Best stem for comfort

[ColinJ]

But increasing tyre widths and (DECREASING?) pressures will give you the most beneficial effect, and many frames can manage a tyre which is 26mm wide (eg Conti GP4S 28-622). With an 85kg all up load mine run at only 75psi front and 90psi rear.

 

[S-Express]

Interesting debate about road buzz. Here's my take on it.

If you're getting lots of vibration through the bars, and it's really jarring, then you're probably putting too much weight though your arms. This is quite common. Most of us have pretty poor core strength. Your core muscles should be supporting your core, to a large extent. Your upper body weight should not all be tilted down through your arms and hands.

I used to suffer carpal tunnel syndrome, when I was doing this, and it's not pleasant. In my view, no amount of damping, or cushioning, will compensate for bad cycle posture like this. Far better to work on your functional core strength. Off the bike, crunches, planks, sit ups, Russian twists, etc, on the bike, practice riding with minimal weight through your arms, or even no weight, as you get better at it.

Improving core strength can also improve power delivery. All power delivered though the legs uses the core (torso) as a base or platform. A stronger core will reduce the rocking or snaking effect through the torso, which is effectively like a worn ball joint.

Jarring and vibration are two different things though, aren't they. Vibration suggests high frequency, low impact, while jarring implies lower frequency, higher impact. I don't think either would be helped by core strength in any case. Fork shape (mentioned in an earlier post) is not relevant either - unless whoever thinks that believes that the fork actually moves visibly under impact - which it obviously doesn't.

You say 'most of us have pretty poor core strength' - but I don't think that's generally the case. Most of us have adequate core strength for whatever it is we do. As presumably most of us on here are cyclists, then our cores will have adapted and/or strengthened according to the needs that cycling places on it.

Forces applied through the legs while cycling are relatively low, at a level already well within the capabilities of most people's cores. Rocking or 'snaking' is usually a symptom of poor fit, or poor technique, rather than a weak core.

 

[Ajax Bay]

Fork shape (mentioned in an earlier post) is not relevant either - unless whoever thinks that believes that the fork actually moves visibly under impact - which it obviously doesn't.

Disagree. Fork shape is relevant. The fact that you can't 'see' the fork moving (ie absorbing some of the input from the road) doesn't mean that it's not moving: your eyes are just not up to it. It obviously does: put a stress on the fork and it will deflect (or compress/extend if the force is directly axial). This will absorb some of the 'road buzz' to a greater or lesser extent. A steel fork with a decent curvature in its lower third (image in @dim 's post #32 above) is designed to do precisely this. Straight carbon blades are not; and don't (to the same extent). But as @ColinJ has said, wider tyres and the reduced pressures thus available have a much bigger part to play. And counter intuitively, at lower pressures, the general shaking around is less (mostly absorbed by the main suspension system (the rider's body)) and so rolling resistance will be less as well. The main argument for narrow tyres is the aero one, with the additional weight of wider tyres in support. So unless you're averaging 25kph +, go wide, and be more comfortable.

 

[S-Express]

Disagree. Fork shape is relevant. The fact that you can't 'see' the fork moving (ie absorbing some of the input from the road) doesn't mean that it's not moving: your eyes are just not up to it. It obviously does: put a stress on the fork and it will deflect (or compress/extend if the force is directly axial). This will absorb some of the 'road buzz' to a greater or lesser extent. A steel fork with a decent curvature in its lower third (image in @dim 's post #32 above) is designed to do precisely this. Straight carbon blades are not; and don't (to the same extent).

No. You might be forgiven for thinking that, but it's not true. Any such fork with 'compliance' built into the blade shape would be uncontrollable under heavy braking load, and would visibly sink with a heavy rider. The fork may indeed flex, but no more or less than a fork of any other shape.

 

[Ajax Bay]

Any such fork with 'compliance' built into the blade shape would be uncontrollable under heavy braking load, and would visibly sink with a heavy rider. The fork may indeed flex, but no more or less than a fork of any other shape.

Where on earth have you dragged up "uncontrollable under heavy braking load"? In what way 'uncontrollable? The fork shape has no effect on steering characteristics which is a function of head tube angle and offset. I've already said that these 'movements' are not visible to the naked eye, however heavy the rider is (and yes the fork will deflect with a heavier load).
So the fork "may indeed flex" then. But you said earlier: "the fork actually moves visibly under impact - which it obviously doesn't". Move? Flex? Why would a different shape of fork not deflect differently? (Answer: no reason: they will deflect differently and a fork with a decent curvature in its lower third will do so having the effect of reducing the effect (at the bars) of 'road buzz'.)
Quoting (highly esteemed frame builder and cyclist) Tony Oliver in "Touring Bikes" IBSN 1 85223 339 7:
"The shape of the [fork] rake will determine the degree of comfort. [Decries large radius 'pneumatic-drill' banana-shaped blades - fine for TT but not for touring/distance.] . . . ... A blade with a small radius bend low-down near the fork-end will minimise the transmission of road vibrations through to the bar. .. . . . Fashion causes some dire compromises and many younger riders (is that you @S-Express ) prefer to have numb hands rather than be seen riding a fork that looks a little old-fashioned (a fork like mine - 103km today)."

 

[S-Express]

I've not heard of Tony Oliver, but it seems he is relying on anecdote, rather than science. Shape has little - if any - effect on fork performance. Pinarello's curvy fork (for example) performs no differently than a straight one - or one with a slight bend.

 

[bozmandb9]

Jarring and vibration are two different things though, aren't they. Vibration suggests high frequency, low impact, while jarring implies lower frequency, higher impact. I don't think either would be helped by core strength in any case. Fork shape (mentioned in an earlier post) is not relevant either - unless whoever thinks that believes that the fork actually moves visibly under impact - which it obviously doesn't.

You say 'most of us have pretty poor core strength' - but I don't think that's generally the case. Most of us have adequate core strength for whatever it is we do. As presumably most of us on here are cyclists, then our cores will have adapted and/or strengthened according to the needs that cycling places on it.

Forces applied through the legs while cycling are relatively low, at a level already well within the capabilities of most people's cores. Rocking or 'snaking' is usually a symptom of poor fit, or poor technique, rather than a weak core.

You're entitled to your opinion I suppose. However mine is based on my experience training and knowledge as a Personal Trainer and cycle coach. Do you have any basis for yours other than your personal experience?

Certainly your statement that the core strengthens according to need is wrong. We can cycle for decades with poor form which never improves, unless we target specific improvements, as I am proving with clients is their 7th and 8th decades.

 

[S-Express]

You're entitled to your opinion I suppose. However mine is based on my experience training and knowledge as a Personal Trainer and cycle coach. Do you have any basis for yours other than your personal experience? Certainly your statement that the core strengthens according to need is wrong. We can cycle for decades with poor form which never improves, unless we target specific improvements, as I am proving with clients is their 7th and 8th decades.

Yeah, I've also got lots of experience, both as a rider and a coach, but that's irrelevant, as is yours. I'm not into saying stuff like "I must be right because I'm experienced" - I would rather rely on empirical evidence. So I'm interested to understand what evidence you have which suggests that cycling does not tax the core muscles in acordance with the demand placed upon them. I'm also interested to understand why the exercise undertaken by the core while cycling, is not enough for cycling? I'm also interested to understand your thought process behind your claim that a better core improves power delivery?

Finally, I'm still not clear what you mean by your statement "most of us have pretty poor core strength". Poor in relation to what? Can you enlarge on that?

 

[Ajax Bay]

I've not heard of Tony Oliver, but it seems he is relying on anecdote, rather than science.

I commend his book to you. He is a physicist by education and early employment, morphing into many years building frames full time of every sort you could imagine, and more (when not cycling (TT and touring)!). Science.
@S-Express said "I'm interested to understand what evidence you have which suggests that" @S-Express said "Shape has little - if any - effect on fork performance". Anecdote?
To convince yourself, I suggest you sketch a curved fork and then mark the forces acting on the fork-end and then do the same with a much straighter if not straight bladed fork. Which do you think will flex more and thus "minimise the transmission of road vibrations through to the bar"? The curved one (with a small radius bend low-down - and I don't mean the Pinarello marketing snake) or the straight one?

 

[Smokin Joe]

A "Straight" fork is not straight. It is angled at the crown in order to replicate the geometry of a curved fork, and if there is any flex from the curved part of a conventional fork the offset on the straight fork's crown will serve the same function.

 

[S-Express]

To convince yourself, I suggest you sketch a curved fork and then mark the forces acting on the fork-end and then do the same with a much straighter if not straight bladed fork. Which do you think will flex more and thus "minimise the transmission of road vibrations through to the bar"? The curved one (with a small radius bend low-down - and I don't mean the Pinarello marketing snake) or the straight one?

Sounds like you might be the one who needs convincing. There is so much more to this than you appear to be grasping. Stiffness not only relies on material, but also tube profile and wall thickness within the plane in which it is supposed to be flexing. The majority of steel hand-builders these days supply frames usually matched with off-the-shelf carbon forks - which flex very little, if at all. If the 'bent' steel fork is so good at 'soaking up road bumps' (lol), then ask yourself why most builders no longer bother making them? If you get a chance to google Rinard's 'fork deflection test' study, it's worth a look. It's a bit out of date now, but hopefully you'll get the idea. Basically, the results show that the difference between the stiffest fork and the flexiest fork were absolutely minimal. It also shows that material choice and blade design are not consistent in terms of which fork offers the most/least flex. In other words, it doesn't follow that the stiffest is carbon/straight and the flexiest is curved/steel.

 

[Shortandcrisp]

Not sure how much core strength is relevant to cycling. A minimal amount is my assessment based on recent personal experience.
Five weeks after leaving hospital having suffered a serious spinal cord injury, I was able to cycle 20-25 miles, albeit at a slower pace than before. This despite finding it extremely difficult to walk, impossible to do one press up, one pull up, hold a plank position or squat using my own body weight.

 

[Ajax Bay]

"Stiffness not only relies on material, but also tube profile and wall thickness within the plane in which it is supposed to be flexing." Agree. What's that got to do with fork shape?
"The majority of steel hand-builders these days supply frames usually matched with off-the-shelf carbon forks - which flex very little, if at all. If the 'bent' steel fork is so good at 'soaking up road bumps' (lol), then ask yourself why most builders no longer bother making them?" My assertion you've disagreed with is about shape not material. Interesting to see (in the graph in the study you referred to (qv)) that the Trek OCLV forks deflected longitudinally most. I had just this fork on a Trek 5500 OCLV: a carbon fork but shaped with a small radius bend lower down.
"If you get a chance to google Rinard's 'fork deflection test' study, it's worth a look. It's a bit out of date now, but hopefully you'll get the idea." Refer to a study and then diss it as being old/ood? Thank you for pointing to it, but pity you can't do so politely ie "hopefully you'll get the idea".
"Basically, the results show that the difference between the stiffest fork and the flexiest fork were absolutely minimal. It also shows that material choice and blade design are not consistent in terms of which fork offers the most/least flex." Don't agree: what do you mean by minimal? What amount would be 'significant'? He only hung a 20kg weight on the forks. The study made minimal reference to blade/fork shape. I have not sought to discuss materials: you keep bringing that in as a distraction (along with "tube profile" and "wall thickness").

@S-Express said "I'm interested to understand what evidence you have which suggests that" @S-Express said "Shape has little - if any - effect on fork performance". Anecdote?

Road vibration is typically absorbed by deflection/damping in various parts (in order) as follows ;
- tyre
- fork (blades and steerer)
- frameset (bending in the top tube and down tube)
- handlebar flexing (hence sometimes more comfortable to go onto the drops)
- wheel flexing
Note (back to the OP) that 'stem' does not feature. It is short and very stiff (compared to the frame tubes).

A "Straight" fork is not straight. It is angled at the crown in order to replicate the geometry of a curved fork, and if there is any flex from the curved part of a conventional fork the offset on the straight fork's crown will serve the same function.

Most of the 'straight' forks are pretty straight, actually. The 'angle' between the steerer and the fork blades is designed to provide the necessary offset at the fork-ends (a distance measured in mm, not an angle) which, with the head tube angle, will define the nature of the steering: slow and steady for tandems, right up to fast and twitchy for criterium racing bikes. I think this abrupt change in angle (steerer/blade at the crown) will not have the same deflection/road vibration absorbing effect (function) as an old-style shape fork with a small radius curve lower down. Why do you think frame makers of old went to all the trouble of shaping the fork blade from tapered tubing that way, when it would have been much easier to just make the fork with straight (steel) blades? Answer: because it provided a more comfortable ride.

 

[S-Express]

@S-Express said "I'm interested to understand what evidence you have which suggests that" @S-Express said "Shape has little - if any - effect on fork performance". Anecdote?

It was very difficult to follow your last post, so I'm not sure if I've understood you correctly. I just referenced the Rinard study. It suggests that shape has little effect on fork performance. Is that what you were asking?

 

[Ajax Bay]

I just referenced the Rinard study. It suggests that shape has little effect on fork performance.

"The study made minimal reference to blade/fork shape."