Cycling UK Forum

Jdsk wrote: ↑19 Jul 2022, 12:25am

Biospace wrote: ↑19 Jul 2022, 12:23am

Jdsk wrote: ↑19 Jul 2022, 12:04am
What commercial source of titanium dioxide doesn't contain nanoparticles?

No idea, the chap who orders it should know but I don't think he would choose to be involved with any of this discussion(!)- but I'll send a link and ask.
...

Please do.

(I'm not aware of any.)

Jonathan

He stopped using the titanium oxide a few years ago, finding zinc on its own was very nearly as good.

Cugel wrote: ↑3 Jul 2022, 9:37am
It seems it might also be degrading their thinker itself, to a condition in which it becomes dysfunctional. Soon they will be babbling on a perch in some expensive gimmery, as Brutus the male "nurse" readies his chemical cosh!

You sure we haven't already reached that point, Cugel?

Science and numbers are fine, but they often don't represent reality especially when it's the weather. We focus so much on air temperature but humidity, air movement and heat radiation are just as important if not more so.

So, today feels twice as hot as yesterday. Going out for a walk through vegetation formed in a mild, damp climate seemed other-worldly with the North African feel from lunchtime onwards, as did the lack of dust and smells of camel dung and other exotic aromas. It's just beginning to cool a little now, but the house still feels near icy cool when you come in.

Windows were shut at 10 this morning, blinds down, aluminium foil over the West-facing folding glass doors. That made a colossal difference compared with yesterday, not only was the glass cool to the touch on the inside compared with hand hot, but the lack of radiation pouring into the room means high 20s rather than mid 40s. A couple of 6" USB powered fans make it very pleasant.

I'd meant to cut up bike boxes to cover the windows with as well as the al foil, but on its own for just a day it's perfectly fine.

al_yrpal wrote: ↑19 Jul 2022, 8:25am Ok, it was a bit hot yesterday but I remember 1976, digging drains with a pickaxe for my new house on the mountain in Wales, the sweat pouring off my nose. It went on for 2 months! The bed of the Thames cracked and next day they appointed a Minister for drought! This spell is nothing, the temperature may get slightly higher but, at the moment its just a short spell created by freak weather conditions.
I also remember Charlie and Diana's wedding whilst we were camping in the Dordogne 1981, the temperature was 44 degrees for about 4 days.
Hysterical BBC and newspaper headlines written by youngsters who werent there methinks

Al

And the Romans were cultivating vines in the North of England, it was likely warmer then than now, before the cooling which started in the 530s and continued right through until the last century.

Of course setting light to oil, gas and coal to provide us with energy is having some effect on our climate, but the anthropogenic part of the carbon cycle is roughly a fifth that of the natural carbon cycle. It's how we're affecting the natural cycle - the unusual way we're farming included - which should be gaining more attention than burning stuff, daft as that is from a pollution point of view.

Yes, it is hotter now than any day in '76 but this heat is for two days. Of course trends are up, because that's how it is coming out of a cooler part of an interglacial period. It's possible, even likely, that AGW is tipping the balance and prolonging this warm part of a glacial era, which given the top half of Britain will likely be covered in ice once gone, isn't entirely a bad thing.

For the OP, my advice would be to try a tyre somewhere between 32-40mm wide, depending on surface. 'Gravel' and 'pavement' can cover a variety of surface quality. You say comfort isn't sought, but ime most comfort equals least effort.

The perfect pressure varies for tyre/weight/surface combinations, starting with tyres pressured right up to max then incrementally releasing this through the increased comfort until you notice drag rising, then increasing pressure to slightly above this point is how I judge what works best. Once used to ideal pressures, they can be judged visually for a given tyre with bounce and 'apply weight' tests, or simply with a push of the thumb against the sidewall.

For mixed riding on and off road I use 26x1.5 and 26x1.75 tyres with a 'slick' tread, choosing the narrower ones when the going is smoother.

Cugel wrote: ↑19 Jul 2022, 11:29am

Jdsk wrote: ↑19 Jul 2022, 11:20am

Cugel wrote: ↑19 Jul 2022, 11:15am
True; but in terms of the test being discussed, a constant speed would make rotational inertia irrelevant, wouldn't it?

Same question: do you mean a constant speed within the run, or the same speed between different bikes?

(Rotational inertia could make a difference in either case.)

Jonathan

I don't mean anything. Why not just read the article and work it out for yourself?

How can rotational inertia make a difference unless it changes during the test? Are you saying that an increase in the RI is equivalent to an increase in the weight of bike and rider? As above, how much difference would such a small weight difference make in comparing one tyres test run with another where the constant speed is different in each case? And when the constant speed is the same over two tests, one with narrow tyres and one with wider tyres, doesn't that reduce any effects of RI to insignificant?

Cugel

With a bicycle in a test like this I'd assume rotational inertia is likely sufficiently small a proportion of the overall energy that it can be regarded as having zero or negligible effect. But it would be good to have been told of the bike and rider weights.

