I’m not a master with fitting, but if your hands are more like A, it sounds like bar width is too wide.
Apologies in advance for the broken record, but your issue could be hip rotation. If you are sitting with your hips relatively vertical and your sit bones firmly planted, them you are likely just leaning forward to get to the HB, which places extra strain on your neck and lower back.
I came up with a new visual the other day that may help grasp the concept…think of the curve of your butt as an arc that you are sitting on…you want to rotate that arc forward so that you are on the front half of the arc, not the middle or back of it.
1 Like
Thanks for the reply. Yep. That’s something I’m aware of. I do think my fitter had made me aware of that when I had the fit done.
I had a 5 hour ride yesterday and my neck wasn’t happy at the end. It was good for 3 hours then I started feeling it. I do feel balanced on the bike and don’t feel like I’m reaching much if at all. And I’m usually pretty light on my hands so there’s definitely not too much weight up front. And during my ride, I did try to make sure my hips rolled forward a bit as you’re describing. I did try to change hand positions a lot as well.
So I still have some investigating to do. I still will work on some stretching and strength exercises as that definitely won’t hurt.
1 Like
For those that may need this.
Link is not working for me:
It’s an add on to the Reverb (only) to either get you farther forward or farther back on the seatpost.
I know I have my saddle slammed back on my XC bikes and most other bikes I’ve had are the same way. With the STA getting steeper, this could be a good choice.
Hump
OK, but you might want to fix your link. I checked your post and you have the following:
Looks like you have 2 extra letters in your link vs what I found when digging through their links.
The second one shows what I got from the link after getting to the product page you mentioned.
Outside of the link issues, the product is interesting.
That was me picking to share the link from my IPhone straight from the website.
OK, I went ahead an nuked those extra characters from the link in your post, and it works properly now.
1 Like
If a Trigonometry guru can assist.
How much does a saddle tilt change as the MTB sags?
Say you start static at 3degrees nose down. Let’s assume 11mm of sag on a 110 shock and a saddle height of 72.5 to saddle center.
Will the nose go up 1 degree, .5 a degree??
Hump
- ETA: I may have misread your info above, but if this means you are using 10% sag for a 110mm total rear travel (shock is probably in the 50-60mm actual stroke length), that is a start as covered below. Just trying to make sure I understand the values you shared.
- Then we still would want to know the front sag info and head tube angle to get the end angles.
The better general data point is relative sag in % and knowing total travel:
- Say 25% of sag on a 100mm rear travel bike = 25mm drop at the saddle in a super simple example.
The reality is that this all gets more complicated since you presumably are also setting sag at the front suspension. So you you have to know sag/travel on both ends, and to a degree you also should know the head tube angle to get most accurate since the front sag is not vertical (while we simplify and assume rear is “vertical” but probably isn’t…).
How’s that for making a simple question complicated? 
1 Like
So simple!!
Let’s take the Epic Evo, in the low setting. That’s a place to start at least since I have one and many others have asked about it recently.
I can’t off the top of my head remember the sag % numbers, but I’m sure all that can be checked.
I’m asking this, since many riders get setup on a size cycle and aren’t transferring those dimensions to the MTB while at sag, which to me, makes since.
It may not mean much, but I know I’ve checked saddle set back static and at sag, and even with a shorter stroke, XC level of sag, it does move the saddle back in space when you are sitting.
Hump
1 Like
- Generally speaking, that’s what I would expect based on the following:
It seems the typical setup is more % sag at the rear (20-30%) while front sag is less (10-20%). Then consider the delta that the head tube angle makes that shorter front sag even less in a pure vertical displacement.
Like you mention, I would be hesitant to use a fitting bike for MTB setup (as yet another reason I am not a fan of fit bikes). I prefer to fit people on their actual MTB with suspension set at the start of the fit if it’s not already dialed in to their preference.
But to boil it down without any hard geo #'s, I’d guess you are talking about 1-2* difference in more upward pitch at sag. In any event, even if I transfer setup numbers from any source or take a stab at an initial setup, it is subject to change on the trail. The more active nature and wider pitch range in MTB may well lead to deviated setup vs what is found in a static fit inside.
