Phil's Ramblings

How do you ride a bike? Part 2

Phil — Thu, 09 May 2013 10:16:50 +0000

Yesterday we continued Cerys’s bicycle training with a bit more balance practice and the introduction of pedals.

After practising the same balance exercises from the previous lesson, we had to decide which pedals to use: the bike was supplied with ‘normal’ pedals, flat platforms with spikes around the edge, to be used with street shoes; the alternative being MTB ‘clipless’ pedals which you use with specialised cycling shoes. We talked about the pros and cons of each option and settled on using the clipless pedals.

The obvious disadvantage to using clipless pedals as a beginner is that your feet are attached to the pedals, meaning you have to add the twist-disengagement to the already complex process of coming to a safe halt.

There are some nice advantages however:

Clipless pedals don’t have sharp spikes that can stab you in the back of the leg
You can’t end up pedalling with the middle of your foot and catching your toe on the front wheel
You can introduce only one pedal and still move the bike with it

I’m not sure I would recommend clipless pedals to all beginners but Cerys has used them for a while on her tricycle so already had all the kit, and a very nice set of hand-me-down XTR pedals which are very easy to get into and out of.

We introduced the right pedal first, because in the balance exercises Cerys was naturally preferring to ground her left foot as she comes to a halt. With one pedal you still need to be working on a downward slope because it’s very difficult to build up any meaningful speed. A couple of runs to get used to performing a controlled stop with one foot still clipped-in, and a couple more to practice disengaging the right foot while on the move, and we were ready to introduce the second pedal.

Before Cerys set off with both pedals I did a quick loop over the same course to put the bike in a gear which was appropriate for the conditions. I had forgotten how much you need lower gears on grass when compared to tarmac.

At this point there are many easy ways to fall over: the foot motion required to disengage the pedals can tip the rider so that they fall down on the opposite (still engaged) side; or the rider can fail to disengage the pedals before reaching a halt before unbalancing; or the rider can get everything right but forget to put a foot down after coming to a halt.

Since most of the ways of falling over happen most readily when attempting to come to a halt, I suggested that Cerys should do some circuits occasionally disengaging one foot and then re-engaging it to continue. Once she was happy that she could disengage her feet safely she could come to a controlled halt without falling over. Fine in theory, not so perfect in practice.

After about an hour of gradual improvement the frequency and severity of crashes looked like it was creeping up again so we called it a day; I think this was around the point at which increasing fatigue was making Cerys’s performance worse at a greater rate than increasing experience was making it better.

On the whole, considering the number of times I would expect a beginner with flat pedals to fall over and the number of times I recall falling over when I first switched to clipless pedals, I think Cerys has fallen over much less than I would expect.

Overnight we made some changes to the pedal tension on one side to make it a better match left-to-right, and we are about to go out for some more practice.

Pebble News

Phil — Wed, 08 May 2013 20:44:16 +0000

It’s been an exciting week in Pebble-land:

RunKeeper for iOS got updated to use the Pebble watch as a second display.
We received our second consignment of Pebble watches; we currently have 6 to sell. They are all black.
I made a new watch-face to give me the information I want:

I will test this watch-face for a couple of days and if it works well for me I’ll make it available to all of you. If you need a Pebble watch so you can install it, or fancy developing your own, get in touch with me either directly or by leaving a message below and I’ll sell you one of the six.

29th Isle of Wight Randonnée

Phil — Wed, 08 May 2013 09:12:24 +0000

I completed the Isle of Wight Randonnée on Sunday. When I completed the course three and a half years ago I had to walk up the two steep ramps just before the floating bridge at the finish in Cowes, so I felt that I had been defeated by the route. This time I feel justified in posting my completion certificate:

The only moment of trouble I had was on a smaller hill near Alum Bay; I had to stop for about 30 seconds before getting back on and finishing the hill on the bike. I think the cause was dehydration, which I came some way to rectifying at the next checkpoint with a can of coke and a refilled bidon. I must have drunk 2-3 litres of fluids after this point without needing to pee, which means I had let it get pretty bad. Other than this hydration failure I managed things pretty well.

It was interesting to ride with a group again; usually I am riding alone for training. I think the average speeds across the group were reasonably comparable for similar levels of effort, but we all had different ways of doing it. Part of the difference is probably due to equipment differences: I ride an SRAM compact chainset and 12-28 cassette, whereas Russell for example has a Shimano double chainset and 11-27 cassette. Up some of the hills, such as York Hill in east Cowes, I could stay in my big ring (SRAM design their front derailleurs to be ridden ‘crossed-up’ when on the big ring) when the others had to drop to the small one which made me comparatively faster; whereas up the two-in-a-row killer climbs on the south-west we were all in the small ring which made me comparatively slower (my small ring being smaller than theirs). Our emergent strategy of whomever was fastest hanging around at the top for the others was a good pragmatic way to deal with it.

