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Stack/Reach numbers, when they don't equate

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Crockpot2001

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Discussion starter · #1 ·
I created a spreadsheet that helped me determine what available bikes met my needs when I chose my XL Camber Expert. Stack and reach played a huge part of my choice. The bike fits great but I may size up to XXL for my next net one so I can reduce stem length from 75 to 55cm.

I read so many times where people claim this bike or that, despite contradictory numbers, rides much bigger. To be specific, people say the Trek stash is great for really tall guys. It is not much bigger than a Large Specialized I was sure stack and reach took out the hocus pocus of the ETT length. What gives?
 
#2 ·
Discussion starter · #3 ·
asollie said:
You might be interested in my spreadsheet: https://docs.google.com/spreadsheet...m/spreadsheets/d/1ByMVDtz6T8EawBQh1gcRDPqN8oJC3tCy-kdNzjuRI8M/edit#gid=36376247

I measure bikes by the distance between the BB and the top of the headtube, which is sqrt(stack^2 + head^2). I think it gives a more fair picture of how big the bike is that ETT does.
Click to expand...
Yup! I totally copied what you had done and did it on my own too. Thanks! It shows how few really big bikes there are. I just don't fell all that big at 6'4" yet only a handful of relatively expensive bikes work. Not that every company should make stuff in my size or bigger (economics 101) but C'mon! Stack numbers are silly low for all but Specialized. I'd love a hightower but don't care to run 40mm of spacers, a riser bar and flipped stem.
 
#4 ·
Crockpot2001 said:
Yup! I totally copied what you had done and did it on my own too. Thanks! It shows how few really big bikes there are. I just don't fell all that big at 6'4" yet only a handful of relatively expensive bikes work. Not that every company should make stuff in my size or bigger (economics 101) but C'mon! Stack numbers are silly low for all but Specialized. I'd love a hightower but don't care to run 40mm of spacers, a riser bar and flipped stem.
Click to expand...
Yeah, Specialized seems to be the only big company that is making genuinely large bikes. Rocky Mountain and Intense have a few big bikes too. Santa Cruz is among the worst.
 
#5 ·
Have you actually ridden whatever bike people say "rides bigger"? Do you agree with the assessment?

I've met a lot of people that for whatever reason, don't believe numbers can convey important information; that you just have to go by feel. Everything from bike size, shock springs/air pressure, I even had one guy tell me gear ratios don't mean anything and you should go by subjective feel (guy was trying to tell me that it wasn't possible to compare one cassette to another).

My point being just because someone said something on the internet, doesn't mean they know what they're talking about. For me, reach is pretty much THE fit parameter (everything else I can work around), and of the bikes I've sat on, they all fit more or less like I expected them to based on reach.
 
#6 ·
Crockpot2001 said:
Stack numbers are silly low for all but Specialized. I'd love a hightower but don't care to run 40mm of spacers, a riser bar and flipped stem.
Click to expand...
On a mtb, stem rising 'up' is the standard set up.

I agree though, the Treks are fairly low.
Tall enough for me though, at 6'5" my Fuel EX 23" has a 5mm riser bar, flat stem and 15mm of spacers. I always want at least that amount of room under the stem for the Velcro strap of a gas tank bag. If you don't use those, get a Carbon cone spacer that makes a nice smooth transition to take up the space.
 
#7 ·
Im only 6'3 (but longer than normal legs) found it more difficult that I thought it would be buying a bike.... I also ended up with a Specialized. Side note, why do manufactures cut the fork steerer off, seems like a free way to make the bikes more "adjustable" for customers by leaving an inch above the stem.
 
#8 ·
Hey guys, new to this forum, 6'6" with a 37" inseam.

I agree that some bikes just "feel" bigger despite what the manufacturers measurements say. I rode Yetis back when 29ers were too slow to compete, then moved to the Santa Cruz Tallboy LTc, and most recently a Bronson. All were XL frames.

Out of all of those, the LTc was the only one that fit well. The reach and stack numbers of the Bronson should have made it just as much fun, but I neglected one important number...

