SKS RaceBlade Long and 650c wheels: Mission Impossible?

UPDATE early 2016: SKS have updated the retaining clip design (good), but fundamentally the stays and mounts are the same. So there's no reason to think this hack wouldn't work on the 2016 model. Here's my in-depth review of the new model: http://road.cc/content/review/181061-sks-raceblade-long-mudguard-set
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As a low-cost foray into road cycling my wife recently purchased a B'twin Triban 3 roadbike from Decathlon - a huge French sports retailer. These £299 carbon-forked aluminium roadbikes with Shimano Sora/2300 components are highly rated as winter trainer or commuter bikes, as they cost not much and do pretty much what you need. Reviews are unanimously positive - no, this isn't a full-carbon Ultegra + Zipp 303 rocketship, but then again it cost less than one shifter or wheel on a posh racer.



It always was our intention to put mudguards on, and the SKS RaceBlade Long was the guard of choice - easily removable, light, robust and good-looking, and can be fitted to bikes without mudguard mounts too, using the quick-release skewer to hold them in place. Reviews are pretty positive too. So £44.95 later the box arrived, and all looked good.

(If you are already convinced, please click here to buy from Wiggle. I get 4% to spend on cheese, bikeparts and beer, the rest foolishly)

Now the accepted wisdom of fitting SKS guards seems to be:

1. Read instructions
2. Read instructions again
3. Discard instructions, make large mug of Yorkshire* tea
5. Get On With It

and I fully concur. So off we go Trev...



...except we ran into a *minor* snag. You see, unbeknownst to us, and certainly not mentioned anywhere on the Decathlon website is the fact that apparently frame sizes below 54cm come with 650c wheels, smaller than the standard 700c ones SKS make the RaceBlade Long to fit. A perfectly acceptable thing to do, as 700c wheels on tiny frames is just silly. It would have been nice to know, however, to ensure spare tyres and tubes were to hand. At this point it was a good thing the children were in bed, as there was some colourful language used.


A quick Google confirmed that apparently no-one on earth makes removable 650c mudguards. So in true No. 8 wire spirit, and with much spousal scepticisim, the Fettling began.

What was obvious was that the stainless steel stays were far too long. No amount of bodging was going to change this fact, so they had to be cut down in a way that didn't compromise the rigidity of the guard or profile against the tyre. Knowing that Mrs GâteauVélo would be insufferable if this lack of Fettliness was allowed to stand, a plan was hatched...

Measure, measure and measure again

 As every bike's mudguard mount location and fork rake differ, there is no perfect calculation to make here. So you have to measure up against the guard on your bike, to get the correct length to cut the mudguard stays to.

Step 1: Leave the stays off the mudguard, and fix the whole setup to the bike as per instructions. Make sure the stays are slid all the way down inside the black plastic endcaps that attach to the quick-release tabs - there is a small Allen screw that locks them in place, so loosen it first to make sure the stays are all the way in. Here you can see the depth of the stay inside the endcap.  Make sure you have the maximum inserted.

Attach the under-brake mounts and get them all lined up nicely, clipping the mudguard into the under-brake mount. Basically what you have done is fitted the mudguard, but not slipped the stays over it so it can flop against the tyre.

Step 2: Lift the mudguard off the tyre to the desired clearance. Stuff some rags in between, folded over to give the right thickness.

Step 3: Take a caliper or ruler, and measure the gap between the top of the mudguard and the BOTTOM of the black plastic stay bridge. This gives you the distance the stays need to shorten by to correctly space the guard from the tyre. In this case, 55mm.

Step 4: Remove the steel stays from their plastic endcaps, and measure along them by the required distance - in our case 55mm. Note this needs doing in two parts as the stay is bent - if you measure direct from the tip you are 'cutting the corner' and will be cutting it too short, which is very bad. I cannot emphasise enough getting this right - if you cut too short then you have just ruined £45 worth of mudguards. Use a pair of pliers to mark the point.


Choppy Choppy

Step 5: NOTE: do this step for just one side of one stay first. Take deep breath and cut the stay. As this is very high quality stainless steel, normal pliers probably won't do the job - use either a high TPI hacksaw or a set of specific cutters (these ones date from 1948, bah gum).

