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Stem Length vs Height - Comparing Adjustments

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Stem Length vs Height - Comparing Adjustments

Old 12-30-21, 07:45 PM
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Noonievut
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Stem Length vs Height - Comparing Adjustments

I know this is personal and the best approach is to make minor adjustments and ride, further adjustments as necessary, etc. However, Iím curious if there are some generalizations with respect to say, lowering stem height 5mm vs. 5mm further reach. So I know have a plan.

I have a new bike, and a bike Iíve ridden for 10+ years. Not surprisingly the old bike fits like a glove. New bike feels good, and Iím down to some minor tweaks to dial it in. I feel a *bit* close to the bars and can get a 10mm longer stem, or drop the bars. When I take measurements (note - same saddles, pedals), the new bike is like 7mm shorter reach and a couple mm higher bars...so the closer to the bars Iím feeling makes sense.
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Old 12-30-21, 09:00 PM
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I also find that a change of a few millimeters makes a big difference in comfort and performance.
I think you'll like this stem comparison site (link below). It allows you to input specs from two different stems and get a sense of how that will change your bike fit.
Stem Comparisons
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Old 12-31-21, 11:00 AM
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In a related matter...

I was getting different reach measurements and finally figured it out. On the new bike I put on some bars I really like (for gravel). I had a 100mm stem before the new bars and all was good (slightly shorter reach but that was fine). So I add the bars, go ride and feel cramped. Use a 110mm stem and that was better but still not sure.

Reach from saddle to top of bars is the same, but the handlebar reach is 10mm longer on road bars. I just figured the longer GRX levers would be longer, but the road bar is still longer by 10mm.
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Old 12-31-21, 11:31 AM
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Years ago I had the thought that if the handlebars were located on an arc around my shoulder sockets it should matter relatively little exactly where in that arcv they were since with the same arm bent, my shoulders (and therefore the rest of my body) doesn't move. So I drew my old raining bike in profile with a sketch of me on it. Added my poor;y fitting fix gear/commuter to the drawing, then the arc about my shoulders. I then came up with a horizontal stem that went from the very high and close headtube to the arc. 180mm! Had that stem made. First ride - 75 miles in the hills north of Seattle, fixed. A breakthrough! Loved it.

So I looked again at my drawing. The short portion of the arc where you would want handlebars was a near straight line. The straight line had a "slope" (very conveniently!) of 1cm up for 2cm horizontal. Perfect for the old days of horizontal quill stems.

I still use that 1:2 25 years later. Now I ride with a lot of forward bend. Ex racer, long and skinny. Wind resistance and wind have been my enemies forever. Someone who rides more upright might be closer to a 1:1 ratio. 2:3 might be a good starter for most.

I see this as a two pronged approach. 1) find the ratio that works for you. (A photo of you in normal riding position from the side to locate your shoulders relative to your handlebars and that arc/line.) 2) the reach/height/location of that line. 2) determines how aggressive that bike will be. 1) determines whether the bike will be long reach (time-trial like or Harley chopper) bike or a compact (track bike or sedate English 3-speed like) ride
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Old 12-31-21, 12:09 PM
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Originally Posted by 79pmooney View Post
<snip>"slope" (very conveniently!) of 1cm up for 2cm horizontal.<snip>
Exactly what I've found. So it you go up 1 cm and out 2 cm, your hip angle won't change.
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Old 01-02-22, 02:53 PM
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Originally Posted by 79pmooney View Post
Years ago I had the thought that if the handlebars were located on an arc around my shoulder sockets it should matter relatively little exactly where in that arcv they were since with the same arm bent, my shoulders (and therefore the rest of my body) doesn't move.
I used to think similarly but Iím less sure now. Iíve noticed that if my arms are angled more forward and up (more forward reach) I feel more tendency to pull myself forward on the saddle when Iím pedaling hard enough that Iím having to pull a lot on the bars to keep myself on the saddle.

It seems to help to have the shoulder to hand alignment angled down and more nearly parallel and opposed to the downward pedal push from hip to roughly the forward pedal position for those times that Iím really pedaling hard in the saddle.

It also seems to work about as well (just in terms of doing the work, not aerodynamics) to be slightly more upright on my touring bars but with arm angle similar to what I would have in the drops. This has also encouraged me to take the approach of minimizing the extension of hoods if I run drop bars by using my old non-aero levers. Again it seems to reduce the tendency to pull myself forward on the saddle.

Obviously, these things all seem to work differently for each of us, and I wouldnít say Iím through with experimenting on ways to optimize the riding positions for my riding style.

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Old 01-02-22, 09:44 PM
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Originally Posted by ofajen View Post
I used to think similarly but Iím less sure now. Iíve noticed that if my arms are angled more forward and up (more forward reach) I feel more tendency to pull myself forward on the saddle when Iím pedaling hard enough that Iím having to pull a lot on the bars to keep myself on the saddle.

It seems to help to have the shoulder to hand alignment angled down and more nearly parallel and opposed to the downward pedal push from hip to roughly the forward pedal position for those times that Iím really pedaling hard in the saddle.

