Correct Stem Length?
 

Hi, I just came across this article on the ideal Stem Length.

http://davesbikeblog.squarespace.com...of-fish-h.html

According to the article "Place your elbow against the nose of your saddle and if your finger tips do not fit behind the handle bars as shown above, then your stem is probably too short. If the bars are more than 2cm. away from the finger tips your stem maybe too long."

I put this test to my Road bike (52cm, 110mm Stem Length) which is sitting in the storage like forever. It turns out i would need a 40mm length stem to fit me. Being a BMX rider most of my short life i seldom ride road bike, but it do seems a bit uncomfortable to lean so far front when i am riding.

Any advice?

Thanks.

When you understand that the main determinant of cockpit length (span between saddle and handlebar) is the torso, not your forearm, you can see the fallacy of this measurement.

Here's how I do it. First set the saddle setback and height comfortably. The lower your torso, the farther back the saddle needs to go. Second, have a friend observe your profile. Sitting with butt firmly in saddle pocket, back extended comfortably, hands resting on brake hoods, and elbows moderately bent (down, not out), your upper arm (humerus) should make roughly a 90+ degree angle with your back. If the angle's shorter, you need a longer stem; if it's longer, you need a shorter stem.

There's nothing magical about this angle, it's just a relationship that seems to work, so it's a starting point. You're trying to find a hand position that works for steering the bike, balancing the upper body, and generating power for sprinting and climbing positions, and there is a bit of compromising necessary.

Interestingly, this fitting technique puts my bar about 5 or 6 cm beyond my fingertips, and my arms are quite long relative to my torso height.

I have a long torso with T-rex arms, so my fingertips end up about where my stem starts. D'oh.

On edit: Probably doesn't help that I'm using the "short" version of a B17...

I've used this technique as a rough guide for many years. Like any sizing guide, it is a starting point. Your actual position could be different. In my case, the tip of my fingers ends up about 2 cm from the bars.

Seems when it's right, I'm looking , line of sight, just see
straight down thru the line of the steering axis..

That only works if your top tube is the right length. If you're of average proportions and you got a spot-on fit on your bike, this will probably work.

dogegg, It's quite possible that your stem is too long, but I wouldn't change anything based solely on your forearm length. Another age-old method is when seated with your hands on the hoods the front axle is hidden by the handle bar. While these two methods are primarily for the drop bar bikes the problem is that there are so many possible combinations of handle bars (primarily), frame geometries, fork off sets and the riders themselves.

Brad

There are all kinds of rules of thumb that fit the average torso. I am short waisted and have very long arms and legs. the rules don't work for me.

Hit the shops and try stuff till you arrive at what feels right..

Its about 90+ degree in that position. Well, i would have to take it out for a longer spin to see how i feel riding in that position.

Staring straight down, i see somewhere between the stem and the hub.

Trying out all bike in the shop without buying, the owner would be piss. Lol

I can definitely see the front axle in that position.

None of the "rules of thumb" are universal, they work some of the time for some of the people. Variables include the size and shape of your bars, the length of your brake handgrips, rider flexibility and geometry.
Your best bet is to try an adjustable stem and see what works.
A newbie rider can expect to lengthen their riding position during the first few months/years as they get used to riding.

I have found I like my stems more erect.

Keep it mind that road bikes with drop bars are used for many different things. The angle of your body depends on how you are going to ride your bike. The 90 degrees between torso thighs is a comfortable position. Look at any road racer in the drops; their body angle is 60-45 degrees and their seat is above the stem. This is uncomfortable but more aerodynamic and obviously affects what the "proper" stem length will be.

I don't think it's possible with any method to get closer than about 10mm to the "correct" length for a given rider without in-person fitting followed by a tryout of the result. Whatever method you use, I would advise trying the result out with an adjustable stem that will allow you to vary things enough to find the just right length before going for the permanent one. If that is not available it is fairly easy to mount and remove a stem without any cosmetic damage, and exchange it for another until you find the right fit.

I agree that the handlebars can affect which stem will work best. I changed my stock hb out to one that comes forward quite a bit more and that also has a significant drop. That results in a shorter stem than would want with bars that have a shorter throw and drop.

