What’s The Best Stem Length For You? | GCN Does Science
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What’s The Best Stem Length For You? | GCN Does Science

October 19, 2019

– If you have ever thought in the past about stem length on your road bike, it is probably because you’ve been thinking about comfort
and fit on your bike. However, mountain bikers, when they think about the length of their stems, they are thinking more about
the handling of the bike, and the way it feels when they stear. – Yeah, so could we change the
way that our road bikes feel by messing around with stem length? Could we make them more nimble,
more agile, faster even? – We’ve been thinking about this subject because of the current trend
amongst professional cyclists who are trying to get longer
and lower at the front end, in order to become more aerodynamic. The problem with that is that they are choosing frames which are one size smaller than they really should
be riding, and therefore, the reach is too short. And to compensate for this, they are using some humongous stems, sometimes up to 14 or even 15 centimeters long. – 15 centimeters, that’s
like six inches Dan, and that is huge. Surely, that is gonna
make things a little bit difficult in the steering department. Surely they’d be better off
with an 11 centimeter stem, a bit more standard, but even, wouldn’t things
be better with an 8. – Oh. – Should we find out? – Let’s do it. We’ve got a selection of the
new PRO vibe aerodynamic stems to try out on Dan’s bike. First of all, we’ve
got this little stubby, eight centimeter number. We’ve got an 11 centimeter
one already on the bike, and then finally, we’ve got this humongous 14 centimeter stem. – That looks longer than 14
centimeters. That’s six inches. – It does look big, doesn’t it? It depends on where you measure it from. You always go from center to center when you measure the stem. – Slight illusion there. What we are going to do is a little course we’ve set here in suburbia, a little bit like a kid’s day skills course. What we’re gonna do is weave
in and out of these cones, around the round about just
behind you, and back again. At first to see, and
mainly to see, how it feels with the different stem lengths, but we are also going to time it, just to see if there’s any
statistical difference. – And also find out who’s
king of the car park skills. – Me or Dan, bring it on. – Three, two, one, go. Oh, no, he’s 11.98, but
with a 10 second penalty. – Ten second penalty?
No, I’m not having that. Three, two, one, go. I think he’s fluffed it. – Have I? – 11.77. – Three, two, one, go. Whoa, oh looking fast,
looking really fast. 11.17, it’s a PB. – Oh, it is, is it? – Yeah. Three, two, one, go. 12.14. – Whoa. – The reason that we think
there might be a difference is that stem length
affects the steering arc. The shorter the stem,
the less you will need to move your hands in order to
turn the wheel a set amount. That’s one reason why mountain
bikers prefer short stems, better for weaving around trees. Now, stem length isn’t the
only thing governing handling. The head angle and the trail of the bike give built in handling traits, like the DNA of the bike. But changing stems can
have a huge difference. What happens, then, on
the slow speed test? – The results are in, Si,
and what I can tell you is that basically, we
got better as we went on, with practice. We were both quickest on
the 8 centimeter at the end. And I also have to tell
you, unfortunately, you were better on every single run. I’m devastated. – I don’t feel so bad about
the rubbish results, then. Okay, given that practice
clearly makes perfect, can we infer anything from the feel? Did it feel different? – Well, I was expecting
a much bigger difference in feel between the stems,
because there’s quite a big difference between 14 and
8, but actually, what I felt was that I was just comfortable
in the 14 centimeter, ’cause that’s closest to
my normal riding position. – Yeah, well I definitely
felt that the 8 centimeter was easier to weave through the cones then weirdly, it was actually harder to get around the bottom corner, so I feel that maybe we need to move from this kind of artificial challenge to a real world challenge, cause, how many Tour de France stages will have
riders weaving through cones and then chuck in a u-turn in a road? – That is true. There’s the occasional dog runs out into the peloton, isn’t there, and sometimes you have
to weave around a couple of spectators to get to the
sign on, but I take your point. Descending challenge, you think? – Descending challenge. – Real world. – You know, it does feel twitchy. My god. – Aaa. – It’s responsive. Maybe a bit too responsive.
