CTC Forum - On the road

Syndicate content
Discussion boards hosted by CTC, the national cycling charity
Updated: 1 hour 14 sec ago

Re: How much does luggage slow you down?

25 August 2015 - 11:47am
Mick F wrote:If the road is flat and you ignore wind resistance, weight means nothing to top speed or average speed. Acceleration is affected, but not speed.

that ignores rolling resistance, which is always proportional to the total weight. For many riders this is a small portion of the whole, but it needn't be; CJ has pointed out in the past that the least powerful riders have the greatest proportion of their effort expended against rolling resistance, and are therefore arguably most affected by it.

It will vary with the rider but if you are doing around 10mph then it is likely that about 50% of your effort is going against rolling resistance. Thus if you increase the weight by 10% you increase overall resistance by around 5%, and the speed will drop similarly.

A more powerful rider (doing, say, 20mph) might only be expending about 20% of their effort against rolling resistance, so a 10% increase in that will only change the total drag by about 2% at that speed, and the actual speed change will be less than that.

So what I'm saying is that the effects of weight increase are certainly not the same for every rider and should not be assumed thus; they can in fact be very different indeed.

cheers

Re: Shame more don't take this stance with traffic offences.

25 August 2015 - 11:37am
I really don't buy into this theory that drivers who also ride cycles drive safer or with more consideration than non-cyclist drivers. I just have this view that people make bad choices and decisions. Driving is not the same as cycling in your awareness and driving positions. They are just too different and IMHO I think most think like a driver when driving a car and think like a cyclist when riding a bike.

I know i try to treat cyclists and other road users with more consideration when in a car but I also acknowledge that I too fail at times. I will take that risky overtake as much as any other driver if I am in the mindset to do so. I am sure I am not alone among us driver/cyclists to do that.

Thinking awareness course? Oh dear, are the authorities trying to throw money down the drain? Who actually pays for this? Is it fully funded by court costs awarded against the offender? I doubt it is so that means tax funded waste of time.

I think some on here are under the impression he will drive without a valid licence and insurance anyway. I wonder if in time there will be a means to prevent cars starting without a valid licence? Imagine that your driver's key had the state of your licence programmed in so the car can check if you are allowed to drive before starting. Or perhaps a key and separate licence slot. Without both the car won't start. Reckon the technology is there. I mean that licence could also contain your insurance details and the state of the car's MOT certificate. If you do not have all these things in place the car won't start. Add in breathalizer and you might cut a few problems with the current system...might!

Re: How much does luggage slow you down?

25 August 2015 - 11:09am
If the road is flat and you ignore wind resistance, weight means nothing to top speed or average speed. Acceleration is affected, but not speed.

If you are a strong rider, you can haul a load up a hill without too much stress and strain. You may not be fast, but you have power. The skill and ability will win the day.

Just watch a good rider climb a hill. I don't mean a racer, I mean a good experienced rider. He'll know exactly which gear to be in to best effect, and he'll know just how hard to turn the cranks. He'll also have good technique in movement and be able to use his power efficiently. He'll have big lungs and strong legs, he won't get fraught and upset with the prospect of the hill. He'll relax and take it in his stride, and he won't rush at it like a bull at a gate.

Now, watch an inexperienced rider. He'll fret and worry, he'll not be "at one" with his bike and he'll tire easily. He'll be in the wrong gear, hold back on the downhills, and try to go too fast on the flat. He'll sway this way and that, and his riding position will be inefficient.

I spent miles and miles over weeks on end towing a concrete block along the lanes of Devon and Cornwall in an effort to be able to absorb the extra weight. In the end, it became "easy" and natural, and I was well prepared for my forthcoming tour. I did the same with the Raleigh Chopper and TBH I found the JOGLE quite easy. It was the awful Chopper saddle that slowed me down!

Weight is weight. You cannot argue this point, but you can get used to it so you don't notice, and you can cope with it through technique and practice.

Re: Shame more don't take this stance with traffic offences.