I made a conscious effort to ride on the bar tops all day, hoping that this would avoid the back and neck ache I had for days after my previous attempt; it seems to have worked. On the day I had some minor complaints from my shoulder muscles but particularly severe or long-lasting. The only physical consequences are a slightly sore bum, which I only noticed when I sat on the saddle the next morning, and sunburnt arms which are a consequence of inadequate planning.

I think my training was reasonably effective; I have learnt a lesson from my dehydration adventure: in the future I will add in some 5-6 hour practise rides to get the habit of effective hydration. The turbo trainer was invaluable training for the long hills; I engaged a gear which made it feel like the level of resistance I get from the trainer and knew that I would be able to maintain that level of effort near-indefinitely.

In addition to the completion certificate I also bought the finisher’s badge:

And of course I have my completed check card; the most meaningful souvenir:

And here’s the back of the check card (only interesting because of my entry number):

How do you ride a bike? Part 1

Phil — Wed, 08 May 2013 07:24:34 +0000

Yesterday I began to teach Cerys how to ride a bicycle. I was not confident that I could do this, so I did a lot of research and planning instead of just winging it. Cerys is blogging about this as well, and her opinion of how it is going is obviously much more important than mine.

Cerys has attempted to ride before as a child and an adolescent but never really managed it. She put the blame on bikes not fitting her well, so the first port of call was to get a bike which does fit her well. We went to Chainey’s Cycles in Shenley Church End and, in stark contrast to what recent issues of Rouleur had led me to expect when taking a lady to the average bike shop, they were quite happy to ignore me and talk to Cerys about what she needed.

The end result is that we spent about £400 on a Giant ‘hybrid’ bike. This is a lot more than we could have spent, on a BSO from Halfords for example, but it will continue to be usefully rideable for many years whereas a BSO would have become useless almost immediately.

Before the first lesson I removed the pedals and set the saddle as low as it can go; effectively changing it from a bike into a balance bike.

Lesson 1

For this lesson we needed a gentle grassy slope over smooth ground. The aim was to give Cerys confidence that she could balance herself on the bicycle while moving, control her speed with the brakes and safely come to a halt without falling over.

We had discussed the principles of bicycle braking before going out with the bike: it is important to brace your bodyweight against the handlebars when braking so that you don’t slide forwards and fall off the front; and it is more pleasant if you apply the brakes smoothly. The latter principle is fairly obvious once you start doing it, and since smoothness is a matter of practice it was probably not worth mentioning in advance.

The first lesson’s objective was for Cerys to be able to roll down the slope with both feet off the ground, control her direction and speed, and end by coming to a smoothly controlled halt putting only one foot on the ground. To prove she was controlling the halt she would say in advance which foot she was planning to ground when she stopped.

Initially she had a lot of trouble; I had not inspected the sloped adequately and about 2/3 of the way down there was a concealed drainage channel which was causing the bike to violently jerk left or right as it was crossed. Obviously that’s the kind of hazard which has to be dealt with at some point but it was an unwelcome intrusion for an absolute beginner. I like to think I have good bike-handling skills and I had trouble staying upright crossing that bump with no pedals. We relocated to a smoother section of the slope and the situation improved significantly.

We still had a few falling-off moments, but they rapidly reduced in magnitude and frequency. I think there was probably about 1 hour and maybe 30 runs down the hill between the initial “roll 2 metres then fall off” and the complete control we were looking for at the end.

For lesson 2, later today, we will relocate to a longer slope and practice these skills a bit more before adding steering and pedalling. I need to do some more research to find out which of pedalling and steering should come first; I would like the answer to be steering but as I ride I think most of the weight-shifting required to steer comes from bracing the legs against the pedals. Probably therefore pedalling has to be first, but there is always a chance that I have been doing it wrong myself all these years.

Puerto

Phil — Wed, 01 May 2013 20:39:44 +0000

As you can read elsewhere on the internet, the trial of Dr Eufemiano Fuentes ended this week. More eagerly anticipated than the verdict was the Judge’s ruling on whether WADA and friends may inspect the blood bags found during the Operation Puerto raids to find out to which athletes they belonged so that they can be outed and punished. The Judge has ruled that the bags must be destroyed.