I’m not sure I like that. – And go. – That feels better, heaps better. – Wow, that made a heck of a difference. Just a totally different
animal down there. That’s the kind of bike
that I know and love. Size matters, clearly,
when you’re going fast. Those of you that are familiar with the new PRO vibe handlebar and stem will note that we’re not exactly getting the most out of its aerodynamic properties, and that’s because we’re still running this external DI2 junction box,
whereas, we should really be using a hidden junction box in the end of the handlebar there, ’cause all the cables can route internally, through the bars and
out at this point here, into the stem and then out of the stem through that hole at the back, then actually down into the steerer tube, completely hidden away. Three, two, one, go. Wow,
rolling out the big guns. – Whoa, well I’ll tell you what, the difference between
this and the 11, is nowhere near as
big as the 11 and the 8, but it does feel, it feels really stable, and particularly interesting, it feels really good around corners, like the bike just wants to rail. That has surprised me a lot. Dan, I’ve got some results. – Go ahead. – It’s highly traffic dependent. – Yeah. Yeah, I thought so. My last run was easily the fastest, because I wasn’t held up by
multiple cars and a tractor. – Well, you’ll also be pleased to know that you have the fastest of the day. – Oh, yes. – So I may be car park king, but you are downhill demon. – That is good to hear. In terms of how it felt
down the descent, though, I was really at home on this one. I realized when I was going down the hill that you don’t turn the bars much at all you’re literally
banking around the corners. Having that long stem
where it’s slightly harder to turn the bars actually made
me feel a lot more stable. I was carving and flowing
through those corners. – Carving and flowing. Well, in contrast, the 80 mm
stem was utterly terrifying from the moment I set
off and got above 20 mph, it felt way, way too twitchy, and really not good through corners at all, and then I suppose the 110
was the Goldilocks, really. It didn’t feel quite as stable, but then, it just felt right. – Yeah, I was happy enough on the 110. I think one thing we
should mention, though, is that in our pro days,
can we mention that? We were trying to get long
and low and aerodynamic, and so quite often we
favored the long stems, and so that is something
we’ve been used to for many, many years, isn’t it? – Well, it is, but I have, since
retiring and getting older, gone shorter, so I now use a 110 mm stem. But it did feel good, nevertheless, going back onto a longer stem. Should you go and buy a longer stem, then, to mimic these results? I don’t think you should,
given that, actually, bike fit would probably
be the determining factor. But don’t be put off by experimenting with a longer stem, I
think, bikes feel good. – Now before we conducted our very own stem length experiment, we did consult with bike design guru, Tom Sturdy, who typically has already done quite a lot of experimenting himself. And what he has found
is that you’re probably not going to be able to
find much of a difference between a long bike with a short stem versus a shorter bike with a long stem. But he does say that that
choice is very important for shorter riders due to
the limit of wheel sizes. If you are a shorter
rider, you really want to go for a longer frame
with a shorter stem. – Yeah, and then in order
to offset that twitchiness that we’ve just been
experiencing, you then hope that the actual geometry of the bike, like you talked about, the DNA of it, would actually mean that it
had more inbuilt stability. But then, thinking about
that point, actually, although stem length doesn’t
have much of an effect on the way it rides, actually,
in order to feel the bike as it was designed to be felt, you should probably use
it with the stem length that it was specced with, I guess, as the designer intended. – Yeah, it does start to get
a bit complicated, doesn’t it? But you can rest assured
that there is a good reason why bike geometry has
remained pretty much the same for decades. – Right then. I guess all we can ask at this point is for you to subscribe to GCN. To do that, just click on the globe. And if you’d like to watch
a couple more videos, Matt did a great video
where he asked the pros why they slam their stems,
that’s just down there. – Yeah, or a few years ago, Si had a look into how you set your bike and stem up, and you can find that
video just down here. – A few years ago. It goes back a bit now. – Yeah, you looked really young.

