Cycling UK Forum

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I made myself some snow shoes from an old pair of walking boots studded with self-tapping screws. They need regular replacement because they wear down a bit quick and tend to pull out, but they grip quite well.

Failing that, you could try a pair of micro spikes.

When I was looking for cycling shoes I discounted the vast majority of them because they had a gauze top that was neither water resistant nor windproof.

(In the end I found nothing suitable, and carried on using ordinary shoes.)

sjs wrote: ↑26 Jan 2025, 7:30pmI had one from 2020 to 2024 and it was a lot more trouble than it was worth.

Tesla are among the least reliable in this month's Which survey (electric is significantly less reliable than petrol, too).

Jim77 wrote: ↑27 Jan 2025, 12:35pm

axel_knutt wrote: ↑27 Jan 2025, 12:33pm Have you tried adjusting the end stop on the derailleur?

Do you mean the high limit screw?

Yes, when the cable's slack the derailleur is positioned by one end stop, and by the other stop when it's taut, the barrel adjuster shouldn't be making much difference unless it's maladjusted to the point where the lever can't get the cable to go from taut to slack.

Have you tried adjusting the end stop on the derailleur?

The main consumer of energy when walking is lifting your bodyweight with every stride. Each time you take a step your leg pivots around the ankle, so your torso follows a circular locus around the ankle, and consumes energy as it rises. Each of my steps uses about 60J in lifting my weight about 80mm, multiply that by the number of steps and it's a lot. On a bike your torso weight is supported, and the weight of the rising leg is balanced by the falling leg on the other pedal, so you're expending almost no energy beyond what it takes to propel the bike.

When walking, your foot and lower leg are working far harder than on a bike, because not only are the muscles constantly flexing to maintain your balance, especially on uneven ground, but they're also carrying your entire bodyweight. On a bike your feet are carrying very little weight and they also have the benefit of a flat platform that swivels to keep itself in contact with the sole of your foot. It amuses me when cyclists insist you need cycling shoes with rigid soles to prevent foot pain, I think they should try a bit of fellwalking on rough virgin moorland.

Walking on level ground your thigh is working less hard than cycling, but not when climbing any significant gradient. Living in Essex, it was difficult finding any ground steep enough to train my thighs for climbing with legs bent when fellwalking, so cycling made a suitable substitute.

Cycles also have gears that enable you to optimise the ratio of force to distance that your muscles experience, and this has a significant effect on their efficiency: muscles prefer a smaller force over a longer distance, but on foot they get no choice but to carry your full bodyweight.

Nearholmer wrote: ↑24 Jan 2025, 6:50pm

The point at issue is whether the number of lives saved by wearing a helmet outnumbers the number of lives lost due to wearing one.

It’s one of the possible points that might be at issue.

So far though, this thread has been about something else, I think. It’s been about why some people might be deterred from cycling by either a compulsion to wear a helmet, or a recommendation to wear a helmet, which is a different subject.

That's not the point I was answering.

You can test the performance of helmets till the cows come home and you'll learn precisely nothing, because that doesn't address risk compensation, only comparing the death rate between cohorts of helmet wearers and non-wearers will do that.

rareposter wrote: ↑24 Jan 2025, 8:09pmSo part of it is you wear the kit appropriate to that sport. You want to at least appear like you "belong", same way that you wear smart clothes to the theatre.

In most sports, it's usually the governing body that decide what safety gear will be compulsory.

Nearholmer wrote: ↑25 Jan 2025, 7:55am I very much doubt that participants would opt for better helmet protection if it decreased their speed, and they clearly don’t all want to wear super-aero TT helmets, otherwise they would be already. None of this is the much-discussed “risk compensation”, it’s about knowingly taking risks, and using a helmet to shave a bit off the magnitude.

Not necessarily. The safety 'benefit' may simply be a side effect of a helmet that improves aerodynamics, in which case the rider is trading any perceived improvement in safety for the increase in performance, just as Risk Compensation suggests he will.

Nearholmer wrote: ↑25 Jan 2025, 7:55am So, to me it does all make some sort of sense if you assume that most sporty cyclists know that they are taking risks in exchange for fun, and know full well that their helmet offers only partial, but worth having, protection, the same as they know that a set of bib-shorts and a short-sleeved top only offer very partial protection against hitting the deck at 30mph. People aren’t quite as daft as some posters here serm to assume.

