Interesting bike sizing concept vid, and help requested for a measurement on a Large and Medium Rise

[Phoenix]

Just came across a really interesting video on sizing :


From this page : Dynamic MTB Fit – Lee Likes Bikes

Interestingly, their metric, called the RAD measurement (bottom bracket to the tips of bars, on centreline - ie. put sthg straight across from tip to tip on bars, and measure from centre of that to the bottom bracket ) on my Levo HT large is spot on as is the listed reach, based upon their formula that ideal reach in mm = height in cm * 2.5

However, based solely on listed reach numbers, it would put me at a medium on the Rise ...
Would one of you guys with a large and a medium rise mind measuring the RAD distance if you can make sense of it?

It that sounds like gobbledygook, watch the vid a couple of times and it should make sense (took me about 4 to get it!). They are basically asserting than almost everyone is riding bikes that are too large for them, based on how designs have evolved, and 'ovestimating' their size when choosing a bike to feed the ego! Its an interesting watch and concept in my opinion.

Oh, I'm 180cm, no lies, or manly upgrading. Always wanted to be 6' tbh so I switched to metric lol (most people approx 1" to 2.5cm, not the actual 2.54, so that does the trick )

I will help try to explain the metrics if its all too confusing

 

[Nebo1ss]

I was convinced i needed a Medium Rise until i arranged a demo at a dealer and rode the Medium. It did not feel right and the dealer without any prompting said i needed a Large.

 

[Phoenix]

I was convinced i needed a Medium Rise until i arranged a demo at a dealer and rode the Medium. It did not feel right and the dealer without any prompting said i needed a Large.

How tall are you?

 

[Gary]

Lee is a fanny.
He's short and has narrow-minded viewpoint because of the fairly narrow range of terrain and conditions he actually rides and his preferred riding style. The guy spends most of his time on dry groomed pumptrack style trails FFS.
The bigger picture means that correct bike sizing is much more open to personal preference, riding style, skill level and what you are trying to achieve.

EG. If you're a playful rider who likes to pop your bike onto the rear wheel at every opportunity but doesn't want or need any extra stability when descending rough trails at speed a shorter bike is more than likely going to suit you better.
If you're taller and like riding rough DH at high speed. Not so much.

 

[Nebo1ss]

How tall are you?

5' 10''

 

[Gary]

When sizing a bike. If you actually know what head angle and fork travel you want/prefer
Downtube length is actually a far more useful measurement to compare between frame to frame than "Reach" or "RAD"

 

[Phoenix]

Lee is a fanny.
He's short and has narrow-minded viewpoint because of the fairly narrow range of terrain and conditions he actually rides and his preferred riding style. The guy spends most of his time on dry groomed pumptrack style trails FFS.
The bigger picture means that correct bike sizing is much more open to personal preference, riding style, skill level and what you are trying to achieve.

EG. If you're a playful rider who likes to pop your bike onto the rear wheel at every opertunity but doesn't want or need any extra stability when descending rough trails at speed a shorter bike is more than likely going to suit you better.
If you're taller and like riding rough DH at high speed. Not so much.

Tell me what you really think lol
Joking aside, I am not well enough connected to the scene to know the characters and agendas, so I appreciate the opinion and advice

I'm reading the comments on that vid atm, and one that stood out from him is that 'RAD is a standing fit for dynamic moves ', which fits with the rest of what you said

 

[Gary]

5' 10''

Yep. A bike shop employee these days would coerce you towards a large. Doesn't mean it's the size you'll enjoy riding most though.

 

[Phoenix]

When sizing a bike. If you actually know what head angle and fork travel you want/prefer
Downtube length is actually a far more useful measurement to compare between frame to frame than "Reach" or "RAD"

Time to do some pythagorean maths with the listed reach and stack numbers
Downtube = Sq.Rt (reach^2 +Stack^2)

Actually, based on that formula, RAD is really ony a subtle variation on downtube size and comparing downtube lengths would capture pretty much what he is saying. You are a wise man!