There is word of an appeal from WADA, but I doubt it can succeed without a change in strategy. Doctor-patient confidentiality is a big deal in any civilised country and no court is going to rule that you can break it without an adequate reason. Obviously this does not apply to the athletes who testified in the case because they volunteered to waive their right to confidentiality.

There is, happily, another way. Fuentes has already been found guilty of the crime of endangering the public health by infusing badly stored blood into people. There is therefore, without introducing any new law or facts, an excellent reason for a court to rule that the names of the others he “treated” should be disclosed: wherever they now are, they must be prevented from donating blood to protect the public health.

Of course WADA can’t ask for this because it isn’t their business. SNS, however, can. Other nation’s health services could also file on the same basis as his clientele came from all over the world. Of course any reasonable system of jurisprudence, such as Spain’s, is going to require the names are used for no purpose beyond protecting the public health before handing the list over.

I imagine that whatever the assurances and protections it would be impossible to keep the list secret from WADA & co once it had been made: someone somewhere would leak it to them. They would never be able to use it as evidence, but it would give them some pointers as to who is worth taking a longer look at. A few conversations of the “we know: confess and tell us everything you know and you’ll only get the minimum ban” nature might unlock a lot of other information.

This near-inevitability of a leak is of course the best argument against allowing health services to have access to the names of Fuentes’ clients; the court would have to decide whether, under prevailing Spanish law, the privacy of athletes outweighs the protection of the public. It would be a reasonable outcome if they ruled that they could only hand over the names of those for whom doping was a crime in their home country at the time.

Power Games

Phil — Wed, 24 Apr 2013 20:28:45 +0000

Ask any follower of cycling what the latest must-have gadget is and they are likely to mention some kind of power meter. As a cyclist who is keen to improve I wanted to understand how they work and how they could possibly help me.

The latter question is simpler to answer, so I shall address it first. The point of a power meter is that it gives you a way to rapidly determine if your training is taking you in the right direction and to quantify to what extent you have progressed. It will not of itself make you faster, unless of course you were planning to carry the cash you have now spent on it while riding.

There are of course cheaper methods to determine if your training is working, such as timing how long it takes you to ride a predetermined route. Unfortunately this (and most similar methods) are very sensitive to the weather and other external factors. To see what I mean, play around on bikecalculator.com and you will find that if you add a very light 5 kph headwind to the initial calculation you have to raise the rider’s power from 150W to 195W to maintain the same speed: a huge difference in power to overcome a minuscule breeze you might not even notice. Sadly you can’t entirely solve this by riding in a loop: the same parameters with a 5kph tailwind require 112W so you would still need to raise your average from 150W to 153.5W; only 2% more, but still not nothing. Ambient temperature, air pressure, tyre condition, tyre inflation pressure, clothing: all these things will likely have a larger effect on your time from one week to the next than changes in your fitness.

One way of riding which does not have many of these problems, because it takes aerodynamics out of the equation entirely, is to time how long it takes to ride a set distance on a static turbo trainer. It is, however, very boring and quite unlike real riding; on the turbo trainer I find it difficult to keep my hands on the handlebars and instead tend to sit more vertically. It is very likely that my performance in these conditions is only vaguely related to my performance when my hands are on the bars.

Of course a significant advantage of the real-world-timing methods is that they inherently take into account the effect of changes in your weight. The turbo-trainer will not do this, and nor will any of the power meters.

Now, let’s survey the various ways to estimate and/or measure power and how they work.

Low-end turbo-trainer

If you have a turbo-trainer already you may be able to find its resistance curve versus speed described online. From this you can calculate a curve mapping indicated speeds to the power outputs required to achieve them. The formula for my Cyclops Fluid², for speeds in miles per hour, is estimated by someone on the internet as:

Power = 0.0115 * speed³ – 0.0137 * speed² + 8.9788 * speed

Others on the Internet suggest, with good evidence, that there is a variance of at least 50W depending on how well-inflated your tyre is and how tightly you have pressed the trainer to the tyre, and that the resistance increases after about 5 minutes once the fluid in the trainer has warmed-up. This means the numbers I can calculate are shaky at best, but should be comparable to each other as long as I warm up for 5 minutes first (which I always do), keep the tyre well-inflated and the turbo cam in the same place.

The obvious advantage of this is that you only need your existing turbo trainer, wheel-speed sensor, spreadsheet program, and a formula that with any luck someone on an internet forum has already worked out. The other big advantage is that what you are measuring is analogous to the power delivered to the road: if you improve your pedalling technique so that your upward-moving foot is providing less opposition to your downward-moving foot you will see that in your numbers.