The problem is that most people don't understand, or won't acknowledge, that different people have differing appetites for risk, and assume that others should have the same appetite as themselves, and then presume they have the right to tell them. It's not commonly understood that people are about 1000 times more sensitive to a risk that's imposed on them by others than they are to one they choose for themselves, either, so someone who doesn't want to cycle themselves is likely to be judging from the point of view of being coerced into doing so.

[XAP]Bob wrote: ↑25 Jan 2025, 11:15am

Equally, what is the difference between hitting a tree at 30mph on a downhill run, and a car doing 30 mph hitting a commuting cyclist ambling along on their way to work? These arguments can be used in both directions.

The energy involved is very different:
- Person hitting a tree = ~100kg at 14m/s = 9.8kJ
- Car hitting a person = ~1000kg at 14 m/s = 98kJ

Those who think that initial kinetic energy is a useful metric for gauging the potential to cause harm might like to consider that the kinetic energy of a 72kg cyclist travelling at 12mph is exactly the same as Dirty Harry's Magnum 44 (1037J, 16g & 360m/s, to save you looking it up).

Comparing energy dissipated on impact is a big step in the right direction** but even that doesn't cut the mustard, as a simple thought experiment demonstrates. If a stuntman jumps from a skyscraper, the outcome will be very different depending on whether he lands on the pavement or an airbag, even though the terminal KE and total dissipated energy are the same in each case.

Different contact area and modulus of materials result in different stopping distance and acceleration, hence the force and pressure exerted in the process are different, and so the outcomes are very different even though the initial and dissipated energies are the same.

**The energy dissipated when even a 1000 ton train collides with a 70kg person at 30mph is just twice as much as it would be if another 70kg person collides at 30mph, not 14,000 times as much (6295J vs 3148J). The reason it isn't 14,000 times as much is that we're looking at accelerating the person to ~30mph, not stopping the 1000 ton train, and the train retains virtually all its KE after the impact because a 70kg person does virtually nothing to slow it down.

cycle tramp wrote: ↑19 Jan 2025, 10:21pmthere will always be some freak events when wearing them works out

No doubt there will. The point at issue is whether the number of lives saved by wearing a helmet outnumbers the number of lives lost due to wearing one.

[XAP]Bob wrote: ↑24 Jan 2025, 9:03am

axel_knutt wrote: ↑23 Jan 2025, 6:35pm That's only true if everyone's reaction times and brake performance are exactly the same, which they patently aren't. When a car in front brakes it takes time to decide how hard they're braking, so people start by braking hard until they've made a decision, that in turn makes the next car brake harder still, so you get a wave travelling back down the line as each successive car brakes harder and harder. You end up with instability like shown in the video I posted. The faster traffic is flowing the worse this effect gets, which is why slowing speeds creates a more stable flow and a greater capacity overall..

You get exactly the same scenario at any speed - the only way to deal with it is to make sure everyone is travelling at constant speed, and preferably really close to the same constant speed - average speed cameras do this, whether set to 50 or 70.

With two seconds between each car you always have the same amount of time to make decisions and to adjust speed. Now if you're driving an Austin 7 and have the braking performance of a supertanker then you're going to want to take more than two seconds, but with two seconds most vehicles have sufficient margin to brake safely.

Going back to the original claim here:

rareposter wrote: ↑16 Jan 2025, 9:04pm

[XAP]Bob wrote: ↑16 Jan 2025, 3:24pm You actually don't need the rails, or the big engine... if the cars are all talking to each other correctly... then a convoy system is a pretty easy thing to do on motorways.

You can achieve the same effect for vastly less time, effort, money and resource by reducing the speed limit a bit (even if only temporarily) which allows vehicles to be closer.

Counter-intuitively, slower speeds maximises throughput of vehicles, mostly by allowing them to be closer and with less variance in speed.

And that's true.

Referring to the videos I posted above, the same number of cars on the same track will make faster progress if you slow their speed because the lower speed eliminates the instability in the flow caused by people trying to go faster and then over reacting when they get too close.

[XAP]Bob wrote: ↑23 Jan 2025, 5:52pm

axel_knutt wrote: ↑23 Jan 2025, 5:15pm

Stevek76 wrote: ↑21 Jan 2025, 4:46pm Not really, the key determinant of capacity is the headway in time, not distance. Whilst the distance might go down with slower speeds, the time stays more or less the same (up until things get so slow that vehicle length becomes significant).