25 August 2015 - 10:55am
I've ridden off (been forced off) the road twice because of exceptionally close passes. Once it was a 2CV with the archetypal 'Nuclear Power - No Thanks' sticker, a driver you'd expect be into green transport and cycling. What's worse I was cycling on holiday in France and it was an British-registered, RHD vehicle, so the driver's position really was right behind me, not a case of not knowing how far I was out or he was over.

Of course it could have been being driven by the owner's 21-year old son who hated cycling and cyclists...

Re: How much does luggage slow you down?

25 August 2015 - 10:52am
hondated wrote:Mick F wrote:Having towed a heavy trailer up and down this fair country of ours, I can say quite categorically that weight makes little difference to overall speed.

It's a surprising fact that it may slow you down on acceleration and up steep hills, but you gain going down the hills and on the flat it doesn't affect anything. Overall, it makes little difference at all.
Given this as been written by you Mick I cannot query it but I find that astonishing.

That may be the 10 kg rule in play: 10 kg is nothing to the average rider. 30 kg may be not be very much to a strong rider. He still had to haul himself and the bike up the hills so the extra weight may not be all it seems. I've got a 20 kg advantage on someone weighing 96 kg and his weight might be flab while mine is well obviously pure muscle.

Re: How much does luggage slow you down?

25 August 2015 - 10:48am
David881 wrote:Does the weight of the rider make a difference? For example an extra 5k of luggage is proprtinally a much larger increase for a rider weighing 60k than one riding 80k, and therefore conceivably could have a different effect on performance

I would have thought it depends on how much of the weight of the heavier rider is muscle. A larger person has the build to move his/her own weight and more but that will vary with the person. How much of Mick F's Clio weight is engine and how much is just extra stuff? AIUI we always (reasonably) assume that the heavier/larger rider is proportionally the same as a lighter/smaller rider. But that obviously isn't always the case.

Re: How much does luggage slow you down?

25 August 2015 - 10:46am
Mick F wrote:Having towed a heavy trailer up and down this fair country of ours, I can say quite categorically that weight makes little difference to overall speed.

It's a surprising fact that it may slow you down on acceleration and up steep hills, but you gain going down the hills and on the flat it doesn't affect anything. Overall, it makes little difference at all.
Given this as been written by you Mick I cannot query it but I find that astonishing.

Re: Shame more don't take this stance with traffic offences.

25 August 2015 - 10:18am
[XAP]Bob wrote: Either that or they just ride off road, so never get close passes...

That thought did cross my mind as MTB's form the bulk of bikes on cars.

Re: Shoreham air crash

25 August 2015 - 10:15am
maxglide wrote:However, the book I checked out says this (It seems to be American so the rules may be different, but the physics would be the same:

The tow rope does dangle a bit, now you mention it. Also in the States, on release, the tug & glider turn
in opposite directions to the UK.

interesting that the turn is different; most single prop planes turn a bit easier one way than the other... I would suppose that there isn't much difference in the typical tug plane here vs the States...? So I wonder what (if any) the logic is there?

cheers

Re: How much does luggage slow you down?

25 August 2015 - 9:23am
We have two cars, a Renault Clio 1.6 16v @ 110bhp, and a Fiat 500 Twinair @ 85bhp.
The Clio is a heavy car due the high spec, but is quite nimble, though not "quick".
The Fiat is very light and very quick, and is wonderful fun to drive.

The Clio has a towbar, and yesterday I collected ten back of coal in the trailer. Clio managed very well, even with the horrendous hill up to our place.

The Fiat doesn't have a towbar (yet) though we may fit one in the future. However, I doubt very much that the car would cope so well with even eight bags of coal .......... or even seven. The Clio leaves it standing when it comes to plain "grunt" and pulling power.

It's not just power to weight ratio, it's more to do with the power curve and how the power is put down.

Re: Shame more don't take this stance with traffic offences.

25 August 2015 - 9:19am
reohn2 wrote:Lance Dopestrong wrote:Let's be honest. Most of us are car drivers, so a decent proportion of us also drive like fools. As a user group I'm not aware of any evidence that we make safer car drivers or at les likely to offend when behind the wheel.

