When did stack & reach become a thing?

[El Chaba]

I confess to being slightly annoyed by the terms….

[Mark McM]

Originally Posted by terry

If I buy a used bike now I look for 57 square and 73 parallel and I’m good to go. I do t like long HT’s but other than that does stack/reach matter?

Stack/Reach matters as much as Seat tube/Top tube does, because they both are used the express the same basic frame dimensions.

It takes more than 1 or 2 numbers to describe frame geometry, but the dimensions of primary importance are the vertical and horizontal size of the frame. When top tubes were horizontal, this was usually done by specifying the seat tube and top tube lengths. This wasn't precise, because the seat tube angle also affected the reach to the handlebars (and to a lesser extent the height of the bars also), but it was a convenient system because the two dimensions could be directly measured on the frame. When sloping top tubes became popular, it became harder to use direct measurements of frame tubes to adequately describe the vertical and horizontal size of the frame. So the Stack/Reach system was developed, which measured the vertical and horizontal frame dimensions referenced to the same common fixed point, the bottom bracket shell. In a lot of ways, this system made more sense, because it decoupled frame angles from the linear frame dimensions. Plus, there's a certain logic to specifying frame dimensions with respect to the BB, since riders are generally fitted to a bike using the BB as the starting reference point.

[retrofit]

Originally Posted by Mark Davison

Stack and reach was in use when I bought a Cervelo R3 in 2011. It gave a good way to compare possible handlebar positions on two different size R3s (which have sloping top tube geometries.)

As early as 1999, for the P2K model and other triathlon models Cervelo geometry charts and/or diagrams listed "Vertical Dimension" and "Horizontal Dimension," measurements that would later be called stack and reach.

It appears that by 2004 Cervelo started using "stack and reach" in their geometry charts on road models -- for example, the geometry chart for the 2003 SuperProdigy did not have S/R listed; the geometry chart for 2004 SuperProdigy did have stack/reach listed.

Level top tubes, by the way.

(All this according webpages archived by Internet Archive Wayback Machine.)

[Dave]

Stack and reach make it much easier to compare frames. Once you have figured out your preferred stack and reach, it's relatively easy to compare the fit. The only snag is that reach can only be compared directly at the same stack height. If you're comparing two frame sizes with a 20mm difference in stack height, subtract 6mm from the reach of the smaller frame, assuming that 20mm of spacer would be used to match the stack of the larger frame. That will correct the reach.

The seat tube angle then only affects your choice of seatpost setback. Every degree of change to the STA changes the setback by 10-15mm, depending on saddle height. The saddle setback is set relative to the BB, so it remains unchanged from one bike to another.

As an example, my last frame had a 527mm stack and 383mm reach. I set it up with a -17 degree (horizontal), 100mm stem and no spacers. I now have frame with a 509mm stack, but use a 15mm taller headset top cover to get the total stack within 3mm - close enough for me. The new frame had a 373mm reach, but after adding 15mm of headset top cover, that reduced the reach by another 4-5mm. I chose a 10mm longer stem.

Since most stems come in 10mm increments, there may be a small difference in reach to the brake hoods, but there's a little adjustment possible in hood position.

The frames both had the same STA, so seatpost setback could remain the same.

[dgauthier]

I thought "stack and reach" became a thing because threadless stems are so difficult to adjust compared to threaded stems.

With threaded stems if you thought your bars were too low you loosened the stem bolt, slid the bars higher, and tightened it again. (Nobody thought about "reach" because your bars already felt good because they were the right height.)

With threadless stems you can only raise your bars:

(a) *if* you have some spacers laying around, and
(b) *if* your fork head tube wasn't cut too short, and
(c) *if* you aren't exceeding the maximum head tube length recommended by the fork manufacturer.

After the trip to your LBS for the extra spacer, and after you carefully adjust the headset bearing preload when you put the whole thing back together, you're lucky if you moved your bars half a centimeter.

(I could swear Grant Peterson wrote an article about this!)

So yeah, with threadless stems you'd better know your "stack and reach" after a careful fitting, because once that stem gets clamped to the fork, it isn't going anywhere.

