Help me understand my Retul Numbers

Hey All,

So I finally had a retul tri specific fit done ahead of buying a new tri bike. Hoping some of the wise folks here can tell me how I should be using these numbers to compare against various frame geometries I am looking at before ultimately making a purchase. Is it just as simple as lining up numbers? A few of my local shops have bikes in stock they claim will fit me based on these numbers—but just want to make sure I do my diligence (always a bit skeptical when the bike they have in stock also just so happens to be the one that fits me)… Thanks in advance for the help!

What bikes are they saying will fit you? What info are you wanting?


Just trying to wise up on what these numbers actually mean in terms of comparing to geometries.

So far I’ve been told that the following bikes will fit:

Giant Trinity Advanced Pro / medium
Cervelo P-Series / 54
BMC Timemachine / medium-long

While I understand that a number of bikes/brands theoretically “could” fit, I guess I am wondering if there is any bike that would fit “best” based on these numbers—or maybe I’ve just had the concept of ideal fit pounded into my head too much?

I guess the ideal geometry bike based on that would have the same seat post angle and frame geometry that would let you re create the other recommended dimensions.

I am a little sceptical of a saddle setback dimension quoted from the nose as saddles come in a lot of different sizes and shapes and some are even noseless.

Thanks. Yes that makes sense. At the end of the day, I fully expect more than one brand/frame could work (possibly even more than one size). Just wanted to avoid buying the bike that was in stock when it might not be the best fit.

AFAIK, most Tri and TT bike sizing it best directed to the Arm Pad location. Each bike brand and model has a particular rectangle (X / Y) that the arm pads can exist. There is usually overlap between sizes on a given bike model. Some models have different layout with longer and lower range vs others. It’s a bit confusing and not all bike makers publish this info, but it is becoming more common.

These articles are worth a read and the ST community is often able to help with picking bike sizes. I got confirmation on “sizing down” when I got my Shiv, when the Specialized charts had me clearly on a bigger bike, that would have been wrong for me.

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Thanks Chad! I was considering a cross-post on slowtwitch once I educate myself a bit more.

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I’ll also echo Chad’s suggestion - understanding the X/Y reference concept was very helpful for me to pick a TT bike on e-bay. Cervelo publishes charts on this and people on slowtwitch can help you decode this for other brands. SO simple compared to other methods!

Also, check out the Tririg alpha one base bar system - you’ll see it talked about a lot on slowtwitch as well which is how I learned about it. They also have a good fit guide that also refers to the same pad X/Y system except make sure you are always checking if the pad X is to center or back of armpads!

I splashed out on one of these over the winter. It’s a fantastic system and a massive upgrade over the stock NP3 front end. It’s like your TT bike becomes a fit bike as it gives you an insanely huge window to work with - independent tilt/reach/stack adjustment can all be done in seconds using a single 4 mm allen key to readily accessible bolts - it’s a fantastic design. Also just happens to be super fast in wind tunnel, UCI legal, lets you hide all cabling, enables clean center pull aero brake integration…

I mention this because you may find it advantageous to consider something like this system + lower/mid-range TT bike frame vs. a much less flexible and costly “superbike” front end that leaves you with a more restrictive fit or difficult/costly adjustments when you do.

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Thanks - I agree this system looks really clean, definitely something I will consider (if I can swallow the price!)

Watch for sales - you can regularly find 10-15% off, often with some nice free items thrown in that ease the sticker shock :grinning: