Fairly detailed analysis, personally, I have slammed my stem (gradually over a year) and noticed my average speeds on the flats have increased by 3 to 5 km/hr. Mind you , slamming stem places additional load on your body if you are not used to it. I included additional stretching exercises in order to accommodate a more lower riding style. Probably the cheapest way to go faster while using marginally less power, cheating the wind.
hornetluca do it. I also do that on my XC hardtail. With a 100x600mm stem/handlebar setup, ya will never wheelie on steep climbs. I literally climbed an almost 28% climb without any wheellift. The main problem was gearing :D
You should not forget that if u lower ur stem to much it gets really difficult to lay down on your handlebar and close up the frontal area. Also it is very important to look at your headposition. A super low end can lead that your head is more above your back. So lower not always faster! I think its good to lool at some TT positions of the worlds best riders.
The lower the slam, the more cervical spine lordosis is required to be able to look ahead on the road, the more risk of eventual cervical neck problems later on in life
@nick thanks for the Mayo link. I've just read it. I'm not sure if a lower stem (in the context we're discussing here) will increase the risk of spinal lordosis later on in life here. According to the article, the number 1 factor seems to be age related. Then cycling, in general, can also put pressure on the neck, but is the difference between a 6-deg stem and slamming on a 17-deg stem all that significant in the mitigation of spinal lordosis at age 60+ later in life? It's not like a cyclist will always be riding in a slammed position, right? I have a slammed stem but I would say only about 10-20% of my riding time is ever spent in such position as i'm upright on the hood most of the time. Usually, cyclists tend to stop using a slammed position when they are no longer racing. And furthermore, cycling in general do tend to make people lighter in weight, and this could also help with other areas of the body, including the neck. All in all, I'm still not overly convinced that using a slammed position when you're racing result in a significant risk of spinal lordosis later on in life. What about people who lift weight, specifically doing exercises like deadlift and squat? These guys also put a tremendous amount of pressure on their neck, yet we don't hear about weightlifters getting spinal lordosis much (well weightlifters do get neck and back injuries, but it is usually because they are doing a 1-rep max heavy lift, but regular people do not need to go crazy like this). Thanks for the link.
Chau Nguyen You dont need data. Quicker to look over a shoulder for that truck on an endurance bike than when your having a conversation with the spoke nipples
It’s truly staggering how much the bike industry and pro peloton teams spend in man hours, effort and money to squeeze out the last ounce of aero or performance gains to save a few watts. At this point there is really nothing left unturned.
0.1? Sounds like ceramic bearings stuff. I think the placebo effect of having it is bigger than the actual effect of having it at that point, but anyway a couple of watts certainly matter, especially if you can find that in 10 places. However, it mostly doesn't matter for the "pro peleton". 1 watt probably won't help you in the peleton, or even the sprint finish. Road races are NOT about such marginal gains. It will help you in the time trial though. It's funny though, because we know how to make bikes faster. It's a matter of making UCI legal bikes faster, which isn't all bad, otherwise you'd have people riding weird contraptions that spectators had no interest in.
I know I'm late to the discussion, but I wanted to add a comment. I think another thing to keep in mind when going from a consistent stem length with let's say a positive 6 degree rise to a negative 6 or more degree drop with the same stem length will also increase the effective reach. My thought is that a 10 degree increase in negative drop will result in approximately a 1 cm increase in reach.
I think I'm reasonably slammed and have been so for several years now. I have to stretch every morning just for general health, but I think that I wouldn't like my position if I didn't stretch. I run my saddle at -6 and stem with -17x100 stem, compact Kforce handlebar. I'm 5'10 on a 54 Cervelo R5, so my position isn't anything extreme. I do get a sore back on the first century ride of the year, but then I get back into shape and don't have any back problems. Now the real story might be what we want to do with the stems on our gravel bikes. I run a -6x100 stem on my longer cockpit gravel bike, and guess it's okay. It still feels a little low in the front on some sketchy terrain.
I know your aiming at the aero gain with this vid, but be carefully everyone, you can’t just take the spacers out and put them on top of your stem. The carbon steerer is supported by a plug which should go deep enough to support the stem clamping. What needs to happen is the stem needs to be cut, so no going back. Also it is not so easy to cut carbon. If you use a normal hacksaw it can delaminate the fibres which will then initiate an incipient fault which can travel down the steerer leading to a failure. You need a special saw with a high tooth count. This is just a warning comment for people who may not beaware. A steerer failure can be very nasty. So leave it to the experts if in doubt.
Wind tunnels, data calcs etc, are all good measures for the pure numbers when riding alone or in a time trial, but for the racer who competes in criteriums and road races, it makes more sense to set your bike up for the most optimal position for handling and power output. A slammed stem will eventually cause issues physically. There are many new aero bikes that achieve the same as a slammed stem while keeping you comfortable and less risk of physical damage. The drop from saddle height to bar is what you should be concerned about. Ask your prostate about that.