The disadvantages are that it takes an amount of effort to work the number out, you have to do it after riding so you don’t get live data, your numbers should be comparable to each other but they cannot be compared to anyone else’s numbers, and it doesn’t give you a way to ride to a target power at an event. Also riding on the turbo trainer is a bit boring.

Net cost (for me): £0.00 + time.

High-end turbo-trainer

Some more expensive turbo-trainers have built-in power-measurement features which are a lot more accurate than the DIY method above. These generally have an electric brake to supply the counter-force to the wheel rotation and can therefore get a very accurate measure of the power you are outputting by measuring how much power needs to be supplied to the system which counteracts it, then factoring in the power-efficiency of that system. They typically also have links to a PC and provide virtual rides for you to go on which make using the turbo trainer more enjoyable.

This has all the advantages of the previous method, to which you can add live power readout & the VR features.

The main disadvantage carried forward is that it doesn’t give you a way to ride to a target power at an event.

Net cost (for me): £1000.00 or so.

Hub power meter

Hub power meters like the CycleOps PowerTap work by measuring the strain on the rear hub as it conveys torque from the drivetrain to the wheel via the spokes.

One advantage of this is that you can fit your power-sensing wheel to any bike you have, so if you want to ride to a given power output at an event you can do so quite easily. It also removes the tyre condition and its inflation pressure from the variables affecting the measured power: the only things left are losses in the chain links and drivetrain bearings, and these are less likely to vary hugely week-to-week. As with the turbo-trainer methods you will naturally see any improvement in technique as an improvement in power.

The biggest advantage is that you can go and ride anywhere you like, you are not limited to your garage or living room as you are with a turbo trainer.

Net cost (for me): £1000.00 or so.

Crank-spider power meter

Crank-spider power meters like the SRM and Quarq work by measuring the strain on the “spider” which transfers torque to the chainrings.

Compared to the turbo-trainers these are more portable: you can ride them outside. Compared to the hub power meters they are less portable. If you have more than one bike it is a massive pain to move the cranksets between them; and that presumes that they have the same bottom bracket so that it is possible. On the other hand, if you have one bike and multiple sets of wheels for various conditions then the crank-based systems will be considerably more convenient.

The advantage of this style of system is that it limits the potential sources of variable losses to the bearings in the pedals and the bottom bracket, neither of which are likely to change significantly from ride-to-ride when compared to the chain links or the rear-tyre condition.

The disadvantages are that it is much more difficult to move from bike-to-bike than the other systems and it is strongly tied to your choice of chainring tooth-counts; if your power meter is 39/53 and you want to ride a given course with 34/50 you will be doing so with no power meter. They also cost a lot, although if you are building a bike from scratch you can deduct the cost of the non-power-meter chainset you would otherwise have needed.

Net cost (for me): £1500.00 or so.

Crank-arm power meter

Crank arm power meters like the StageONE work by measuring the strain on one or both of the crank arms. The mechanisms we have looked at so far are at points in the drivetrain where the action of both of your legs have been mechanically combined, so if your pedalling technique has your upward-moving foot opposing the force of your driving foot you will see that as reduced power. Unfortunately, if you measure this in a naïve way with a crank-arm strain gauge it will show up as increased power. For this reason I am skeptical about the accuracy, and therefore usefulness, of any of single-crank-arm power meter.

The main advantage of a single-arm system when compared to a crank-spider system is that only the non-drive side crank arm needs to be replaced, which does not affect the rider’s choice of wheels, pedals or chainrings at all.

A two-arm-measuring system gives you the same combined power number as a crank-spider system, although the sides are combined in software not mechanically. The advantage is that pedal technique defects can be directly detected and highlighted: a significant benefit? Perhaps. The disadvantages are the same as for crank-spider strain gauges.

Net cost (for me): £1500.00 or so (two side).

Pedal axle power meter

Pedal axle power meters work by measuring the strain on the pedal axles. The systems I have seen measure both pedal axles; a single-axle system could be made but would obviously have the same problems as a single-crank-arm system.

Provided that a pedal axle power meter for your preferred type of pedals is available, these systems are much more attractive than crank-arm or -spider systems. It is easy to transfer pedals from one bike to another (although not as easy as switching a wheel) and it does not in any way limit your chainring or wheel choices.

The other advantages of the two-crank-arm systems are also available in these systems.

Net cost (for me): £1500.00, plus I have to switch to Look pedals which I don’t want to do.

