Help with bike choice

homers_double

He had a beard, he must have been right.

imposter2.0

cowboyjon wrote:

I have no intention of getting into any kind of debate with you, whether you are right or wrong.

My issue with you is no matter the topic, you will find a way to pick a fight with someone and derail the thread with your nonsense.

As far as I can see there's a lot of people absolutely sick of listening to you and your opinions and I don't doubt they end on this forum.

I have no idea what you bring to the table other than negative vibes and pettiness, hence you should in my opinion be sent to the shadow realm, never to be seen again.

I'm only getting your biased opinion there cowboy, mainly, I suspect, because I called out your nonsense previously on another thread and you've never got over it.

Like I said earlier - if you want to disagree with anything I've said or if you want to debate the science, then come up with some reasons why. If you want to complain about me as a forum member, then report my posts and let the mods do their job. Otherwise, sit down and be quiet.

imposter2.0

homers double wrote:

He had a beard, he must have been right.

He did have a beard - and there's some of his stuff that I don't 100% agree with. But his summarisation of this particular issue is accurate, imo..

photonic69

If it is a "Cycle to Work" bike and you are intending on using it as such, then buy the one that can take mudguards/panniers and possibly 28mm tyres if possible. Makes the commute far more bearable

Wheelspinner

Imposter wrote:

homers double wrote:

He had a beard, he must have been right.

He did have a beard - and there's some of his stuff that I don't 100% agree with. But his summarisation of this particular issue is accurate, imo..

Are you sure? I'm not convinced this bit is strictly "accurate".

"..The seat stays (the only part of this system that is actually part of the frame) are loaded in pure, in-line compression..."

If you are riding a unicycle, it would be correct, but for any typical road bike, it isn't. But perhaps he only rides a unicycle, since he also neglected to even mention chain stays, which are indeed part of the frame as well, and also usually quite intimately involved in the transmission of road shock caused by a rear wheel hitting a bump.

imposter2.0

Wheelspinner wrote:

Imposter wrote:

homers double wrote:

He had a beard, he must have been right.

He did have a beard - and there's some of his stuff that I don't 100% agree with. But his summarisation of this particular issue is accurate, imo..

Are you sure? I'm not convinced this bit is strictly "accurate".

"..The seat stays (the only part of this system that is actually part of the frame) are loaded in pure, in-line compression..."

If you are riding a unicycle, it would be correct, but for any typical road bike, it isn't. But perhaps he only rides a unicycle, since he also neglected to even mention chain stays, which are indeed part of the frame as well, and also usually quite intimately involved in the transmission of road shock caused by a rear wheel hitting a bump.

Effectively, he's correct, as the seat stays form one third of a triangle along with the chain stays and seat tube, and there is minimal or no movement in that vertical plane. Whether you want to describe it as 'in-line' or not, the net result is the same.

bobones

Imposter, you're going on about rear triangles, when I was talking about the difference in feeling at my hands. Are you of the opinion that material and shape of forks has zero impact on comfort when all other factors are equal and handling is "normal"?

imposter2.0

bobones wrote:

Imposter, you're going on about rear triangles, when I was talking about the difference in feeling at my hands. Are you of the opinion that material and shape of forks has zero impact on comfort when all other factors are equal and handling is "normal"?

Yes, I am of that opinion. Thought I'd made that clear, but there we are. 'Comfort' is subjective though and I thought we were talking about road 'bumps'?

bobones

I just wanted to be sure, as yours seems quite an extreme position, which flies in the face of common sense and accepted wisdom. It's also easy to disprove with one single counterexample.

I'm using "comfort" as a term related to amount of perceived shock or vibration transmitted to the hands from the road surface. It's subjective only if you have no way of measuring it.

My damaged wrist makes my pain receptors more sensitive to bumps in the road, and it's actually easy for me to discern a difference between the 2 bikes mentioned (which differ only in frameset). As I said, this is not a subtle, subjective difference: it is dramatic. This pain is not easy to measure, but the swelling or lack thereof, after a long ride is measurable and objective. The fact that there is a difference is the counterexample which proves to me that you are wrong, whether you believe my "anecdotes" or not.

Nevertheless, I was thinking that it's probably feasible to design an experiment that does measure this objectively, and sure enough, someone clever clogs at MIT have already done the work. If you refer to the section on vibration, you will see they can clearly differentiate between frames of different material: in their words, "demonstrated the ability of the test method [to] distinguish between different bicycle frames". http://web.mit.edu/2.tha/www/ppt/Bike-ISEA.pdf

Matthewfalle

PhotoNic69 wrote:

If it is a "Cycle to Work" bike and you are intending on using it as such, then buy the one that is the most fun and sod being practical - just leave clothes & towels at work, fit clip on mudguards and enjoy the ride unencumbered by trash and clubbie acoutrements. work is craapp enough without having ride a craaapp bike there and back.

ftfy - hope you don't mind

#carpediem

imposter2.0

bobones wrote:

I just wanted to be sure, as yours seems quite an extreme position, which flies in the face of common sense and accepted wisdom. It's also easy to disprove with one single counterexample.