OK, I am not in love with my sketch as I think I might be rushing, but I have some basic results.
-
With some rough info per Epic Evo in Large and once you apply what might be typical sag values… I get nearly no angular change!
-
The angle of the head tube angle alters height delta more than I expected when compared to the more vertical motion at the rear end. So it may well be that it is as close to level as practical unless someone is running a larger delta in sag % between both ends than what I shared above.
-
I was expecting more due to the head tube angle, but it may be a non-factor in the grand scheme.
-
-
If someone runs a lot more sag in the rear than the front, I was getting close to that 1* estimate above, so it might matter for those with a setup that is sort of “choppered” with a really low rear end.
ETA: a quick hack to try would be to take a small bubble level and tape it to your frame with no rider, set dead level on the bubble. Then hop on at desired sag and see if the bubble moves and which direction.
Or, if you happen to have one of those gravity angle finders or similar app on your phone, use those to get some real angular values. My interest is up now and I may have to test this if I get time this week to see if my quick sketch is way off or not compared to reality.
For full suspension with regular sag, it may be a non-issue. For hardtails though, and particular ones with longer travel forks, this could be far more important. But the real angle change may still be minor even though it is a solitary drop which might mean a larger issue to actually adapt setup for with saddle angle.
I can tell you that, I take a laser line projected up thru the BB.
Check static to nose of saddle, then sit on bike and check the same dimension, and I’ve seen 1 to 2 cm distance change.
Static, saddle at 5, sagged, at 7 (cm) behind BB
Hump
Jeff Lenosky did some videos on the difference he saw between fully suspended and a Hardtail.
He had matched his HT geo to his fully and found out that at sag, the bike lengthens.
I’m always in a quest for optimal position, and for me, that’s seated. I am looking for speed and power transfer. What the saddle does while I’m standing doesn’t make much difference, since it’s usually on a drool post.
Hump
Hump
- With what control on the bike motion forward / backward?
- Meaning, what part of the bike is held stationary in the horizontal direction?
I am guessing something is “moving” rearward which may well indicate a different motion than what would relate to an saddle angle change that you started with in this question.
So the info on bike direction along with actual sag values are necessary to really understand why you are seeing what you are seeing in the horizonal nose delta distance.
- I would need to know exactly what this means. Are we talking about “Reach” between saddle and bars or something else?
And as ever, knowing sag is essential to understand unladen and sag deltas.
I redid my sketches over lunch and have a very good model for experimentation now.
- This shows a Large size Epic Evo in
- Red at Unladen height.
- Black at Sagged height, with 20% sag at both ends just to show one example.
- This is with the fore-aft location of the BB held, so the frame is not “moving” forward or backward in this example. It does show the relative drop and angle change of the frame, along with wheel shift in the horizontal since the tires are held flat on the ground plane.
- This pic shows a measurement between the effective top tube at both heights.
- Note that the angular difference is out to the 3rd decimal place, so it is dead level for all intents and purposes. Meaning there would be no need to alter saddle angle between unladen and sagged heights.
I can quickly alter the sketch once I get your sag data (@HumpDiesel) in either % of total travel on each end, or actual distance sagged. Then we can see more of what you have in your use case. I can also change from restraining the horizontal movement at the BB to the front or rear wheel if those are closer to what you are doing in your evaluations.
But in short, unless you have a very different amount of sag front vs rear, I don’t think the delta you are getting above is from angular change. Something is more likely moving in the horizontal plane between your unladen and sagged states.
-
Evaluating horizontal shift with BB held vertical, we see a slight shift at the rear, with nearly 10mm at the front.
-
With an even 20% sag at both ends, there could be a horizonal delta at the saddle nose if you locked the front tire, which would mean the bikes moves “forward” at the saddle 10mm or so.
Here is an example of 10% front sag with 30% rear sag (what I mentioned as “choppered” above).
- There is about 1* rearward tilt which would impact saddle angle.
- There is 12mm rearward shift at the saddle (again holding BB in horizontal location)
So this may correspond with the laser measurements you mentioned above.
1 Like