Best stem for comfort

[Reynard]

If I remember my 2nd year undergrad dynamics correctly, the vibrations you feel depend on a) the excitation i.e the vibration induced to the object in question (in this case, that provided by the uneven road surface) and b) its natural frequency. If those two frequencies are wildly different, theoretically you shouldn't feel a thing. But if those frequencies are similar, you will most certainly feel a noticeable vibration. If the frequencies are identical, then that really does spell trouble...

The material for said object isn't so important as its natural frequency and the vibrations to which it is subjected. This is where dampers come into play if there is a danger of those frequencies being similar. Examples of these are the weights you see hanging from power lines or on suspension bridge cables, or, in the case of a bike, the tyres themselves (and the pressure at which they run). These act to alter the natural frequency of the object in question to one which it is unlikely to encounter during service.

If you ever want to see the effect of natural frequency and induced vibrations (in this case a gusting wind) matching, look up the Tacoma Narrows bridge.

 

[Deleted member 1258]

 

[vickster]

If I remember my 2nd year undergrad dynamics correctly, the vibrations you feel depend on a) the excitation i.e the vibration induced to the object in question (in this case, that provided by the uneven road surface) and b) its natural frequency. If those two frequencies are wildly different, theoretically you shouldn't feel a thing. But if those frequencies are similar, you will most certainly feel a noticeable vibration. If the frequencies are identical, then that really does spell trouble...

The material for said object isn't so important as its natural frequency and the vibrations to which it is subjected. This is where dampers come into play if there is a danger of those frequencies being similar. Examples of these are the weights you see hanging from power lines or on suspension bridge cables, or, in the case of a bike, the tyres themselves (and the pressure at which they run). These act to alter the natural frequency of the object in question to one which it is unlikely to encounter during service.

If you ever want to see the effect of natural frequency and induced vibrations (in this case a gusting wind) matching, look up the Tacoma Narrows bridge.

Good Lord, don't let science get in the way of marketing

 

[Reynard]

Good Lord, don't let science get in the way of marketing

 

[smutchin]

Good Lord, don't let science get in the way of marketing

View: https://youtu.be/Z4cEfEgNvwY

 

[e-rider]

resonant frequency - 3Hz makes you lose control of your bowels, or so it's claimed - let's not get a seatpost that resonates at 3Hz on surface dressed roads then.

 

[Randy Butternubs]

If you ever want to see the effect of natural frequency and induced vibrations (in this case a gusting wind) matching, look up the Tacoma Narrows bridge.

According to one of my university professors this is a common misconception. The bridge actually failed to aeroelastic flutter.

(Yes I do love ruining things)

 

[iandg]

I've had tyres that hum, but never heard a road buzz........road vibration a different thing tho' - a steel frame with a nice pair of 28c's is much smoother than an alloy with 23c's - I sold my only aluminium bike after only a few months of riding.

I used to have a flex stem on my MTB which helped dampen vibration through the bars.

https://flic.kr/p/9FLbRJ

 

[Smokin Joe]

I've had tyres that hum, but never heard a road buzz........road vibration a different thing tho' - a steel frame with a nice pair of 28c's is much smoother than an alloy with 23c's - I sold my only aluminium bike after only a few months of riding.

I used to have a flex stem on my MTB which helped dampen vibration through the bars.

https://flic.kr/p/9FLbRJ

I think the clue is 23's and 28's.

 

[iandg]

I think the clue is 23's and 28's.

My steel audax bike is comfy with 23c and 25c tyres too - I even tried 25c on the aluminium giant but it was so 'bumpy' I ditched it pretty quickly and went back to a steel frame

 

[Smokin Joe]

My steel audax bike is comfy with 23c and 25c tyres too - I even tried 25c on the aluminium giant but it was so 'bumpy' I ditched it pretty quickly and went back to a steel frame

Same geometry and brand of tyre and tube as the aluminium bike?

 

[iandg]

Same geometry and brand of tyre and tube as the aluminium bike?

No, but I've ridden my old 1970s Raleigh which has the same geometry/wheelbase as the 'ex' giant and used the same Rubino Pro tyres and that was far more comfortable too.

 

[HLaB]

My first road bike was great but I could get a bit of what I'd call 'Road Buzz' over a slightly rougher surface, it had alloy forks; I've never experienced it on far rougher surfaces on subsequent bikes with carbon forks. A carbon stem might have a slight dampening effect but I doubt you'll notice it; forks, wheels and tyres are probably your better bet. Try just simply dropping a few psi on the tyres (not too low as you'd be subject to p'tures).

 

[dim]

My steel audax bike is comfy with 23c and 25c tyres too - I even tried 25c on the aluminium giant but it was so 'bumpy' I ditched it pretty quickly and went back to a steel frame

Hmmmm .... I'm not so sure about that. There's not much difference in ride quality between a carbon framed bike and a good aluminium framed bike. Most/all good aluminium framed bikes have carbon forks. My S-Works (aluminium) weighs slightly less than my Giant TCR carbon bike (it weighs just over 7.5kg) and rides just as comfy .... same applies to steel (I also have a steel Surly LHT, and owned a few other (good) steel bikes in the past

here's some more info:

 

[iandg]

Hmmmm .... I'm not so sure about that. There's not much difference in ride quality between a carbon framed bike and a good aluminium framed bike. Most/all good aluminium framed bikes have carbon forks. My S-Works (aluminium) weighs slightly less than my Giant TCR carbon bike (it weighs just over 7.5kg) and rides just as comfy .... same applies to steel (I also have a steel Surly LHT, and owned a few other (good) steel bikes in the past
y
here's some more info:

I remember now it was an early 2000s Saracen Aubisque with alloy forks, not a Giant

I'd expect the audax/tourer to be more comfortable because it's shallower and has a few more inches of wheelbase than the alloy Saracen.

I've never ridden carbon fibre so couldn't compare - my experience has been with 1970's 531 steel and a 2005 631 audax tourer. They all rode better than the Saracen - I didn't imagine it, it was a harsher, bumpier ride. That's why I ditched it within 2 months. The 1978 Raleigh Professional was a much better ride and the bike I've done my fastest rides on. I went back to riding it after ditching the Saracen.

Probably not fair to compare 531 steel against a production aluminium frame but that's all I've had experience of. Been building up a steel Genesis Equilibrium with carbon forks to replace the 40 year old Raleigh so will have another experience for comparison in the not too distant future.