No matter where you are seek a qualified triathlon bike fitter and get your fit dialed in. 


See THIS ARTICLE about Tara’s experience at The Energy Lab.

Video provided by Marc from The Energy Lab’s fitting system:

A bit of disclosure – Marc is a friend from our community.  We swim with him and have run into him on rides (but he’s way faster than us on his Ventum).  We agreed to write up our fitting experiences as part of a trade for Marc’s fitting services and some product discounts.  Eric is also creating a website for The Energy Lab through his company SherpaWeb as part of the agreement Keep an eye out for a new Energy Lab site soon.

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