Search found 157 matches

by StephenW
4 Jan 2021, 11:48am
Forum: Bikes & Bits – Technical section
Topic: Chain case/ chain guard
Replies: 22
Views: 1028

Re: Chain case/ chain guard

I have the Hesling Original. I fitted it to a bike which previously just had a "hockey stick" chainguard. I have also fitted the Hesling Miranda to a bike which previously had a "hockey stick" chainguard and the Nexus chainset, which has a big bulge in the middle.

I agree with Brucey that the Hesling Original would be a good choice. My bike already had the type of chainset which fits through the small hole. These types of chainset are not expensive.

Do you ride fixed? The chain case could make it harder to set the chain tension really accurately, although I suppose one of those tugs would solve that problem.

Although there may a little faffing involved in getting it set up, I think it is definitely worth persevering with, because a chain case is such a handy thing! I think most bikes without derailleurs ought to have them.
by StephenW
7 Dec 2020, 10:59am
Forum: Bikes & Bits – Technical section
Topic: Steering dampers: care to share your?
Replies: 35
Views: 1159

Re: Steering dampers: care to share your?

Hi Tenbikes

I have one of the steering springs. For me, it is a compromise between having the spring tight enough that it has some effect when the bike is parked, but loose enough that it doesn't affect the feel of the steering when you are riding. I don't like the feeling of the spring interfering with the steering when riding.

I don't have any experience of a true damper (like the motorcycle one in Brucey's picture). I think they are useful on bikes prone to shimmy, such as certain cargo bikes or recumbents (with certain riders, this doesn't necessarily affect everyone equally).

I think you are wanting to make the steering light and easy to turn, yes? In that case, I think the best thing to do is carry none of your luggage on the forks or handlebars (unless it is really light stuff). Adding weight here inevitably adds intertia to the steering, requiring more force to make sudden changes of angle. If you really want to carry anything at all heavy at the front of the bike, there are racks which attach to the frame and don't turn with the steering. These will not make the steering feel heavy, although the height of what you can carry on them will depend on the height of your handlebars.
by StephenW
26 Nov 2020, 11:48am
Forum: Non-standard, Human Powered Vehicles
Topic: End of Rainbow Ligfietsen?
Replies: 11
Views: 714

Re: End of Rainbow Ligfietsen?

I thought that Challenge, Raptobike and perhaps some others were taken over by Elan. I think Elan is basically just one guy, and prefers to sell to local customers. But if you really want one and are patient, perhaps it can be done.

Perhaps Elan will also take over the Nazca designs.

I wonder who actually makes the bikes for Elan?
by StephenW
25 Nov 2020, 1:01pm
Forum: Bikes & Bits – Technical section
Topic: Gilles Berthoud saddles - any users care to comment?
Replies: 37
Views: 1578

Re: Gilles Berthoud saddles - any users care to comment?

Tompsk wrote:Any experience from users here on Hollandbike shop as I am tempted by that saddle.


I bought some things from Hollandbikeshop, including a stem. They sent me the wrong stem. They said, "Keep that stem, we'll send you another one".

This stem was also wrong. They said, "Keep that stem, we'll send you another one".

Finally, it was the right one! So it took a while, but now I have two free stems!
by StephenW
18 Nov 2020, 12:07pm
Forum: On the road
Topic: High Performance Cars
Replies: 335
Views: 8188

Re: High Performance Cars

Jdsk wrote:
StephenW wrote:By "good", I mean activities where the risks to the participant are greater than the risks to other bystanders, and where the perceptions of risk of the participants are in line with the reality.

I'm not sure that you meant it quite like that... as a first approximation only the bystanders should be making decisions on risks to themselves. As printed on the back of tickets to motor sports events.

You often see statements in dangerous sports along the lines of "He knew the risk he was taking". This is rarely true in any quantitative sense. And we're learning more about cognitive biasses that get in the way.

But basically I don't think that there's any law of conservation of risk. Almost every aspect of life has become safer.

Jonathan


Yes, I probably should have said that the risks to bystanders is minimal. (Realistically it will never be zero).

There are some sources of danger that are in no way pleasurable. If these can be eliminated, that's great! In that case I would not expect to see an appetite for risk popping up somewhere else. For instance, I wouldn't expect a reduction in farming accidents to lead to an increase in motorcycling or skiing.

But when we are talking about risk-taking behaviours which the participants enjoy, maybe it's different?

Regarding "good" risky activities, if the activity feels more dangerous than it really is, that is ideal!
by StephenW
18 Nov 2020, 11:20am
Forum: On the road
Topic: High Performance Cars
Replies: 335
Views: 8188

Re: High Performance Cars

Jdsk wrote:
StephenW wrote:
StephenW wrote:If we seek to squash down the opportunities for risk-taking in one area of life, will it pop up somewhere else, perhaps in a worse form?

Not necessarily.