John Riggs plus when cornering very hard, ya are less likely to get that tipping over feeling. I slam my 110mm -17° and it corners so hard i actually roll a bit on my rims(had 23mm tires)
You really don't want more weight over the front. That creates a wash out situation. You want it at the lowest center of gravity .....which is the bottom bracket.
I totally agree with you.... I have no scientific background to prove it, but I have two signs.... One is that I made some KOM's and top 10's on high speed segments on Strava, the other sign is that all of my cycling mates prefer to stay in front instead of riding behind me.... Of course they are between 8-12 cm taller than me, but it is not a such difference..... But what all they saidcafter I asked them is that they prefer to stay in front, because it is clear that the must work harder and they can handle the effort. If they draft behind me they need nearly the same output, but there is a negative psychological effect for them!
When you increase your reach on the bars you are getting lower aswell because you have to reach out and that also lowers your back I can ride a bigger framed bike with the bars higher then the seat and I will be much lower then on a bike with a lowered slammed stem because I'm being stretched out more on the bigger bike.
considering that according to your chart with percentages at the start handlebars make up for over 14% of total drag, can you make a video about gaining time through handlebars?
-Their isn't a watt gain, you don't get stronger -All that is nice but 90% of people are riding bars too wide (I'll 42cm because it came like that) Bikes should be spec'd 36-38 on 50/52cm bikes / 40 for 54/56cm bikes and 42+ for 56+cm bikes
@Charles Gagnon I am not sure if the wider bars have more negative impact than to be less Aero.... To small of course, but to wide? Look at the bars in MTB.... I am sure that competitors in CC are also looking for performance
The head tube on most current day road bikes are way too tall. I tried to buy a Trek Emonda a few weeks back, with it's ridiculous tall 14 cm head tube I just could not get a good slammed position so I did not buy one. Bicycles are now being designed for unfit people with money to blow that want to sit upright. A Garcia, going down a frame size is not an option on the Emonda because they have paired a short top tube to those tall head tube. My current 54cm frame is more than a full inch longer in the top tube than a size 54 Emonda and I already use a 140mm -17 stem. I would need 165mm stem to get my length and a size 52 Emonda still has a much taller head tube than I am used to. Pro riders do not get the same geometry as is found in bicycle shops.
Long head tubes are ugly on race bikes. My caad12 has nice geometry but was only supplied with 3 cm conical spacer, no default slam option. Power savings are substantial, slammed long stem @20 mph about 10% ~ 20w.
A Garcia, going down a frame size is not an option on the Emonda because they have paired a short top tube to those tall head tube. My current 54cm frame is more than a full inch longer in the top tube than a size 54 Emonda and I already use a 140mm -17 stem. I would need 165mm stem to get my length and a size 52 Emonda still has a much taller head tube than I am used to. Pro riders do not get the same geometry as is found in bicycle shops.
John O'Neill sounds as if your torso and arms are unusually long, and if your proportions are that far off from the average that fine tuning components won’t get you a proper fit, either you ought to be riding a fully custom frame or seeking a second opinion from a qualified and experienced fit tech.
possibly but anyone who does any aero testing in going to consider this, plus it was in the Velominati rules....Rule #45 " Slam your stem" a maximum stack height of 2cm is allowed below the stem and a single 5mm spacer above. ;)
i do not believe in slam stems too much because people with a very low position tend to never ride on drops i think is better a correct bike fit to allow you to ride the most aerodynamic position for most of the time
wouldn't the most comfortable aero position be a slammed setup so that your hoods are as low as possible? And then drops are even lower for more leverage and a lower head during a sprint?
Slamming the stem night make the bicycle alone more aero, but if the rider is holding the arms straight downwards, the arms are like barn doors to the wind. If I want to get aero, I don't bother with slamming, I just bend my elbows more so that my forearms and back are flat. Then if I want to ride more upright, I still can because my stem and bars are not ridiculously low.
Bingo, and if you bend your elbows in the drops, you have a very comfortable position to recharge on the tops, letting you get back aero again for round two.
@@bigring6424 but it's more aero to have forearms horizontal while on the tops. There are large aero losses by having hands on the drops. Drops are used for descending, cornering and sprinting.
with today's slopy top tube, an excessively negative (eg, -17 deg) stem makes the whole bike look a bit ugly as the top tube doesn't flow inline with the stem. Couple this with a tall head tube, and the bike is now hideous.