Conclusions

Right now I would favour getting a rear-hub power meter from eBay, if I were to do anything. Fancy turbo trainer is a strong second because making it less boring to ride in the garage for hours at a time is an excellent side effect. For the future I think pedal axle meters are the most promising.

Pebble Watch Bike Mount

Phil — Sat, 20 Apr 2013 11:16:05 +0000

I cycle quite a lot, and I always carry my iPhone: not merely in case I need to call a ride home after a severe mechanical failure, but also for GPS navigation and to harvest data about my heartrate, pedal cadence and wheel speed. I think my Pebble watch has the potential to significantly enhance this setup.

The iPhone battery doesn’t last very long if I have the screen on with the brightness turned up all the time, so I can’t have the phone’s data accessible to me at all times: I have to stop cycling and fiddle with the phone if I want to look at the maps it contains or see what my heartrate/speed/cadence numbers look like. In practice this means I only look at the phone when I am aware that I am lost; this wastes a lot of time because I have often been lost for quite a long time before becoming aware of it. It also means that I can’t train to heartrate zones or use the cadence data to inform my gear selection on climbs.

My Pebble watch gives me a potential way around this: because its screen doesn’t need to be backlit and consumes minimal power unless it is being updated it can display everything I am interested in without consuming its battery or the iPhone’s battery.

There are two things which need to exist to make this a reality: a mechanism to get the data I want from my iPhone displayed on my Pebble and a mechanism to attach the Pebble to my bike where I can see it easily. For the former I have to wait until the Pebble guys open up their API to third-party developers, although I can already start using the preview watchface SDK to work on what the data display will look like.

However, I can build the bike-attachment mechanism now. I decided to design a mount to attach it in the stem area because the handlebars are a busy place on a road bike: I need most of the space for my hands and the small central area is (a) tapered and (b) significantly interfered-with by cables.

An interesting innovation I first saw on this iPhone mount on Shapeways is to replace the headset top cap; I like the idea of mounting the watch above the steerer tube because it means the strap can lie along the top of the stem where it can be tied down out of the wind with a velcro strap. I didn’t want to replace the top cap because it loaded in a complex way and its integrity is relatively important.

I therefore designed my Pebble mount to replace the topmost 5mm spacer in my headset stack. You can have a look at my 5mm spacer-replacement bike mount for Pebble watch on Shapeways, and as soon as I have received my order and validated it I will make it available for sale. Of course if it fails to work in some way I will be redesigning it instead.

Pebble watch

Phil — Wed, 17 Apr 2013 20:05:49 +0000

I got my first delivery of Pebble watches this morning; this batch is already sold except for one which is slated for our development purposes. Unfortunately the development opportunities are slightly limited because the current SDK does not yet allow for communication with apps on the iPhone.

However, I thought it would be a good idea to build something with the current SDK. This afternoon therefore I wrote a new watchface which rather than telling the time generates a new insult each minute. Every minute’s insult is unique so if you manage to memorise all the insults you can indeed use it to tell the time.

You can download it from this link, perhaps.

Snowboard Art

Phil — Sun, 31 Mar 2013 19:11:54 +0000

Cerys and I bought a blank snowboard each and have been painting them for the last few weeks. I finished mine last night and lacquered it this morning. Here is what it looks like, click to go to DeviantArt where there is a higher-resolution version available:

Campangolo Zonda Wheels: Good

Phil — Sat, 30 Mar 2013 12:00:05 +0000

As I mentioned in an earlier post, I bought a secondhand set of Campagnolo Zonda wheels from eBay with the intent of using them for special occasions and continuing to train on my existing wheels.

Of course, in order to determine whether this plan is good, I needed to ride the Zonda wheels in a training session to compare them to my existing wheels. I did that this morning, so I can now be sure that I know what they are like to ride.

They are more stiff than my newly-retensioned 3-cross regular wheels, despite having far fewer spokes. The bike feels really stable whether I’m in the saddle or out of it; and accelerations feel more immediate. The difference is not huge but it is noticeable. I expected them to feel indistinguishable on a short ride but that I would reap significant benefits from the reduced weight and reduced aerodynamic drag after a few hours in the saddle on a long randonnée. To get a better feeling of liveliness as well is a nice bonus.

I had problems when I first fit them because the braking surfaces on the Zondas are a little further apart than they are on the Open Pros, so the wheels were locked until I loosened the brake cables a little. I will see how the brakes are when I swap them back tomorrow: hopefully I can find a place where both are OK.

The plan to use the Zondas for special occasions and my other wheels for training seems very sensible. If I ever need another wheelset I will definitely be looking at Campagnolo’s lineup.