"56" doesn't mean the same thing for each brand. A 56 Cannondale slice (2013) has a stack of 529 and reach of 407, whereas a 56 QR PRFive has a stack of 560 and reach of 435. I won't speak as to whether it's the right size for you, but that's why a QR PRFive in 56 is bigger than a Slice in 56 and could be considered a better fit for you

I have a PR6, I'm 6'2" 34inch inseam and ride a 54cm. I don't know what the very lap in size is but I went down in size to make sure I could get lower if I ever wanted to.

Can you post a video of you riding the bike on a trainer?

Nobody can say if you got the right size with the information you provided. With the ability to swap stems combined with the Profile Design bars, that bike has a huge adjustment envelope and will probably fit you in some configuration. And the 56 is the most likely size for you.

You should work off of Pad X,Y to be sure. You need a Pad X between 460 and 560 and a Pad Y between 640 and 760 to make that bike work (and look) reasonably well. You could hit more extreme positions, but you don't really want to put a 60mm +/-25 degree stem or a 140mm +/-17.

at 188cm i'd say you're on the border of a 54cm and a 56cm. i'm 187cm and i'm a 54cm, and here i am on it, along with peter hurley, who owns QR.



it depends on how you ride. QR sizes down a size, basically. QR feels its sizes ought to mean something and it's decided the bike's stack is its size. so, a size 54 has a 54cm stack (and a 42.5cm reach). a Felt IA in the same stack and reach is a size 56. that same stand and reach in a Canyon and a Dimond is a size M. in a Speed Concept it's a L.

this is the beauty of stack and reach. it's a truth teller.

hard to say whether you're on the ride size frame. you can make that 56cm work in any case, and it might be perfect.

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Dan Empfield
aka Slowman

I’m 6’0” (182.8cm) with a 543mm stack (54.3cm) and 406mm reach (40.6cm), and have a PR6 disc on order in size 54 frame. Without knowing your stack/reach I won’t say you got one a size too big because I just don’t know... I have a PDF file from QR sent in an online chat with their entire stack/reach range and adjustability for the 2.0 stem based on every frame size available, but again, we need your stack/reach to size you up properly. I believe that stem is the standard on all their bikes now IIRC.

If I were you, I’d get a professional bike fit STAT. That’s the best way, and the only real true way to know. Personally, I got a Retül bike fit from a master fitter before purchasing, which included a consultation session afterwards about which bike is best to buy. I listed off about 10-12 Tri bike companies, we pulled up their stack/reach geometries, and discussed from there. I found out there’s about 6 bike company (including some big names) that just simply don’t work, like Giant, Cannondale, Canyon, etc... do not fit me. I’m in between stacks/reaches on their bikes and I’d either be cramped and not have the hips opened up enough, or too stretched out. Again, get a professional bike fit before 30 days is up. QR’s fits a massive majority of people. They have a super wide range of adjustability.

Edit: Forgot to mention.... If you go the route of getting a bike fit, pick a damn good one. The plum bob crap has never worked for me. I’m not a spokesperson, but, there’s a reason I have no problem paying $300 for a properly done 3-rd part bike brand agnostic Retül fit. When looking at stack/reach, each company measures the reach specifically from either the middle of the saddle or tip of the saddle. There’s a drastic difference in the 2. Just take that into consideration when looking at stack/reach numbers with your fitter. 🤙

you need more reach, or rather, MOAR REACH

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Eric Reid AeroFit | Instagram Portfolio
Aerodynamic Retul Bike Fitting

“You are experiencing the criminal coverup of a foreign backed fascist hostile takeover of a mafia shakedown of an authoritarian religious slow motion coup. Persuade people to vote for Democracy.”

as others have said, it depends.

Depending on your morphology, you might run out of reach on the 54, or you may run out of stack (to get low) on the 56. Personally, if that were the trade-off I'd put you on the 56 sight unseen, but as Jim said post a video of you on the trainer and we can be more helpful.

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Eric Reid AeroFit | Instagram Portfolio
Aerodynamic Retul Bike Fitting

“You are experiencing the criminal coverup of a foreign backed fascist hostile takeover of a mafia shakedown of an authoritarian religious slow motion coup. Persuade people to vote for Democracy.”

can i hijack your post? when you say this is your stack and reach, what do you mean by those numbers?