Another great video by this presenter! I have one question about the very interesting drag budget displayed at 0:30. What is meant by the "handlebar/stem drag," which shows a value of 14%? Is this just a typo-namely, it's just missing the decimal pt (so should instead read 1.4%)? If it's not a typo...I recognize how highly amplified the aerodynamic drag of leading-edge surfaces is in an undisturbed slipstream...but I simply cannot believe that, even with this emphasis noted, the aerodynamic drag of the handlebar/stem could be remotely close to that of the rider's body volume shown as 18% (maybe the arms in isolation, and even that seems like it would be pushing it). So if this is not a typo, does the 14% somehow incorporate elements of the rider's body...or what explains the 14%? Some other points that aren't incorporated in the spreadsheet, which I a realize has a value on simplicity/elegance, are: (i) There's a limit to how much you can lean down and still benefit (or even not suffer) aerodynamically. There's even an optimum lean angle beyond which drag will start to increase again. (ii) Wind tunnel testing has revealed that you are more aerodynamic with your forearms level to the ground on the hoods than with your arms extended to the drops (constrained by the same back ht / position). (iii) Your head/neck position is astoundingly important (getting your head low and out of it's own slipstream); a raised head acts like a parachute-this effect even feeds back into the body lean angle because of the neck/eye strain at excessive body lean angles as you try to maintain some semblance of a fwd road view. So leaning down further to a theoretically advantageous height might be wasted or even detrimental if you just raise your head back up to see the road. Time trialists know this last challenge all to well. But back to my main question, I'd love to better understand the 14% handlebar/stem drag figure!
Re handlebar drag (including cables) have a look at this link: djconnel.blogspot.com/2014/08/cervelo-s5-and-aero-road-bars.html i) There's a limit to how much you can lean down and still benefit (or even not suffer) aerodynamically >> there is certainly a limit to comfort, power delivery and safety but aero? (ii) Wind tunnel testing has revealed that you are more aerodynamic with your forearms level to the ground on the hoods than with your arms extended to the drops (constrained by the same back ht / position). >> basically arms are a drag too, can be modelled by two x2 cyclinders (iii) Your head/neck position is astoundingly important (getting your head low and out of it's own slipstream) >> agreed
So at 6:13 in your own video you say you can't work out how much you could save or lose because "we know all that, yeah." When I was a kid 20+ years ago, I had a custom TT frame made with 531 tubing and an 82 degree seat angle. The top tube and down tube was so long it required the tandem tubeset. I was 5'11 with a 34" inseam but the front end of this TT bike was essentially a 19" bike with a massive seat tube and a 24.5" top tube. The difference between the saddle and bars was more than a foot. Fast forward two decades I find out that I would be faster with a much higher position. Such is the wonders of now owning a power meter. When doing video's like this there needs to be a reference to the bar height relative to the front end of the bike rather than 'does it need to be slammed' because head tube heights vary so much.
Swampster70 interesting comment but given the comparison is between two positions with the same head tube height I think it drops out of equation in an approximate calculation. Do you disagree?
You make the comparison between a high and a low position and unsurprisingly, a lower position is more aero but you should also look at going a bit lower and longer. It'll allow you to drop the shoulders as with the slammed stem but put less stress on the neck as well as allowing you to 'shroud' the head more effectively with the shoulders (think shoulder shrug). The ultimate test is going out and riding for a few hours in the new position and seeing if it works. If you can only hold it for 10 minutes it's pretty much useless don't you think?
no this is normal, if its unlocked from experience a small number of people make crazy changes to the actual coding or wreck the sheet. For safety, just request permission to enter your own data into the cells and it will work for you. Even on patreon google sheets require permission request. Its only excel sheets that are unlocked.
Fastfitnesstips Thanks! It was hilarious watching live updates with multiple users in the Aero bikes weight/value sheet for sure! Keep up the great content 👍
John Dove Sort of a Gimmick for the money, saves something like 2.5 watts and I would say in ideal conditions. Some people like them so they can rest their fore arms on to get more aero with comfort. I would say these gains would trump the bars by themselves. So I would say, it depends on your reason and riding style for buying.
i have a question. lowering the drop to an extreme 25 degree down angle is comfy for me but when climbing out of the saddle it is too low to dance up the climb. wouldn't it be nice if we could pres a button and have the bars rise and lower as needs be, like with some saddles? or is that a danger from an engineering perspective? i absolutely realize i need to compromise but surely some engineer out there can build this?
Good idea, how about this, double bars, for high and low position (canyon grail): coresites-cdn.factorymedia.com/rcuk/wp-content/uploads/2018/03/MG_18_02_Canyon_Presscamp_4776.jpg
There's too many variables to have an absolute result in wattage saved or gained. With regard to frontal area, bar width and all riders are of different sizes, (height and weight) helmets are also of different shapes. These will be significant variables with regard to CdA. Not too mention YAW and the angle ( direction) of airflow in relation to the bike and the rider.
This. If an aero position is not sustainable for at least long enough to perform an FTP test, then what is the use? It's no good saving 14 watts for five minutes then having to waste 20 watts for the next fifteen minutes because you are so slammed that flat fore arms is not sustainable. I have found my best compromise is to setup a flat forearm position with a compact bar that is sustainable in the drops for 3-5 minutes. This provides me an aero hoods position that is sustainable for 30 minutes, a straight arm drops position that I can comfortably use to descend and follow wheels and a short term aero drops position when hammering.
