Matching tyres to frame.

[peetee]

I was in conversation with a friend the other day regarding bikes and cars. At one point we were discussing how vehicles should have dampers that match the springs. It got me thinking.
On a steel bike the frame is, by nature, springy. The tyres, on the other hand, act like dampers - they compress then return to shape.
Last year I bought some Gatorskin tyres. I had come across many people who used them and loved their performance but on my steel bike they were awful making it feel nervous and edgy on bends and poor surfaces. I instantly transformed this by changing to Grand Prix GT tyres.
Was this just a poor batch of tyres?
Did I create the problem with a poor choice of tyre pressure?
Does this frame/tyre matching theory hold water?
Am I barking up a tree that’s not there?

[tim-b]

Hi
IMHO tyres are shock absorbers rather than dampers (two terms that many get confused)
I used Gatorskins once and when Autumn/Winter came I found them skittish on damp metal grates and damp white lines. Swapped them for 4-seasons (and GP4000 on the fine weather bike) and didn't look back. Whether that was partially a rigidity issue in the casing I don't know
Regards
tim-b

[iandusud]

Tyres are more akin to the suspension springs on a car than the dampers as they have very little in the way of damping properties. Gatorskins have a very stiff carcass so don't flex well. Not the best of tyres IMO for a good ride quality.

As to the debate about the ride quality of steel vs ally, carbon, Ti that's a different can of worms. However I would say that it has more to do with frame design vs the material used, i.e. any of those materials can produce a very stiff or very springy frame and the design of any frame should reflect its intended use.

[Jdsk]

IMHO tyres are shock absorbers rather than dampers (two terms that many get confused)

I think that the terms are interchangeable, eg:
https://en.wikipedia.org/wiki/Shock_absorber

What do you see as the difference, please?

Thanks

Jonathan

[iandriver]

IMHO tyres are shock absorbers rather than dampers (two terms that many get confused)

I think that the terms are interchangeable, eg:
https://en.wikipedia.org/wiki/Shock_absorber

What do you see as the difference, please?

Thanks

Jonathan

Personally, I see it as flick a spring and it will keep spring for a while after the initial shock that caused the spring to move. Damping stops the spring continuing to move after the initial shock. So spring absorbs the shock, damping prevents unwanted further movement once the shock has passed.

[Jdsk]

Yes, there's a difference between an elastic spring and an energy-dissipating thing.

But in the world of vehicles damper and shock absorber seem to be used interchangeably for the object of interest.

Jonathan

PS: Apart from spokes the third edition of Bicycling Science only briefly discusses suspension, but Wilson does observe "By far the greatest suspension capability is that inherent in the human body.".

[tim-b]

Hi

Yes, there's a difference between an elastic spring and an energy-dissipating thing.

But in the world of vehicles damper and shock absorber seem to be used interchangeably for the object of interest.

Jonathan

PS: Apart from spokes the third edition of Bicycling Science only briefly discusses suspension, but Wilson does observe "By far the greatest suspension capability is that inherent in the human body.".

iandriver has saved me some writing
The words have merged over years of misunderstanding, a bit like "decimate" which in the original context was to kill 1 in 10 of a mutinous Roman Legion, but which now generally refers to the destruction of a large proportion of a population
If you look at the Spax Performance website then you can buy "Exceptional Shock Absorbers Made in Britain", but as soon as you get into their Racing Pedigree you can only buy Competition Dampers and Bespoke Dampers, possibly because more technical folk would consider those items??
MoT Testers (ooops, another one, we haven't had a Ministry of Transport since 1970, but DfT or DVSA Test doesn't work as well ) also test "springs" and "shock absorbers"
Regards
tim-b

[Jdsk]

What's the misunderstanding about the objects called shock absorbers and dampers?

Thanks

Jonathan

[tim-b]

Hi

What's the misunderstanding about the objects called shock absorbers and dampers?

Thanks

Jonathan

The spring absorbs shock (the bicycle tyre in this context) the damper dissipates the energy stored in the oscillation (the mass of the rider, frame, etc)
Regards
tim-b

[Jdsk]

Yes. Those effects are different.

But that's not how the names of the objects shock absorber, damper are used in the world of vehicles.

And tyres also dissipate mechanical energy. And the human body on top also behaves like a spring and returns energy. The functions are mixed across the components.

Jonathan

[tim-b]

Hi

Yes. Those effects are different.

But that's not how the names of the objects shock absorber, damper are used in the world of vehicles.

And tyres also dissipate mechanical energy. And the human body on top also behaves like a spring and returns energy. The functions are mixed across the components.

Jonathan

It isn't how the names are used, but that doesn't make it correct. How many times have you read "Princess Diana", but it wasn't ever correct
Bicycles are often a closed system in respect of damping oscillation, it's the same for balance.
IMHO a scientific paper would be needed to decide what does which function
Regards
tim-b

[Jdsk]

IMHO tyres are shock absorbers rather than dampers (two terms that many get confused)

If that had read springs and dampers are different, or springing and damping are different I think that we'd be agreeing...

Jonathan

[MikeF]

Hi

What's the misunderstanding about the objects called shock absorbers and dampers?

Thanks

Jonathan

The spring absorbs shock (the bicycle tyre in this context) the damper dissipates the energy stored in the oscillation (the mass of the rider, frame, etc)
Regards
tim-b

The spring may absorb shock, but it's not regarded as a shock absorber.
I think "damper" is an American term now widely used in the UK for what were always called shock absorbers here. Some vehicle suspensions eg torsion bar, were largely self damping. They still had shock absorbers, but these never had to play a large part in the ride as in this case the effectively two springs absorbed most of the shock. It depends if you regard the tie rod as a damper or spring. It is in effect both.
Shock absorbers also absorb shock because they restrict the rate of movement of the spring. Some used to be friction devices eg similar to two clutch plates.

[Brucey]

I'd say that springs store energy, rather than 'absorb' it. Hence dampers are shock absorbers, whether they have springs combined with them (coil-over shocks) or not.

But putting semantics aside and returning to the main point, I think that there is an argument for matching the tyres to the frame/fork.

Gatorskins are slightly harsh-riding at any given pressure and the rubber compound is relatively hard and lacking in grip. This makes these tyres 'nervous' on road imperfections. At least one of my chums won't train on gatorskins that are more than a year old; they are usually so hard by then that you get wheelspin on some of the local hills (such as they are).

cheers

[Jdsk]

I think "damper" is an American term now widely used in the UK for what were always called shock absorbers here.

That feels right, but I haven't checked. But many "American English" terms are the original "English English" term which then changed...

Jonathan