When you extend the seatbost 14" out of the seat tube and ride in the stratosphere, the SEAT TUBE ANGLE is very important. On a slack seat tube angle, that extension increases your reach and ETT. The "modern mountain bike geometry" is "low and long" which should be great for tall riders. However, they counter and try to make it more efficient by steepening the seat tube angle so you have more leverage over the cranks and a more balanced weight distribution between the front and rear axle. This loses you precious cockpit space and makes it impossible for taller riders to feel stable. I had the same issue of the Trek Remedy and Slash, but the Stache actually felt pretty good. I'm thinking of picking one up now that the Bronson is with a new owner.
 
#9 ·
BSamps said:
When you extend the seatbost 14" out of the seat tube and ride in the stratosphere, the SEAT TUBE ANGLE is very important. On a slack seat tube angle, that extension increases your reach and ETT.
Click to expand...
You're exactly right. I wish there was some way to calculate the Actual Top Tube length given your needed distance from BB center to your seat. I don't think it is possible though, since seat tube angle is meaningless when you don't know where the "seat tube" starts from. I think you'd have to get the distance and length from the bottom bracket to the top of the seat tube, and then the angle from that point at which the seat tube protrudes. If you had those numbers I _think_ you could come up with some complicated trig to figure out how far back you'll be once you raise the seat to a certain height.

I think once you did so, you'd realize that for a lot of very tall riders, their seat is positioned so far back that they would probably do better with much longer chain stays than what is currently en vogue.
 
#10 ·
asollie said:
You might be interested in my spreadsheet: https://docs.google.com/spreadsheet...m/spreadsheets/d/1ByMVDtz6T8EawBQh1gcRDPqN8oJC3tCy-kdNzjuRI8M/edit#gid=36376247

I measure bikes by the distance between the BB and the top of the headtube, which is sqrt(stack^2 + head^2). I think it gives a more fair picture of how big the bike is that ETT does.
Click to expand...
Thanks for the spreadsheet. I picked the XXL tallboy specifically because of its long reach. All other bikes just felt to small. XL Ripley and even the hightower wouldn't fit me without a 90mm stem. I like a low stack and am glad Santa Cruz keeps it low. its easy to raise a stem even if you don't like the look, but it's not possible to lower it. A negative rise 50mm +-6 degree only gets you -6mm. FYI I'm running a a 20 riser bar with the stem flipped for a 14mm stack increase. Still playing around with setup. My xc race bike stack height is 40mm lower.
Seat tube angle doesn't really matter. As long as you have the range to move the seat forward/back to the same relative position over the pedals. Evil is the only bike that comes to mind where you can't push the seat forward enough.
 
#11 ·
Thanks for this post. I'm also 6'-6" with a 37" inseam, and have always had some difficulty finding bikes long enough. I've had great luck with the Turner 5Spots in XXL and even an XXXL, but the 27.2" top tube was long even for me.
I'm hoping to buy/ build a new bike this spring and am looking into options for 160mm travel trail bikes, preferably with DW link suspension.
I'm not fat- only weigh 190 lbs.

I'm looking into Turner RFX 27.5- however, Dave thinks I'm too tall.
Evil Wreckoning 29, but not stoked on single pivot suspension, even if it is Dave Weagle designed.
Trek Slash, but crazy expensive as frame is almost $ 4000.

Any other bikes you guys would recommend?
Santa Cruz are all too short for me, and the TallBoy is too steep of head angle for my preference. Looking for a 66 degree preferably.

Thanks.
 
#12 ·
Spinster said:
Any other bikes you guys would recommend?
Santa Cruz are all too short for me, and the TallBoy is too steep of head angle for my preference. Looking for a 66 degree preferably.

Thanks.
Click to expand...
Have you looked at the Niner RIP 9 29, Maxx FAB4 29 or Specialized ENDURO EXPERT CARBON 29?

Almost nobody makes 29ers as slack as you want. My Carbine 29 is great but its only 140 in the rear.
 
#13 ·
Thanks for the feedback.
I would have bought an Enduro 29, but I may need to swap out a lot of parts to make it fit.
The seat post is only 125mm of travel, and I usually need some spacers under my stem as well. The top tube is less than the Turner RFX-which is my preferred company of choice as they have been great to me on several different bikes.
Also, I had concerns with the Enduro seat tube angle of 75 degrees. as it may not get me back far enough at full extension. Its hard to know as I live remote- southern Colorado, and no shops seem to stock XL Enduros.. or XL anything long-travel for that matter.

