sunday when i saw it was a time for a change, killed the czar and his ministers

tlw1

Pinno wrote:

Stevo 666 wrote:

Bottles of oxygen might be quite handy as well - that's over 1,000m higher than the top of Mont Blanc...

It'll shut him up for a while

Stevo_666

Pinno wrote:

Stevo 666 wrote:

Bottles of oxygen might be quite handy as well - that's over 1,000m higher than the top of Mont Blanc...

It'll shut him up for a while

At his age, so would not mentioning oxygen bottles :P

sungod

Pinno wrote:

...and seriously pricey.
I thought those things would be a nightmare in the Island Sirocco's?
At least the tabbies would hear him coming.

actually got this pair for a few hundred euro when lightweight customer services offered me a brand new 11s set after the old (10s) front had the side caved in during a crash, remarkably it stayed true, after a bit of tentative checking i rode it several km home

as long as the front tyre is about the same width as the leading edge of the rim they're stable, still get shoved if there's a string crosswind, but it's predictable, there's no 'snatching' as the yaw angle changes which is the key thing

however even going a couple of mm wider on the front, with a 23mm say, turns them pure psycho in strong wind - with the fashion for wide tyres, i suspect that's why people think they're dodgy in the wind, they never try the best tyre size

strongest wind i had there last few weeks was pretty steady c. 50kph, did about 110k that day, as long as you are on the ball, watch out for gaps in cover etc. it's ok, just a joyless grind going into it head-on for the first half

they make a lovely roar, especially cornering hard

Matthewfalle wrote:

picture of whole set up please.

obermayers. mmmmmmmmmmmmmmmmmmmm.

#tdn&obermayers.lush

think i posted it before, this is a while back when i was trying dugasts, grippy but a bit heavy, back on my favourite veloflexes since then, sprinter/criterium front/rear

Matthewfalle

sungod wrote:

Pinno wrote:

...and seriously pricey.
I thought those things would be a nightmare in the Island Sirocco's?
At least the tabbies would hear him coming.

actually got this pair for a few hundred euro when lightweight customer services offered me a brand new 11s set after the old (10s) front had the side caved in during a crash, remarkably it stayed true, after a bit of tentative checking i rode it several km home

as long as the front tyre is about the same width as the leading edge of the rim they're stable, still get shoved if there's a string crosswind, but it's predictable, there's no 'snatching' as the yaw angle changes which is the key thing

however even going a couple of mm wider on the front, with a 23mm say, turns them pure psycho in strong wind - with the fashion for wide tyres, i suspect that's why people think they're dodgy in the wind, they never try the best tyre size

strongest wind i had there last few weeks was pretty steady c. 50kph, did about 110k that day, as long as you are on the ball, watch out for gaps in cover etc. it's ok, just a joyless grind going into it head-on for the first half

they make a lovely roar, especially cornering hard

Matthewfalle wrote:

picture of whole set up please.

obermayers. mmmmmmmmmmmmmmmmmmmm.

#tdn&obermayers.lush

think i posted it before, this is a while back when i was trying dugasts, grippy but a bit heavy, back on my favourite veloflexes since then, sprinter/criterium front/rear

pheck thats nice. top work that man

#mewantnow

Matthewfalle

as an aside, do you reckon the tyre thing is the same with all wheels?

i've just gone from 23mm on the 80/90 combo on the S3 that worked perfect in all conditions to 25s f & r - now pondering if I have open a can of worms .......

#potentialwibblewobble

sungod

Matthewfalle wrote:

as an aside, do you reckon the tyre thing is the same with all wheels?

i've just gone from 23mm on the 80/90 combo on the S3 that worked perfect in all conditions to 25s f & r - now pondering if I have open a can of worms .......

#potentialwibblewobble

depends how wide the rims are, in general what you want to avoid is a 'lightbulb' profile where the tyre bulges wider than the rim, on the lightweights that's a recipe for instability

this article is worth a read...
https://blog.silca.cc/part-5-tire-press ... rodynamics

the airflow separation plots for different tyre/rim combinations illustrate the impact of tyre/rim mismatch

Matthewfalle

《heads off to garage to have a look》

#headscratching

step83

Cracking bike SG, think I'll be checking mine later, they are a handful with 25/28c, rims are 21.2mm external so may explain a lot.
Are they clinchers or tubs? I was always under the impression veloflex don't recommend then on clinchers, or open tubs as they call them

Matthewfalle

mine are a bit lightbulby but nothing massive.

either way i'll give it a bash and see what happens - may ehd up 23/25 combo or may buy somewider rimmed Primes.

or may just leave it becuse i am, inherently, lazy.