It also seems to work about as well (just in terms of doing the work, not aerodynamics) to be slightly more upright on my touring bars but with arm angle similar to what I would have in the drops. This has also encouraged me to take the approach of minimizing the extension of hoods if I run drop bars by using my old non-aero levers. Again it seems to reduce the tendency to pull myself forward on the saddle.

Obviously, these things all seem to work differently for each of us, and I wouldnít say Iím through with experimenting on ways to optimize the riding positions for my riding style.

Otto
Very simple solution: don't do that. Don't be using your arms for anything other than steering, braking and supporting a very small amount of your torso weight. Just sit there and make your legs go around. Set up your saddle fore-and-aft so that you can briefly take your hands off the bars without sliding forward on the saddle. Use the stem to adjust reach, not the saddle.

There are several ways to train yourself to pedal smoothly. This video is what I did to get the hang of it - all the stuff she says including the rollers, though I did exactly what she's telling us to do and just found this video this evening. You're doing it right if you have almost no upper body motion. Another test is to pedal very fast, say 120 cadence without bouncing on the saddle. It did take me a few years to get it right. For one thing, this needs muscles and neuromuscular coordination which can only be developed by cycling. It's worth it though. Life is long.

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Old 01-03-22, 09:50 AM
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Originally Posted by Carbonfiberboy View Post
Very simple solution: don't do that. Don't be using your arms for anything other than steering, braking and supporting a very small amount of your torso weight.
Thanks but there is nothing there I donít already know and do to the extent possible. Saddle position is good, and I use that same test. Bear in mind I ride SS on platform pedals. I push through the bottom more than most folks think is possible without clips. Still the physics requires a counter force on the bars or I will push off the back of the saddle. Same as a sprinter reaches a point of pulling up on the bars. Itís that level of effort Iím talking about. The one that can lift you out of the saddle. You may be able to manage torque, power and cadence differently with a geared bike, so you may be able to avoid this more.

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Old 01-03-22, 12:53 PM
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Originally Posted by ofajen View Post
Thanks but there is nothing there I donít already know and do to the extent possible. Saddle position is good, and I use that same test. Bear in mind I ride SS on platform pedals. I push through the bottom more than most folks think is possible without clips. Still the physics requires a counter force on the bars or I will push off the back of the saddle. Same as a sprinter reaches a point of pulling up on the bars. Itís that level of effort Iím talking about. The one that can lift you out of the saddle. You may be able to manage torque, power and cadence differently with a geared bike, so you may be able to avoid this more.

Otto
I get it. Like that first remark in the video - you can't do this in platforms. You have to have some sort of foot retention to be comfortable when going hard. As soon as toe clips were available in the 1890s, most cyclists had them. All modern bike fitting is based around the idea that the rider will have foot retention. Like everything, it's all about choices.
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Old 01-03-22, 08:52 PM
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Then there is this video that basically says to not worry about your pedal stroke and use what is comfortable for you.

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Old 01-03-22, 09:01 PM
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Then there is this video that basically says to not worry about your pedal stroke and use what is comfortable for you.

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Old 01-05-22, 01:57 PM
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Stack affects reach very little because headtubes are not perfectly vertical. But, the angle is slight enough that the trigonometry calculation on the angle means you are multiplying the reach by 0.995 or 1.005 when you raise or lower the stack by normal amounts. Those numbers are made up, but just to illustrate how minor it is. So dropping the bars won't affect reach. That's reducing stack, which reduces hip angle.

Set the stack the same as the other bike first, then measure the reach on the new bike, then buy the right length stem to attain same reach as old bike. You probably were able to fiddle with the saddle height and setbacks well enough to get those same for same to the old bike.
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Old 01-05-22, 10:28 PM
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Originally Posted by Sojodave View Post
Then there is this video that basically says to not worry about your pedal stroke and use what is comfortable for you.
There's always lot of, I would hope, silliness about these discussions. What is carefully never mentioned is that the object of the "smooth pedaling" game is not to apply some even force on each pedal. Positive force on the upstroke and the lack thereof is a straw man, trotted out as though this were some important information. What's never mentioned is that the object is to apply as even a total torque on the bottom bracket as one can, while not overworking the more minor muscles. Looking at force on each pedal separately is silly. We use both pedals, all the time. OF course this only works with foot retention.

The real object of the smooth pedaling game is to reduce leg force variations at the same power as much as is practical for the individual rider. Reducing maximum force results in greater endurance. Thus using EPO gave Lance such a great aerobic advantage that, with endless training,, he could pedal at 110-115 in time trials, greatly reducing maximum pedal force and increasing muscular endurance and thus average speed.

Training is the process of changing the uncomfortable into the comfortable. Starting with the comfortable and maintaining that level of effort doesn't get results.

The above said, it should be obvious that as power increases, the major movers will be able to develop more force at the most favorable knee angles and thus BB torque will become more uneven as power increases, though training to pedal smoothly at lower powers will still have a positive effect on average speed.

It's easy to tell if a rider is pedaling smoothly by looking to see how still their upper body is. I find it interesting to compare the pedaling of say, TdF riders and real endurance riders who operate more in zone 2. Here's a guy riding the old Furnace Creek 508:
Look at that, eh? A riding buddy of mine won it in 29:10 some years ago, It's a tough race.
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