A friend in Moab just mentioned the Niner Rip 9 this morning, and I may head over to check that out next weekend.

How do you like your Carbine 29?
 
#14 ·
Spinster said:
I'm also 6'-6" with a 37" inseam, and have always had some difficulty finding bikes long enough.

I'm looking into Turner RFX 27.5- however, Dave thinks I'm too tall.
Evil Wreckoning 29, but not stoked on single pivot suspension, even if it is Dave Weagle designed.
Trek Slash, but crazy expensive as frame is almost $ 4000.

Any other bikes you guys would recommend?
Click to expand...
My people! Glad to know I'm not alone in the universe.

Yeah, I was looking at the Wreckoning too, but I think its just too much bike for what I ride 95% of the time on dusty CO switchbacks. I also agree that Santa Cruz just runs too small (see my failed attempt at my bronson below for proof). However, I've heard RUMORS Santa Cruz will move forward with the XXL Hightower, which would be great. Not a 160mm enduro bike, but very capable.

I personally ruled out RIP 9 RDO based on reach. I threw a leg over a RIP back in 2010, but nothing since. Could be worth another look. The WFO also looked intriguing. I also ruled out the Salsa Horsethief, Yeti 5.5, Spot Rollik 557, and Kona Process.

Right now I'm tracking down a Pivot Switchblade XL to test. The stack is low, but the reach is MASSIVE. Also room for a water bottle and comes "overforked" with a 150mm fork and 135mm rear. With the 17mm riser spacer, the stack is within adjustment range and the HTA slacks to 66.5. I'm excited about this prospect, but want to ride one to be sure.

Lever tried the Enduro29, but I hear they fit tall guys well. I just have a personal thing against specialized that should have no weight on anyone's decision but my own.

alexbn921 said:
Seat tube angle doesn't really matter. As long as you have the range to move the seat forward/back to the same relative position over the pedals.
Click to expand...
Disagree. For ME, the STA combined with a low stack puts my upper body mass way too far forward to enjoy any kind of downhill. Its fine for pedaling, and I understand why you would be fine with it for XC racing, but the STA with a short stack negates any chance of a modern long reach actually improving my comfort level.

On my Bronson, I had the bike fitted with the whole fancy computer tracking program and made sure the riding kinematics were perfect. Then I took it on the Whole Enchilada trail outside of Moab and caused a permanent bone bruise from clenching the TT with my knees. I couldn't get far enough back on the bike to descend with confidence! Not a huge deal in the XC race, but the Bronson is a long travel enduro machine. What gives?

All the geo numbers put it larger than my old Tallboy LTc. Reach and ETT were 5 cm and 2.5cm longer, respectively. I kept staring at the numbers until I was numb in the head. Finally, after reteaching myself basic middle school geometry (yay SOHCAHTOA), I realized the stack and STA were the smoking gun. I knew I wasn't supposed to be able to see faceplate of my stem when descending...

So STA does play a role. Why else would frame manufacturers make a big deal about it on new models? It just does something different for us super tall, gangly guys.
 
#15 ·
Seat tube angle does not dictate saddle position. Most seats have a 3 to 4 inch range of adjustment, add in setback posts and you have 5+ inches of movement from your seat. If your Bronson had the seat to far forward then it was setup wrong or your dropper wasn't long enough. Seat placement is a personal thing that is based off of the BB and cranks on your bike. Seat tube angle only becomes important when you run out of room to adjust the seat. It has zero effect on how a bike handles, pedals, feels. Just like estimated top tube length means absolutely nothing. Reach is the important measurement because its based off your BB location just like your seat is.
Also when your descending your not sitting on the seat so it doesn't influence the handing of the bike.
Edit:
Example of 2 very different seat tube angles, but my seat is in the exact same location relative to my BB. My reach is also identical given the 40mm difference in stem length.
 