[Mark McM]

Originally Posted by dgauthier

With threadless stems you can only raise your bars:

(a) *if* you have some spacers laying around, and
(b) *if* your fork head tube wasn't cut too short, and
(c) *if* you aren't exceeding the maximum head tube length recommended by the fork manufacturer.

Or if you have one of these:

[benb]

I think I became aware of it when shopping around 2013 and thought it was important by around 2015.

I don’t recall being aware of it when I got my Serotta in 2007 or my BH in 2011.

In general I do find it much easier to compare bikes with stack and reach.

[ripvanrando]

I was going to say it was Cervelo.

Why? Not sure other than their seat tube angles are 73 degrees for all sizes and to get proper torso balance over the pedals, that angle does not work well for me even with the saddle slammed all the way back. It seems to me that focus only on stack and reach regrettably takes seat tube angle out of the fit equation

[Peter P.]

Originally Posted by ripvanrando

I was going to say it was Cervelo.

Why? Not sure other than their seat tube angles are 73 degrees for all sizes and to get proper torso balance over the pedals, that angle does not work well for me even with the saddle slammed all the way back. It seems to me that focus only on stack and reach regrettably takes seat tube angle out of the fit equation

Cervelo's design seems to adhere to Lennard Zinn's theory of frame fit. Decreasing the seat angle as frame size gets larger closes up the hip angle and leads to injuries and discomfort, particularly for taller riders. He suggests keeping the seat angle at 73 and using long cranks to get the proper fit, which is why Zinn offers custom crankarms in a myriad of lengths.

Originally Posted by e-RICHIE

It’s a fallacy. Head tube lengths in isolation mean nothing, or little to be kind. One needs to be reminded that the bottom of the head tube is a function of many dimensions, fork stack, frame drop, and head tube angle among them. Without keeping the discussion wide and including these variables, the actual finished (overall) length isn’t as telling as some would like to believe.

Yeah, but aren't all the specs in bold you mentioned tied to the bottom location of the head tube? You could theoretically make the top end of the head tube as tall as you want, in effect raising the bars, then just connect the seat tube and head tube with a sloping top tube. Isn't that what stack is all about?

Help me understand.

[RoosterCogset]

How well does stack and reach help define this bike's fit?

https://www.condorcycles.com/product...nt=36249781834

[Dave]

If you know that a 73 degree STA doesn't work, then you can focus on the few companies that offer something less. Some offer 72.5 in the largest size.

I assume that you already use a 25-32mm setback post.

[avalonracing]

Originally Posted by Mark McM

Yes, it was at 7:53pm, just before "That 70's Show" came on at 8pm.

Stack and Reach, the best cop show since Starsky and Hutch.

[Dave]

Originally Posted by RoosterCogset

How well does stack and reach help define this bike's fit?

https://www.condorcycles.com/product...nt=36249781834

If measured correctly, it's no different than any other. Tough to buy any bike without a geometry chart.

[ripvanrando]

Originally Posted by Peter P.

Cervelo's design seems to adhere to Lennard Zinn's theory of frame fit. Decreasing the seat angle as frame size gets larger closes up the hip angle and leads to injuries and discomfort, particularly for taller riders. He suggests keeping the seat angle at 73 and using long cranks to get the proper fit, which is why Zinn offers custom crankarms in a myriad of lengths.



Yeah, but aren't all the specs in bold you mentioned tied to the bottom location of the head tube? You could theoretically make the top end of the head tube as tall as you want, in effect raising the bars, then just connect the seat tube and head tube with a sloping top tube. Isn't that what stack is all about?

Help me understand.

I have a custom Zinn. It used to wear 200 mm cranks.

I don't think you understood what I was trying to say. If the STA is too steep, you cannot position the torso or center of mass properly resulting in too much weight on the hands. Knee over Pedal is hogwash.

This link explains my feeling on the topic in more detail

https://www.stevehoggbikefitting.com...or-road-bikes/

[mhespenheide]

Originally Posted by ripvanrando

It seems to me that focus only on stack and reach regrettably takes seat tube angle out of the fit equation

They're supposed to take the seat tube angle out of the frame measurement reporting, because there's an interplay between seat tube angle and top tube length that not everyone is familiar with.

If you're a discerning rider, stack and reach by themselves are not enough. Neither are seat tube and top tube length enough by themselves.