Cycling UK Forum

^^ Highly amusing thread I think. Very uncertain about the stress given to people who fornicate with those who have given birth . . . or the way that common language is "moderated" here but if we had a "like" button it may well cause a lot of the distastfull pedentry that occurs on this forum to fall away.

Clearly I don't actually know which is the steepest road in the UK. or exactly what the gradients are (who measured them anyway? and how?) but I can say that it is definitely pleasurably and satisfyingly possible to cycle up ffordd penlech across stryd fawr and up pen dref to the top of the hill, with camping kit on board. This is a lot more hill than just ffordd penlech, which is no-but a short little sprint. One then has an incredible view across the Irish sea and towards the Lleyn peninsular to the West, to Pwllhelli and Llanbedrog across the bay. To yr Swyddfa in the North (if it is not to cloudy and mist shrouded).

It is a very satisfying climb that I thoroughly recommend.

Of course you are only talking about the bottom fraction of ffordd penlech. If you go straight across Harlech upper high street it carries on to the top of the hill - over a mile with no breaks - although it does ease fractionally in a couple of places.

horizon wrote:Parallel thread alert but otherwsie great stuff Giles:

viewtopic.php?f=7&t=120418

Sorry Horizon, did'nt realise. What happens about that then?

You are absolutely right Cyril Haearn. Are you anywhere nearby? I sometimes have a lot of "doings" in the Eryri area and consequently commute to there from here not infrequently - usually in the warmer months.

Has to be said today if I had to go anywhere - which I don't - I would weigh up shanks pony or take a bike, thing is the more heavily used roads are (mostly) pretty easy to cycle but you have to get to them first.

Well todays commute came about because a couple of my neighbours needed "vital" suppllies nappys, milk,beer, etc. - and various 4x4's were blocking the route. I chose to use my MTB bike ( Dawes Durango - otherwise known as my "shopping trolley") for this due to the conditions.

It was a 14mile round trip to Rhayader by the quickest way but over 17 the way I chose. I went over the "bouncy bridge" at the confluence of the Avon Elan and Wye rivers, and various other lanes.

I wonder has anyone else gone on a bike commute lately because it is the only viable method in the conditions?

Have to get off the internet again right now due to lack of electric.

Again I have to disagree with Brucey, who I think is very well informed and his posts are mostly well mostly well considered.

Plainly ;it is a matter of opinion only whether hub dyno's are " the best solution we have at present".

Many of the objections to bottle dynamos are spurious or else rarely happen. Today I took out my "Mule" fitted with road tyres - because a freind could'nt get to feed her horse due to road conditions, stuck 4x4's already blocking her route. . .

Due to the fashion police on this thread I ran my bottle dynamo and found that through the snow drifts I encountered that in this dry powdery snow it coped quite happily. So very rare that they won't work due to snow - I did change to my mountain bike for a further commute for neighbours supplys though due to grippy tyres being a definite advantage ( Subject of "todays commute thread).

I wonder - I bet a marathon or similar tyre may well have the highest [u]average[u] rolling speed on mucky or glass infested roads.

As I said earlier I could'nt care less what legal lights others use - so long as you are happy with it, but many of the imagined problems with bottle dynos either rarely happen or don't exist that's all. Of course they have developed (as have hub dynos) a great deal from those we remember using years ago.

Slight fly in the ointment their Andrew is that you don't need to have a wheel built to fit a bottle dyno.

This is where we disagree then Brucey.

Due to the extra around 500grams (approx, depending on exact dynamo, IRC the B+M weighs 120grams,) you always carry with a hub dynamo and the slight eddy drag of even the best, taking into account the fractional extra drag of a bottle dyno in operation you will find that you will need to be using lights at least 90% of the time for the best hub dyno's to be more efficient.
I don't think the point about which tyre you choose is very relevant really as this is in no part dependant on the dynamo. You do not need a tyre with a dyno track whatever type of dyno you use.