Exactly. Just saying you should slam the stem because it's more aero is too simplistic to be of any use. You body 'finds' the position it wants to be in when making an effort. If you slam the stem with not other considerations, you'll probably find that you have straight arms and don't use the drops, arriving back in the same torso position and hip angle that you had in the first place. Remember, the pro's are not a good model for normal people.
This info is all well & good in estimating how many watts can be saved etc BUT please guys & gals don't just slam your stems after watching this. If you're serious about your riding & want the correct inprovements that will give you sustained power output & comfort, invest in a proper bike fitting. Being aero doesn't mean you'll be comfy or in a good position to sustain power &/or comfort. I've 25+ years as a bike fitting specialist & i'm happy to carry this out for anyone in the UK.
You can tilt up to minus 15 degrees without slipping. Nose down allows the pelvis to tilt forward, moving the lumbar spine into a more neutral position. If the UCI rules loosen up further, the Pros will definitely adopt an even steeper angle because low back pain continues to be a problem in professional cycling.
Those are estimates from an old marginal gains calculator I wrote a few years back...since then we have improved the model of losses several times to account for rider speed, bike type, CDA etc.
@@Fastfitnesstips : Thanks, I am a bit surprised though by the contribution of body position : 4.5+18.8+8.5=31.8% of the total, so about 45-50% of total drag when all publications mention between 85% and 95%. Most notably but not limited to Table 2 of "Cycling on Earth, In Space, on the Moon", Eur J Appl Physiol (2000) 82: 345-360 by Pampero in 2000. What is your view on this ?
@@sebastienricciardi883 very roughly whole body drag is around 70% of aero losses (bike and equipment 30) which can be divided into 45% body 15 clothing 3 feet 5 head...but when combined with all losses body and clothing aero drag makes up around 40% at 40kph
So which is faster, dropping the riders shoulders by dropping the bars or dropping the riders shoulders the same amount by keeping the bars the same height but pushing the bar out forward? I know the answer to this. Do you?
This is very unscientific. Using studies of individuals and using extreme variances in height is all very very well - I guess you're comparing racing positions versus bunter positions - but if you think that slamming your stem is the only aim, you could be very wrong. Your current marginally higher position could be faster - if you move your position down 3cm to get the slam and it creates a poor body position, maybe some over-reaching where your shoulders don't sit optimally, you will actually create more drag than your slightly higher position. Apart from the changes to hip flexor angles, lower back position, ability to stomach breathe, etc. affecting power and performance, if we are talking about only a slight variation in height, it is far more important to be narrow.
Slam those mothers lol.. plus it looks better 👍👍 think pro .. act pro .. slam slam thank you mam 🚴🚴🚴🚴🚴🚴🚴🦏🦏🦏🦏🦏💣💣💣💪💪💪💪💪⚡️⚡️⚡️⚡️⚡️⚡️⚡️⚡️🌬🌬🌬 great info as always ..many thanks for the video
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Fairly detailed analysis, personally, I have slammed my stem (gradually over a year) and noticed my average speeds on the flats have increased by 3 to 5 km/hr. Mind you , slamming stem places additional load on your body if you are not used to it. I included additional stretching exercises in order to accommodate a more lower riding style. Probably the cheapest way to go faster while using marginally less power, cheating the wind.
I've never thought of flipping my stem, I'll definitely try it out.
hornetluca do it. I also do that on my XC hardtail. With a 100x600mm stem/handlebar setup, ya will never wheelie on steep climbs. I literally climbed an almost 28% climb without any wheellift. The main problem was gearing :D
You should not forget that if u lower ur stem to much it gets really difficult to lay down on your handlebar and close up the frontal area. Also it is very important to look at your headposition. A super low end can lead that your head is more above your back. So lower not always faster! I think its good to lool at some TT positions of the worlds best riders.
The lower the slam, the more cervical spine lordosis is required to be able to look ahead on the road, the more risk of eventual cervical neck problems later on in life
I would be interested in data supporting this statement
@nick
thanks for the Mayo link. I've just read it. I'm not sure if a lower stem (in the context we're discussing here) will increase the risk of spinal lordosis later on in life here. According to the article, the number 1 factor seems to be age related. Then cycling, in general, can also put pressure on the neck, but is the difference between a 6-deg stem and slamming on a 17-deg stem all that significant in the mitigation of spinal lordosis at age 60+ later in life? It's not like a cyclist will always be riding in a slammed position, right? I have a slammed stem but I would say only about 10-20% of my riding time is ever spent in such position as i'm upright on the hood most of the time. Usually, cyclists tend to stop using a slammed position when they are no longer racing. And furthermore, cycling in general do tend to make people lighter in weight, and this could also help with other areas of the body, including the neck. All in all, I'm still not overly convinced that using a slammed position when you're racing result in a significant risk of spinal lordosis later on in life. What about people who lift weight, specifically doing exercises like deadlift and squat? These guys also put a tremendous amount of pressure on their neck, yet we don't hear about weightlifters getting spinal lordosis much (well weightlifters do get neck and back injuries, but it is usually because they are doing a 1-rep max heavy lift, but regular people do not need to go crazy like this). Thanks for the link.