Step 6: Using a vice, get an un-cut stay as a guide and bend the newly-cut one to match, in the same direction it will need to sit into the endcap. Do not try to bend it in the endcap - they are not strong plastic and the force needed to bend is considerable.

Step 7: Take your newly-cut-down stay and slide it onto the mudguard, into the correct position, 1/3 of the distance between brake and rear. Re-insert it into the plastic endcap. Check your handiwork (leave the other side out of the plastic cap for now). If there is a God in Heaven your mudguard should now be correctly spaced from the tyre, with some adjustment room left in the endcap if needed. If correct, now measure and cut the other side of the stay the same length. If you have measured correctly but need a bit less clearance, just cut down the stay a few more mm or whatever. If you have cut the stay too short and there isn't enough adjustment in the plastic endcap to hold it securely, re-read Steps 2-5, collect credit card and off to eBay with you. Do not pass Wife.

Step 8: If all is good with the 'top' stay closest to the brake, now repeat process for the 'bottom' stay furthest away.

Step 9. Make another mug of Yorkshire tea. Do all over again for front wheel.

And Voilå! You now have a rock-solid set of removable guards on a 650c wheelset. These guards are easily strong enough to pick the bike up with, don't rub at all even under heavy pedaling/cornering, and unclip / refit in a few seconds each. A bonus in putting a 700c guard on a 650c wheel is that the guard extends even lower down the back of the wheel, offering even more protection from water/crud.

With guards removed - not too shabby.

If you want to buy a set of Raceblade Long guards, your LBS should be able to oblige. If you intend to purchase online, please click here to go to Wiggle's online store - I'll get a whopping 4% of your purchase, and this will of course be spent wisely on beer, cheese and bike parts.





* don't ask me why it has to be Yorkshire tea. Just trust me. Any subsequent tendency to suck your teeth, say 'eee lad' or stroke a whippet is entirely a personal issue.

The Power of Strava. And Fudge.

Yesterday I had a full VO2Max and blood lactate threshold test done at Winchester Uni, as part of a critical power research program I'm a lab rat for (full article to follow). It said my threshold for blood lactate is around 240W 226W. This is on a £35k SRM bike with a darned fancy blood analyser thingy and a blood sample being taken every 3 minutes as the power increased.

Going back over my 'baseline' 1hr / 30km Strava segment that I do maybe twice a month, Strava has consistently pegged me at between 230 and 240W over the hour, over the last 6 months rides. It's a ride I do as fast as possible, and I've got a good feel now for how hard I can go initially on the flat without blowing up 40 minutes in on the hills.

 Brace yourself, Marsha:

One correlation pointed out in the below article is that sticking to 65-75% of maimum heart rate is typically the lactate threshold (LT) that you can sit on pretty much all day. For these rides where I've logged 230-240W, my HR has hovered around 160, or around 85% of my Max HR. Noting that for this particular ride, Strava had it at 872KJ burnt, whereas the Suunto HRM said 768. I'd probably be inclined to believe the HRM over the Strava estimate based on a GPS track, as Strava can't account for wind, tyre pressure, bike aero-ness or weight, wheel efficiency etc.

So if Suunto's energy consumed measurement is accurate, then you'd expect that real-world average power would be a bit less - maybe 10%. But if the HRM's 85% is accurate (which I believe it is), that one hour rate of work must be above my LT. (This is possible - I could try doing two laps and see if I can maintain the 30kph average. One for better weather methinks).

BUT, I know from experience in adventure races that I can go at an average of 150BPM or ~80% for four to eight hours without blowing up

***
UPDATE: James the PhD advised that on closer analysis of the lactate curve, the LT figure is more like 226W, not 240W. Which almost perfectly correlates with the Strava 1hr data. I doubt very much I'd be able to do another lap at that speed, so it's probably a shade over or right on my LT. So the lower HR average of 150 for day-long races would reflect the real LT of 226W. Hover just under that and go all day if you keep the flapjacks and water coming. So it looks like my above guess that 85% or 240W is indeed above my LT, and I'd be asking for cramped-up-in-a-ditch-vomiting trouble trying to sit on 85%. So Strava is most likely reading a bit under in terms of power / over in terms of KJ consumption, but close. And Suunto HRM's are pretty much spot on. Thinking more on this, these historic 1hr laps were done on a Cyclocross bike with around 80PSI knobbly CX tyres on - certainly a world away from 115PSI road slicks, and no doubt not what your average Strava-ite would be seen dead wearing. Having just fitted some decent slick rubber I should get out there and start collecting some new data, I'd expect Strava to come more into line with reality, all things considered.
***

Hmmm...fudge....

