Search found 17133 matches

by Vorpal
13 May 2021, 6:44pm
Forum: Helmets & helmet discussion
Topic: David Millar on ITV4 making unsubstantiated claims re helmets
Replies: 12
Views: 954

Re: David Millar on ITV4 making unsubstantiated claims re helmets

Marcus Aurelius wrote: 13 May 2021, 6:21pm https://www.dailyecho.co.uk/news/192984 ... collision/

Would a helmet have helped here? I think it would.
From the the article
There is no evidence to suggest that Mr Murray, of Holyrood Avenue, would have survived the incident if he had been wearing a helmet.
by Vorpal
13 May 2021, 6:07pm
Forum: The Tea Shop
Topic: Anti cycling tropes on a gardening forum!!!
Replies: 94
Views: 1811

Re: Anti cycling tropes on a gardening forum!!!

This seems to have become anti-cycling tropes on a cycling forum :(

I have removed a number of posts that were personal, insulting, or degenerating into insults.

Please argue nicely.
by Vorpal
13 May 2021, 6:04pm
Forum: Bikes & Bits – Technical section
Topic: Best wishes for Brucey
Replies: 498
Views: 30328

Re: Best wishes for Brucey

Welcome back! It's good to hear from you.
by Vorpal
10 May 2021, 10:11am
Forum: The Tea Shop
Topic: Scotland - do you predict that it will be an independent administrative political entity within 10 years?
Replies: 564
Views: 11240

Re: Scotland - do you predict that it will be an independent administrative political entity within 10 years?

Paulatic wrote: 10 May 2021, 9:01am
KTHSullivan wrote: 9 May 2021, 11:43pm Am I missing something here?
I think the biggest resource you’ve missed out of your list is the potential for renewable energy. A coastline double that of England and enough rain and water to reliably fuel any hydro.
And offshore wind https://www.offshorewindscotland.org.uk/
by Vorpal
10 May 2021, 9:34am
Forum: On the road
Topic: Active cyclist protective driving?
Replies: 32
Views: 1074

Re: Active cyclist protective driving?

The police and organisations such as IAM and RAC generally advise that when someone is following too closely, the best thing to do is slow down gradually, and make sure that you leave extra braking room to the car in front.

Slowing down does two things. It reduces the stopping distance for you & the car behind. It also makes it easier for the tailgater to overtake, if that is their intention.

That doesn't mean creating an obstruction; just reducing speed so that the distance to the car behind is appropriate.

Highways England are trialling cameras that detect tailgating on the M1 https://www.rac.co.uk/drive/news/motori ... 0installed.
by Vorpal
10 May 2021, 8:20am
Forum: Using the Forum - request help : report difficulties
Topic: sticky or section for posting video content / links?
Replies: 6
Views: 123

Re: sticky or section for posting video content / links?

This thread was created from a request on viewtopic.php?f=5&t=145720&p=1604901#p1604901 to have a sticky or section for posting links like that.

For me, the simplest thing is to have an ongoing thread, like the favourite tea shops one, where people can post links they find interesting or inspiring. However, I though I'd put it here for discussion, first.
by Vorpal
10 May 2021, 8:16am
Forum: Bikes & Bits – Technical section
Topic: Henry Wildeberry & Ms Cools
Replies: 9
Views: 573

Re: Henry Wildeberry & Ms Cools

I created a separate topic about a home for content & links like this viewtopic.php?f=14&t=145747
by Vorpal
7 May 2021, 6:57pm
Forum: The Tea Shop
Topic: I don't like living in England....
Replies: 830
Views: 17904

Re: I don't like living in England....

[XAP]Bob wrote: 7 May 2021, 6:14pm
Oldjohnw wrote: 7 May 2021, 6:05pm I praised his vaccination programme. It doesn’t mean he is not an elitist, entitled liar or that his government is not corrupt. If it were a Labour, Lib Dem or Green leader I would say the same.
It was a reasonable gamble, and it has paid off.
The problem is that he can't even get boasting about it correct, you know what - something you touched didn't turn to faeces, celebrate it...
It wasn't a gamble. He banked on it. And it cost 150 thousand lives.
by Vorpal
7 May 2021, 4:24pm
Forum: The Tea Shop
Topic: Tower Block Disaster - Grenfell
Replies: 560
Views: 19629

Re: Tower Block Disaster - Grenfell

More than 100 firefighters have tackled a blaze that ripped through a 19-storey London tower covered in flammable cladding.

The London Fire Brigade (LFB) was called to the New Providence Wharf development, near Canary Wharf, on Friday morning.

It said 125 firefighters and 20 engines were at the scene of the fire, which engulfed three floors.

London Ambulance Service said a “number of people” have been treated, though the extent of their injuries is not yet known.

Approximately 22% of the building’s facade features ACM PE cladding panels, which were found to be a key factor in the Grenfell Tower fire in 2017.
https://www.essexlive.news/news/uk-worl ... ll-5386593
https://www.standard.co.uk/news/uk/new- ... 33833.html
by Vorpal
7 May 2021, 12:59pm
Forum: Does anyone know … ?
Topic: Books for young cyclists
Replies: 11
Views: 477

Re: Books for young cyclists

Wheels of Change: How Women Rode the Bicycle to Freedom (With a Few Flat Tires Along the Way)
by Vorpal
7 May 2021, 8:14am
Forum: Family Cycling
Topic: Bike carrier recommendations (I have no idea)
Replies: 41
Views: 825

Re: Bike carrier recommendations (I have no idea)

Traction_man wrote: 6 May 2021, 9:03am
I have the Saris Bones that I use on my saloon Mazda 3, it's a rack that takes 3 bikes but the way they hang off the back of the boot would worry me with the weight of 3 bikes--1 bike on I am happy with, 2 at a stretch but 3, no.