Chau Nguyen You dont need data. Quicker to look over a shoulder for that truck on an endurance bike than when your having a conversation with the spoke nipples
I laughed at the "conversation with the spoke nipples" line.
Absolutely true.
It’s truly staggering how much the bike industry and pro peloton teams spend in man hours, effort and money to squeeze out the last ounce of aero or performance gains to save a few watts. At this point there is really nothing left unturned.
why is it staggering? Isn't it expected?
Even a 0.1W gives you an advantage over you opponent so why not take it? If you have the budged for it.
0.1? Sounds like ceramic bearings stuff. I think the placebo effect of having it is bigger than the actual effect of having it at that point, but anyway a couple of watts certainly matter, especially if you can find that in 10 places. However, it mostly doesn't matter for the "pro peleton". 1 watt probably won't help you in the peleton, or even the sprint finish. Road races are NOT about such marginal gains. It will help you in the time trial though. It's funny though, because we know how to make bikes faster. It's a matter of making UCI legal bikes faster, which isn't all bad, otherwise you'd have people riding weird contraptions that spectators had no interest in.
A few watts over hundred miles and 4 hours, is many watts for advantage.
I know I'm late to the discussion, but I wanted to add a comment. I think another thing to keep in mind when going from a consistent stem length with let's say a positive 6 degree rise to a negative 6 or more degree drop with the same stem length will also increase the effective reach. My thought is that a 10 degree increase in negative drop will result in approximately a 1 cm increase in reach.
I think I'm reasonably slammed and have been so for several years now. I have to stretch every morning just for general health, but I think that I wouldn't like my position if I didn't stretch. I run my saddle at -6 and stem with -17x100 stem, compact Kforce handlebar. I'm 5'10 on a 54 Cervelo R5, so my position isn't anything extreme. I do get a sore back on the first century ride of the year, but then I get back into shape and don't have any back problems. Now the real story might be what we want to do with the stems on our gravel bikes. I run a -6x100 stem on my longer cockpit gravel bike, and guess it's okay. It still feels a little low in the front on some sketchy terrain.
Thanks Prof. Back permitting I shall try this with my stem.
I know your aiming at the aero gain with this vid, but be carefully everyone, you can’t just take the spacers out and put them on top of your stem. The carbon steerer is supported by a plug which should go deep enough to support the stem clamping. What needs to happen is the stem needs to be cut, so no going back. Also it is not so easy to cut carbon. If you use a normal hacksaw it can delaminate the fibres which will then initiate an incipient fault which can travel down the steerer leading to a failure. You need a special saw with a high tooth count. This is just a warning comment for people who may not beaware. A steerer failure can be very nasty. So leave it to the experts if in doubt.
Wind tunnels, data calcs etc, are all good measures for the pure numbers when riding alone or in a time trial, but for the racer who competes in criteriums and road races, it makes more sense to set your bike up for the most optimal position for handling and power output. A slammed stem will eventually cause issues physically. There are many new aero bikes that achieve the same as a slammed stem while keeping you comfortable and less risk of physical damage. The drop from saddle height to bar is what you should be concerned about. Ask your prostate about that.
I love your nerdy analysis, marginal gains ftw!
Thanks......I think!! ;)
I've always found slammed more comfortable :O
Because you used to it too
Me too..
You can also corner better as you have a bit more weight over the front of the bike!
John Riggs plus when cornering very hard, ya are less likely to get that tipping over feeling. I slam my 110mm -17° and it corners so hard i actually roll a bit on my rims(had 23mm tires)
You really don't want more weight over the front. That creates a wash out situation. You want it at the lowest center of gravity .....which is the bottom bracket.
I totally agree with you.... I have no scientific background to prove it, but I have two signs.... One is that I made some KOM's and top 10's on high speed segments on Strava, the other sign is that all of my cycling mates prefer to stay in front instead of riding behind me.... Of course they are between 8-12 cm taller than me, but it is not a such difference..... But what all they saidcafter I asked them is that they prefer to stay in front, because it is clear that the must work harder and they can handle the effort. If they draft behind me they need nearly the same output, but there is a negative psychological effect for them!
When you increase your reach on the bars you are getting lower aswell because you have to reach out and that also lowers your back I can ride a bigger framed bike with the bars higher then the seat and I will be much lower then on a bike with a lowered slammed stem because I'm being stretched out more on the bigger bike.
considering that according to your chart with percentages at the start handlebars make up for over 14% of total drag, can you make a video about gaining time through handlebars?
