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Singlespeed & Fixed Gear "I still feel that variable gears are only for people over forty-five. Isn't it better to triumph by the strength of your muscles than by the artifice of a derailer? We are getting soft...As for me, give me a fixed gear!"-- Henri Desgrange (31 January 1865 - 16 August 1940)

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Old 04-16-11, 01:31 PM   #1
rbpanaligan
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Saddle Adjustments & Stem Length Questions

I want to adjust my saddle height, saddle distance and maybe replace my stem to get better efficiency when riding.

Is there a way to figure out how far back or forward the saddle should be? How far stretched out should you be on drop bars? Should your elbows be straight or bent when riding the hoods? I'm thinking my stem might be a little too long for me (5'6. 100mm stem on a 50cm bike).
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Old 04-16-11, 01:48 PM   #2
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This all differs person to person and cannot be evaluated over the internet. Go to your lbs and chat with em.
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Old 04-16-11, 01:49 PM   #3
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I like my back to be no more than about 45 degrees when on the hoods. seat position is slight bend in knee at bottom of pedal stroke and the hips remain still, no rocking as this would mean that the saddle is to high. The for and aft I am not sure were that is measured on the knee but is something like a line off of the knee when cranks are parallel to the ground that the ball of the foot and the knee are centered as close to the center axle of the pedal as possible, but not sure what part of the knee the plum bob hangs from though. Maybe look at the Lemond fit book.
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Old 04-16-11, 01:54 PM   #4
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Or, post a picture of your bike and a picture of you on your bike here. That can help us lead you in the right direction.
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Old 04-16-11, 03:08 PM   #5
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I'd like to think i have as much money as brains.
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Old 04-16-11, 03:35 PM   #6
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Originally Posted by rbpanaligan View Post
(5'6. 100mm stem on a 50cm bike).
this tells us nothing
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Old 04-16-11, 04:38 PM   #7
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To OP: post a picture/video breh
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Old 04-16-11, 05:49 PM   #8
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Thanks for the replies. I took my bike to my local LBS and they said everything is good except i need a shorter stem.

I'm going to order a 90mm stem today. Does anyone have a picture of a 82 degree stem? I have no idea of how much difference it is from my 6 degree stem. I don't want to steer too far away from the stem angle which is why I'm wondering if the Deda stem is much different.

This is the stem i'm going to order. http://www.universalcycles.com/shopp...s.php?id=12805
Is the picture of the 82 degree stem?
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Old 04-16-11, 05:55 PM   #9
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Originally Posted by rbpanaligan View Post
Does anyone have a picture of a 82 degree stem? I have no idea of how much difference it is from my 6 degree stem.
There is only a 2 degree difference, which is hardly noticeable. Sometimes stem angle is measured relative to 90 degrees, so an 82 degree stem is the same as 90 - 82 = 8 degrees.
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Old 04-16-11, 05:58 PM   #10
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Wow, i didn't realize that.. Thanks for your help!
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Old 04-16-11, 06:11 PM   #11
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I'm surprised you are 5'6", riding a 50cm frame and the LBS told you that you need a shorter stem.

50cm "sounds" small, not having seen you. My thought would be that if you were short legged, long torso, you would fit a 100mm stem just fine, unless the bike has dumb geometry by having a crazy long TT. If you're long legged w/ a short torso, then your bike is too small. You would have to jack the saddle way high, then since the bike is small, the drop from saddle bars would be excessive, necessitating the need for a shorter stem, when in reality you just need a bigger bike.. like a 53cm.

Like the others have said, it's hard to say w/o seeing you on the bike, but I too have tried to fit on a little bike, and it never worked out well. No amount of stem, seatpost or saddle adjustment will make a poor fit, correct.
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Old 04-22-11, 09:51 PM   #12
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Yeah, I think I'm going to re-install my 100mm stem. It feels a bit different compared to the 90mm stem. I felt a bit stretched out in my 100mm stem but I feel more of my body weight in the front compared to my 100mm stem.

I adjusted my seatpost height and saddle position based on the video and it feels A LOT better. It's just the stem issue that I have to fixed. I tried riding around w/ both stems and I don't know which I like better.

How do you guys like to be positioned over the bike? Do you guys have any side view pics of you on your bike?
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Old 04-22-11, 10:36 PM   #13
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Do not use fore/aft positioning to adjust the cockpit length. I usually first set my saddle height to 109% of my true inseam length (not pant inseam). This measurement will equal the distance from pedal axle to the top of the saddle, +/- a few centimeters. Then set the saddle's fore/aft so that a plumb line from your tibial tuberosity (just below your kneecap) crosses the pedal axle when the pedals are horizontal. Stem length/angle/height can be hugely variable and depends on your flexibility and desired position.