 

[Gary]

That's some pretty piss poor mathematical geometry workings bro. 2/10 for effort though + 1 for spelling
Clue: a bikes downtube doesn't go to the top of the head tube (where the theoretical measurements reach and stack are measured to) .
Downtube is an easily measured actual physical measurement. From centre BB to centre lower head tube.
Use a tape measure.
#oldskool

 

[Phoenix]

That's some pretty piss poor mathematical geometry work bro.
Clue: a bikes downtube doesn't go to the top of the head tube (where the theoretical measurements reach and stack are measured to) .
Downtube us an actual physical measurement. From centre BB to centre lower head tube.
Use a tape measure.
#oldskool

Yah, I know it's an approximation, but for comparisons it should work ok, no? gonna need some pretty crazy head tube variations to mess it up
My tape measure wasn't working too well on the website ... #sittingonmyass

 

[Gary]

I've compared front centres between bikes of the same purpose by measuring downtube since the 90s. Its only useful if you have a good idea of the general front end geometry you're looking at and already know your preferred H/A fork length, bar height etc. So no use to beginners.
But neither is reach or RAD. Bike shop staff rarely even understand how stack works alongside reach or what it actually means to the feel of a front end and your average punter has no idea at all. The Internet is full of threads with riders comparing just the reach numbers oblivious to their fuckwittery.

 

[Zimmerframe]

Most people never have these problems with unicycles.

 

[Gary]

Where downtube length as a physical measurement shines is its a physical connection between your steering axis (steerer tube) and your pivoting axis (BB axle)

On a unicycle that same measurement = zero.
Or perfect (for a one wheeler) if you prefer

 

[Phoenix]

Where downtube length as a physical measurement shines is its a physical connection between your steering axis (steerer tube) and your pivoting axis (BB axle)

On a unicycle that same measurement = zero.
Or perfect (for a one wheeler) if you prefer

I hear you.
What I'm really trying to achieve here is as close an estimate of how the sizing of the Rise will be to my only comparison, a Large Levo HT (which I did use the tape measure and some acrobatics on !) which fits well
The head tube angle is 1 degree less on the Levo and the head tube 5mm shorter for the large rise - probably close enough to be valid, right?
The bastardised maths spits out a BB to top of Head tube number of 768mm on Levo to 786mm on the Large Rise. Medium Rise gives 760mm and the Head tube is 15mm shorter.
And I am absolutely none the wiser for all that mental gymnastics , my head now hurts, and I need a drink

 

[Phoenix]

I've compared front centres between bikes of the same purpose by measuring downtube since the 90s. Its only useful if you have a good idea of the general front end geometry you're looking at and already know your preferred H/A fork length, bar height etc. So no use to beginners.
But neither is reach or RAD. Bike shop staff rarely even understand how stack works alongside reach or what it actually means to the feel of a front end and your average punter has no idea at all. The Internet is full of threads with riders comparing just the reach numbers oblivious to their fuckwittery.

Don't tend to do NYeve stuff, so been learning instead
Pretty sure I understand what you are saying now - both downtube length and RAD are only useful in relation to an understanding of of the H/A etc as they are both just a measurement of the distance between BB and the steering axis at differrent points. Without H/A or head tube length, that makes them meaningless to pretty much anyone, and definitely to amateurs. Perhaps a more useful measurement would be the perpendicular distance from steering axis to BB. Combined with distance to top of head tube that would potentially be a useful sizing guide as it defines the front of the bike. Lengthening stems, changing bars etc is all just tweaking these fixed parameters.

I guess, us inexperienced folks are looking for a magic number to choose a bike from, and it doesn't exist, it's a combination of all the variables, which can only be understood through experience on and off the bike. I can now see why you think RAD isn't any sort of holy grail

 

[Gary]

I'm still drunk but sounds about right.

Happy new year

 

[Phoenix]

I'm still drunk but sounds about right.

Happy new year

As anyone with 'Old Tartan Bollocks' in their profile ought to be!!

Happy new year to you too

And thanks for sending me off down that rabbit hole, was a deep but interesting one

 

[mark.ai]

I hear you.
What I'm really trying to achieve here is as close an estimate of how the sizing of the Rise will be to my only comparison, a Large Levo HT (which I did use the tape measure and some acrobatics on !) which fits well
The head tube angle is 1 degree less on the Levo and the head tube 5mm shorter for the large rise - probably close enough to be valid, right?
The bastardised maths spits out a BB to top of Head tube number of 768mm on Levo to 786mm on the Large Rise. Medium Rise gives 760mm and the Head tube is 15mm shorter.
And I am absolutely none the wiser for all that mental gymnastics , my head now hurts, and I need a drink

I find this website useful for comparing geometry: Bike Insights - Geometry comparisons and design analysis

The Turbo Levo Hardtail doesn't exist in their database (but you could add it ...)