Hello. This is my first post, but I've been reading the comments here and found the discussion interesting.

I am wondering if you could share info regarding your overall height, (effective) top tube length, and stem length. I know that stem length and dimensions are personal and may not apply to everyone, but I would like to get a rough idea.

Thanks.

Here's a very generic guide: http://bicycling.about.com/od/howtor...ike_sizing.htm .

Brad

Thank you. I was actually referring to oldbobcat's stats for his fitting, but I will definitely read this article.

Since you asked, here are my stats: total height 5'11.5", leg length 35" (89 cm), wing span (fingertip to fingertip) 6'0". My ride is a M/L Giant TCR with 57 cm top tube, 17 cm head tube, and 175 mm cranks. My stem is a 13 cm Ritchey (-6), my bar a Ritchey WCS Curve, 44 cm. I'm comfortable with considerable drop, about 9-10 cm, because of arm length and being able to ride with a straight, flat back (no hump). Credit years of exerting myself with a horizontal torso in swimming pools. Also, the bar came down a centimeter or two when I started using modern "compact" bends. The brake lever height has remained unchanged but the top of the bar came down a bit.

In my opinion, the most important element of fit on a road bike is feeling athletic but balanced and relaxed in the position you spend the most time in.

The 70mm difference between the forearm method and what you have is so large that the odds are good that the stem is too long. In addition 110mm seems literally a stretch for a 52cm bike. My experience has been that a very large proportion of bikes come with stems that are likely to be too long for the average person who would fit the bike. It may be due to the fact that a short stem does not look as "cool" or "racy."

I don't think it's possible with any method to get closer than about 10mm to the "correct" length for a given rider without in-person fitting followed by a tryout of the result. Whatever method you use, I would advise trying the result out with an adjustable stem that will allow you to vary things enough to find the just right length before going for the permanent one. If that is not available it is fairly easy to mount and remove a stem without any cosmetic damage, and exchange it for another until you find the right fit.

As stated before the handlebars can certainly affect which stem will work best. I changed my stock hb out to one that comes forward quite a bit more and that also has a significant drop. That results in a shorter stem than would want with bars that have a shorter throw and drop.

p.s Should go without saying but it's critical to get saddle height, fore-aft and tilt correct before judging stem and bar. The challenge is that how you feel on the saddle, rather than solely some formula, is part of the process and that of course can be influenced by stem and bars.

There's a custom bike shop in town that has a fully-adjustable trainer with power meter. He starts by setting the correct crank length (.21-.216 * leg length crotch to foot), then adjusts positioning for maximum power/comfort. Every person I've met who bought a bike from him has said the same thing: the fit was PERFECT the moment I swung a leg over the bike. I regret not consulting him before we bought our tandem last year.

Certainly that is one of the best solutions, as you are able to combine what "should" be right with actual results in both efficiency and comfort. I would certainly say it would be worth the money to take advantage of such a service if available but would assume there are very few shops that have that type of equipment and service. I don't see how the crank length formula is terribly helpful though, as that corresponds to about a 5mm difference between .21 and .216.

When we carried Speciaized, I found the stems their bikes came with to be pretty spot-on for the majority of customers. Treks fit a little closer in and a bit lower in front because of shorter top and head tubes, and last year they started coming with stems about a centimeter shorter and an extra centimeter of spacer. Scott and Bianchi, perhaps trying to maintain a sportier or more Italian image, tend to come with longer stems, but Bianchi has been coming in with an extra 1cm spacer.

In observing what recreational riders are riding around here on Saturday mornings, I see most on bikes that are too small, but they're using spacers and riser stems to achieve a very upright, close-in posture.

Are your cranks within that 5mm range? The range reflects anatomical diversity. More importantly, aside from 167.5 and 172.5, how may times do you find cranks in 2.5mm increments?

My wife is short, and prefers a lower cadence than I. Our tandem dealer suggested slightly shorter cranks for her to help "equalize" the cadence difference (170 vs. 165mm). The equation suggested that she be on 144-148mm cranks; when we put her on 150mm cranks it was a whole new world.