Search found 528 matches

by Chris Jeggo
26 Mar 2024, 10:07am
Forum: Fun & Games
Topic: English Language - what "Does your head in" ??
Replies: 2256
Views: 126149

Re: English Language - what "Does your head in" ??

Mick F wrote: 25 Mar 2024, 6:24pm The other one I was thinking about today, was "agenda". It was being said on R4 this afternoon with a politician chappy.

When I went to meetings ......... and chaired them many many times ............ was we discussed the agendum.

Looking it up earlier due to R4, the modern stuff is "agenda" as the singular, and "agendums" as the plural! :shock: :shock: :shock:

Even the spell-checker on my Mac doesn't like "agendums".
In Latin agendum means 'that which is to be done' and its plural is agenda.
In English agenda usually means the list of things to be done and is considered singular, the plural being agendas.
Like Jonathan, I would be curious to know who came up with agendums.
by Chris Jeggo
25 Mar 2024, 1:32pm
Forum: Touring & Expedition
Topic: Best tyres for touring
Replies: 27
Views: 1006

Re: Best tyres for touring

simonhill wrote: 24 Mar 2024, 11:32pm.....
Although a recent thread said weight on wheels no more important than weight elsewhere
......
Well, that sent this thread off on a tangent.
by Chris Jeggo
25 Mar 2024, 1:12pm
Forum: Touring & Expedition
Topic: touring wheels upgrade
Replies: 66
Views: 2589

Re: touring wheels upgrade

rareposter wrote: 25 Mar 2024, 1:05pm You don't really need maths to prove anything though. Put some 2.5kg wheels on a bike, go and ride up a hill.
Replace the wheels (keeping the same tyres/pressures etc) with a pair weighing 1.5kg , go and ride up the same hill at the same power.

The lighter wheels will feel better (which is a bit subjective) and will be measurably faster (which is purely objective).

There's a reason that performance wheels are lighter and it's not all marketing or snake oil!

OK, for touring I'd probably prioritise reliability and standard parts over purely lightweight but it'd still be a consideration even once a bike is loaded with touring gear.
Equally true. The inertia of rims+tyres is significant compared with inertia of rider+cycle when a second or so really matters.
by Chris Jeggo
25 Mar 2024, 1:03pm
Forum: Touring & Expedition
Topic: touring wheels upgrade
Replies: 66
Views: 2589

Re: touring wheels upgrade

531colin wrote: 25 Mar 2024, 12:53pm I can accelerate the wheel by brushing it with my hand.
I need to use both legs to accelerate rider plus bike.
While I am accelerating rider plus bike, the difference between a regular tyre ( accelerate the wheel with a brush of your hand) and a light tyre ( accelerate the wheel with a light brush of your hand) is insignificant.

Unless you would like to produce real numbers demonstrating that accelerating a bicycle wheel takes a significant proportion of what it takes to accelerate rider plus bike plus any luggage.
True. The inertia of rims+tyres is insignificant compared with inertia of rider+cycle+luggage.
by Chris Jeggo
25 Mar 2024, 11:58am
Forum: Touring & Expedition
Topic: touring wheels upgrade
Replies: 66
Views: 2589

Re: touring wheels upgrade

simonhill wrote: 25 Mar 2024, 9:55am In English please?

Is the following true?

Apart from the weight they add to the overall weight of the bike, heavier wheels and tyres make very little difference to pulling away or rolling.

Someone has written on the touring tyre thread "So pulling away at a junction, 1kg on a tyre feels like 2kg on the frame". Is that untrue,?
roubaixtuesday has beaten me to it, and he's dead right. He has bitten the bullet and produced the equations I declined to do previously. The rotational kinetic energy of rim+tyre equals the translational kinetic energy. So yes, 1kg on a tyre feels like 2kg on the frame when accelerating.
by Chris Jeggo
11 Mar 2024, 4:51pm
Forum: Bikes & Bits – Technical section
Topic: "Plus" vs breaker for fairy protection
Replies: 16
Views: 959

Re: "Plus" vs breaker for fairy protection

531colin wrote: 11 Mar 2024, 12:00pm ....

What I think must happen is the front wheel goes over the object and flips it up, so that it is standing on end as the back tyre runs over it, and your weight drives it through the tyre.

....
I have known that to happen and cause a car tyre to deflate in a couple of seconds.
by Chris Jeggo
11 Mar 2024, 10:34am
Forum: Does anyone know … ?
Topic: Cateye cycle speedo/computer adds stealth miles overnight?
Replies: 15
Views: 883

Re: Cateye cycle speedo/computer adds stealth miles overnight?

When I put my cycle computer on the desk next to my laptop it does erratic speeds of up to 100-ish mph. I blame Harald Bluetooth.
by Chris Jeggo
6 Mar 2024, 11:12am
Forum: Touring & Expedition
Topic: touring gearing ?
Replies: 18
Views: 1199

Re: touring gearing ?