All of that is just a start - it will take time to fine tune.
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Old 04-22-11, 10:47 PM   #14
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Quote:
Originally Posted by rbpanaligan View Post
Yeah, I think I'm going to re-install my 100mm stem. It feels a bit different compared to the 90mm stem. I felt a bit stretched out in my 100mm stem but I feel more of my body weight in the front compared to my 100mm stem.
With the shorter stem, you probably need to adjust your saddle aft-wards, to redistribute your weight (butt vs. chest) around your changed center of gravity. In my experience, it's rare to change one variable (stem length, stem angle, saddle height, etc.) without having to adjust a second or third. Here's a thoughtful approach you may want to read: http://peterwhitecycles.com/fitting.htm. It may or may not work for you, but ought to at least give you insight into the dynamics of finding your fit.
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Old 04-22-11, 10:56 PM   #15
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that video tt posted is pretty much the basis of where you should work from. use it as a starting point and if you have troubles beyond that its definitely worth trying the LBS for a complete fit. its worth your money either way.
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Old 04-22-11, 11:43 PM   #16
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It is perfectly reasonable to be 5'6" and ride a 50cm bike. It all depends how the 50cm is measured

SADDLE FORE-AFT = is used principally to position your knee in relation to pedal spindle. This affects your centre of gravity, your core and power efficiency. You may have read somewhere your knee cap should be over the pedal spindle at a 9 & 3 pm crank position. This is just a general guideline and NOT an inviolable rule. Use that understanding as a starting point and fine tune accordingly.

A more forward position has the effect of making the the seat tube more vertical (closer to a triathlete's setup). Setting the seat further back makes the angle more relaxed. Generally speaking shorter people will like to have their seat more forward, while riders with longer legs and femurs (thigh bone) will prefer more set back in the seat.

At the correct position for you, you will not only feel more comfortable, but be able to generate more power resulting in less effort for the same speeds you used to ride, or better climbing on hills.


SADDLE HEIGHT.
A good foundation is to measure the height of your inseam from the floor while standing in your usual cycling shoes. Call this your inseam measurement.

INSEAM X 0.883 = DISTANCE FROM MIDDLE OF THE BOTTOM BRACKET TO THE TOP OF THE SEAT.

If the seat is too high, your hips will rock from side to side, and your maximum cadence will be less than if the seat was lower. If the seat is too low, you will lack power and joint injuries may occur. Using the above formula as a starting point, you can tweak it 1 cm way to settle on something that works for your unique measurement. When the height is right, you will be able to spin freely without rocking thereby maximizing power and efficiency while minimizing injury. At the right height, you should be able to lock your core and only have the legs pumping without the body moving side to side.

You are your own. At the right height, your leg should have the kind of bend which resembles this picture when the crank is at 6pm.



Shorter riders will have less of a saddle to bar drop than taller riders.


STEM LENGTH
Set the saddle fore-aft and saddle height first before dialing in the stem length. The stem length should allow you to balance yourself, crouch into the drops and remain balance in an out-of-saddle climbing hill position with relative ease. A shorter stem will make the steering more twitchy\sensitive, while a longer stem will make the steering feel more stable or slower.

Read more here: http://davesbikeblog.blogspot.com/20...rearm-and.html




STEM HEIGHT
Stem height is often overlooked in bike fit and can be a source of cantankerous debate. Aesthetically, young people seem to like to show a huge saddle to bar drop leading to a slammed stem look (see here: http://slamthatstem.com/)

While this may be applicable for racing and short sprints, riding for an hour or longer at a time may require a different stem height. Depending on age, flexibility and intended use, a stem height that sets the bars at saddle height and plus\minus an inch from saddle height will yield more comfort while preserving aerodynamic options to ride fast or combat windy conditions. I ride my bikes with the bars about 1 inch below saddle.



Dave Moulton on Bike Fit:
http://www.prodigalchild.net/Bicycle6.htm

Dave Moulton on bar height:
http://davesbikeblog.squarespace.com...-position.html

Last edited by puppypilgrim; 04-23-11 at 12:03 AM.
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Old 04-23-11, 02:21 AM   #17
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Awesome, thanks for all the tips/links/replies.

I think I have everything down (saddle height, saddle angle and saddle position) except the stem height and stem length. I think the stem angle/length should be different for everyone?

With the 6 degree 100mm stem, I feel that it's comfortable flipped (angled upwards) with one 3mm spacer (stem almost matches seat height). I kind of felt like I was stretched out a bit but when I tried using the 90mm stem, i felt kind of cramped. With the 6 degree 90mm stem, I feel most comfortable with the stem unflipped and about two 3mm spacers to raise it a bit. At this set-up, the stem is about 1-2 inches below the saddle. I felt a bit upright with the 90mm stem flipped.

I've tried riding using both stems and it's difficult to figure out which is best because I'm not sure how proper bike posture is suppose to look like. I'm looking for a good mix between comfortable (i usually go on rides between 20-30 miles) and a little aerodynamic.
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Old 04-23-11, 03:45 AM   #18
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just ride.
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Old 04-24-11, 06:06 AM   #19
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Go with whatever is most comfortable. Don't worry over these little differences you are down to now with your fit.

From the side, my San Jose's stem looks a bit dorky but when I'm on the bike, I can't see the rise of the stem at all. And it's comfortable and I'm plenty fast. If I want to be more aero, I use the drops. Since I ride on the road, I use what works on the road.
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