Luka Cordedda well spotted that was actually bars and stem and front height combined
-Their isn't a watt gain, you don't get stronger
-All that is nice but 90% of people are riding bars too wide (I'll 42cm because it came like that)
Bikes should be spec'd 36-38 on 50/52cm bikes / 40 for 54/56cm bikes and 42+ for 56+cm bikes
good point: watt equivalent gain by reducing drag
And 54er bar for Steven Kruijswijk
@Charles Gagnon I am not sure if the wider bars have more negative impact than to be less Aero.... To small of course, but to wide? Look at the bars in MTB.... I am sure that competitors in CC are also looking for performance
@Charles Gagnon by the way.... Rolling in would be a sign for me that the bar is to small 😉
Thanks as always!
Goint at this rate we’d soon find bikes with handle bar relocate from top to bottom of head tube. ;)
We need to think outside the box and not be totally reliant on manufacturers. I manage to slam my flat handle bar with my own customisation.
I'm curious.What was your improvisation?
The head tube on most current day road bikes are way too tall. I tried to buy a Trek Emonda a few weeks back, with it's ridiculous tall 14 cm head tube I just could not get a good slammed position so I did not buy one. Bicycles are now being designed for unfit people with money to blow that want to sit upright. A Garcia, going down a frame size is not an option on the Emonda because they have paired a short top tube to those tall head tube. My current 54cm frame is more than a full inch longer in the top tube than a size 54 Emonda and I already use a 140mm -17 stem. I would need 165mm stem to get my length and a size 52 Emonda still has a much taller head tube than I am used to. Pro riders do not get the same geometry as is found in bicycle shops.
I am inclined to agree....why don't manufacturers offer a high stack height option and a low stack height option in the same frame series?
Do what the pros do. Go down one frame size.
Long head tubes are ugly on race bikes. My caad12 has nice geometry but was only supplied with 3 cm conical spacer, no default slam option. Power savings are substantial, slammed long stem @20 mph about 10% ~ 20w.
A Garcia, going down a frame size is not an option on the Emonda because they have paired a short top tube to those tall head tube. My current 54cm frame is more than a full inch longer in the top tube than a size 54 Emonda and I already use a 140mm -17 stem. I would need 165mm stem to get my length and a size 52 Emonda still has a much taller head tube than I am used to. Pro riders do not get the same geometry as is found in bicycle shops.
John O'Neill sounds as if your torso and arms are unusually long, and if your proportions are that far off from the average that fine tuning components won’t get you a proper fit, either you ought to be riding a fully custom frame or seeking a second opinion from a qualified and experienced fit tech.
Alex, do you think the new UCI seat angle rules are reason they (pro's) are Slamming the stems? There wasn't much talk about it before this.
possibly but anyone who does any aero testing in going to consider this, plus it was in the Velominati rules....Rule #45 " Slam your stem" a maximum stack height of 2cm is allowed below the stem and a single 5mm spacer above. ;)
Yes
velominati rules are stupid AF
i do not believe in slam stems too much because people with a very low position tend to never ride on drops i think is better a correct bike fit to allow you to ride the most aerodynamic position for most of the time
wouldn't the most comfortable aero position be a slammed setup so that your hoods are as low as possible? And then drops are even lower for more leverage and a lower head during a sprint?
It could be easier to assess the road and be more comfortable to ride with a slammed stem and avoid the drops this way.
Slamming the stem night make the bicycle alone more aero, but if the rider is holding the arms straight downwards, the arms are like barn doors to the wind. If I want to get aero, I don't bother with slamming, I just bend my elbows more so that my forearms and back are flat. Then if I want to ride more upright, I still can because my stem and bars are not ridiculously low.
Bingo, and if you bend your elbows in the drops, you have a very comfortable position to recharge on the tops, letting you get back aero again for round two.
@@bigring6424 but it's more aero to have forearms horizontal while on the tops. There are large aero losses by having hands on the drops. Drops are used for descending, cornering and sprinting.
this is probably the best cost free way to make your bike more aero and no more wheelie on steep climbs for me
with today's slopy top tube, an excessively negative (eg, -17 deg) stem makes the whole bike look a bit ugly as the top tube doesn't flow inline with the stem. Couple this with a tall head tube, and the bike is now hideous.
brilliant thanks!!
been slammed for 4 years no neck problems at 33.
Another great video by this presenter! I have one question about the very interesting drag budget displayed at 0:30. What is meant by the "handlebar/stem drag," which shows a value of 14%? Is this just a typo-namely, it's just missing the decimal pt (so should instead read 1.4%)?
If it's not a typo...I recognize how highly amplified the aerodynamic drag of leading-edge surfaces is in an undisturbed slipstream...but I simply cannot believe that, even with this emphasis noted, the aerodynamic drag of the handlebar/stem could be remotely close to that of the rider's body volume shown as 18% (maybe the arms in isolation, and even that seems like it would be pushing it).
So if this is not a typo, does the 14% somehow incorporate elements of the rider's body...or what explains the 14%?
Some other points that aren't incorporated in the spreadsheet, which I a realize has a value on simplicity/elegance, are:
(i) There's a limit to how much you can lean down and still benefit (or even not suffer) aerodynamically. There's even an optimum lean angle beyond which drag will start to increase again.
