Cycling UK Forum

BBC breakfast this morning were hyping on about Porton down making Titanium. Alchemy indeed it'll be gold next week. why couldn't they say it was a new technique to refine Titanium. Give Joe public some credit for their intelligence.

Tangled Metal wrote:You measure cycle parts on grams but do your care about the origins of the unit or just looking to compare the weight in grams of two items to get the lightest?

Do you care about the way a metre is determined. I believe there's a problem with the standard and they're looking into changing to a less solid option to determine it which can be carried out repeatedly anywhere with the lab facilities. IIRC using light to determine it.

So why do you care how gear inches is determined? Just know what a higher or lower number means and compare two figures. There's online and app based calculators for working it out. You just need details from your bike that you can get by looking at the relevant parts.

So IMHO obsessing over correct use or meaning of terms is the realm of nerds and pedants. Did you not understand that 90 gear inches on Boardman's bike is a high gear? If so meaning imparted.

Sorry to be pedantic but it's not the metre definition that's the problem but the kilogram.

Incidentally perhaps someone can explain why the SI unit of mass is a multiple of a smaller unit whereas the other units are not multiples ( the metre, the candela etc). I've never been able to find the reason - perhaps we just need another name - the pound perhaps?

ANTONISH wrote:
Sorry to be pedantic but it's not the metre definition that's the problem but the kilogram.

Incidentally perhaps someone can explain why the SI unit of mass is a multiple of a smaller unit whereas the other units are not multiples ( the metre, the candela etc). I've never been able to find the reason - perhaps we just need another name - the pound perhaps?

Stackexchange has the answer to the 'prefix' on the SI unit of mass https://physics.stackexchange.com/quest ... ic-si-unit

Vorpal wrote:

ANTONISH wrote:
Sorry to be pedantic but it's not the metre definition that's the problem but the kilogram.

Incidentally perhaps someone can explain why the SI unit of mass is a multiple of a smaller unit whereas the other units are not multiples ( the metre, the candela etc). I've never been able to find the reason - perhaps we just need another name - the pound perhaps?

Stackexchange has the answer to the 'prefix' on the SI unit of mass https://physics.stackexchange.com/quest ... ic-si-unit

Thanks for that - interesting that originally the unit would be "the grave". I'd have no objection to that as the name for a unit of mass - once a definition can be agreed on.

I now want to watch a bike race where they get to a hill so stop to collect a smaller wheel from their team car, then once up the hill, change again to a really big wheel, or their bikes are somehow carrying a variety of differently sized wheels to swap to.

Mike_Ayling wrote:Clipless pedals!

Mike

I call them 'step in pedals' but even that can be misinterpreted. Quite a few people I know refer to putting their cleats on when referring to shoes with a retention element fitted.

Then of course - 'Toe Clips' themselves are hardly clips, that would be quite painful

We could go on, Hand Pump (clearly for inflating hands)

Postboxer wrote:I now want to watch a bike race where they get to a hill so stop to collect a smaller wheel from their team car, then once up the hill, change again to a really big wheel, or their bikes are somehow carrying a variety of differently sized wheels to swap to.

Sort of same thing ....................

There once was a track cyclist who had two chains and two chainwheels, one left and one right.
He had a rear wheel with a freewheel on the left, and one on the right - or was it a fixed on the right and left, or was one a freewheel and the other a fixed?
One sprocket/freewheel was unscrewed a bit and was a higher gear ratio then the other one.
He started off in the lower ratio on one chain, then the other side of his hub tightened slowly up as he went - maybe as he reached the first bend perhaps?
Basically, as he accelerated as he went, he changed into a higher gear.

Someone could perhaps put the right story here with the correct info.

do you mean he had a lower gear by pedallling backwards, like this one https://youtu.be/HcTgbPQonVc
description on wiki https://en.wikipedia.org/wiki/Retro-direct

No.
Two chains driving the same hub in the same direction.
The lower gear was a freewheel and as he went, the higher gear (fixed) tightened up on its threads.

Eventually, the fixed sprocket tightened on the threads and provided the drive, whilst the lower gear freewheeled.

Mick F wrote: ... Someone could perhaps put the right story here with the correct info.

I've posted about this before. It's quite some time ago, but I saw it happen on telly. IIRC, the rider was from New Zealand. It worked by the freewheel having a lower gear which enabled the rider to make a faster start. As soon as the fixed sprocket had tightened up, the freewheel freewheeled, leaving the rider in the higher fixed gear. It was something of a five minute wonder. I think the main point was that as a bike for track racing must have fixed wheel, the freewheel was not allowed. Also, the fixed sprocket wasn't properly fitted with a lock ring.

I don't think misunderstood terminology came into it.

Thanks TC.
I brought the subject up due to a comment about changing wheel sizes on a road race.

thirdcrank wrote:

Mick F wrote: ... Someone could perhaps put the right story here with the correct info.

I've posted about this before. It's quite some time ago, but I saw it happen on telly. IIRC, the rider was from New Zealand. It worked by the freewheel having a lower gear which enabled the rider to make a faster start. As soon as the fixed sprocket had tightened up, the freewheel freewheeled, leaving the rider in the higher fixed gear. It was something of a five minute wonder. I think the main point was that as a bike for track racing must have fixed wheel, the freewheel was not allowed. Also, the fixed sprocket wasn't properly fitted with a lock ring.

I don't think misunderstood terminology came into it.

If the freewheel was on the right side then the fixed sprocket on the left unscrewed and tightened against the lock ring.
Or if no lock ring it must have been a custom hub and fixed sprocket with left hand threads

A pet peev is the bicycle trade needlessly metricising imperial measurements. It's even more infuriating where it is done inconsistently: "Ah, you'd like to buy a stem. Do you have a 1 inch headset or a 1 1/8" headset? Are your bars 25.4mm or 31.8mm?"
Tyres sizing is particularly ridiculous. What British tourists refer to as 700C, their German counterparts refer to as 28 inch!

much as it pains me to say it, the Germans have a fair point. The French pinched the original British Dunlop 28" rim sizes (and reused them for different tyre widths in some cases) and relabelled them as 700A, 700B, 700C. As per the original Dunlop standard the idea was to have a wheel that was a certain overall diameter using tyres that were of a single width for each rim. So the 28 x 1-3/4" rim size became the 700C size which gave a 700mm dia wheel with a 37mm tyre or a 28" wheel with a 45mm tyre (45-622 in ISO). Of course various other widths of tyre were made to fit the same 622mm BSD rim and they all (arguably wrongly) became known as '700C' tyres.



The upper half of the above shows the Dunlop rim dimensions, (circa 1911). The rim lips were each 9/32" high thus the BSD of each rim is about 9/16" smaller than the ODs listed above. All six rim dimensions listed above (590, 584, 571, 642, 635, 622mm BSD respectively) still exist and are still used, although the 28x 1-3/8" size (700A) is now rare.

cheers

AdamS wrote:A pet peev is the bicycle trade needlessly metricising imperial measurements. It's even more infuriating where it is done inconsistently: "Ah, you'd like to buy a stem. Do you have a 1 inch headset or a 1 1/8" headset? Are your bars 25.4mm or 31.8mm?"
Tyres sizing is particularly ridiculous. What British tourists refer to as 700C, their German counterparts refer to as 28 inch!

I assume this is a result of parts, in this case stems and bars, being designed in the USA then marketed to the rest of the world. Bar diameters were already described in mm for road (26.0 and various slightly variant designs).