But then there's no proof that cyclists who drive are more likely to drive like fools.
If anything there's a fair chance that having been at the receiving end of bad driving,they're more likely to have empathy with other road users especially the vulnerable.

Either that or they just ride off road, so never get close passes...

Re: How much does luggage slow you down?

25 August 2015 - 9:18am
Bmblbzzz wrote:I do think – though I certainly don't have any figures to demonstrate – that we should differentiate between rider weight and off-rider weight. So if two riders both develop 250W and have the same total (rider + bike + luggage) weight, A weighs 60kg, bike 15kg, luggage 20kg = 95kg; B weighs 80kg, bike 10kg, luggage 5kg = 95kg; rider A is going to be more affected by the weight he is propelling. So, yes, luggage weight should be considered in proportion to rider weight and power, but it's not a straight ratio.
If both weights are the same and the power is the same, then the only difference is in aero and/or rolling resistances.

The thing is that the larger rider is probably able to push more power...

Re: How much does luggage slow you down?

25 August 2015 - 8:59am
I do think – though I certainly don't have any figures to demonstrate – that we should differentiate between rider weight and off-rider weight. So if two riders both develop 250W and have the same total (rider + bike + luggage) weight, A weighs 60kg, bike 15kg, luggage 20kg = 95kg; B weighs 80kg, bike 10kg, luggage 5kg = 95kg; rider A is going to be more affected by the weight he is propelling. So, yes, luggage weight should be considered in proportion to rider weight and power, but it's not a straight ratio.

Re: Shame more don't take this stance with traffic offences.

25 August 2015 - 8:53am
Lance Dopestrong wrote:Let's be honest. Most of us are car drivers, so a decent proportion of us also drive like fools. As a user group I'm not aware of any evidence that we make safer car drivers or at les likely to offend when behind the wheel.

But then there's no proof that cyclists who drive are more likely to drive like fools.
If anything there's a fair chance that having been at the receiving end of bad driving,they're more likely to have empathy with other road users especially the vulnerable.

Re: Shame more don't take this stance with traffic offences.

25 August 2015 - 8:52am
Lance Dopestrong wrote:Let's be honest. Most of us are car drivers, so a decent proportion of us also drive like fools. As a user group I'm not aware of any evidence that we make safer car drivers or at les likely to offend when behind the wheel.

Indeed, I've had close passes from quite a few cars with bikes on the back.

Re: Shame more don't take this stance with traffic offences.

25 August 2015 - 8:49am
Valbrona wrote:So The Birch has evolved into a 'Thinking skills programme'?
Corporal punishment only ever hardened my resolve again authority.

Re: Shame more don't take this stance with traffic offences.

25 August 2015 - 8:44am
Lance Dopestrong wrote:Let's be honest. Most of us are car drivers, so a decent proportion of us also drive like fools. As a user group I'm not aware of any evidence that we make safer car drivers or at les likely to offend when behind the wheel.
I don't know about cyclists in general but I reckon cycling makes me a better driver as in I'm more aware of others and their requirements. Having said that I'm far more tolerant of others idiocy when in my car than I am when on my bike...

Re: Shame more don't take this stance with traffic offences.

25 August 2015 - 8:16am
Let's be honest. Most of us are car drivers, so a decent proportion of us also drive like fools. As a user group I'm not aware of any evidence that we make safer car drivers or at les likely to offend when behind the wheel.

Re: How much does luggage slow you down?

25 August 2015 - 7:29am
Yes, it must.
I wonder if we should be talking about over-all weight to power ratio?

Re: Shoreham air crash

25 August 2015 - 4:59am
However, the book I checked out says this (It seems to be American so the rules may be different, but the physics would be the same:

The tow rope does dangle a bit, now you mention it. Also in the States, on release, the tug & glider turn
in opposite directions to the UK.

Archive

  • Patron: Her Majesty The Queen
  • President: Jon Snow
  • Chief Executive: Paul Tuohy
  • Cyclists' Touring Club (CTC): A company limited by guarantee, registered in England no.25185. Registered as a charity in England and Wales No 1147607 and in Scotland No SC042541

Copyright © CTC 2015

Terms and Conditions