Does moving a seat back just 3/4" really make a difference?
 

I have been having pain just above my left knee cap for a while after a 20 km ride. So I moved my seat back 3/4" and the pain seems to have subsided. While pleased, I was surprised how such a small change can improve my biking experience so much.

This is a comfort bike so I sit almost bolt upright. Perhaps these bikes require a more forward peddle then hybrid or road bikes.

Does moving a seat back just 3/4' really make a difference?

YES it can.

If you have resolved an issue then you have done well. If you want to continue making adjustments to experiment with power/endurance/comfort outcome then record position before and after adjustments then ride the same route and record results.

IMO, the prime objective is to find the fit that allows one to simply ENJOY THE EXPERIENCE

You moved the saddle 0.75" and call it JUST 3/4"? "Just" in saddle movement, in my book, is 1/8" or so!

3/4" is a huge seat adjustment. It almost surely requires a seat height adjustment as well

Yes, I thought it might. So I took it out right after making the adjustment and the height still seems OK. I can almost fully extend my knee for normal riding. Which I believe is the goal. Actually the suspension seat post means the more effort I put into peddling, the farther I can extend my knee LOL,

And .75" I suppose is more then a little for seat adjustments. I thought having the seat more forward with my short legs would be better on this small frame bike. Apparently not.

Now, mark that location with a piece of tape. Carry both the seatpost clamp wrench and seatpin wrench. Note how you feel riding, Try moving the position a little closer to what you had, Better? Do a little more. Worse? Try sliding the seat further still, keeping a record of where you started and the past position, Go (in the direction of the change that makes things better) until your body says "too much" and back off to the last setting.

Moving the seat back means it is probably higher than you started and perhaps should come down. Same rules apply to seat height. You may also find that the best tip for your seat has changed.

3'4" is a huge change. Almost like going out and buying a new bike. (I too consider 1/8" quite real.) But it sounds like you are on to a discovery of what works for you. Keep experimenting. (One equipment change that will make the experimenting much easier is a two-bolt seatpost. Thompson and some of the Nittos come to mind and there are others. Advantage is that you can loosen just one bolt, slide the seat and retighten without changing the tilt or loosen the one, make a small adjustment of the other, re-tighten the first and make incremental tilt changes.

Ben

Emphatically YES!

When I first got my new seat, got the height right and marked with electrical tape. Later, in initial rides, and due to insuficient torque, seat was slipping back. My knees, elbows, and especially lower back, let me know when this occurred. Properly torqued, no problem. I also have a quick check of placing my thumb on the seat railing to see that it is staying in adjustment.

I had a small tiny bb size spot of pain in one knee.
I moved my boom out 1/3 of an Inch,
Problem solved.

Thanks for the insights. I will make a note of where the seat is now for future reference.

It's just nice when things work out.

Not in general.

Yeah, my bike fit tweaks to saddle, stem and handlebar are often in the 1/8" to 1/4" range. If I need to make 3/4" adjustment, it was way off to begin with.

The older I get, the pickier my neck, back, shoulders, knees and hips are. A fit that feels right this week may not next, so I adjust stuff to suit myself whenever I like. Depends on barometric pressure, moon phase and lotto picks.

The "goal" is not to fully extend your knee. I'm assuming you mean fully extend your leg? There should be a slight bend in your knee when at the bottom of your stroke. If you are fully extending you might end up with a knee problem.

^ this, exactly. You're finding what the right position is for you on that particular bike. The two-bolt posts give you very fine control over saddle pitch.

I could not agree more with the advice to get a two bolt seatpost. One came on a new gravel bike I bought and it made such a difference I bought one for my other bike. Great piece to aid in making exacting changes to my seat. I had back surgery in 01 and the seat placement is critical to my enjoyment on any bike. Sounds like you are on the right track and have gotten some great advice from the previous posts. Be safe.

Yes. I try.not to fully extend my leg, but get close at the bottom of my stroke

Those 2 bolt seat posts look like a good idea every time I loosen the bolt the seat angle loosens too. Worse the seat angle positions are WAY too limited Theres only 2 or 3 positions it will lock that are remotely useful. No in between.

yes..
cycling us a game of mm.

Everything is relative. If your seat was too far forward by 3/4", then your 3/4" back is not that drastic. If you are pedaling as fast as before with the same amount of power and no pain, don't sweat it. If your cycling is suffering a bit and you feel too far back, follow the advice above and move it up by 1/8" increments and ride it at each position long enough to see how you like it.

John

I adjust the tilt using the forward bolt, I use the rear simply as a clamp. I note that I dropped the nose of the seat (say) 1/4 turn. Then I can go back exactly, halfway or further as needed, (And yes, I take all three adjusts to the seat very seriously.)

You have one of those posts I hate. (Don't feel bad, There are thousands out there.) I set my old custom up when it was new with a 2-bolt post. All was good until it broke (not something you will see with either Thompson or Nitto; they are both excellent posts). In the early '80s, 2-bolt posts had disappeared from the market. I bought one of the standard single-bolt post. Well the right tilt was halfway between clicks. I got it tight and right - and rode the seat without touching the seatpost for most of a decade knowing if I ever backed the bolt off, I would never get that tilt again. Then one day I saw a new 2-bolt post! It was a 26.8mm MTB post. There was a proper road post next to it for 3 times the price which I didn't have. The MTB post came home with me and got installed with a shim I made. Rode that seat and the proper tilt the next 12 years (and loved that I could adjust it anytime I wanted!)

