So I'm very comfortable on my Cervelo RS, and so of course am thinking what I can do to change. No, really, I have gotten more flexible in the 18 months I've owned it, and have already flipped the stem. I have a few spacers on it (I'm 55!) and am wondering whether I could tolerate (or learn to tolerate) more drop–I like to go faster unless pain ensues. But the steering tube is cut to my current configuration. If I remove spacers there'll be one of those bumps that look dangerous. I suppose I could try it temporarily? I could also get a negative stem, but that would look weird with spacers. Oh, if this doesn't work it's gonna be because of my neck, which feels okay now but which does not feel like it has lots of room to raise my head back as I ride. So anyone with advice for neck stretching, feel free to give.

I've gone through the same process, since buying my Roubaix 2 years ago. It came with a positive stem and lots of spacers. I gradually lowered the stem, until all the spacers were above the stem, which I then reversed. I do experience some neck pain after about 2 hours, so I may have reached my flattest ride posture.

I haven't thought of the "bump" as being dangerous, until reading your post. Thanks!

some manufacturers tell you not to have spacers above the stem (other than a very small one to get the top cap to hit right.) the reason is that it moves the clamping force of the stem below the portion of the steerer tube which is reinforced by the compression plug.

This appears to make some sense if you use a glued in aluminum sleeve to hold the start nut.

That said I wouldn't worry about it, particularly on the temporary basis, as long as you're careful torqueing the stem bolts.

Huh, I've always heard the opposite - that you should have a small spacer above the stem so that torquing the bolts doesn't crush the end of the steerer, which is the weakest area. Either way, I wouldn't worry about it unless you have more than 2 cm or so of spacers stacked above the stem, or more than a couple mm of the stem stick up above the top of the steerer.

A small, i.e. 5mm spacer is one thing, and commonly recommended. A stack of spacers above is another.

https://cdn.specialized.com/OA_MEDIA/...n_Guide_r2.pdf


According to Cdale:

"DO NOT EXCEED THE MA XIMUM STA CK HEIGHT OR LO CATE SPACERS ON TO P OF THE STEM. MAXIMUM
STACK HEIGHT is a distance spacers may be stacked between the top of the head tube and the bottom of
the stem. Exceeding this distance with spacers or locating spacers on top of the handlebar stem can place
significant stress on the steerer tube. It could break.
For technical information and specifications, see https://www.cannondale.com/tech_center"

https://media.cannondale.com/media/Ma...ual_124451.pdf

Regarding handlebar height: it's commonly understood that lower, further away handlebars give an aggressive position that may be worse for the back and that higher, closer bars give a more comfortable, back-friendly position. But this is a dangerous generalization. You can have the bars closer and higher, but because of saddle height and setback have your spine under a lot of tension. Or you can have the bars lower and/or further away but with a neutral spine under a lot less stress. A lot of riders are surprised to find that they are more comfortable after a re-fitting that actually moves them into a more aerodynamic, lower position. It's important to remember that handlebar position is just one of three contact points in a bike fit (hands, in this case), and its effects can't be considered without the relationship between that and saddle height (butt) and setback (feet). How hard the rider typically goes is also important, as torque from the hips can also take some of the weight off of the hands. Whether you're a racer or just cruising, though, the key is that your position be balanced and keep your back as neutral as possible.

As an example, I recently changed my position by moving my saddle up and back a bit, while putting on a 1 cm longer stem. I'm actually more comfortable with this position as it has caused my hips to tilt forward on the saddle, releasing my lower back from a lot of tension. The major adaptation is not my back or shoulders, but my diaphram and core, which were used to being scrunched up rather than elongated. It has also closed up my hip angle a bit, which helps with power in a sprint, but can hurt aerobic output a bit. As a result, I find myself hopping out of the saddle on climbs more often to open it up a bit.

I would suggest consulting a fitter who focuses on racers or performance-oriented cyclists if you want to get lower. If your saddle setback is appropriate for your current bar position, this change will probably require that your saddle come up and forward a bit - effectively rotating you forward without altering your position so much. A fitter can help you move it the right amount. On the other hand, if your position is already pathological, as mine was (hence my moving the saddle back, not forward), the fitter can help you get it right, enabling you to get not only lower but more comfortable and less prone to injury as well.

As usual Merlin is correct and you are misinformed. Too many spacers above the stem clamp displaces the steer expander higher. This doesn't allow for the expander to reinforce the ID of the carbon steerer tube in the area of highest stress where the stem clamp bolts are torqued...or below where the lower edge of the stem clamp induces a stress riser due to handlebar torque applied by the rider.

What you write about is true and why fit can be somewhat counterintuitive. A longer and lower position may end up being both faster and more comfortable. Of course it may be the opposite as well. Only way to know is to experiment. If I see a common mistake, it is recreational riders ride with their handlebar too close to their saddle. If pros are to be emulated, I believe it should be less with drop and more for net reach. Riding cramped is poor for comfort and power.

I've been a stickler about CF steerer spacers and manufacturers tech data in other threads...but I'm starting to wonder just how precise this needs to be. (probably needs its own thread, really...)

For instance; Cannondale CF steerers. Due to the interface C'dale specifies NO spacers on top. Period. Yet the C'dale pro tour team bikes are pretty much all violating that guidance on their shiny Supersix Evos.

Other CF steerers, like Bontrager; 2-3mm above the stem, with a 5mm spacer. This is due to their interface.

Easton EC90; 7-8mm above, with an ugly honking 10mm spacer. Yet with their unique thread-in "bung", and the thickness of the CF steerer, why not 2-3? And, of course, pics of bike shop and team bikes routinely show "violations" of all these things. Aside from some Bontrager forks, there have not been a rash of steerer failures out there. (And Trek blamed FSA in the end, so there we go...)

I have a Roubaix and recently lowered my bar; only one very thin dust cover; then the stem and on top of that four 5 mm spacers; carbon and alu mixed(!) as my lbs did not have carbon spacers enough. Anyway, the ride is very nice. I may cut the steerer eventually; or not - I do not really care.

Like any rule of this nature, its nuanced. Purpose of course for safeguarding against a stack of spacers on top is lack of expander reinforcement where it matters down below. Specialized which has a pretty elaborate and long reinforcement expander for example had a recall on their forks for breakage. 99% of riders won't be affected. Its worse case 'stack ups' that kill companies. What is this? Its an anomalous combination of events.
In this case, a hospital visit may result if:
- Big stack on top of the stem
- Stem bolts overtorqued
- Stem clamp design creating biggest stress riser
- 250 lb weight lifter sprinting out of the saddle in the drops putting ridiculous torque of the handlebars.

Mfr's have to safeguard designs against worse case scenario. Most of us would not be affected by stacking spacers above a stem. I have done it on many bikes. And of course, no two manufacturers have the same expander designer or even the same fork steerer tube strength. So difficult to quantify the risk for any given bike model...mostly being rider (weight and strength) dependent.

OP - I'm a little bit younger than you and have only been riding since last October, but have found that I have been able to get into a more aggressive poosition, as the flexibility has improved. If you have the ability to alter it yourself, you could try changing it one 5mm spacer at a time - ride for a while and then weigh up your options to leave it as is, or try another 5mm spacer - until you get to where you reckon you're at your most efficient / comfortable.

cheers

LOL. I thought Merlin's clarification was, well, clearer, but thanks.

Indeed, I see lots of riders (including racers) with their handlebars very low but close, the worst cases with their elbows locked and arms essentially vertical from the shoulders down to the hoods or drops. It looks both uncomfortable and like a very scary way to ride. It can't be easy to handle the bike confidently with the bars in that position.