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Critique my (express) fit
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A few weeks ago I was lucky enough to do an express fit with Dan during the Slowtwitch Roadshow at Bonzai Sports’ new store. It was a very cool experience. Dan encouraged me to share the results, so after getting a few rides in, here they are.


Some Background
I picked up a used Cervelo P3C a few years ago. Shortly after I did a professional fitting. I now know I did the process backwards, but was lucky enough that the bike generally fit with only a few adjustments. No coordinates were provided during that fitting. I have been mostly satisfied with the original fit. It was comfortable and has allowed me to be somewhat competitive on the bike at local sprint/olympic races, which is what I primarily do at the moment. However, whenever I would see a race picture it was clear the position was not very aggressive and there was room for improvement. The goal of a new fit was to be faster.


Express Fit
During the express fit I explained this background to Dan along with the goal of understanding what frames/sizes I should consider for a future bike purchase. I got on Bonzai’s 'Purely Custom' fit bike (with my existing pedals and saddle) and Dan dialed me through a few positions. Starting from relaxed to overly aggressive and then back to the final result. It felt like we quickly found a position we both were happy with. I was lower than before, but not uncomfortable and I was able to hold power. Dan then took and explained the measurements in excellent detail. We reattached and repositioned my saddle, then he used the Slowtwitch Stem Calculator to recommend a new stem and we were set. I went downstairs to Bonzai's shop where they swapped my stem. I gave it a test ride, purchased a few other items and was all set.


Here’s a video of the same positions: https://photos.app.goo.gl/K9xneuar836EFce63

This is what it looked like pre-fit, fit and post-fit. (Not sure if an image like this is helpful).



Fit Coordinates:
* 770mm Saddle Height
* 45mm Saddle Setback/Forward
* 865mm Nose to Extension
* 140mm Pad Elevation
* 502mm Pad X
* 630mm Pad Y
* 527mm HX
* 570mm HY
* 530mm Saddle to Armrest
* 260mm Armrest Width
* 390mm Extension Length


For reference, I'm 6'2" with a 32" inseam. Bike is a 2009 58cm Cervelo P3C with 175mm cranks, ISM road saddle and Profile Design aerobars. Dan suggested I consider new frames that are 56cm for Cervelo/Trek, or 54cm for Quintana Roo.


Post Fit
Since the express fit I've done a number of trainer sessions, two outdoor rides and a sprint race. I'm very happy with the new fit. My neck and shoulders certainly felt some pain when in the new position for 10+ minutes, but that has dissipated with each ride. It won't be an issue for the short course races I typically do. My power might have dropped 5-10 watts immediately after the new position. But I no longer see any drop.


There's a small local sprint race I do at the start of each the season as a tune up / benchmark. I was extremely excited to compare my past results against my new position. However, for the first time ever, my power meter wouldn't pair in transition so I sadly have no power data for a true comparison. I only ended up 4 seconds faster than last year (on a 31:01 time), and was able to post a top-5 OA bike split. I believe I rode too conservative and under my target power, but it's anyone's guess. Run off the bike did feel good.


Summary
So what's the point of this post? First, to give a thanks to Dan for the express fit. Second to share the Slowtwitch Roadshow express fit experience for others in the future. Be sure to bring your bike, saddle, pedals, race shoes, a phone to record video, and I'd recommend getting a proper "before" video for comparison. And finally, this post is to get any fit critiques from the forum.


You'll have to be very convincing to make a different recommendation from the fit bike pics/video. However, the weak link in all of this is translating the coordinates from paper to my bike. Perhaps less of an issue when the fitter is the one adjusting your bike (Dan was not involved in this part, he was on to the next express fit). So in my case any of these precise coordinates could be slightly off on my bike. But I'm happy and comfortable!

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Re: Critique my (express) fit [mlbTri] [ In reply to ]
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No question, it looks a lot better to me. But let me ask: you race with a helmet on don't you?

Right, then why would you adjust your position with no helmet on?

Looking at the post-fit position, it looks to me like you may end up with a big helmet way up in the wind (especially if you wear the wrong helmet). They could negate most of your aero gains. But there's no way to know until you get on the bike with a helmet. Seemingly good aero positions can be crap once you put a helmet on.

My latest book: "Out of the Melting Pot, Into the Fire" is on sale on Amazon and at other online and local booksellers
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Re: Critique my (express) fit [jens] [ In reply to ]
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Thanks. It's a good thought. Not something that was discussed or that I considered during either of my fit sessions.


I thought the fit process was to find an ideal body position, and then map those coordinates to a bike. Contact points (saddle/aerobars) were considered. But other gear (helmets, hydration, clothing, etc) were tested after the fit and selected based upon how they work with the fit, not as part of the fit. Or do others approach it holistically and helmets are part of the fit solution? Obviously if one has access to a wind tunnel that changes a lot.


Any helmets you'd recommend based upon the position you see above? I currently ride with a Specialized Evade.

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Re: Critique my (express) fit [mlbTri] [ In reply to ]
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I'm sure 95% of fitters do seek "an ideal body position," as you say, first and then choose equipment later. I think they're mistaken. You can't even begin to decide on an ideal body position until you see the overall effect on aerodynamics -- and helmet and possibly skinsuit are a huge component of that.

In your case, I'm just concerned that your helmet (probably any model) may stick up and render some of the drop pointless. There's no way to know until you try it though.

My latest book: "Out of the Melting Pot, Into the Fire" is on sale on Amazon and at other online and local booksellers
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Re: Critique my (express) fit [mlbTri] [ In reply to ]
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mlbTri wrote:
Thanks. It's a good thought. Not something that was discussed or that I considered during either of my fit sessions.


I thought the fit process was to find an ideal body position, and then map those coordinates to a bike. Contact points (saddle/aerobars) were considered. But other gear (helmets, hydration, clothing, etc) were tested after the fit and selected based upon how they work with the fit, not as part of the fit. Or do others approach it holistically and helmets are part of the fit solution? Obviously if one has access to a wind tunnel that changes a lot.


Any helmets you'd recommend based upon the position you see above? I currently ride with a Specialized Evade.

It looks like Dan set you up with some forearm tilt. Your pre and post bike fit has your forearms flat or angled down. Any discussion with Dan or the bike mechanic about dialing this in on your bike?
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Re: Critique my (express) fit [mlbTri] [ In reply to ]
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I wouldn't worry too much because all sorts of helmets offer all sorts of fits.

Without a helmet, my head looks in a fairly similar place to yours. I rode with a Bell Javelin for the last 5 years, and now replaced it with a MET Drone Widebody. Both can be slightly rotated backwards so the tail is flush with my back - one straight line. Obviously, unless I aero-test there's no way of knowing whether this is faster in any way - but I figure it is least likely to be aero-harmful.

Other options are short-tailed true aero helmets like the POC Cerebel or the new Oakley Aro 7, which probably won't even stick out above your back line even if you don't rotate them.

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Re: Critique my (express) fit [SummitAK] [ In reply to ]
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Did not discuss any tilt (or I missed it). The fit bike aerobars had a ski-bend to them (Profile Designs T3+), while my bike's bars are straight. I'll take a closer look and might experiment with pointing up a few degrees or so. Thanks.

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Re: Critique my (express) fit [tessar] [ In reply to ]
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Something with a short tail and more forgiving at different positions is appealing. The POC Cerebel you mentioned seems to fit that bill, with positive reviews and has tested well for some. Will get my hands on one to see if it works well for me. Thanks.

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