(ii) Wind tunnel testing has revealed that you are more aerodynamic with your forearms level to the ground on the hoods than with your arms extended to the drops (constrained by the same back ht / position).
(iii) Your head/neck position is astoundingly important (getting your head low and out of it's own slipstream); a raised head acts like a parachute-this effect even feeds back into the body lean angle because of the neck/eye strain at excessive body lean angles as you try to maintain some semblance of a fwd road view. So leaning down further to a theoretically advantageous height might be wasted or even detrimental if you just raise your head back up to see the road. Time trialists know this last challenge all to well.
But back to my main question, I'd love to better understand the 14% handlebar/stem drag figure!
Re handlebar drag (including cables) have a look at this link:
djconnel.blogspot.com/2014/08/cervelo-s5-and-aero-road-bars.html
i) There's a limit to how much you can lean down and still benefit (or even not suffer) aerodynamically
>> there is certainly a limit to comfort, power delivery and safety but aero?
(ii) Wind tunnel testing has revealed that you are more aerodynamic with your forearms level to the ground on the hoods than with your arms extended to the drops (constrained by the same back ht / position).
>> basically arms are a drag too, can be modelled by two x2 cyclinders
(iii) Your head/neck position is astoundingly important (getting your head low and out of it's own slipstream)
>> agreed
I just did this, i try to move my spacers at the above of the stem. 😁😁
and that about less wide front end?heard thats making bigger difference in aero drag
So at 6:13 in your own video you say you can't work out how much you could save or lose because "we know all that, yeah."
When I was a kid 20+ years ago, I had a custom TT frame made with 531 tubing and an 82 degree seat angle. The top tube and down tube was so long it required the tandem tubeset. I was 5'11 with a 34" inseam but the front end of this TT bike was essentially a 19" bike with a massive seat tube and a 24.5" top tube. The difference between the saddle and bars was more than a foot. Fast forward two decades I find out that I would be faster with a much higher position. Such is the wonders of now owning a power meter.
When doing video's like this there needs to be a reference to the bar height relative to the front end of the bike rather than 'does it need to be slammed' because head tube heights vary so much.
Swampster70 interesting comment but given the comparison is between two positions with the same head tube height I think it drops out of equation in an approximate calculation. Do you disagree?
You make the comparison between a high and a low position and unsurprisingly, a lower position is more aero but you should also look at going a bit lower and longer. It'll allow you to drop the shoulders as with the slammed stem but put less stress on the neck as well as allowing you to 'shroud' the head more effectively with the shoulders (think shoulder shrug).
The ultimate test is going out and riding for a few hours in the new position and seeing if it works. If you can only hold it for 10 minutes it's pretty much useless don't you think?
my problem is easy, i am simply to heavy to do that stuff :D since i hit the gym...and my weight is about 86 kg
on 177cm
Hey Alex, I had to request permissions to access the spreadsheet in drive, are you keeping it for patreon members for the moment?
no this is normal, if its unlocked from experience a small number of people make crazy changes to the actual coding or wreck the sheet. For safety, just request permission to enter your own data into the cells and it will work for you. Even on patreon google sheets require permission request. Its only excel sheets that are unlocked.
Fastfitnesstips Thanks! It was hilarious watching live updates with multiple users in the Aero bikes weight/value sheet for sure!
Keep up the great content 👍
haha! Yes I think I need to start cloning more copies when n>100
Aero bar and stem vs integrated? Hard to justify $500 US for integrated unless they are markedly better over aero drop bars.
John Dove Sort of a Gimmick for the money, saves something like 2.5 watts and I would say in ideal conditions. Some people like them so they can rest their fore arms on to get more aero with comfort. I would say these gains would trump the bars by themselves. So I would say, it depends on your reason and riding style for buying.
I slammed my stem the day I got my bike(the one in the profile pic).
Never looked back.
I am really surprised that handlebars have almost as much drag as whole body.
"Slamming" or "unslamming" is about finding the Goldilocks zones.
i have a question. lowering the drop to an extreme 25 degree down angle is comfy for me but when climbing out of the saddle it is too low to dance up the climb. wouldn't it be nice if we could pres a button and have the bars rise and lower as needs be, like with some saddles? or is that a danger from an engineering perspective?
i absolutely realize i need to compromise but surely some engineer out there can build this?
Good idea, how about this, double bars, for high and low position (canyon grail): coresites-cdn.factorymedia.com/rcuk/wp-content/uploads/2018/03/MG_18_02_Canyon_Presscamp_4776.jpg
What stem angle degree should i will use if i want the dropbar be level on the toptube
Im using aero dp
Tnx
the answer depends on your stem length and head tube but is easily calculated here goo.gl/ajVPbP
Hes right, and I'm reaping the benefits!
Is negative stem appropriate on a roadbike?
