Recent Posts

11

The Pub / Re: Motors for propellers on deep-dive submersibles - sealed?

« Last post by Feanor on Today at 11:17:04 am »

Yes, that's right. The motor, gearbox and hydraulic pump sit bathed in the reservoir of non-conductive hydraulic oil.
This circulating hydraulic oil also serves to cool the motor.
This assembly is cylindrical, some 6" in diameter and several feet long, to fit down a wellbore.
The top end of the reservoir has a floating equalizing piston, the other side is open to the hydrostatic pressure of the wellbore.

None of the components 'see' any  pressure this way; it's all just ambient at the current hydrostatic, but at a very high absolute value.
The bearings are nothing special, pressure-wise.

It means that for example when we attempt to extend probes out from the instrument using hydraulic pressure, we are not pushing against a huge differential between an atmospheric internal pressure and a huge external hydrostatic. It's all very clever. Until the equalizing piston jams as you pull the instrument out of the hole, and you end up with a severely over-pressured hydraulic reservoir back on the surface...

12

Audax / Re: Audax - night riding/sleep deprivation/tiredness and possible calamity

« Last post by this_is_the_way on Today at 10:55:17 am »

Tired driving is dangerous, but it doesn't carry the kind of stigma that drink driving does. Maybe it should though. Here is a study that tried to relate the effects of fatigue with alcohol: https://sci-hub.se/10.1136/oem.57.10.649

They didn't even need to keep them up for nearly as long as Audax riders are out to reach the equivalent of a 0.1% blood alcohol content.

At a BAC of 0.1%, equivalence occurred after between 17.74 and 19.65 hours of wakefulness

Of course it's possible to object to trying to relate two different phenomena and there is variability between people. You do wonder though, what would those numbers look like if they'd made the subjects pedal a bicycle through an entire night and day cycle instead of just keeping them awake in a nice lab environment. They certainly would not have been better. The fact that this would almost certainly never pass IRB should add weight to the findings. Actually, the fact that audax itself beyond 300km probably wouldn't pass IRB should maybe give us all pause 

I say this not as someone moralizing. I have driven tired more times than I'm would like to admit, and with others in the car. After I became aware of this study though I much more often pull over for a nap.

13

The Knowledge / Re: Tyre width

« Last post by mrcharly-YHT on Today at 10:21:54 am »

Were we wrong in the 1980s to assume 18mm tyres would be faster than wider ones?

Not necessarily wrong, but the differences between tyres are so small (especially on overall speed) that one may believe whatever fanciful bollocks one likes about why one’s own choice is the best.

Empirical measurements say that it isn't fanciful bollocks if you are racing or TT (or indeed, doing audax).

The differences can be many watts. Even tens of watts really adds up over the course of a race.

14

Gallery / Re: Very satisfying Odo reading

« Last post by Cudzoziemiec on Today at 10:10:20 am »

Same odometer, new bike:

"Ballrigg Lane" requires some erudite smut.

15

The Pub / Re: The Grumble Thread - No energy for a full on rant.

« Last post by Cudzoziemiec on Today at 09:58:21 am »

The day after we of the Democratic Ruthless Bastards Party seize control of the means of production we will be tasking the Sweeney with tracking down the people who:

• Pluck items from supermarket shelves, and
• Peer at them myopically, and
• Put them back somewhere other than where they originated

and smashing up their living rooms on a basis both frequent and regular until they get the message and emigrate.

Can you extend this to the people who pick up a book, whether in a bookshop or a library, from Authors: A and replace it at Authors: D, or from History and replace it at Medical Sciences, etc, ect, and moreover so on? Thank you.

16

The Pub / Re: The Good News / Bad News Thread

« Last post by The Family Cyclist on Today at 09:47:57 am »

GN the Ford ride London classique ladies bike race goes past the end of my road
BN I'm working that Saturday so will miss it

17

The Pub / Re: Tune Association II - Son of Tune Association

« Last post by rogerzilla on Today at 09:45:47 am »

Hound Dog - Elvis Presley

18

Audax / Re: Audax - night riding/sleep deprivation/tiredness and possible calamity

« Last post by Laid Back Rich on Today at 09:39:19 am »

After years of doing our Dauntsey Dawdle 400 start at 6am, we are trialling 6pm this year (this week as it happens), TBH our chief consideration was for the finish helpers who will now be required from noon to 9pm Sunday rather than midnight to 9am, but it will hopefully be safer for those attempting to drive home afterwards, who will still have the offer of a free night at the scout hut.

Anyone here fancy drafting something to put up to the AGM as mooted above?

19

The Knowledge / Re: Tyre width

« Last post by Keef66 on Today at 09:34:13 am »

As a teenager in the early 70s I remember riding thousands of miles on my gas-pipe Raleigh Tour of Britain on 27 x 11/4 tanwall tyres.  Wore the buggers right down to the carcass.  I suppose I was commuting and touring.  I recall the combination of steel frame and those tyres providing a comfortable ride, but my youthful body was likely more tolerant of abuse than my present shrivelled husk.  As mentioned upthread, using a simple frame pump I have no idea what pressures I used. Possibly lower than most?

FFWD to 2007 when after a dalliance with mountain bikes I returned to road cycling aged 50.  Bad timing; 23mm tyres were still common and even the Racelight Tk I bought would only take 25s.  5 years later I compounded my blunder by buying one of the CR1-SL frames Wesbtrooks were selling off cheap.  Marvellous frameset but it takes a max of 25mm tyres, and even then the chainstay clearance is so tight I have frequently run a 23 on the rear.

If I was buying a bike tomorrow it would likely have disc brakes and I'd spec 32mm tyres purely for the comfort.  Speed is of no concern to me, but it sounds like they'd be no slower than the 25s...

20

The Pub / Re: Tune Association II - Son of Tune Association

« Last post by Mr Larrington on Today at 09:34:01 am »

Beat The Dog ~ Jesus Couldn’t Drum