I think the 'constant speed' could be a mis-type or lost in translation into British English, I took it as either meaning 'same start speed' or 'constant slope'. I take the test as always starting with the same speed at the start and freewheeling down the 184m of 0.5% incline.

In this sort of test, extra mass (whether rotating or not) will tend to gather speed a little more quickly, everything else being the same. I think it would be correct to say the possibly slightly greater internal friction and air resistance associated with a wider tyre would be a larger part of the equation with a light rider - as all the other frictional forces would be.

Taken to the extreme, a very light wheelset and very heavy bike and rider could create an odd feeling as a wheel might encounter an obstacle which it had to be 'pushed over' against its will, as it were. A lightweight rider and bike on a heavy wheelset in the same situation I would imagine would feel more stable as the wheel would tend to power its way through the obstacle.

This reminds me of a lightweight car with small engine but very heavy flywheel which feels to power up smaller inclines and not be affected so much on a gusty, windy day, but not snappy in a standing start.

Jdsk wrote: ↑19 Jul 2022, 12:04am

Biospace wrote: ↑18 Jul 2022, 11:44pmIn contrast, oxide powders in suncreams are not significantly absorbed into your body unless nano-sized.

What commercial source of titanium dioxide doesn't contain nanoparticles?

Thanks

Jonathan

No idea, the chap who orders it should know but I don't think he would choose to be involved with any of this discussion(!)- but I'll send a link and ask.

I would suggest a suncream made with the smallest oxide particles will be see-through or clear. One made with larger particles will be white in appearance. The smaller the particle, perhaps the easier it is to pass into the skin and beyond.

Jdsk wrote: ↑18 Jul 2022, 11:07pm

Biospace wrote: ↑18 Jul 2022, 10:56pm'Disputed status'. Can you elaborate a little, please? Regarding what 'disputed status' means, since titanium oxide is regarded as safe for use in commercially available sunblock.

I used a block with this in, years ago - should I be concerned?

I wouldn't be concerned in the least about using as recommended a commercial product sold in the EU or the UK.

That is perhaps where we diverge. History shows how people have been harmed by blindly trusting commercial products in the belief they must be safe.

Jdsk wrote: ↑18 Jul 2022, 11:07pm But it wasn't me that brought up "a bottle of chemicals"or "repeat once they've been absorbed into the body" or "knowing what's used on your body" or "anywhere near as hazardous as some of the stuff many regularly ingest". Or the idea that traditional preparations are safe because they're traditional.

How does mentioning any of the above make any difference? It's almost as if you're energized because I draw attention to what the skincare, pharma and food industries would prefer not to be widely known.

I didn't state that because something is 'traditional', it is safe - nor was said friend. Perhaps smoking is the best example of how this clearly isn't the case - something the both the medical establishment and tobacco industries denied for years, even when very clear evidence suggested to the contrary.

Jdsk wrote: ↑18 Jul 2022, 11:07pm But I wouldn't handle titanium dioxide powder without adequate precautions. So I wouldn't make my own sun block if it required me to do that.

Of course - in the same way we take precautions not to inhale french chalk powder when puncture repairing, the nano-particulates from a wood stove or modern diesel engine, emissions from car interiors when exposed to the sun etc.

Supplied with an oxide powder should be a H&S sheet, detailing handling and so on.

Jdsk wrote: ↑18 Jul 2022, 11:18pm
If i told you that a chemical had been banned from food because it was thought to carry a risk of causing cancer, genetic alterations and effects on reproductive health when ingested would you be happy to rub it on your skin... the biggest organ of your body?

NB My comment on its safety above.

Jonathan

You're now using one of my points regarding oxybenzone and the other organic compounds which are absorbed into your body through the skin! These are linked with endocrine disorders and cell damage in humans, as well as the toxic effects on other life - which we then ingest, unless vegetarian.

In contrast, oxide powders in suncreams are not significantly absorbed into your body unless nano-sized. Which I clearly pointed out this mate of mine avoids, unlike many officially endorsed, commercially available products using oxide powders.

Jdsk wrote: ↑18 Jul 2022, 11:07pm

Biospace wrote: ↑18 Jul 2022, 10:56pm'Disputed status'. Can you elaborate a little, please? Regarding what 'disputed status' means, since titanium oxide is regarded as safe for use in commercially available sunblock.

I used a block with this in, years ago - should I be concerned?

I wouldn't be concerned in the least about using as recommended a commercial product sold in the EU or the UK.

But it wasn't me that brought up "a bottle of chemicals", "repeat once they've been absorbed into the body", "knowing what's used on your body" or "anywhere near as hazardous as some of the stuff many regularly ingest". Or the idea that traditional preparations are safe because they're traditional.

But I wouldn't handle titanium dioxide powder without adequate precautions. So I wouldn't make my own sun block if it required me to do that.

Jonathan

Oh. So it is safe for topical use?

