so, when you talk about opening your hips, etc., yes, but what tom and i are talking about is whether you can retrofit a road bike to duplicate your tri position exactly. and, yes. you can. but most of our ass-over-teakettle crashes stopped taking place once we moved to bikes made for the position, and there is one thing i've always wondered which tom can help with: what happens to Crr when you add an extra 20lb to the wheel? and i don't mean the drive wheel, but, what happens when you add payload to the wheelbarrow. i'd like to see the results of that test.

Since by definition the Crr is the ratio of retarding force to wheel load, the Crr of each tire is unchanged. However, the retarding force attributable to the front wheel is increased by Crr (front tire) x 20lb...then again, the rear wheel retarding force is reduced by Crr (rear tire) x 20lbs. If one is running the same tires front and rear, then it all "comes out in the wash", and the total retarding force attributable to both wheels together is basically unchanged.

In fact, if one is running the same Crr tires front and rear, then one can estimate the total retarding force by just multiplying the Crr by the total bike+ rider weight. The distribution of retarding forces front and rear will be proportional to the weight distribution percentages.

i hear you bro. i would still be interested in seeing it tested.

I think one of the more overlooked benefits of switching from a road bike, even one diligently set up to resemble a tri-bike, to an acutal TT bike is the run. When considering a TT bike, we all ask "how much faster will I be on the bike?". I definitely got faster on the bike when I switched from my road bike (which had aerobars), but I also improved on the run. I'll defer to the experts on this forum, but my general sense is that having my hips more open and being less scrunched up in an aero position saved me energy on the bike that I could devote to the run. It's something to consider when deciding whether to make the switch. (By the way, I would never recommend getting a TT bike without first getting a fitting).

Hi Forum,

being a runner I started Triathlon two years ago with an Aero-Roadbike with Clip-Ons. Over the past months I "converted" this bike to a Tri-only bike by:

• a forward seatpost giving me 76° seat angle
• a split-nose saddle (ISM PN3) making it possible to sit on it´s front in aero-position
• removing all spacers and change to -17° stem
• change the dropbar to a Syntace Stratos CX basebar with PD Supersonic (J5) bracket and 35a extensions
• upgrade to SRAM eTap (to be able to shift in both positions)
• change front brake to TriRig Omega and modify cableing to make it "cleaner"
• planned for winter: change stem and hydration to PD Aeria Ultimate

IMHO this is now pretty close to a Tri Bike... or not? The only parameters I cannot change is the seat-angle (76° is max - can´t make it steeper) and the tall headtube. About the seat-angle I am not sure if I would need/benefit from anything above 76° - though that would at least give me more options. The tall headtube also seems to be no problem as I could still go lower should I wish (different stem, undermount bracket). Besides, in real life I see a lot of short-headtube bikes that then use all kinds of spacers and risers anyway.

As much as I would like to apply rule N+1 I cannot find reasons to justify that. Or what am I missing? What would a proper Tri-Frame give me? Better position, more comfort, ease of use/ride? I currently do HIM and OD (no LD plans), and ride approx 3,3W/kg which usually means between 36 and 38km/h average.

I attach a pic (sorry for the bad quality) and appreciate your feedback. Let me know if you need more information.