Only registered users can comment.

  1. Smaller riders that are faced with the 'dilemma' of long bike short stem vs short-bike long stem should look into the Reach of the handlebars themselves aswell. Good ones range from 65-80mm with Specialized making one in 65mm Reach.

  2. 110 to 120 mm stems are the sweet spot for me personally.. Smallest frame possible with a longer stem is my preference

  3. Short MTB stems are usually combined with humongous handlebars to maintain balance. So it had been better when you had paired the 80mm stem with a wider bar.

  4. For goodness sake, get some meat on your bones! You will definitely go faster. Downhill. Thanks for all the well-made and interesting videos. Pizza.

  5. 130mm here, but my frame fits like a glove too. gradually built up to this over the years getting lower and longer. I feel like it's way better handling with a short ht and long stem. Cannondale evo/caad geo ftw.

  6. I ride a 30cm frame with a 320mm stem and a 550mm seatpost, light as fuck, helps with the clown shoes I wear for my day time job …

  7. I started with a 110 on my first bike, went up to a 120 for a bit more reach, but I have the saddle as far forward as it goes. However on my last 2 bikes I have gotten, I use a 90, but I have my bars lower. Even going between the bikes (1st bike a Cannondale CAAD 9, 2nd & 3rd bikes BMC SLR02 & TMR02) I find that they are just right after a few pedal strokes. So to me if the bike is set up to feel, and not areo, it will always feel right when you hop on it. They all have their riding characteristics, but if it works for you, just use that. There is no need to do what the pros do.

    Now one thing that feels strange to me is when I go from my mountain bike to a road bike as everything just feels supper tiny on the road bike

  8. where can i learn more about the benefits of a long frame short stem that was mentioned at the end for a shorter rider? My frame is a bit big but I'm too attached to it/ cant afford another one so I've ordered a shorter stem. Would be nice to further fuel my confirmation bias on this issue?

  9. My triathlon bike was twitchy and unsafe with a 95cm stem. Switching to a 110 stem made the bike safer and faster (because I can go downhill with greater control. Would really like to try a 120 stem to see what that would be like.

  10. Any particular reason you guys like the double the volume when you play music in your videos? It doesn't do anything to make your videos more dramatic it just makes it impossible to watch your videos in a place where there may be other people around who do not wish to hear what your listening to. It's rather annoying.

  11. Bike geometry has remained the same because the UCI have banned certain bikes out of bicycle races. Recumbent bikes are certainly faster downhill then an upright. A recumbent low racer will murder an upright.

  12. You mentioned a great topic at the beginning of this video. What is faster a small fram with long stem and laid back seat post or a proper fit frame. Or what is faster fit French fit, Eddie fit or compative fit

  13. I have just changed stem from 110mm to 80mm, it's more comfortable for me, I have no numbness in my hands but it's a bit harder to keep straight line when I'm holding drops.

  14. I ride a 49cm frame with an 80mm stem with no spacers under it as a 5'3" male rider (1.6m), and that is plenty long for me. The only issue I have with my fit is that I wish the drops on my bars were traditional instead of ergo. The ergo grip has my elbows about as far back as my hips, where I'd prefer to be a little more stretched out, and even with my levers as close to the bars as possible, I can still barely reach them with my longest finger in the ergo position on the drops. A 140mm stem would have me laid out like Superman if I were on the hoods, and completely unable to use my drops. I feel Emma Pooley's pain on the fit side of things. Regarding the longer frame with a shorter stem – that is good advice. Toe overlap is definitely real on small frames. I can't turn my wheel more than about an eighth of a turn without having to pay attention to which foot is forward. My next bike will probably use 650b wheels unless it's a TT bike where I don't need to worry about sharp turns or track standing.

  15. Does stem length affect how likely you are to go over the bars if you pull the front brake hard? I can't help wondering whether a longer stem makes your handlebars a longer "lever" which rider weight would act upon. And does it make a difference if that lever gets near or in front of the wheel axle?