Ben

That makes sense to me. It never occurred to me that the proper seat position not only effects comfort and healthy knees, But power delivery too. While power and speed is not what comfort bikes are about it does seem like I need less effort to coax this 35 lb bike (with accessories) then I did before. It could just be a perception as their are many variables to consider. But I might try making small 1/8" adjustments to see what effect they have.

I might try the 2 bolt post too. I do like the suspension on the stock post though.

common bike fitting wisdom is that your leg should have 25-35 degrees of bend at the bottom of the pedal stroke.
personally, I would not consider that "almost straight", but those words might mean something different to you.

being able to notice even a 1/4" change in fit on any dimension is not that unusual.

Sure.

IMO, a major fraction of an inch is quite a lot, actually, and can really matter in some cases. People speak of a couple millimeters raising or lowering the nose of the saddle eliminating remaining aches, and moving a small fraction of an inch foreward or rearward making the last little bit of difference.

I've got a very sensitive old injury in the leg, and so saddle position is crucial to my overall comfort level. Minor changes can, indeed, make all the difference. I'm all for fitness and strength improvements ... those are nice. But with injuries involving damaged muscles and nerves, it's hard to sidestep aches without exacting fitment. At least, in my case it is.

I know nothing about bike fit or kinesiology. There is so much info out there on the "correct" setup. When I first started KOPS was the basic starting point and I pretty much used that as a guide. But it has been so long that now I just use the setup from one bike as the starting point on another.

But I do know that, at least for me, there is not a single point on the saddle for all my riding. I have no idea the amount of movement, but I know that I am seated slightly more forward when I'm spinning out in the drops, and slightly further back when I'm grinding up a hill. I suspect it has to do with less extension needed for spinning and more extension, leverage, for grinding.

I tend to error on the saddle further back, than further forward. At 68 and decades of riding, I feel blessed to be able to ride relatively pain free.

John

After some reading and thinking about things recently related to KOPS (knee over pedal spindle) and whether it's really the bee's knees, I experimented by setting my saddle back approximately 1.5 cm.

It was awful. I didn't also drop the seat post a tad, which I should have, and not doing so left my legs feeling much closer to overextending during the pedal stroke. The worst, though, was just the way setting back my saddle changed the angles of my knees and whatnot during the pedal stroke. I was now "behind" the pedals, and I didn't at all like how it felt. I was kind of shocked at how obvious it all was, and I'd assumed that ~1.5cm wouldn't be all that dramatic, and yet it was. I gave it several rides to see if I really felt that way because it was worse, or whether I just didn't like it because it was different than what I was used to. After several rides I still didn't like the effect it was having on my pedaling and my knees, and changed it back.

It can go both ways. In my case what I'd previously dialed in when I first got this bike was at least very close to an ideal for me (I'd used a plum-bob and did KOPS, which some will say is a rubbish technique, but it worked for me and was the "rule of thumb" for ages for a reason), and setting back 1.5cm from that made it worse. If you were in a worse position, of course, then a 1.5cm change might make a dramatic improvement. I'd say if you're not willing to pay a pro for a fit (I haven't paid anyone, just read and experimented and did it myself) then consider just starting out with KOPS and go from there. In my case I sat on the bike in my garage using one hand to hold onto my car while balancing on the bike, got one of my pedals to the 3 O'Clock position with my foot cleated in to the pedal, and dangled a thread with a little weight attached to it from my kneecap to see where in relation to the pedal spindle the weight hung, and adjusted my saddle until it was over the pedal spindle. It's possible that there's a better position for me than this, but I know for a fact now that 1.5cm behind my original position ain't it.

Yup, it's all trial and error from here...

Well, let's see:
1) You managed to have your saddle way too high during the experiment. I would have thought that setting saddle height would be basic. The reason your knee angle changed was that you didn't reset your distance between saddle and pedals. Many riders find they climb better about 1 cm behind KOPS, which may be because they tend to climb in a more upright position.
2) You didn't adjust your hip angle. If you're going to close your hip angle like that, you need to open it back up with the bars if you expect muscle usage to remain the same. Maintaining hip angle is the reason that TT and tri riders move their saddles so far forward. One notices that this far forward position works for them.
3) Of course the other thing is to assume muscle usage will change and retrain your neuromusculsr system for the new position. This is the reason that racers have to train on their TT bikes, a lot. Different positions aren't wrong, they simply require one to train in them. That said, incorrect saddle height is certainly wrong.
4) If one ignores where the center of the earth is w/r to bike position, one sees that there is an angular relationship only between the body parts. There's upper arm/torso angle, hip angle, knee angle at full extension, and ankle/lower leg angle. These angles remain the same, no matter where the center of the earth is. We use the same position whether on the flat, climbing, or descending. Thus using a plumb bob is irrelevant. What matters is being accustomed to a particular set of angles. There are standard angles used by bike fitters which have been found, over the years, to maximize cycling efficiency in the average rider, though there's a good bit of variation in them, depending on one's exact location in the wide world of cycling sport. One notices that "pedal forward" bikes are designed to be ridden in an upright position.