What's your issue with my mentioning "a bottle of chemicals"or "repeat once they've been absorbed into the body" or "knowing what's used on your body" or "anywhere near as hazardous as some of the stuff many regularly ingest"?

I would use a good hub gear on an all-time favourite light(ish) weight bike, unless it was used almost exclusively for 'racing'.

By light(ish), I mean more like 8 or 9kg - not sure if that's regarded as light on this forum?

Nearholmer wrote: ↑18 Jul 2022, 10:52pm If the load path through the hub is as complex and lossy as the SA 5-speed that is on one of my utility bikes, then it can surely only be fit for a utility bike, not because of weight, but because of losses.

I’m not super-fussy about weight, because often the ‘argument’ is about less than the difference between two water bottles and one, but I find losses in gearing, and ‘boggy’ tyres quite frustrating.

I'm with you on this, lack of efficiency in a geartrain is one of my pet hates - yet I still use an IGH quite happily. The chain is generally in a more efficient condition, there aren't the frictions of a couple of extra pulleys, the chainline is always spot on and more.

This wouldn't have been my pov when 25, mind!

Jdsk wrote: ↑18 Jul 2022, 10:34pm

Biospace wrote: ↑18 Jul 2022, 10:25pm

Jdsk wrote: ↑18 Jul 2022, 10:10pm Titanium dioxide hasn't been commercially available for "centuries" let alone "millennia".

Sure, he didn't say it was.

Biospace wrote: ↑17 Jul 2022, 5:52pmWhich is why above mentioned mate makes his own sunblock with Zinc and Titanium oxide and carrier wax/oils - not only does he know what he's using on his body but it costs a fraction of ready-made products.

Biospace wrote: ↑18 Jul 2022, 9:12pmI emailed him your question... his response was that what is commercially available passes all the safety tests yet routinely causes bad reactions in people and has longer term questions over safety - and that the stuff he uses has safety data which has evolved over millenia, adding it's the same as used by 'posh' sunblocks.

My emboldening.

Jonathan

PS: I assume that everyone is aware of the disputed status of titanium dioxide in different jurisdictions' categorisation of carcinogenicity.

'Disputed status'. Can you elaborate a little, please? Regarding what 'disputed status' means, since titanium oxide is regarded as safe for use in commercially available sunblock.

I used a block with this in, years ago - should I be concerned?

Jdsk wrote: ↑18 Jul 2022, 10:10pm Titanium dioxide hasn't been commercially available for "centuries" let alone "millennia".

Jonathan

Sure, he didn't say it was.

You appear to be treating what he said in a quasi-legal context when he was simply letting people know a little about his years-long experience of using his own sunblock, having had a bad experience with supposedly safe, commercially available varieties.

Pebble wrote: ↑18 Jul 2022, 2:22pm
But getting back to reg plates, agric rules are in a parallel universe to the rest of motorised transport.

My experience of the agricultural community is that they're able to evade the road traffic laws like no other, at least in this part of the world. The extensive use of contractors adds to the problems, with vehicles and employees often travelling from tens of miles away, usually working to finish jobs in the fastest possible time.

'Parallel universe' tends to apply to the agricultural community as a whole from what I know, not just their reg plate rules!

Jdsk wrote: ↑18 Jul 2022, 9:39pm

Biospace wrote: ↑17 Jul 2022, 5:52pmWhich is why above mentioned mate makes his own sunblock with Zinc and Titanium oxide and carrier wax/oils - not only does he know what he's using on his body but it costs a fraction of ready-made products.

Biospace wrote: ↑18 Jul 2022, 9:12pmI emailed him your question... his response was that what is commercially available passes all the safety tests yet routinely causes bad reactions in people and has longer term questions over safety - and that the stuff he uses has safety data which has evolved over millenia, adding it's the same as used by 'posh' sunblocks.

What does "safety data which has evolved over millennia" mean? There are plenty of traditional preparations which we now know are harmful.

And who has been applying titanium oxide (sic) to themselves for "millennia", let alone recording the effects?

Thanks

Jonathan

I don't think he was wording a legal document, just expressing that much of what he uses has been used for centuries if not more, that which hasn't been passes the safety testing in ready-made modern, commercial sunblock.

My experience of racks and eyelets even when shared with mudguard fixings, is that eyelets don't fail, but racks can. The fixing bolts (lower ones, usually) will loosen off when fitted without good anti-rattle washers, preferably nuts too.

Jdsk wrote: ↑17 Jul 2022, 6:00pm
How does he know whether that mixture is more or less hazardous than a commercial product?

I emailed him your question... his response was that what is commercially available passes all the safety tests yet routinely causes bad reactions in people and has longer term questions over safety - and that the stuff he uses has safety data which has evolved over millenia, adding it's the same as used by 'posh' sunblocks.

The downside is that because this homemade mix doesn't use any modern techniques, there are times he looks a little... white. Someone once suggested he added colour to break up the monotony, which was written off as a 'daft idea'.