Not to mention that with all things considered hub dynos are enormously more expensive.

"Also, surely a small wheel dynamo should be more efficient as spins faster ?"

That old chestnut, for a bottle dynamo - think on a little - you need the same number of meters of tyre/ mile whatever tyre size you have, therefore at the same speed, er, they turn at the same speed.

I may have misunderstood you though - a hub dyno would spin faster- more/mile of course.

What a shame Mercalia. I have got a spare fortunately.

That second picture of my Carlton of course is straight out of the shed. If I had of wanted the lights that mud would just immediatly fly off as soon as I began to move.
I don't really care what (legal) lights others use, but I say again that those who don't use bottle dynamos imagine all sorts of problems about them that either don't or very rarely occur, if they are well fitted. I have no trouble with slippage and the first picture shows a Marathon tyre which has already done 3400miles - many at night, as it is close to threequarters worn I expect close to the same mileage again (barring accidents) from it. - First half of a tyre wears in about a quarter of the miles till worn out, due to tread "squirm". If you want to check that one I would suggest looking on commercial vehicle tyre web sites. The power figures for the dynamo are available on the B+M web site last time I looked.
They are the lightest you can have and if you do your calculations even though they do drag slightly (a fraction of a W) more than hub dyno's unless you ride over 90% in the dark they are the most efficient energy wise. Their output is identical to a hub dyno at optimum including voltage regulation, but occurs at a lower speed. They don't need inordinately expensive wheel builds either. Here is a link to a type of wheel I use https://www.taylor-wheels.com/bike-wheels/26-inch-bike-wheel/26-inch-rear-wheels/taylor-wheels-26-inch-bike-rear-wheel-ryde-zac2000-5-8-speed-cogset-black Which I usually find has the spokes a little more slack than I would desire, so a quarter turn on them rectifies it. I don't regard spending a penny more as in the slightest bit advantageous, which is of course the same attitude I take concerning my lights - but I will only use legally approved types.
(Afraid there seems no way to give the url a short title.)

Thanks for that info Mercalia, had a look at xnview.

The way I have them fitted they run on to the wheel, which is no doubt one reason why I have no trouble with them slipping. The B+M is of course adjustable in this respect. I have one mounted on a bracket that is fastened with the cantilever brake bolt. The other which is on a frame with caliper brakes I have made my own simple mounting which is much neater than those one can buy. It is very similar to the braze on that I think Thorn(?) offer for such. In my case it is bolted of course. (Shame the forum won't accept my pictures.)
On one of my bikes the dynamo is running on a Marathon tyre which has so far clocked 3400 miles with extensive night riding - it has just about made the shwalbe label illegible.

Cyril Haearn wrote:

Giles Pargiter wrote:I know it is deeply unfavoured and unfashionable in the UK but I use modern B&M bottle dynamos on my bikes, upon which I do a considerable amount of night riding.
These are the lightest type of dynamos available and due to the fact that they revolve much faster suffer from no flicker at all even when wheeling the bike. When turned off they are completely off.

..
.

Unfashionable is good I think
Like to see some pictures, front or back? Diolch
I was always a bit afraid a bottle dynamo might go into the spokes

Sorry about the inordinately long time for to reply, I live off grid and my internet access and power is sometimes a bit "random" and not always available.
People seem to imagine all sorts of problems about these dynamos, that just don't happen. They can very occasionally have trouble in very sticky mud or snow, but this is rare. For example traversing one of the hills yesterday afternoon, traction between my tyre and the road in the snow almost meant I had to walk up it - the dynamo was absolutely fine.
Here are a couple of pictures of them mounted. In the usual Brit way I prefer them behind the rear stay. They are better protected there, the spray in wet weather does not make your legs wet, you can hardly here the magnetic whine. A little awkward to turn on when panniers are in use.
Well I would include pictures but I'am informed the "file size to large" it is a 635kb Jpg so I am at a loss on that. I am definitely not buggering about putting them online somewhere.