Clearly there's a ton of fudge involved comparing all these various fruits. But overall, for a *free* app that only needs a phone, Strava is pretty good at power estimation. This is potentially invaluable info, and if I had a HRM that could show accurate average power (or a correlating metric) I'd definitely use it on long rides to ensure I was staying away from The Wall. Maybe I'll continue to stick with aiming for an 80% average HR.

Or maybe I need one of these.


No, dammit, I definitely need one.


Question is, which kidney to sell?


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Here's an excellent, reasonably-understandable article on Glycogen, Glucose and Lactic Acid, and how they relate. While it's running-centric, the same mechanisms apply. I was surprised to read that 'Hitting The Wall' isn't a lack of Glycogen in the muscle, rather the effects of the buildup of Lactic Acid . I was also surprised that after 1hr of running your body gets 3 times the energy from burning fat as from muscle glycogen or blood Glucose. Those long, slow miles really are the best for loosing fat.

"Above the anaerobic threshold, the volume of carbon dioxide production exceeds the volume of oxygen consumption. The removal of carbon dioxide (through exhalation) can no longer maintain blood acidity within reasonable limits. The rapidly rising hydrogen ion concentration and falling blood pH cause the fatigue and cramping we know as the Wall. Labored breathing is a sure sign of this process, and therefore monitoring it will help you determine how close you are to the threshold. For average marathoners, running at about 65% but perhaps up to 75 % of your maximal heart rate will keep you just below the threshold. This is how you avoid hitting the Wall."

Teaching children to ride (or: 'Why trainer wheels are the devil's accessory')

If you have a child, chances are they will want to ride a bike. Children rate cycling only second to swimming as a fun thing to do.

The traditional way to teach a child to ride is to buy them a small bike, slap trainer wheels on it, and then watch them fall off the very tippy tricycle you just made them until they grow past the counter-intuitive physics setup you put them into.

Let me explain: When you turn a corner on a bike, you lean inwards. A tricycle cannot lean. If you try to lean on a tricycle, you end up on two wheels. As a bike fitted with trainer wheels gets its drive from the rear bike wheel, leaning lifts the wheel off the ground, so the child's legs then spin forward quickly and unexpectedly as traction is lost. A typical tricycle has the wheels equi-distant. It is a 'perfect triangle', and therefore very stable.

A bike with trainer wheels is anything but stable. The trainer wheels are relatively close together compared to the distance to the front wheel, making for an isosceles triangle that is very easy to tip side-to-side.

Usually a child with trainer wheels puts pressure on the wheel arms so much that they bend upward. This then allows them to corner correctly - until the lean over too far, the trainer wheel contacts the ground, the rear bike wheel lifts and carnage usually ensues.

All this delays the child's ability to cycle freely, sometimes by years. Seriously. There are 5- and 6-year-olds out there on trainer wheels who could have been cycling at 3 or 4.

So what's the answer? How to tech your child to balance in a way that doesn't kill your back and gives them the sense of independence and freedom to let their brain focus on the bike? A stick.

There are many types of stick - from a broomstick right up to custom-built multi-pound ones made form space-age steel or aluminium. Fellow Kiwi Gary Moller wrote an excellent how-to guide on the subject years ago - here's a photo from the eBook:

But if DIY isn't your thing, there are commercial alternatives now available all over the place: just Google on ' balance handle child bike ' and a whole range come up to suit different budgets, taste and bike design. All these contraptions do the same thing: connect an adult's hand to the bike, at a comfortable height.

Once fitted, it's as easy as walking or jogging behind your child. You'll both know when it's time to let go.