Jonathan


Is an individual's appetite for risk fairly fixed, or does it depend on the situation? (nature vs nurture etc.)

If the former, perhaps we should be positively encouraging "good" risk-taking activities? Perhaps this would make relinquishing control of the car more tolerable?

By "good", I mean activities where the risks to the participant are greater than the risks to other bystanders, and where the perceptions of risk of the participants are in line with the reality.
by StephenW
18 Nov 2020, 10:25am
Forum: On the road
Topic: High Performance Cars
Replies: 335
Views: 8188

Re: High Performance Cars

Why do people drive quickly?

I think it's:
1. Impatience
2. A desire for excitement, danger, freedom etc.

This appetite for risk varies a lot between people, but I think it is fair to say that it is usually strongest in young men. There are various outlets for this urge for risk, and some are much better than others. I think mountain biking is one of the best, and fast driving definitely one of the worse ones.

If we seek to squash down the opportunities for risk-taking in one area of life, will it pop up somewhere else, perhaps in a worse form?
by StephenW
7 Oct 2020, 3:37pm
Forum: Non-standard, Human Powered Vehicles
Topic: Hypothetical design
Replies: 15
Views: 687

Re: Hypothetical design

If you had rear wheel steering then you could make the drivetrain simpler. You wouldn't need CV joints any more. This would be lighter and more efficient. It would also allow the width of the vehicle to be reduced, because the front wheels wouldn't need the space to steer any more. This could improve aerodynamics.

You could also get rid of the universal joints if you wanted to - I can think of two ways of doing this:
1. Non-independent front suspension AKA a live axle. This could be suspended either by a five-bar linkage (four trailing arms and a Panhard rod) with coil springs, or with leaf springs. The cassette, derailleur and double freewheel would be in the middle of this axle. I'm not sure if this would result in a higher vehicle overall because the axle would be cutting across at hub height and might get in the way of the rider's legs. In general non-independent front suspension is considered a bad thing, because going over a bump on one side of the vehicle only results in gyroscopic forces from the wheels which are not cancelled out, affecting the steering. But that is with front steering; I'm not sure of the effect with rear steering.

2. Leading arms (like on a 2CV), with a separate chain going to each wheel. There would be a jackshaft (slightly in front of the rider's bottom), with the derailleur and double freewheel in the middle and a sprocket at each end. These sprockets would be connected to the hubs by short lengths of chain, one on each side. Although this introduces an extra stage to the drivetrain, if the sprockets are reasonably large and and positioned so the chain length doesn't change with the suspension going up and down (so no tensioner is needed), the losses might be small.

I reckon option 1 could be fast in a straight line but terrible going round corners or on uneven surfaces.

Also, I think it is difficult to design a vehicle that handles well with rear steering! (But maybe computers could help?)
by StephenW
14 Sep 2020, 11:22am
Forum: Bikes & Bits – Technical section
Topic: Suspension cover - worth having?
Replies: 3
Views: 218

Re: Suspension cover - worth having?

My main worry was dirt on the damper which might damage the seals over time, as it goes in and out. But as you mentioned, corrosion could also be a problem. If the piston gets corroded then that would also damage the seal.

Perhaps I could stretch a piece of old inner tube over the spring?

I quite agree about front forks. It is very strange to me that suspension forks don't have those rubber boots any more.

(This particular bike doesn't have front suspension).
by StephenW
11 Sep 2020, 3:26pm
Forum: Bikes & Bits – Technical section
Topic: Suspension cover - worth having?
Replies: 3
Views: 218

Suspension cover - worth having?

You can get neoprene covers to protect rear suspension shocks from getting covered in mud, water etc.

This seems like a good idea to me. Does anyone here use one? Or perhaps a homemade alternative?

(It would go on recumbent BTW).

https://www.wiggle.co.uk/lizard-skins-s ... gJKOvD_BwE
by StephenW
7 Sep 2020, 2:42pm
Forum: Bikes & Bits – Technical section
Topic: Hallett's Howlers
Replies: 95
Views: 5860

Re: Hallett's Howlers

I've twice been a subscriber to cycle, once when CJ was technical officer and once when R Hallet was. I found CJ's articles more insightful because they were based on an understanding of the fundamental principles at work, whereas I don't think Hallet has that level of understanding. I feel he is more liable to be swept along by current trends.

I think the perspective of starting from the underlying maths and physics is very useful indeed, especially for cutting through marketing mumbo-jumbo. I can think of two potential pitfalls of this approach though:

1. Rejecting experiences which don't match with the model. (e.g. "this must be faster than this because the maths says so...")
2. Downplaying the importance of the subjective. Most of us ride bikes for fun, not to win races. It's fine to be subjective, as long as you are honest about what you are saying. E.g. "I liked this because it felt zoomy." Rather than, "The improved torsional stiffness of the frame increased my acceleration".

