Talk To Me About Slammed Stems On Road Bikes

What advantages does this confer? I have recently switched from a 110mm to 90mm stem and it has changed my bike’s handling hugely. Bike feels a lot more nimble, reacts quicker when sprinting and means more of the saddle is available to me when I move about. I love it.

I am now considering removing some of the spacers to get lower down because it is a near zero cost option to change how the bike handles. I think maybe the benefit is a more aero position, but would like to confirm this before getting the hacksaw out. I am pretty flexible so lower position and back issues are not a problem.

All advice gratefully received!

Just put the spacers above the stem and see how it feels!

Bend your elbows to drop your upper body by the height of your spacers; that’s the effect it will have.

To try it another way, just take the spacers off, put the stem on, and stack the spacers above the stem.

my bike became a lot more comfortable – especially in the drops – which I did not expect.

But if I take the spacers my Garmin won’t fit!

Alright, I’ll stop being a lazy git and do it.

Still interested in knowing if there are any measurable advantages though. I don’t want to do it just because it looks “Pro”.

@zilog6128 the drops position is pretty comfy already, but I will check that too.

Still interested in knowing if there are any measurable advantages though

There might be a very small, minute, teeny weeny aero advantage, but only if you can pedal as powerfully when in the drops with the stem slammed.

How many spacers are there now?

Go crazy, take a set of Allen keys on a ride and try it. Will take all of five minutes to swap around.

I refer you to rule #45

A maximum stack height of 2cm is allowed below the stem and a single 5mm spacer must always – always – be stacked above. A “slammed down” stack height is preferable; meaning that the stem is positioned directly on the top race of the headset.

2 spacers right now and I am violating all over Rule #45’s face.

Any advantages when not in the drops? Perhaps something comfort related?

Ye i dont think it’s really about the aero advantage. I certainly feel that a lower stem allows me to recruit a little more power, climbing either on the tops or stood up, and drops my elbows a little further under my armpits/lats, which was made more so by going from a 130 to a 120 stem.

Like the others say, just swap the spacers round and try it, not just for a ride, give it 15-20 hours of total riding before you make judgement and make sure you try riding for as long as you normally tend to ride (not just hour blasts).

Can’t deny slammed and reversed is aesthetic, it’s really about how much your neck can’t cope. I was checking them out bikes on stage 1 yesterday and was surprised to see some even some long head-tubes with spacers and + angles.

Listen to people that follow the rules and you’ll end up with something like this.

your stem should be positioned where you can sustain your maximum power output for the length of ride you intend to be doing ….

varying position can change the time and ammount power you can sustain

How tall are you? 90mm is fairly short for a road bike stem. I think longer and lower feels better, especially when descending.

I found it stiffer and more comfortable, especially when on the drops. Also think it is more aero.

Interested in knowing how height affects things.

It has eliminated of the elbow stiffness and sorted the reach while on the hoods with the 110mm stem. Could maybe get away with 100mm, but the 90mm stem was a Ritchey WCS 4-Axis one I had lying around doing nothing so a good use for it.

Been on the 90mm for a week with a 156km ride yesterday and a couple of 50km+ rides too and it feels fine going up and down so I’ll keep it for now. Got some Easton EA70 bars lying around too which need to go on at some point.

Going lower and longer usually makes you more aero and will not make you more powerful.
Lets see a picture of your bike.

experiment without cutting stuff first-I’m still playing around with mine and its gradually getting lower (possibly as Ive got used to road riding I’ve adapted to the position and got more flexible). Got mine inverted and “slammed” bar one 5mm spacer (on a Lapierre which has a short, racey headtube), just come back from a 70 miler with no aches and pains and was surprised how comfortable it felt even on the drops.

I’m not desperate to slam it for aesthetics or roadie kudos, just trying to find a comfortable efficient set up and as a middle-aged born-again roadie I expected to need/want it higher.

You’d be better off with a longer stem and a shorter reach bar; look at FSA Omega Compact bars, even the cheapest are a brilliant shape, and will allow you to go longer in the stem and maintain the same reach. They also bring the drops to a much more usable place, in my opinion.

Also check you saddle to bar drop. You don’t want to get too far below your saddle hight.

Advantages:
-More aero (not by loads)
-More weight on the front wheel, good for cornering
-bike looks ‘pro’

Disadvantages:
-Flexibility issues could reduce power output
-More weight on front wheel, perhaps not so good for hard front wheel braking
-flexibility issues may make you look very ‘untidy’ when pedaling

If you’re bike has a short head tube i.e. <12cm then you’ll need very good levels of flexibility (very few people actually are flexible enough, including the pros e.g. Gilbert) to get away with slamming your stem. Slamming it if you are not will just delve you into a world of bio-mechanical issues with your neck, recruiting the glutes and hip flexors, lower back issues etc. If you’re uncertain, get a bike fit.

Fiddle with the spacers, that’s what they’re there for. Try flipping the stem.
90 is short, well in my opinion. Deda do wickedly short reach bars for under 20 notes.
Long stems are great for many things, especially climbing as you can get right over the front.

Cheers guys. I have a follow up with the bike fit man on Friday so I’ll test with spacers removed prior and see what the analysis comes up with once I’m there.

The main reason I swapped to the 90mm stem was so I could reach the brakes when on the hoods better. It wasn’t much of an issue on anything under 30km, but on longer rides my arms got really stiff. If the Deda bar will solve my reach problem with the brakes then I will look into that too.