The way the rack works, with weight on the rear bumper and straps on the boot edges, means I think a lot of stress is placed on the boot hinges, as well as the bumper, perhaps I am being overly cautious but I don't want to see our bikes disappearing in my rear view mirror...

I'm looking at a roof rack at the mo as a replacement though these are it seems to me very expensive.

all the best,

Keith
I've carried 3 bikes on mine. I've also carried 2 bikes and a trailer bike. The boot hinges are designed for far worse conditions than hanging bikes off it, even with wind and speed. I do add a couple extra bungees to reduce how much the bikes can move.
by Vorpal
7 May 2021, 8:06am
Forum: Electric bikes
Topic: Negative comments
Replies: 48
Views: 1096

Re: Negative comments

I Norway, e-bikes are replacing cars, rather than non-assisted bikes. The same appears to be happening elsewhere.

I think that's fantastic. And I honestly don't care if the same people *could* ride a non-assisted bike in the same way. They didn't.
by Vorpal
6 May 2021, 8:27pm
Forum: The Tea Shop
Topic: I don't like living in England....
Replies: 830
Views: 17904

Re: I don't like living in England....

Charity is poor substitute for support.
by Vorpal
5 May 2021, 7:26pm
Forum: Bikes & Bits – Technical section
Topic: Broken spoke
Replies: 47
Views: 1513

Re: Broken spoke

531colin wrote: 5 May 2021, 5:25pm Don't feel alone; I don't understand what I'm saying either!

I think Andrew refers to the outside of the bend being under enough tensile load to yield, and the inside of the bend being similar situation with compressive load; but metal in the middle stressed insufficiently to yield.

You refer to some areas of metal at or near yield point.

How should I refer to these areas of the spoke? They haven't been taken to yield point, they haven't yielded, they are being held bent at a particular angle by the areas which have yielded?
They are constrained by the points which have yielded and are now work hardened in their new form. You can refer to them as being highly stressed, or having stresses at or near yield. Metallurgists may have a specific name for it, but if so, it's not one in common use in other engineering fields.
by Vorpal
5 May 2021, 4:42pm
Forum: Bikes & Bits – Technical section
Topic: Broken spoke
Replies: 47
Views: 1513

Re: Broken spoke

531colin wrote: 5 May 2021, 3:30pm
andrew_s wrote: 4 May 2021, 1:38am .......................Cold setting doesn't mean there's no resulting stress.

When a spoke is bent to form the J-bend, the metal on the inside and the outside of the bend sees enough stress to permanently deform, but in the middle of the spoke, between the compressive stress on the inside and the tensioning stress on the outside, these are regions where the metal is both unstressed, and stressed not quite enough to deform.
If you cold set something, you'll notice it springs back some when you let go. That's the un-deformed metal in the middle attempting to return to its original position.

The closer a bit of metal is to the deforming stress, the fewer stress cycles it will take before it starts to crack.
Stress relief is adding enough extra stress, temporarily, that the metal that was previously just about to deform does so. This means that the remaining undeformed metal isn't so close the the deforming stress under normal use.
Andrew; thanks for this. Its something I don't find easy to understand in depth. (I have a background in biology, not engineering.)
Can I just check with you that I have understood properly your sentence which I have turned red?

"When metal is stressed into shape (ie. not permanently deformed) cyclic stresses imposed in addition to the static stress will initiate a crack. Crack initiation is quicker if the static stress is close to that stress which would cause permanent deformation, and with greater cyclic stresses."
I'm sorry, but I'm not sure that I understand what you are saying. Metal cannot be stressed into shape without permanent deformation. But what happens when it is bent is
bent spoke stresses.jpg
bent spoke stresses.jpg (19.27 KiB) Viewed 71 times
The bending has changed the structure of the material, and these stresses can only be eliminated by changing the structure of the material again, through something like heat treating. This is what engineers & metallurgists think of as stress relieving. One of the things about this though, is that the process of bending also causes something called work hardening. Because the microscopic structure has been changed, it resists further changes. This is advantageous for spokes because we want them to be stronger at the bends, and heat treating would also take out the work hardening. Straightening the wire from how it was coiled, threading the ends, and cutting the spokes also introduces stresses, though other residual stresses are relatively small by comparison.

As Andrew noted, the stresses vary, and because in order to work the material, some bits have been brought beyond the yield (plastic deformation) point, this leaves some parts of the material at or near the yield point. If these are subsequently cycled repeatedly in that condition, they will break. It's like taking a wire & bending it repeatedly.

The point of stress relieving is to get these points in the material to relax. A spoke normally operates at some fraction (1/4th? 1/2?) of it's capability, so the 'firm grasp' method increases the forces enough to take these highly stressed bits in the metal structure beyond the yield point. It doesn't affect other parts of the spoke because they are not at or near yield.

The diagram was borrowed from https://www.thefabricator.com/thefabric ... d%20radius.