#16 ·
Right now I'm tracking down a Pivot Switchblade XL to test. The stack is low, but the reach is MASSIVE. Also room for a water bottle and comes "overforked" with a 150mm fork and 135mm rear. With the 17mm riser spacer, the stack is within adjustment range and the HTA slacks to 66.5. I'm excited about this prospect, but want to ride one to be sure.

Hey, you should talk with Billy, manager of Poison Spider bikes in Moab. He rides a Switchblade and has been happy with it. He is putting on a demo event next weekend in Moab if you can make it.
I'm personally looking for more travel. The Firebird had potential at 170/160, but I have heard it is not an efficient climber, and I live at 9600 feet with most climbs at a couple thousand vert, so bike needs to climb well.
I just looked up the new Norco Range 27.5 which is boasting 170/160 and a decent top tube. They also have a 29er version at 160/150 with an even longer top tube of 667mm, but super short head tube. Can't find anyone who has these in stock yet though.
Cheers.
 
#17 ·
Spinster said:
Hey, you should talk with Billy, manager of Poison Spider bikes in Moab. He rides a Switchblade and has been happy with it. He is putting on a demo event next weekend in Moab if you can make it.
I'm personally looking for more travel. The Firebird had potential at 170/160, but I have heard it is not an efficient climber, and I live at 9600 feet with most climbs at a couple thousand vert, so bike needs to climb well.
I just looked up the new Norco Range 27.5 which is boasting 170/160 and a decent top tube. They also have a 29er version at 160/150 with an even longer top tube of 667mm, but super short head tube. Can't find anyone who has these in stock yet though.
Cheers.
Click to expand...
I have a bead on an XL Switchblade in Golden CO. Just need appropriate riding conditions. Can't quite make the 6.5hr trip to Moab just to demo a bike :(

I'm also intrigued by the Norco Range. Too early to tell, but maybe I'll be looking at that next year...

Good luck in your search!
 
Discussion starter · #18 ·
Glad to see the discussion ongoing.

FYI - There is a guy at the Flagstaff, AZ Absolute bikes who is 6'8" and his name is Nate. I **** you not. He let me test his 2xl Stumpie 27.5+. Maybe we want to get a list going of where Right-sized bikes can be tested or bought.
 
#19 ·
alexbn921 said:
Seat tube angle does not dictate saddle position. Most seats have a 3 to 4 inch range of adjustment, add in setback posts and you have 5+ inches of movement from your seat. If your Bronson had the seat to far forward then it was setup wrong or your dropper wasn't long enough. Seat placement is a personal thing that is based off of the BB and cranks on your bike. Seat tube angle only becomes important when you run out of room to adjust the seat. It has zero effect on how a bike handles, pedals, feels. Just like estimated top tube length means absolutely nothing. Reach is the important measurement because its based off your BB location just like your seat is.
Also when your descending your not sitting on the seat so it doesn't influence the handing of the bike.
Edit:
Example of 2 very different seat tube angles, but my seat is in the exact same location relative to my BB. My reach is also identical given the 40mm difference in stem length.
Click to expand...
Interesting. Is this photo centered on the BB? Its pretty hard to tell from your image. If so, you have managed to maintain the same effective seat tube angle. Yes, the actual tube in which the post runs is a different angle, but the angle to the BB is the same. The Evil Wreckoning is a great example of this because the BB is so far offset from the imaginary junction of the ST and DT.
 
#20 ·
BSamps said:
Interesting. Is this photo centered on the BB? Its pretty hard to tell from your image. If so, you have managed to maintain the same effective seat tube angle. Yes, the actual tube in which the post runs is a different angle, but the angle to the BB is the same. The Evil Wreckoning is a great example of this because the BB is so far offset from the imaginary junction of the ST and DT. View attachment 1124407
Click to expand...
Yes I centered both bikes at the BB. I set up both bikes independently on what felt right and wanted to check how close they were to each other.
You're right about the Evil having a STA that puts it out of range for tall riders. I have seen Evil's with their seats pushed all the way forward and still not in the desired position.
Knee position and seat setback/ height is always your first thing you do to fit a bike. seat tubes from 73 to 67 will usually allow you to put the seat in the correct position. That is the import part of the measurement. The actual angle means nothing.
I run a 200mm dropper so my seat disappears on super steep technical terrain.
 
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