No pressure.

25 09 2015

A recent mtbr thread (I know, I know…) got me thinking…

Here is my input on a thread about ‘plus’ tyres…

“So I got to thinking about this a bit more. I dont know too much about the physics, but I do know I like the combination of a higher volume tyre at lower pressure for my relatively low speed, reasonable tech riding on a hardtail or rigid bike.

Why is that?

Considerations for tyres (and/or wheels):

Rolling resistance
Puncture resistance
Rim durability

My thoughts:

a) Lower pressure = more comfort given the same casing construction

b) A bigger volume tyre feels similar to a small volume tyre at less pressure (pounds per square inch…I guess it is self explanatory) given similar casing

c) Less aggressive tread gives less rolling resistance given the same casing construction and size (I don’t know how true, but for rolling resistance of pick up truck tyres, 60-70% is often associated with the tread design)

d) Increased hysteresis can lead to increased rolling resistance (‘tacky’ DH tyres anyone?)

e) Increased hysteresis gives more traction (‘tacky’ DH tyres anyone?)

f) Less tyre pressure is unlikely to make you slower (increase rolling reistance) given the range that is realistic for bikes. It is also, probably, unlikely to make you faster if considered in isolation

g) Bigger volume tyres create a bigger foot print in general, though pressure and casing design affects this

h) Bigger foot print is associated with more traction

i) Lower pressure tyres can lead to pinch flats with tubes, and rim strikes

j) Casing design can be beefed up (specifically on the sidewall) to mitigate this, but then the tyre becomes less supple – see hysteresis

k) Casing design can reduce or promote sidewall wear and piercing type puncture risk

So: a bigger tyre volume, with a lower pressure, and less aggressive tread might provide similar or better traction than a smaller, narrower tyre.

It might roll at the same speed (or perhaps faster if the tread allows) and it might be more comfortable.

If it is made well – with good quality casing – it might not wear fast or be at risk from punctures and it might not be too heavy.

Given the whole light strong cheap triumvirate, it is unlikely to be inexpensive.

Depending on how you load the tyre this may be a *good thing*. If it is more likely to flop around on the rim (too narrow a rim, or just high bulbosity) and is used in a high speed/direction changing terrain, it might feel more vague. This is probably why enduro racers/DHers are using no more than 2.5” tyres I suspect.

I guess that, in a nutshell, is why I like ’em?

Now – I am no expert – this was purely typed as a vague self assessment. I’d love to hear if anyone else has any thoughts on all this.”


Treading lightly.

13 09 2015

The irony wasn’t lost on me. I had literally just finished writing a piece for The Ride Journal, which – in part – touches on how seldom the weather is ideal for big rides in Scotland, when BAM! the weather was ideal for a big ride.

Often, when I run to the hills, I run to the Cairngorm and it was thus as I rolled the pedals, early in the morning, up the ski road towards Cairn Lochain and the edge of the Northern Corries. I had never ridden this section and I wanted to do so, go over Cairngorm itself and look at the various ridge line descents, as well as the new trail that has been dropped to Loch Avon.

The climb was particularly interesting because I was on the fat bike. The low pressure and large foot print allowed me to make many of the steppy-rock sections I had never cleared before and as I rolled towards the March Burn, I was nowhere near as fatigued as I have been previously.

I decided to avoid the climb to Cairn Lochain. I wanted to take the trail from Lochan Buidhe around Coire Domhain and then make my way up Stob Coire an t’Sneachda, the first Munro of the day.

The views opened up as I climbed the loose trail and there were many walkers who were basking in the sunshine. I had replenished my water at one of the wee streams that drains in to Coire Domhain but I had misjudged the strength of the sun for the day and forgotten to apply sun screen. I knew I needed to keep moving rather than soak up the UV.

The descent from Stob Coire an t’Sneachda was tremendous: slow, steppy, technical and at times risky. The adrenalin flowed as I came around the top of Aladdin’s Couloir. There is a descent directly down from here, but it was rough and very loose and also a bit early in the day to be heading down. Another time.

Instead, I took a look down Coire Raibeirt at the (improved?) new trail that eventually drops to the north side of Loch Avon. Part of a future project, there can only be a couple of hundred meters of tough elevation gain and this opens up the Etchachan descent to a smaller loop – missing Lairig an Laoigh, the sometimes boggy Feshie, or (shudder) the Lairig Ghru. More on this later. You can just see, in the photo above, the trail as it drops, steeply, to the Loch Edge.

After regaining the corries’ edge, I climbed up Cairngorm itself – the second of the days Munros and broke out the map, looking for a way to descend into Coire na Ciste. In the end I wasn’t confident that I would find a worthwhile way down so I took the slabby, rock armoured trail for walkers which was … interesting, then dropped off the far end of the Bathaich Fionndag car park into the bottom of Coire na Ciste and made it down to Glenmore Lodge purely on account of the wide tyres – it is a boggy route in places!

It was a great day.

HED ~ what’s the Big Deal ?

9 09 2015

About a month and a half ago, I broke a HED Big Deal rim. It was the rear wheel and it broke while I was riding on rocky terrain on the East Coast of the USA. I had about 8 hours of riding on the wheel in total, which was shod with a tube and a Maxxis Mammoth 4″ tyre at 9psi. For the record, I weigh 88kg and I don’t believe I am a clumsy rider.