  16. Bike geo hasn't changed in decades? Wot?! Seat tube/top tube ratios sure have changed. Perhaps more so in MTB, but seriously?

  17. at the end of the video, it was mentioned shorter rider needs larger frame and shorter stem, I dun quite get it, need some enlightenment!

  18. The issue isn't so much geometry or wheelbase as it is the placement of the bars over the front hub….too far back and it's twitchy. It's all about leverage.

  19. Great videos! I noticed you don’t have bar tape on the tops of your handlebars. It looks so much better and is prob more aerodynamic. But do you just not ride on the tops? I can’t find anything about wrapping bars just past the shifters.

  20. In itself, the stem length is entirely meaningless. Consider a car steering wheel; hands at 3:00 and 9:00 are akin to a zero stem length. Put them at ten and two, and you're out about a 150 stem. Your hands are normally positioned from ten to twenty-five centimeters from the steering tube, on either side, and stems are really more about accommodating rider position balance and fit in the cockpit between crank, saddle setback, reach, and drop. Within normal ranges, stems just locate the bars in relation to those other measures forward or back, varying with frame length and geometry, and little more than that. If length provided a consistent change, why in their test was the middle length the worst? What besides balance and practice is really tested? MTB have necessitated short stems, because slacker head angles, more upright rider positions, and wider bars all add up to people not leaning or reaching near as far forward as early MTB XC racing position used.

  21. 10:40
    ehm… yeah, the reason for that is that the UCI prevents any progress by making millions of restrictions on how a bike is allowed to be…

  22. When your seating itself is good but you still find your reach too far then it would make sense to look at stems, I did a 2mm change from 10 to 8 to improve I do expect some loss of stability for the better seat and reach.

  23. #1 who am I to dispute anything you guys say so I won't speak for the Pros just the weekend riders. For an amateur if you shoulders are burning at 70 miles your stem is too long. You're in what we call a Superman position, reaching out too far. Hold a 5 pound weight at full arm's length, then compare it to a slight bend in your elbow. The closer to your body the more power you have. For that reason most people with the proper bike fit don't need a long stem. By long I mean 110 or 120, most of my bikes have an 80mm stem. Fatigue is common but pain isn't and it will change the way you ride. That part can be corrected very fast and very cheap. If you've never had a pro fit go get one. I see people all the time that will give $5,000 for a bike and won't give $100 to be fitted to use it.

  24. Hello to the GCN crew. Who from the GCN presenters ride that Trek bike daily? I would like to get some more feedback about that Pro Stealth saddle. Every person is different, anyway…don't want to buy and regret myself

  25. This is a GCN bro-science at it's finest. bike manufacturers established a sound science and implemented the science to their bikes including stem length and angle harmonious with the bike geometry to the millimeter accuracy. and all GCN does all the time is spreading baseless BS to idiots to follow.

  26. I'm interested in the subject, but I couldn't watch because of the wide swings in volume between the speaking voice ( important) and the loud music (not important). I find this present in most CGN or whatever…is it CBM? I don't know! If they were to become more aware of themselves…I would probably Like, Share and Subscribe. Or is it Bike, Share and Imbibe? I don't know!

  27. im 6'2 with a long upper torso and long arms i prefer that long dick i mean stem….lol jokes aside its a lot easier on my neck n stuff

  28. Look the days of fignon and Hanault. They rode 130 quill stem and gert-Jan theunisse rode 135 quill stems, why cause able them to have an equal balance on both wheel especially in the front making decending much more precise and stable. Colnago steel frames of the day where designed on basis you had a 130 stem.

  29. Have you a practical chain stay length comparison video? And symmetrical vs asymmetrical chain stay comparative review?