ANTONISH wrote: 6 Mar 2024, 9:44am
LuckyLuke wrote: 6 Mar 2024, 9:21am Hi, just to echo the others above, it sounds like your existing triple will take a 24T inner. Spa sell a steel one that I’ve found works well.
.....
A caveat ; I bought just such a steel inner ring and kept it for a while.
Eventually I decided to ride the C2C and realised I had a new inner ring - so fitted it to my 9sp setup.
Unfortunately I fitted it at the last moment so it wasn't used until I was actually on the ride.
I found that the chain was sucking on the small ring - very disconcerting on a climb as I had to rapidly unclip and get my foot down to avoid a fall.
When I consulted here on this problem it was pointed out that the chainring was probably 7sp and was too snug a fit on my 9sp chain.
I had a steel 24t inner ring (9sp), probably bought from Spa, which produced chain suck. On investigation I found burrs caused by pressure from the chain rollers. The tooth profiles had also changed a bit. I filed off the burrs. Some while later I found smaller burrs, but if I remember rightly these had not caused chain suck. I filed them off and that was the end of the matter. The tooth profile had obviously changed to something that was able to stand the pressure.
by Chris Jeggo
5 Mar 2024, 10:11am
Forum: For Sale - Complete bikes ONLY - state FRAME SIZE in title
Topic: 21" frame 1980s step through Falcon with new bits £225ono
Replies: 3
Views: 626

Re: 19" frame 1980s step through Falcon with new bits

My wife has one of these, Super Tourist De Luxe, bought in 1975 for £55. Hers is almost the same, but it does not have the chrome fork ends. It's a lovely bike.
by Chris Jeggo
2 Mar 2024, 2:43am
Forum: Bikes & Bits – Technical section
Topic: Will these fenders fit on my bike?
Replies: 19
Views: 844

Re: Will these fenders fit on my bike?

ericoutdoors wrote: 1 Mar 2024, 8:41pm
Sum wrote: 1 Mar 2024, 8:10pm The rear fender is intended for tyres that are 44mm wide. Your tyres are 50mm wide. Fenders are sometimes wider than the tyre they are intended for so they may work but then again they may not. You could try asking the seller to measure the actual width of the fender.
Thanks. I'm thinking of trying anyway. I understand that some fenders are intended to fit very close to the wheel, but I don't think these fenders are, so if I fit them with enough of a gap I'm thinking the 3mm on either side will be irrelevant.
Your tyres are 56mm wide. Fenders intended for tyres that are 44mm wide are unlikely to be more than 54mm wide and will not intercept all the dirty water thrown off a 56mm tyre.
Example of a suitable fender: https://www.sks-germany.com/en/products ... ver-11820/ - click on 'MORE DETAILS'.
by Chris Jeggo
27 Feb 2024, 3:45pm
Forum: Helmets & helmet discussion
Topic: Review of neck injuries and cycle helmet use
Replies: 44
Views: 3539

Re: Review of neck injuries and cycle helmet use

mjr wrote: 27 Feb 2024, 12:06pm
Chris Jeggo wrote: 27 Feb 2024, 11:31am If you search "Colin Clarke Cycling UK" you get this: Colin_Clarke.png
(from https://www.researchgate.net/profile/Colin-Clarke-6).

I hope Cycling UK are having serious words with him regarding his membership.
Is he not a retired Cycling UK campaigner, then?
Yes, he is, but clearly, from this and previous threads, some readers of his papers get the impression that his views are those of CUK, while CUK clearly thinks otherwise. This needs to be sorted out. I would suggest that CUK insist on his including a disclaimer in future papers - something along the lines of "... represents the views of the author, not those of Cycling UK".
by Chris Jeggo
27 Feb 2024, 11:31am
Forum: Helmets & helmet discussion
Topic: Review of neck injuries and cycle helmet use
Replies: 44
Views: 3539

Re: Review of neck injuries and cycle helmet use

If you search "Colin Clarke Cycling UK" you get this:
Colin_Clarke.png
(from https://www.researchgate.net/profile/Colin-Clarke-6).

I hope Cycling UK are having serious words with him regarding his membership.
by Chris Jeggo
27 Feb 2024, 11:09am
Forum: On the road
Topic: Road marking
Replies: 13
Views: 1488

Re: Road marking

Not 'fart backside' then?
by Chris Jeggo
21 Feb 2024, 1:34am
Forum: Touring & Expedition
Topic: touring wheels upgrade
Replies: 66
Views: 2589

Re: touring wheels upgrade

I did this stuff at A-level. As regards the inertia of the bicycle as a whole, adding 1kg to the circumference of a wheel is equivalent to adding 2kg to the bicycle frame. Or you could say it's equivalent to eating a 2kg meal! Or a 1kg meal plus a litre of beer.

I decline to provide proof in the form of a page of equations, but note that the Wikipedia article "Rotational energy" states "The rotational energy of a rolling cylinder varies from one half of the translational energy (if it is massive) to the same as the translational energy (if it is hollow)."