But this is the visual comparison of Turbo Level Comp L vs Rise M (with the 150mm fork):

(Link: Compare: 2021 Specialized Bicycles Turbo Levo Comp L vs 2021 Orbea Rise 150mm Fork Medium - Bike Insights )

And vs the Rise L:

(Link: Compare: 2021 Specialized Bicycles Turbo Levo Comp L vs 2021 Orbea Rise 150mm Fork Large - Bike Insights )

The Levo is white and the Rise black in each.

Assuming that 2021 dual suspension Levo is similar to the Levo HT you are familiar with (I have no idea ...)

Notice for the medium Rise that the seatpost & head tube top are "inside" the Levo ones (so closer together). Whereas for the large Rise they are both "forward" of the Levo ones (so roughly the same distance). All relative to the bottom bracket where the overlapped geometries are aligned (since that is where your feet go). Probably the size of the large Rise most closely matches the large Levo in this example.

It looks like either can work for you depending on what you want to achieve and how you setup your seat, stem & handlebars etc.

(Also note the diagrams don't consider the effect of compressing the suspension ... which will be different for different bikes ...)

 

[Phoenix]

Thank you, that is great into, going to head over to that site right now.
Pretty much came to the same conclusion, that either could work for me. I score pretty high (+4) on the ape factor, so I think that probably swings it towards the large

EDIT : What an awesome site, added the Levo HT and the 140mm fork Rise
Cant figure out how to DL the image :/

 

[Phoenix]

The results were very similar - Large is a very close match to current fit
With both it look likes when you add in the seat, seat-to-bar distance will be significantly shorter on the medium due to the differing seat tube angles - more noticeable vs the 2017 HT. Will have similar effect on the Large size, it will be a bit shorter. I think that + Ape seals the deal on the Large

Orbea Rise L vs Turbo Levo HT Large

Orbea Rise M vs Turbo Levo HT Large

Thanks for all your help

 

[Jfive]

The results were very similar - Large is a very close match to current fit
With both it look likes when you add in the seat, seat-to-bar distance will be significantly shorter on the medium due to the differing seat tube angles - more noticeable vs the 2017 HT. Will have similar effect on the Large size, it will be a bit shorter. I think that + Ape seals the deal on the Large

Orbea Rise L vs Turbo Levo HT Large
View attachment 79140
Orbea Rise M vs Turbo Levo HT Large
View attachment 79141

Thanks for all your help

Have you received your Rise? I'm curious to know what the RAD measurement is.

 

[Phoenix]

Have you received your Rise? I'm curious to know what the RAD measurement is.

Yes, I ended up with a Large, but returned it.
I did however play with the RAD measurements (including the lying on my back with the bike on top lol)
Out of the box the RAD was 86cm, which was in theory about 3cm above 'ideal'. Rotating the bars towards the seat and moving a spacer above the stem got that down to 83cm, which felt comfortable. At 5'11" with 34 Inside leg and long arms, I felt like I was definitely at the lower end of sizing for a Large
Hope that helps

 

[Jfive]

Yes, I ended up with a Large, but returned it.
I did however play with the RAD measurements (including the lying on my back with the bike on top lol)
Out of the box the RAD was 86cm, which was in theory about 3cm above 'ideal'. Rotating the bars towards the seat and moving a spacer above the stem got that down to 83cm, which felt comfortable. At 5'11" with 34 Inside leg and long arms, I felt like I was definitely at the lower end of sizing for a Large
Hope that helps

Thank you! That helps for sure. I’m 5’10” but my RAD is 77cm so the large is definitely too big for me. Did you get a medium instead or a different bike? If a diff bike, I’m curious to know why?

 

[Phoenix]

Thank you! That helps for sure. I’m 5’10” but my RAD is 77cm so the large is definitely too big for me. Did you get a medium instead or a different bike? If a diff bike, I’m curious to know why?

Option 3 : No new bike ( but I would have stuck with the large )