I don't think CJ fell into these pitfalls, I am just thinking in general terms here.
by StephenW
15 Jul 2020, 12:14pm
Forum: Non-standard, Human Powered Vehicles
Topic: New to me Azub Origami
Replies: 31
Views: 5595

Re: New to me Azub Origami

Would Nazca open-cockpit stem or bars work? They are cheaper than the prices you mentioned. The stem doesn't fold, but it is telescopic so could be dismantled if necessary. Could be combined with a basic stem-raiser if more height is needed.
by StephenW
12 May 2020, 4:12pm
Forum: Non-standard, Human Powered Vehicles
Topic: Direct Chain Line
Replies: 11
Views: 623

Re: Direct Chain Line

I believe the Challenge Mistral doesn't have an idler, at least in some versions. I have never ridden one.
by StephenW
30 Apr 2020, 4:10pm
Forum: Non-standard, Human Powered Vehicles
Topic: Direct Chain Line
Replies: 11
Views: 623

Re: Direct Chain Line

I do feel that the psychological advantage of a smooth and silent drivetrain is not to be sneezed at! It can really help me to pedal more enthusiastically if everything is running smoothly, whereas I really dislike noise coming from the bike.

On some of the longer, lower bikes, without an idler the chain would be sawing through the rider's bottom! But on shorter, higher bikes it seems to just rub on parts of the bike.

I have an idea of how RWD recumbents in general could be better, which would also make it easier to run without a power idler. What I think is needed is a much wider rear hub, with a much longer freehub body. This would allow many sprockets to be fitted (17 perhaps?), without resorting to making them really thin. The rear dropouts would then be offset to the right. This would give a dishless rear wheel, which is nice and strong. Because there are lots of sprockets, you can have a single chainring and still have a really wide range of gears, without big gaps between them. This single chainring could be quite large, which would keep the chain tension down, reducing problems with flex in the frame while climbing.

(This setup would be no use on an upright bike, because the chainline would be terrible, and the rider's right heel might catch on the chainstay. On a RWD recumbent neither of these is a problem).

The relevance of this to having no power idler, is that it would keep the chain further to the right, meaning that it is less likely to rub on the frame, seat bracket etc. Having a single front chainring makes it easier to protect the rider from the chain, without resorting to things that rub on the chain (i.e. chain tubes). (Perhaps also easier to cover the chainring for safety reasons - don't want to impale anyone with a chainring in a crash).

With a single front chaining, you could also have a chain-keeper (maybe consisting of two rollers which the chain passes between), which moves up and down according to what gear the bike is in. I'm imagining that the chain will just avoid touching the rollers whilst it is under tension, but when the rider stops pedalling or goes over a big bump then the chain will touch the rollers.
by StephenW
29 Apr 2020, 1:22pm
Forum: Non-standard, Human Powered Vehicles
Topic: Direct Chain Line
Replies: 11
Views: 623

Re: Direct Chain Line

A few thoughts:

1. The fact that idlers don't get hot doesn't prove that they are not wasting energy through friction. I'd expect most of the friction to come from the chain being forced to bend whilst under tension, rather than the idler bearings or friction between the chain and idler. The idler itself has ball bearings which are clean and well-oiled, whereas the parts of the chain rub off each other and are liable to be dirty. There is a good flow of air across the chain, and it is a good conductor of heat, so any heat generated within the chain would be dissipated easily. Nevertheless, I don't think all that much power is lost through friction from power idlers (and even less from return idlers).

2. Based on point 1, the thing that matters in terms of friction is the radius of the idler, not the amount that it deflects the chain. If the chain is in full contact with the idler, the amount that each link has to bend is the same, regardless of how much the chain is being deflected.

3. I reckon the key point about power idlers is that they put bending loads into the frame. If you had a stick bike with no idlers, the chain would be loading it in compression, which is very stiff. If you add a power idler, you put in a bending load, and the frame is much less stiff in this direction. The problem is particularly bad if you are climbing in a small chainring, because that makes the chain tension higher.

4. It might be good to remove the power idler to reduce frame flex, but you have to balance this up against more droop in the long unsupported run of chain. This droop can make pedalling a little spongy, and is also not ideal. Perhaps a clutch derailleur or extra-stiff sprung tensioner might help? The Raptobike has the chain forces aligned with the boom and fork, and also has only a short horizontal run of chain, so pretty ideal in both respects.

5. Droop and flex are both less bad if you use larger chainrings and sprockets to achieve a given gear ratio, because chain tension is lower and chain speed is higher.

I tried riding my metabike for a while without any idlers. The chain rubbed on the seat bracket in certain gears, but if you avoided those gears then it was OK. I couldn't say if it was faster, but I really liked how smooth and silent it was! The chain did flap about a bit over the bumps. If you used a hub gear you could avoid the chain rubbing on the seat bracket, but then you would also introduce a new source of losses and possible sponginess. I wrote a thread on here about it ages ago.