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Assuming one has the correct frame size for one's height, can there be more than one perfect seat post height for the type of riding? I usually ride only in the city with traffic and less than 3 miles one way most of the time.

But when I am doing longer rides I prefer to the seat post higher and my riding body said that there should only be one height- its either perfect or not..

I should say that my bike is an aero carbon road bike which I prefer to use even in the city but also on longer rides in the weekends about 25 miles or so.

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For what it's worth, on my most recent bike I went up a frame size so I could put the seat at the height I wanted without overextending the pist. (I'm a touring rather than racing rider; I spend most of my time sitting and want the seat high enough to use the full leg.) – keshlam Feb 18 at 4:40
up vote 5 down vote accepted

I am a daily commuter and I have been riding (mainly) road bikes on the road for over 40 years.

Comfort is important to me and more so as I spend longer periods in the saddle.

A setup that suits another, may not suit you and vice versa however, there is plenty of information on settings to get you into the ballpark. Improvement requires a bit of experimentation and sometimes a good "eye" comes in handy.

Body position, especially when in motion, is not static. I consider riding position to be somewhat "dynamic" therefore, some range of movement must be accommodated within your static bike setup.

I have found that riding position (mainly fore-aft along the saddle) changes in varying degrees dependent upon multiple factors, E.g.: cycling-fitness level, energy levels, pedalling technique and predominant workload characteristics (E.g.: climbing, time-trial, interval, climate, load carrying, etc.)

Given the same frame, changes in equipment such as, shoes and/or cleats, bars and saddle, can also have an impact.

I generally won't make adjustments to my normal, stationary ("static") setup if changes due to the above-mentioned factors are temporary and I can make "dynamic" changes by moving my body around to accomodate. Otherwise, I have found that minor adjustments to the saddle/seatpost/bars (1-5mm) may be necessary if "dynamic" adjustments aren't sustainable, E.g. induce significant discomfort, or risk

Based on my experience, the initial choice and adjustment of your normal static setup should allow for minor "dynamic" adjustments in your riding position -as necessary. If you find that you can't comfortably accommodate minor changes in riding position, consider further adjustments to static setup. The important points are: Make minor adjustments in one aspect at time (eg. seatpost height). Record your changes (via marks or notation) and allow sufficient time for your body to adjust to the change before making another change or reverting to a previous setting. Remember there is a difference between "uncomfortable" and "unfamiliar" in terms of position.

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Yes. However, it varies by type of riding and conditions. All Mountain is probably the extreme example of this (and the main market for dropper seatposts). All Mountain bikes are designed to be able to climb and for that generally one would want the seat in a "high" position to be efficient. During a technical descent, however, the seat is generally preferred to be low and out of the way, useful for providing additional movement if necessary, but low enough to get behind for extreme braking.

Other riding types may have only one "ideal" position. Trials bikes, for example, will most often have no seat, since it is rarely used and only adds weight and gets in the way. So there is an "ideal" position. Most road disciplines generally have what is considered an ideal position and will not vary by riding conditions in that discipline.

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Yes, there is.

If you spend a lot of time standing on the pedals and not using the saddle then you will probably want the saddle to be low so that it doesn't get in your way.

If you spend a lot of time pedalling hard or fast when sitting down you are more likely to want the seatpost high so you can pedal efficiently from that position - probably high enough to almost straighten your leg at the bottom of the pedal stroke.

Trials bikes have extremely low saddles, and at the more extreme end some don't even have seatposts because they are designed for a style or riding that doesn't use a saddle.

I think 'Dropper seat posts' are a relatively well known optional feature on mountain bikes. With these you can adjust the seatpost height during a ride, which you might want to do when you transition from one type of terrain to another.

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Your buddy is arguing one set up is optimal regardless of type of riding? Would he argue one handle bar height is optimal period? Is there even one bike that is optimal for all types of riding?

Ideal can mean a lot of things. For city stop and go I go just a tad shorter as I feel it is both more convenient (e.g. on off) and more efficient (but that is probably more perception than reality). On a long ride I like a little taller - but I also have a separate long ride bike.

On multi-day road race it would be interesting if they had a different height for flat versus hill day even riding the same bike. Not sure if it is true but I read Lance once complained the seat felt low and when they checked it as off by 1 mm.

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For commuting, I use a lower seat height in snow+ice compared to nice weather. Makes it easier to escape the bike when its falling over and easier to control if you want to shift your weight back behind the saddle. – Batman Feb 17 at 19:28
    
The Lance Armstrong story sounds dubious to me: a person's height changes by more than 1mm during the course of the day so I'm pretty sure nobody would notice that their seat height was "wrong" by 1mm. I'd argue that the true story is "Lance thought his seat was low. He was wrong: it was 1mm off" rather than "Lance thought his seat was low. He was right: it was 1mm off." Anyway, +1 because that doesn't materially affect the answer. – David Richerby Feb 17 at 19:43
    
If you put in the time to ride 36 hours a week, it's entirely possible you will start to notice the smallest changes on your bike. – Suspended User Feb 17 at 20:32
    
@SuspendedUser Real or imaginary I will move seat and bars 1 mm at a time to get what feels best for me. – Paparazzi Feb 17 at 20:36
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@DavidRicherby Height changes throughout the day are due mostly to spinal compression/decompression. There is far less change in your lower torso, where lengths are relatively unaffected. – Suspended User Feb 17 at 20:41

With a high bottom bracket the ideal seat post may be impractically high in certain situations. Depending on your preferred foot for putting down and the typical camber the bike may have to lean more than you'd like if you sit in a ready-to-go position at traffic lights.

The biggest example for me though is with a toddler seat on the back. That's a lot of weight high up and your acceleration suffers as well as your balance. So you can't lean the bike as much with your foot down and you're more likely to need to put your foot down (rather than riding extremely slowly waiting for your turn). That makes a difference of about 2cm on my seat post compared to how I have it for commuting without the seat on the back.

Body geometry is highly variable but even with my big feet I have to tilt the bike to put just my toes down. I don't recommend this for long stops if you're prone to cramp in your calves. For a flat-footed stop, dropping forwards off the saddle is always necessary.

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Erm, simply get out of the saddle when stopping? If you can comfortably put your feet down while sitting in the saddle it’s probably way too low. – Michael Feb 17 at 22:03
    
@Michael normally yes, or rather sit bones off the saddle while tilting the bike (coming right off the saddle is awkward if I don't unclip both feet because of long thighs. With the seat on the back I don't clip in. Long feet mean I can put tiptoes down with little or no lean and stay in contact with the saddle. Re comfortably: not really, I'll edit – Chris H Feb 18 at 6:44
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A toddler on the back sounds like a tandem with a lazy passenger who won't do their share. – Criggie Mar 18 at 0:20
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@Criggie I'll tell her you said that. – Chris H Mar 18 at 7:40

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