Whilst descending a sweet singletrack, near Frederick’s Watershed, on rocky but not sharp edged terrain – think smooth, rounded rock – a loud crack announced a rim break. The rim edge basically frayed apart for 2.5-3cm circumferentially and there was a crack into the flat area of the rim, around 1cm. The tyre wasn’t punctured and I would admit I felt it was pretty bad luck as I was still feeling my way to full speed on the bike (which was new) and had not anticipated any particular risk. There is no real doubt in my mind this was caused by a rim strike.

To add some background to my experience – I have ridden extensively on 3 other brands and 5 sets of carbon rims on terrain accross europe and the USA for many years. I have had more rim strikes than I can count due to punctures or just hard impacts. I have had one rim delaminate, in a very minor way, which was replaced by the company in a responsible and timely fashion. I have had no significant rim damage from riding. All the rims in question have marks, scratches and signs of a happy and good life, but that is all.

On building the HED wheels (being from the UK, HED Big Deal rims are available separately, unbuilt, whereas in the USA they are only available built by HED) I was mesmerised not just by the lack of heft, but the unimaginably thin rim bead seat edge. In truth, I was half expecting the rims not to hold up to all trail conditions.

So – why was I riding rocky trail if I was potentially expecting a rim break? Well, HED’s assurances* that the rims were up to it was part and also I would add that I have spent years assessing bike parts not just for my own use but at times for public consumption through UK bike publications. I needed to see if these rims would hold up to back country scottish riding – the purpose of the bike they were mounted to.

The answer? no.

At the time, I was fairly sanguine about the break. I figured that given the previous assurances, publicly* and to several good and astute friends (including Sean at Vertigo Cycles), I would probably be able to replace the rim with a crash replacement – admitedly at what I believe to be 75% of cost – but at least I would then know the rims were only suitable for me on snow or buff trail in the future.

Well, it has been over a month now after HED have been contacted, repeatedly, sent pictures for assessment and I have had no response.

Personally, I find that unaceptable, regardless of the performance of the rim.

I am aware there are others – including riders I know in the UK – who have had no issues with the rims. That’s fine. For me, they would not inspire confidence in any situation where I was fully relying on them to get me home and the trail was even moderately rocky. Perhaps with wider tyres, >4″ so the edge was more protected? or perhaps with higher pressure this would not be the case, but then this requires stipulation by the company to allow the user to decide if they are buying the right product. There is always going to be a market for the lightest stuff, even if conditions of use are limited.

It is the lack of communication I find so disappointing.

So, I can count myself lucky that I can chalk this up to experience. I have repaired some carbon fibre parts in the past and will do so with this rim and continue to use it at times, out of curiosity, but I will also build another brand of carbon rim into a wheel for use where I believe the HED rim is not up to the job.

Of course, perhaps I have a rim that had a manufacturing defect – this happens, occasionally – but if HED are not interested then we will never know.

If you are looking at a set of HED Big Deal or BFD rims, I would self assess very clearly before buying them. They are expensive and may not hold up to general riding as advertised. If they dont, you may find yourself, like me, ignored.

A couple of last points:
As mentioned in the building post, I bought these rims from Sideways Cycles in Alsager. Tim is a good friend as well as one of the people whose knowledge and experience in the bike world I respect the most. He has tried untiringly to engage HED. I can only thank him for all the effort, above and beyond.
Sean broke his rear HED rim on the same ride, in the same way.

*at a couple of points I mention the fact HED publicly okayed the use of Big Deal rims in an unrestricted fashion. There was nothing equivocal about this. This is a post from HED’s instagram account.

Although it has proven reasonable to be skeptical, it remains the lack of communication that I find the most disappointing aspect.

Time sensitive.

4 09 2015

When did my life become so time sensitive? When? when? quick, quick, answer me!

Yeah, a bit like that. I’m going to keep this brief, because it might just cross the border and become a personal whinge. There is very little place in the world today – with all the trouble and strife, hate and hardship – for languishing in self-absorbed doldrums, but the issue of time sensitivity ranks high on societies’ ills, so I’m going to allow myself this small space to (briefly) talk about it.

You see, every task I take on these days has either to be done within a certain time scale or is pressured due to the potential worsening of outcomes tick by tock. I awake and start running (more or less) and from the opening of my eyes, everything has to be completed by a certain time or else something will be delayed and there be dragons. I eat my breakfast and drink my coffee while commuting and then there is the desperate rush to get all the days tasks done within the day. No time to dwell. No time to think, at least in any appreciably expansive way. By the time I am home, I am short on energy and frazzled due to the mental and emotional focus it takes to not make mistakes in a high-stakes poker game of a job and, by then, time is already marching on – I need to be asleep – I will be woken up soon and I need to be on my game tomorrow.

Even recreation has to fit between a predestined start and finish time, gone is the vast freedom youth and a lack of responsibility affords.

Of course, so much of this is pressure produced inside oneself. It is a response and a poor one at that. As a practitioner of mindfulness and a one time adherent of Taoism, I can sense this inexorable strangulation, the ratcheting up of pressure and expectation, but oddly, ironically, it takes time to break it down, time to breath slowly and stay in the here and now.

So, what to do, what to do….I will be honest, I have no answer. Perhaps I should stop filling the small gaps with needless things like clicking on social media. Perhaps I should learn to manage time better. Perhaps I should just suck it up buttercup, ’cause there are worse things.

Perhaps I should go ride my bike.

Who knows…