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Dan Empfield
aka Slowman

Yes sir. Well, it’s not my original post, but, those were the numbers that I received with my Retül bike fit. A-typical definition of frame stack and frame reach apply. Although... I say a-typical, however, as you know and I mentioned above, some companies measure these differently, so... stack/reach was measured from the horizontal and vertical distance from the center of the bottom bracket to the center of the top of the headtube. That definition was a copy/paste from the Retül PDF file btw... I’m not a bike fitter rocket surgeon, but, all I know is that it felt good, my power was right on, and it was sustainable for hours on end. My biggest complaint was shoulder pains, and dropping the bars made it much better, with shoulder issues eliminated.

that's not stack and reach as we refer it to it here... pad x and pad y

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Eric Reid AeroFit | Instagram Portfolio
Aerodynamic Retul Bike Fitting

“You are experiencing the criminal coverup of a foreign backed fascist hostile takeover of a mafia shakedown of an authoritarian religious slow motion coup. Persuade people to vote for Democracy.”

you have stack and reach correctly defined tho as eric pointed out, there is another, similar metric called either Pad Stack and Reach or Pad XY that's the rise and run to the pads (either center or rear, depending on who's measuring). Here's the stack/reach point of bikes of similar frame stack and reach numbers:



as you see, we have a cluster of frames that are all around the same size. they'd fit the same way. and they have a stack and reach pretty similar to the stack and reach you suggested for yourself. however, let's take a look at these frames in another way:



if you're looking at superbikes, this graph tells a different story. a more expansive story. i'm using a cartesian graph with number on the X and Y axis that go much higher, and that grouping of similar frames is reduced in the second graph to points on the bottom left of that graph. this is so i can show you the available pad placements for each bike. the giant trinity advanced pro has a lot of pad length available, but not much pad height. the scott plasma premium has the opposite: plenty of height, but not much length.

now, i believe that since this chart was made giant has come out with addition height options for its bike, and i suspect the newer profile design pad hardware make its way to the plasma premium (i hope!) giving it some extra length.

however, it's not really that helpful these days to say, in tri, i'm a frame stack and reach of thus and so, because the front ends of the bike are different from each other in their adjustability. so, in the image of me above riding with peter hurley, the discussion was, "i have a size run of bikes in kona, want to go on a ride? we'll have a bike ready for you." and my answer was, "yes, made the pad y and x - to pad center - 640mm and 505mm respectively, saddle - if it's an ISM - at 785mm measured bb to 40mm behind the nose, and we'll go riding!

in fact, i had to move the saddle down a little when i got the bike, maybe because the cranks were longer than what i've got on my bike, who knows, but otherwise, as you see, the bike was set up pretty well for me. pad xy is more useful than frame stack and reach. but if you MUST choose a frame out of multiple that'd fit you in a size run (which is what the OP's situation is) then there are best practices for that.

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Dan Empfield
aka Slowman

Very informative. Appreciate it! Thanks.

thank god an expert came in here to set us straight.

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Dan Empfield
aka Slowman

I am almost the same size (187cm with 88cm inseam) and recently bought a PRfive 56. When it arrived I had the same question... mainly because the headtube/stack looks quite high. I had a bike fit last week and they placed me at a very comfortable 10,2cm Pad-drop. Honestly, that still looks a bit un-aero to me so I am not sure if I´ll will try to drop a bit over time. Anyway, this setup is with the standard setup, 17° Stem, no spacer and one 10mm riser. By using a slam-set, another Stem (Syntace Flatforce or the like) and removing the riser I could easily increase drop to approx 13-14cm (which is probably close to best-practise for an ordinary M45 AGer).

Below is the previous quick&dirty DIY setup (left) and the fitted position (right). As I said... looks very (too?) comfy to me, but I´ll work it out from there:



As you are a bit taller I would also think 56 is OK... unless you want to ride with 15+cm Pad-Drop.

Dave -

When you say "with the ability to swap stems", are you referring to just between their old 1.5 stem and the new 2.0 version? This bike won't take just any standard stem will it?