  30. You could always get different handlebars too with a different reach as well as a different stem

  31. I've been thinking about shortening my stem on my main bike, as my other bikes have shorter stems and they feel better when out of the saddle/on a climb. All my bikes are steel and the newest frame is from 1986. My main bike is a 1981 Dawes (531) has been converted to use a modern group set – campag veloce. It's top tube is longer than my others, and I'm running a 125 cinelli stem with criterium bars. Thinking of going down to a 90mm

  32. So ultimately it comes done to the bike not really being sized right for you… You can change some stuff to improve handling, but what it comes done to most is an ill-fitting bike, either you got a good deal on a wrong size bike or the bike shop doesn't really know what they are doing.
    A "comfortable" position may not be the best "riding" position for you.

  33. Back in the day (or should I say…back in my day….have been riding/racing since 1980) I think bike builders (notice I didn’t say “brands” all had their own approach to geometry. A Gios Compact or and Olmo SLX were great crit bikes with their shorter wheel base vs a true road machine such as. Merckx or DeRosa. Top tubes ultimately varied a lot and you simply compensated for the “Nose Over The Stem Can’t see the front hub” set up. We adapted our riding styles and cornering techniques to suit. A major contributor was also handlebar width as others have pointed out but wheel base was the area of concern. The Longer, the more stable. The shorter the more twitchy and nervous. Road bike, crit bike. One way that we dealt with cornering longer wheel base bikes was counter steering which either is now an accepted norm or not known as you don’t hear much about it. Steering this way effectively shorten the angle of attack and the longer stem gives you a lot more control where a stubby stem would be something like: Zip, Slant, Squat. eg…road rash. Maybe a video on counter steering is in order???

  34. I remember Dan worked for a mountain bike magazine in the early 1990's. He heavily critised road racers and that they suffered white line fever, now look at him on his racing bike. Where's your crap mountain bike now mate!

  35. I have a 90mm stem, and I love the responsiveness. Especially when there's an unexpected blemish in the road.

  36. I've learned more about bicycles and cycling during this Summer than ever before from Dan, Simon and the whole GCN Crew. Much appreciated. And now that I've been gathering the components to do a flatbar to dropbar conversion on my Specialized fitness bike, I was relieved to hear Dan advise that "If you are a shorter rider you'll need to go for a longer frame with a shorter stem" since I intend to swap out the 100 mm stem for shorter 80 mm to compensate for the slighly longer top tube. I'll let you know of observations in the reach and steering handling in due course.

  37. what a great clip – well scripted, great visuals – glad to see you make the product promo clear and obvious. THANKS

  38. Tener una u otra longitud de potencia no es definitivo para la conducción, tienes más importancia tu como conductor

  39. I still follow the Greg LeMond rule: Down in the drops you should be able to just see your front hub just behind your handle bar tops.


  40. How short you should be to consider your recommendations on longer frame/shorter stem? I'm 5'-9" would I be able to go a frame smaller with longer stem?

  41. I have a flatbar specialized city bike and I am older. Comfort is most important to me, so I put on a shorter stem with a pivot adjustment with degree marks. Boy was that a mistake. Super twitchy and not all that comfortable. I have hills where I live and I could not let it go downhill without the bike feeling like it had a frame made of gummy bears. I went back to the original….and I felt like it was on rails.

  42. A lot of fit is really dealing with what position you can get into. Few people outside of racers can ride normally in a race position. That's a fact. Even though i raced for a few years on the road and more off road, a full rae position was difficult. Now with a little belly, it much harder…

  43. The handling does change. My stock Cervelo S5 was a little too twitchy. I installed a 120 mm stem and the bike calmed down to a more "weekend warrior in the peloton" acceptable level.

  44. I'm 62 and have ridden for years for exercise and pleasure.. not racing. However my hands always get numb and I have to pump them a lot in the air from time to time to get more circulation and stop the pain. I have a 1998 Jamis cross country and not sure of the height because I am short and I can straddle the bar a hands width or so. I've been through about 3 seats in over 1000 miles riding since I bought it new. I know I could go further if I could get the most comfort out of my bike for my old body. 🙂 Thanks.

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