It's not 'extreme' and it doesn't fly in the face of any 'accepted wisdom' or 'common sense' - quite the contrary in fact. If you look up the 'Rinard fork deflection test', it is exactly in line with my earlier comments, specifically in relation to forks. This is another link to Sheldon's site, where the test is described and discussed, but there are many other discussions about it elsewhere. Have a read:

https://www.sheldonbrown.com/rinard/rin ... ktest.html

bobones wrote:

Nevertheless, I was thinking that it's probably feasible to design an experiment that does measure this objectively, and sure enough, someone clever clogs at MIT have already done the work. If you refer to the section on vibration, you will see they can clearly differentiate between frames of different material: in their words, "demonstrated the ability of the test method [to] distinguish between different bicycle frames". http://web.mit.edu/2.tha/www/ppt/Bike-ISEA.pdf

Your link deals with an issue which we aren't even discussing. I thought I'd already made it clear that the issue I was challenging was your claim that road 'bumps' are absorbed by your frame/fork - not road 'vibrations'. Carbon fibre tends to have a lower density for a given amount of material than other frame materials, so will react differently in terms of vibration. But that's not what we were talking about. Go back and check the earlier posts if you like..

bobones

My claim was on the difference in perceived pain/comfort levels felt on different bikes due to vibrations from bumps and irregularities in the road. You have repeatedly said the frame/fork design and material has no effect on comfort, and that I am lying, talking rubbish, or just plain wrong. But now presented with contradictory evidence, you're backtracking by saying you were talking about something else that excludes vibration, which just proves that your contribution to this thread has been nothing more a classic case of straw man.

I will ask the same question, "Are you of the opinion that material and shape of forks has zero impact on comfort when all other factors are equal and handling is "normal"? Remember you said "yes" the last time. Note, that question isn't prefixed by, "Excluding vibrations,"!

photonic69

Matthewfalle wrote:

PhotoNic69 wrote:

If it is a "Cycle to Work" bike and you are intending on using it as such, then buy the one that is the most fun and sod being practical - just leave clothes & towels at work, fit clip on mudguards and enjoy the ride unencumbered by trash and clubbie acoutrements. work is craapp enough without having ride a craaapp bike there and back.

ftfy - hope you don't mind

#carpediem

Haha! Yes, much better idea! Make going to work fun! Then after 12 months get n+1 with the sensible “beard, pipe and slippers” options for wet days.

imposter2.0

bobones wrote:

My claim was on the difference in perceived pain/comfort levels felt on different bikes due to vibrations from bumps and irregularities in the road. You have repeatedly said the frame/fork design and material has no effect on comfort, and that I am lying, talking rubbish, or just plain wrong. But now presented with contradictory evidence, you're backtracking by saying you were talking about something else that excludes vibration, which just proves that your contribution to this thread has been nothing more a classic case of straw man.

I will ask the same question, "Are you of the opinion that material and shape of forks has zero impact on comfort when all other factors are equal and handling is "normal"? Remember you said "yes" the last time. Note, that question isn't prefixed by, "Excluding vibrations,"!

I've tried to be very clear - and as I said on my first post on page 1, I was referring specifically to the absorption/deflection of bumps in the road - not the 'road buzz' that you now seem to be talking about. Go back and see for yourself. This difference might explain your apparent confusion.

As for your second question - as I said before, it would depend on how you are defining 'comfort' as it's not a precise term. But generally speaking, fork choice makes little if any difference to 'comfort' in the general sense. See the fork deflection study I linked to earlier.

You seem very sensitive to being called out as a 'liar' or for 'talking rubbish' - despite the fact that I've never said anything of the sort. Some of your assertions are incorrect though, as I've pointed out.

matt71

Cheers for your help , I went for the better one in the end !

I will let you all get back to your conversation regarding frames and comfort again :roll:

bobones

I am not confused.

What you've done is the very definition of a straw man argument.

My claim was about comfort/pain and how I can easily differentiate between 2 carbon bikes I own:

I recently replaced my Scott CR1 (carbon) frame with a De Rosa (also carbon) and there is a massive difference in comfort level in favour of the De Rosa with the same tyres , pressures, wheels, bars etc. I can feel every bump in the road through my damaged wrist with the Scott such that I used to remove my hand from the bars to avoid the impact whereas the De Rosa just glides over the same bumps with virtually no pain to my wrist. I was always a bit sceptical about how much difference a frame can make, but it's actually quite astonishing.