One of my favouritest things about the setup sheets that come out of bikefitting sessions is that they never spec the bar reach or drop. It’s like bike geometry tables that will tell you the minutiae of the head tube rise, but never ever the stem length fitted on that bike, or how many spacers are underneath it.
As for yours.. Try moving it 10mm a time without cutting anything. I’d avoid too shorter stem as you’ll knock your knees on short sprinty climbs, so check the reach of the bars

The drops aren’t the most aero position, the tops are, with your elbows bent. The drops give you plenty of control because they’re a wider stance.

You will be more aero with a slammed stem, whether that’s measurable is another question, but reducing your frontal area will make you quicker, assuming you can still actually pedal.

So have they been getting it wrong for years ? 🙂

Shred
Also check you saddle to bar drop. You don’t want to get too far below your saddle hight.

My saddle to bar drop is 112mm.

bikewhisperer
One of my favouritest things about the setup sheets that come out of bikefitting sessions is that they never spec the bar reach or drop.

When I had my Retül fit I got a PDF with saddle height, setback, angle, effective seat tube angle, grip angle, frame stack/reach, saddle to bar reach, saddle to bar drop, grip (saddle to hoods) reach, grip drop, bar reach, bar width, bb to grip reach, bar stack, bar reach

So maybe you’re not going to the right bike fitting sessions.

Also check you saddle to bar drop

Saddle to drops drop really. My saddle to bar drop is 8cm, but I have full 17cm bar drop on top of this. Compact bars allow a shorter drop for the bars and can eliminate the spacers. They are less comfortable when riding on the inner bend if you need to stand up.

So spacers and proper bars or slammed and compact. It’s all aesthetics . 😉 . I find the length of the drops is important, too short and the hands are reaching too far forwards – hence a shorter stem to bring them back.

90mm is pretty short though, on anything less than a small/52cm frame.

54cm frame.

I’m yet to notice any drawbacks though. What should I look out for?

Slammed stem = better handling, better position (i.e. more aero, more comfortable, and just easier to do everything), and looks a lot better.

Disadvantages? Go too long, and too low, and you might end up being a bit uncomfortable, and if you go stupidly low and long it can be a little bit trickier to get the power out.

Currently slammed with a 130mm -10 deg stem on my main road bike, recently swapped over from 110mm – it’s definitely better, but it’s still taking me a little bit of time to get used to it.

Go too long, and too low, and you might end up being a bit uncomfortable

Nah, you’ll end up riding everywhere on the hoods. As I said earlier, if you find yourself riding on the hoods a lot, then your bars aren’t adjusted properly. Half-in-half is a good target to aim for, then build time on the drops from there.

I’d disagree, for normal riding I’m probably on the hoods 90% of the time. Drops for faster more technical descents, and the tops occasionally when climbing.

Half-in-half is a good target to aim for, then build time on the drops from there.

Why?

I’m probably on the hoods 90% of the time. Drops for faster more technical descents, and the tops occasionally when climbing.

pretty much what I do IANAroadie tho. First time I’ve heard the 50/50 thing TiRed, not saying you’re wrong, I’ve no idea, not really looked much into it TBH.

Also,

http://www.slamthatstem.com

Half-in-half is a good target to aim for

I don’t think so. I’m on the hoods most of the time, and on the drops for fast technical sections – so I’d agree with the 90/10%. If your’e 50/50, I’d say your bars are way too high… but each to their own and all that.

To the OP, I find a longer/lower stretched position far more comfortable than shorter & higher, even for long days.

The main advantage of a slammed stem is you get to comply with a set of arbitrary rules.

Being comfortable on the drops is more efficient and saves energy. If you have to ride 20 miles into a headwind (Saturday) you want to be efficient. As I said, if you aren’t riding on the drops much then your bike isn’t fitting properly. The design of modern “race” bikes makes this harder. Older pro bikes had higher front ends. There was an excellent article in the Comic a few weeks ago on just this subject.

It’s an averages thing;
Average speed = %time on drops x speed on drops + %time on hoods x speed on hoods.

Optimize that for comfort with stem length, spacers and bar geometry to bring the bars closer (and the drops, but not necessarily the hoods up). Now I’ve fitted my new bike properly, I’m seldom out of the drops and it’s a revelation. Of course it’s a comfort bike with spacers 😆 but I rode a 60 mile club ride on Saturday and about 3/4 or more was on the drops. In fact the hoods feel slightly too high for long comfort. But the saddle to drops is 22cm.

Sorry to hijack the thread and that, but I have the opposite problem, namely a too low riding position for my recently dodgy lower back. This is exacerbated by the fact that mine is a 90s racer with a quill stem that has been raised to its limit. My LBS have told me that the forks are only compatible with a quill stem and that I can’t get one with any kind of rise, therefore only option is change forks for new stem (ie loads of moolah and ruin aesthetic of bike). Is this the case and if not, what are my options? Any advice most welcome 🙂

As I said, if you aren’t riding on the drops much then your bike isn’t fitting properly.

Hmmm. I’m using the drops much more than I used to, yet I haven’t changed my bike set up in 3 years. I put it down to having spent a lot more hours in the saddle this year, which has got me used to holding a more aero position with less discomfort.

If you have to ride 20 miles into a headwind (Saturday) you want to be efficient.

But as mentioned, the drops isn’t the most aero position – on the hoods with bent elbows is – you have a smaller frontal area.