I am trying to figure out my sizing as well for this bike. After talking to QR a while ago I was certain 52 was the right size. And now there is a really good closeout deal on a 2017 PR6 in a 52 that I am thinking of buying. I checked and found it has the older stem, and got the pad chart for the old stem from QR. And although it seems hard to believe, as I am currently on a M/L CD0.1, the 52 is too small for me. My padY on the CD0.1 is 60.5 cm, and bottomed out on the old stem the PR6 size 52 only goes as low as 62. (my padX is 42.9, the 52 with the old stem has a minimum of 43) And for the record, although I've never been fit on this or any other bike, I feel good in this position and I am extremely happy with how I've been both riding in it and running off of the bike, so I want to keep this setup.

The PR6 has 165 cranks on it, I currently ride 172.5. I know you are a strong proponent of going to shorter cranks, so at 5'9" and 32" inseam that seems like a good option for me. So I think that means to get the same fit I would need to raise the saddle and the bars by 7.5 mm, bringing my pad stack to about 61.25, still too little for the 52 PR6. However the 2.0 stem does bottom out at 60cm on the 52, and the reach goes as low as 40.5 with the new stem, so that one puts me well within range of the 52.

However, I wasn't even thinking about other stems. And it also seems to me that these numbers are all dependent upon a given aerobar, and are all going to be different based on what aerobar you have anyway, so I am even more confused.

Dave, I know you've done a ton of fits and I recalled this thread so I thought I would dredge it up and get any input that you might have.

Thanks,

Doug

Sorry to ressurrect an old thread but I thought it'd be better than adding yet another one for a similar question.

I have an opportunity for a good deal on a size 56 QR PRThree. I am 6'1". I read the articles that Slowman wrote about the PR series and also a couple threads like this so I am concerned about this sizing. But QR's own site has a rough sizing chart that says 54 goes up to 6'1" and 56 is 5'11" to 6'4". Wouldn't I be better off being snack in the middle of the range?
https://quintanarootri.com/pages/sizing-fit

I know I should be seeing a fitter and I have several around me that I can go see but not very soon and I don't want to miss this opportunity so please excuse the rookie behavior.

I am 6’0”, but rounding down slightly. I have a QR 54. The bike could easily adjust to fit me if I was an inch taller. When I stand it up to a couple other brands’ 56 size bikes, it’s essentially equivalent.

I am 6 foot 1 inch and ride a 54cm QR PR5. Rode a Cannondale Slice size 58cm before that. Good luck

as you see from the posts of others, a size-54 is bigger than you'd think in QR's sizing scheme. figure it this way: if you're ride a 60cm bike as your road race bike, that's about what a QR tri bike would ride like in size 56. if you would ride a 60cm road race bike successfully, then the 56cm tri bike would work for you too. one good thing: because it's a PRthree, it takes a standard stem, and standard stems allow you more adjustment options than the fully integrated front ends. this could help make this bike work for you.

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Dan Empfield
aka Slowman

The guy riding it now is 6'1" too, fwiw.

Slowman, are you saying it's worth giving it a try? Or is a fit the only way I can really know before buying?

if the guy riding it was now 5'9" that would not mean it's okay for another 5'9" guy to ride it. as to whether this bike would work for you, two things: first, it's pretty easy to just calc this out. you know how ian and eric work the canyon and cervelo threads respectively? you provide pad x/y, they work you thru the solution? it's not hard to do with that this bike either. are you confident in your current bike position? provide the pad x/y, we'll work thru it.

otherwise, what i'm saying is that the fact that this is not a superbike, that helps. if the bike comes (let us say) right now, as you buy it, with a 10cm stem, -6° pitch, just changing the stem to, say, a 70mm or 80mm with a -17° pitch, you probably normalized for the difference between a 54cm and a 56cm bike right there. in other words, in changing the stem, you reversed all the extra height and length between the two frame sizes. in that case, yes, that bike will work fine for you.

if this was a first-gen PRsix, with the original integrated PRsix stem, then you'd be screwed.

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Dan Empfield
aka Slowman

Just for another data point I'm 6'+ riding a 54 PR3. I could ride a 56 PR3/5 but the *old proprietary stem for the PR6 would add too much stack for my fit. I bought the 54 because it was the right price and either worked.

*at the time the new stem hadn't been released.