There's too many variables to have an absolute result in wattage saved or gained. With regard to frontal area, bar width and all riders are of different sizes, (height and weight) helmets are also of different shapes. These will be significant variables with regard to CdA. Not too mention YAW and the angle ( direction) of airflow in relation to the bike and the rider.
Was Eddie etc unfit, when they rode bikes with drop of 1-2 inches from saddle height to bar height?
This. If an aero position is not sustainable for at least long enough to perform an FTP test, then what is the use? It's no good saving 14 watts for five minutes then having to waste 20 watts for the next fifteen minutes because you are so slammed that flat fore arms is not sustainable. I have found my best compromise is to setup a flat forearm position with a compact bar that is sustainable in the drops for 3-5 minutes. This provides me an aero hoods position that is sustainable for 30 minutes, a straight arm drops position that I can comfortably use to descend and follow wheels and a short term aero drops position when hammering.
Exactly. Just saying you should slam the stem because it's more aero is too simplistic to be of any use. You body 'finds' the position it wants to be in when making an effort. If you slam the stem with not other considerations, you'll probably find that you have straight arms and don't use the drops, arriving back in the same torso position and hip angle that you had in the first place. Remember, the pro's are not a good model for normal people.
What the hell is with your seat angle? You'll slide off that thing mate.
lol. minus 9 now uci legal!
This info is all well & good in estimating how many watts can be saved etc BUT please guys & gals don't just slam your stems after watching this. If you're serious about your riding & want the correct inprovements that will give you sustained power output & comfort, invest in a proper bike fitting. Being aero doesn't mean you'll be comfy or in a good position to sustain power &/or comfort.
I've 25+ years as a bike fitting specialist & i'm happy to carry this out for anyone in the UK.
You can tilt up to minus 15 degrees without slipping. Nose down allows the pelvis to tilt forward, moving the lumbar spine into a more neutral position. If the UCI rules loosen up further, the Pros will definitely adopt an even steeper angle because low back pain continues to be a problem in professional cycling.
i ride slammed. Train you abdominal muscles and one wille be able to sit lower without back problems
I am super interested and at the same time puzzled by the image at 0:29, what is the source of all these numbers ?
Those are estimates from an old marginal gains calculator I wrote a few years back...since then we have improved the model of losses several times to account for rider speed, bike type, CDA etc.
@@Fastfitnesstips : Thanks, I am a bit surprised though by the contribution of body position : 4.5+18.8+8.5=31.8% of the total, so about 45-50% of total drag when all publications mention between 85% and 95%. Most notably but not limited to Table 2 of "Cycling on Earth, In Space, on the Moon", Eur J Appl Physiol (2000) 82: 345-360 by Pampero in 2000. What is your view on this ?
@@sebastienricciardi883 very roughly whole body drag is around 70% of aero losses (bike and equipment 30) which can be divided into 45% body 15 clothing 3 feet 5 head...but when combined with all losses body and clothing aero drag makes up around 40% at 40kph
@@Fastfitnesstips I just noticed that the total equals 85.85% and that there is not the rear wheel drag. Are some elements missing ?
@@sebastienricciardi883 must be rear wheel drag then?! As mentioned this is a very old version of one we use for our coached athletes
You can’t really rely on wind tunnel because wind in real life hits and comes in different directions
For all you proponents of slamming go and look at pictures of Graham Obree’s homemade bike for the hour record and then just think about it ……
So which is faster, dropping the riders shoulders by dropping the bars or dropping the riders shoulders the same amount by keeping the bars the same height but pushing the bar out forward?
I know the answer to this. Do you?
This is very unscientific. Using studies of individuals and using extreme variances in height is all very very well - I guess you're comparing racing positions versus bunter positions - but if you think that slamming your stem is the only aim, you could be very wrong. Your current marginally higher position could be faster - if you move your position down 3cm to get the slam and it creates a poor body position, maybe some over-reaching where your shoulders don't sit optimally, you will actually create more drag than your slightly higher position. Apart from the changes to hip flexor angles, lower back position, ability to stomach breathe, etc. affecting power and performance, if we are talking about only a slight variation in height, it is far more important to be narrow.
Have you completed our turbo training survey? www.surveymonkey.co.uk/r/BMR8HLZ (382 replies so far, need last 18!)
I live in a windy mountainous island...slamming the stem of my bike is just necessary...
Wow, what a lot of words to say lower your bars for a 1-2% gain.
I slammed my Bike rise handlebar whahahah
Надорвать спину из за этой хрени?
None. Because nearly all that do so ride on the hoods 99% of the time.
Slam those mothers lol.. plus it looks better 👍👍 think pro .. act pro .. slam slam thank you mam 🚴🚴🚴🚴🚴🚴🚴🦏🦏🦏🦏🦏💣💣💣💪💪💪💪💪⚡️⚡️⚡️⚡️⚡️⚡️⚡️⚡️🌬🌬🌬 great info as always ..many thanks for the video
Zero.