You set up the straw man with this:

that would imply that the DeRosa frame is actually compressing/flexing in order to deflect the impacts from these bumps in the road

Your implication is fallacious and ignores material damping or vibration. That's the straw man right there: my claim is about comfort, your straw man is about deflection.

You cannot refute my initial claim with your argument about deflection. Of course vibration and road buzz play a factor in comfort! No one is arguing with you about deflection!

Anyway I am done wasting time with this so go ahead and have the last word. :roll:

imposter2.0

Thanks, I will. I think what I've said on this thread is clear enough, bob. I stand by it and I don't think there's anything else to add. Others can decide for themselves.

Wheelspinner

Imposter wrote:

Wheelspinner wrote:

Imposter wrote:

homers double wrote:

He had a beard, he must have been right.

He did have a beard - and there's some of his stuff that I don't 100% agree with. But his summarisation of this particular issue is accurate, imo..

Are you sure? I'm not convinced this bit is strictly "accurate".

"..The seat stays (the only part of this system that is actually part of the frame) are loaded in pure, in-line compression..."

If you are riding a unicycle, it would be correct, but for any typical road bike, it isn't. But perhaps he only rides a unicycle, since he also neglected to even mention chain stays, which are indeed part of the frame as well, and also usually quite intimately involved in the transmission of road shock caused by a rear wheel hitting a bump.

Effectively, he's correct, as the seat stays form one third of a triangle along with the chain stays and seat tube, and there is minimal or no movement in that vertical plane. Whether you want to describe it as 'in-line' or not, the net result is the same.

Er, sorry, I didn't describe it as "in-line" - Sheldon did, and you are quoting him as the "science" to support your opinion. Factually, "effectively" he's still quite wrong, and the impact of that error is significant. The claim there is "no movement" in that vertical plane is also factually wrong. Minimal movement - yes. None? No, utterly wrong. It is theoretically the ideal behaviour if the frame members and the materials involved in their manufacture have infinite resistance to bending (moments of inertia) but they don't - far from it, in fact. (Sorry to use the fact word again.) In material properties terms, we should be very grateful that there *is* movement, because the alternative is that the repeated shock will fatigue the frame members to the point of failure much more quickly. That little bit of elasticity in the materials to absorb even a small proportion of the force from the impact certainly helps extend the frame life if nothing else.

In isolation, the amount of movement of the triangle (and therefore the wheel axle) will depend on the materials used, shapes of the frame members, and the geometry of the frame in general. This last bit determines the frame response to the input force of hitting the bump. One reason a lot of the current "sportive" type endurance/comfort frames (pick term of choice) have dropped seat stay designs is that this geometry changes the behaviour of the rear triangle (and also main triangle) under load. There will be relatively *more* bending force applied around the joint between seat stay and seat tube in this design, because there is proportionally *less* axial compression component into the stay due to the change in angle of the stay relative to the direction of the applied force (that bump). In this dropped stay design the seat tube itself will also deflect (bow) slightly at the point of intersection with the seat stay. That all means the wheel axle will deflect more than a more traditional design. This is all simple, fact-based engineering stuff.

Since the force applied to the seat stay is decidedly not purely axial, and is actually a bending force, the behaviour of both the seat and chain stay is that the top surface will be in compression and the bottom side will be in extension. The material's elastic properties determine how far it bends before springing back to it's natural shape, and only when this elastic limit is exceeded and behaviour becomes plastic do you have a problem.

The amount of movement in the rear triangle will likely indeed be minimal in comparison to deflection and damping in tyres, seat posts, saddles, handlebar tape and what have you, but there *will* be movement, and it *may* be noticeable. I get that "in your opinion" (and apparently Sheldon Brown's) it isn't noticeable and that's fine. Unless you can legitimately claim to have ridden every single bicycle frame ever made and assessed their relative frame flex characteristics with some degree of scientific rigour, then an opinion about whether all frames behave the same is simply a vague assumption. You may have tried a dozen different bikes made variously of carbon, steel, titanium, of combos thereof, and decided you can't feel a difference. So what?

I've no interest in discussing whether your opinion is good, bad or indifferent, because opinions are like that - you can hang on to whatever you feel is appropriate. Just don't claim that the science in this case proves your opinion is the only valid one. It doesn't.

imposter2.0

You’re attributing claims to me that I have never actually made. And your post contains a lot of words, but no evidence in support. Other than that, there’s nothing to add to what I’ve said previously.