Stopping distance is proportional to the square of the speed so if you halve the speed the spacing can be a lot less than than half, so the capacity increases. The real bugbear is reaction time though, and the effect of that is less significant at slower speeds.

Nope - you need a 2 second gap... irrespective of speed, it's not about stopping distance (because the vehicle in front of you also has to stop) but reaction distance.
That 2 seconds is the limit for single traffic lane, about 1800 vehicles an hour.

That's only true if everyone's reaction times and brake performance are exactly the same, which they patently aren't. When a car in front brakes it takes time to decide how hard they're braking, so people start by braking hard until they've made a decision, that in turn makes the next car brake harder still, so you get a wave travelling back down the line as each successive car brakes harder and harder. You end up with instability like shown in the video I posted. The faster traffic is flowing the worse this effect gets, which is why slowing speeds creates a more stable flow and a greater capacity overall..

Stevek76 wrote: ↑21 Jan 2025, 4:46pm Not really, the key determinant of capacity is the headway in time, not distance. Whilst the distance might go down with slower speeds, the time stays more or less the same (up until things get so slow that vehicle length becomes significant).

Stopping distance is proportional to the square of the speed so if you halve the speed the spacing can be a lot less than than half, so the capacity increases. The real bugbear is reaction time though, and the effect of that is less significant at slower speeds.

[XAP]Bob wrote: ↑22 Jan 2025, 1:56pm

Bmblbzzz wrote: ↑22 Jan 2025, 9:59am AV convoys are usually spoken of as a means of saving energy not increasing capacity. But as already pointed out, in both aspects they are inferior to an actual train.

And a train is massively inferior if you want to get somewhere that isn't a train station...

Or don't want to wait for the next train. My commute home:

17.01 Finish work
17.10 Train leaves
17.13 Arrive at station
17.56 Next train leaves
18.35 Train arrives
18.40 Arrive home

Or by car:

17.01 Finish work
17.02 Get in car
17.40 Arrive home

The only occasion I've ever had the gap between tyre and mudguard completely clogged it was with a dog turd.

Cycling on a canal towpath once I heard a loud crunch when changing gear, and when I looked the cassette had become a complete ball of grit, with a groove in it where the chain had been. The noise was the chain cutting a new groove through to the adjacent sprocket. I've cycled a lot of gritty railways and towpaths though, and that was the only time it happened with grit, but I have had the same happen with ice once. On that occasion the snow had built up on the spokes until the wheel became a solid disc.

PH wrote: ↑23 Jan 2025, 10:56amThat's what you'd expect with any modern box rim, the box section should hold it together as it starts to wear through.

Not all rims have wear indicators, because the first manufacturers to introduce them patented all the ideas so that by the time the tardy companies like Mavic realised they were becoming de rigueur all the designs had been snapped up already. My Mavic T520/A719 rims had rim wear indicators on originally, but it had been removed again from later ones, presumably because they were infringing someone else's patent.

Here's Chris Juden on the subject in 2002:
. .

deeferdonk wrote: ↑23 Jan 2025, 11:47amBy void, does it mean a distinct gap that is built in the rim that gets exposed once its worn down, or just dishing as the rim is worn down by the brake block?

There are various methods used, such as putting a groove in the braking surface that disappears as it wears, like tread on a tyre, or as on my T520, a small notch on the inside which appears as a hole when the rim reaches its limit.

You need to get an Iwanson gauge, and check regularly.

Carlton green wrote: ↑23 Jan 2025, 9:49amRim wear is, I think, influenced by the brake blocks used. I’m really not sure what the best blocks are but anything that noticeably wears the rim is something to consider avoiding and I suspect that some high performing blocks aren’t (self) sacrificial.

I use Shimano M55/T brake blocks, which are very abrasive, and get about 20,000 miles out of my A719 rims, but I don't know how that compares with other rims/blocks. Kool Stop are less abrasive, but less effective in the wet, too.

Cyclothesist wrote: ↑22 Jan 2025, 5:27pm

axel_knutt wrote: ↑22 Jan 2025, 5:18pm I go for the hands-free option in case both my hands are occupied with both the brakes.

+1

I can't think of a situation urgent enough to need a horn or bell that doesn't need brakes and steering more urgently, which is why I don't think I've ever used a car horn except for trivia.