#decisons
#sloth

sungod

Step83 wrote:

Cracking bike SG, think I'll be checking mine later, they are a handful with 25/28c, rims are 21.2mm external so may explain a lot.
Are they clinchers or tubs? I was always under the impression veloflex don't recommend then on clinchers, or open tubs as they call them

tubs

not tried the veloflex open tubulars, nor vittoria's equivalent, these/others with similar construction seem risky with some rims due to the sidewalls being damaged by sharp rim edges

step83

Tubs makes sense.

I did think that was the case with the sharp edges. I know the 28's on mine are very bulbous, feel lovely, but are not going to be pleasant on anything bar a still day.

#wriggly

pinno

sungod wrote:

this article is worth a read...
https://blog.silca.cc/part-5-tire-press ... rodynamics

Although the article doesn't really go into the correlation between tyre width, rim width and rim depth.
It doesn't once mention cross winds. How many situations are there that give you a direct head wind along an unwavering route? It's improbable.
In a group situation, how much turbulence is created and what effect does that have on wheel aerodynamics?

,,,and i'd much rather be comfortable on my 27c 'light bulbs' than going 3% quicker on a 23mm tyre on our rough roads.
You ride tubs SG - that's to mitigate them.

sungod

tubs for lightness, plus over the years i've found them way better/safer if flatted, no room for fat tyres on my frame anyway

for me tyre-rim width matching is for handling not speed, head-on there's typically not a huge difference in drag (barring extreme mismatches) and there's no separation asymmetry to affect handling

the handling action is in the higher yaw behaviour, i.e. crosswind, i posted that link primarily for the separation cfd examples, which indicate crosswind behaviour differences...

These subtle differences can make for very large changed in drag, and even greater differences in handling. Many brands have similar CFD imagery to this on their sites, the critical point is that subtle variations in rim shape can and will change aerodynamic drag as well as handling, but none of it is possible unless the rim is at least 105% of the tire width.

(my italics)

for more you'd need to dig out the references and other research, which isn't always easy, i remember a couple of us papers, not sure there's much published for oversized tyres vs. rim as spending time/money on 'known bad' system is probably not attractive

wheel manufacturers cherry pick what they publish, it's little use, i think hambini may have published some data but afaik he then had irate marketers, trolls and lawyers come after him, not sure it's still around

Matthewfalle

now i'm utterly undecided about whether to buy some new Prime 85s or not ......

#decisons

Matthewfalle

sungod wrote:

tubs for lightness and because they are proper tyres for proper bikes for proper riders, plus over the years i've found them way better/safer if flatted, no room for fat tyres on my frame anyway because I don't ride an old person's bike/tourer.

ftfy - hope you don't mind.

#fixin'n'fiddlin'

hopkinb

Matthewfalle wrote:

now i'm utterly undecided about whether to buy some new Prime 85s or not ......

#decisons

You know the answer.

Do it. Do it now.

Matthewfalle

hopkinb wrote:

Matthewfalle wrote:

now i'm utterly undecided about whether to buy some new Prime 85s or not ......

#decisons

You know the answer.

Do it. Do it now.

fine. i will.

just got to get discounts sorted. may even have them sent out of the eu to save VAT then get them dropped to me in a couple of weeks

#thrifty

sungod

Matthewfalle wrote:

now i'm utterly undecided about whether to buy some new Prime 85s or not ......

#decisons

wide rims, use a wide tyre just a smidge narrower, easy

step83

Tubs or clinchers? Looked them up tubs are 25mm external, clinchers 27.5, girthy one could say. Look like Novatec hubs from the classic ABG marking should be dead easy to maintain and rather clicky.

Matthewfalle

Step83 wrote:

Tubs or clinchers? Looked them up tubs are 25mm external, clinchers 27.5, girthy one could say. Look like Novatec hubs from the classic ABG marking should be dead easy to maintain and rather clicky.

tubs. proper tyres for proper bikes. if i wanted clincher i'd buy a hybrid. if i wanted tubeless i'd buy a dawes galaxy with discs.

agree completely re hubs - Novatec, Sapim spokes, generic Chinese rims but sensible price rather than something like that H brand that mug people.

Look sweet, nice and clicky, wide enought to swallow 25mm tubs. Sensible price, 85 back and front.

whats not to like?

#potential

Matthewfalle

sungod wrote:

Matthewfalle wrote:

now i'm utterly undecided about whether to buy some new Prime 85s or not ......

#decisons

wide rims, use a wide tyre just a smidge narrower, easy

25mm rims = 25mm tyres, yah?

#confirmation