jmaccelari

I started off with "normal" (platform) pedals because I didn't like the idea of clipless ("click in") pedals. After my first race I went out and bought clipless pedals, cleats and MTB shoes. The ability to clip in to the bike is not just for allowing you to have a better pedal stroke (up and around as well as pushing down), but is a massive safety feature. The race I did had a long downhill section on grass tufts. Within 10 metres my feet were thrown off the pedals and I bulleted downhill in a state of absolute terror and totally out of control. If you do go clipless, do so before the race and make sure you have time to get comfortable with them, clipping in and out... jmaccelari2010-01-19 03:39:00

Being a Vaalie, I have never been there, but their mail order service is really efficient...

Does this Dave character drive a black X5? We were similarly "buzzed" by a maniac in such a vehicle two weeks ago (two of us riding in single file) who also hooted at us. I saw him repeating this to every group of cyclists ahead of us until he disappeared. He was also speeding at a horrific rate (hypocrite)...

If you ride MTB, road helps. If you ride road, MTB helps. I also do 2 x 8km jogs per week and am looking at starting Pilates to help with code strength.

Lovely dog! Of course - labbies are VERY intelligent and love rotational kinematics. Here's one for him...

Brilliant! I love the fixie/free wheel combo. How did you do it?

Whether it's on a bicycle, a motorbike or in a car, you'll always find some moron with a chip on his shoulder and looking for someone to take it out on...

Hello, my name is Jeremy and I have been tubeless for nearly 4 years now and wouldn't image going back...

I think this thread needs a conclusion (sorry GoLefty!!). eclipse posted a thread about carbon clinchers. Kiwi then posted "So a 100 grams saved at the rim will have a much bigger effect than a lighter frame for instance." Johan then laid into Kiwi: "This old old-wive's tale refuses to die. If you do the maths, and believe me, it is not difficult stuff, you'll see that this story is nonsense." Kiwi then presented Johan with a mathematical proof (go to page 1). Johan then tossed this out of the window (Newton turns in his grave): "One place where you should not take physics lessons is from bicycle company websites and from the back of bicycle product boxes." What Johan forgot to say was that you should take the physics if it is correct (even if you don't like it). Johan then went on to intimidate everyone by asking for data to plug into a formula (which remains secret to this day). Johan then goes off topic calculating power and asking irrelevant questions about times and so on - hoping people will lose interest and bugger off.. Everyone is suitably impressed and Johan stares the Hub down... Tumbleweed rolls across an empty street... I am then asked offline and unaware of the thread to investigate the topic. I look at a "generalised, ideal" wheel so I can prove the results for all wheels that have ever and will ever exist. I prove that the "old wive's tale" is true, albeit not a major factor. I post this in the Hub with full derivations, explanations and conclusions. Johan gets upset with me disproving comments like: "I've just shown you what a 200 gram difference makes. It doesn't matter whether that is from nipples at the hub or from carbon instead of aluminium at the perimeter." Accept it." He's wrong again... I tell him we can use simple maths to model the system and this will have the same result as the most tedious (not complex) numerical approximation (his tape & scale crap and thousands of measurement points). The numbers may be slightly off, but the conclusion stands. Back to obfuscation. I have proved he is wrong for every wheel in existence, but Johan is going to prove me wrong. Instead of arguing the original argument, he is going to show me how complex it really is. He has to give me the data because he is incapable of doing the maths himself (even though I gave him the formulae). I do some first level approximation for him, which will give a very good approximation and still proves that lighter wheels save more energy than a lighter frame. He is not happy. He then says my modelling isn't accurate enough. I say I don't care because no matter how accurate or inaccurate the modelling is, it won't make any difference to the basic conclusion. Johan then comes back with irrelevant nitty gritties and still refuses to accept that no matter how the wheel is modelled, his original attack on Kiwi's statement and subsequent proof are wrong. So now we wait... with baited (sic) breath... (The funny thing is, that from the things he has said, he seems to be using the same equations I am, but cannot interpret them on a universal level and just has to keep on plugging numbers in to prove the statement for each wheel. That's a lot of wheels to go through...) Oh. And on the way we amused, entertained and irritated a lot of people. Sorry eclipse, but I think Kiwi answered your question correctly on page 1... jmaccelari2010-01-10 11:44:29

Oh my gawd!!! So I WAS WRONG!!! Can I do a JB on this and continue haranguing you for 20 pages (so far) so you go away and I can pretend I was right?

OK - now that I've got it off my chest, let me try and explain to someone who is clearly on the wrong track. Read my lips: the actual figures do not matter. The concept remains the same no matter what hub/spoke/nipple configuration you throw at me. The physics is true for every wheel. Even (and you may have a problem getting this fact) - even the one in your hand. So to continue: The number of spokes doesn't matter. It just changes the final number a little little. The actual value of the final number does not matter. It does not change the basic physics. Nice guess' date=' but you overlook the fact that the spokes are longer than the internal radius of the rim minus the outer radius of the hub. This implies what? [/quote']No I didn't smart arse. You gave me the lengths. I assumed even you were capable of properly measuring a spoke length. BTW, since you can't even do the basic sums, I made and approximation that meant we could avoid using the parallel axis theorem (bet you haven't heard of that one, Mr Smartypants!). (The formula given is for when the spoke starts at the axle. We know it doesn't - it starts on the outside of the hub. Bet you didn't spot that one, hey?) This states that: I = 1/12 * m * L^2 + m * h^2 in our case h is 0.13 so we are out by 14% for the spokes (which means we are out by 0.2%. Wow! What are you going to prove with 0.2%? Why are you suddenly so concerned by 0.2% when your initial reaction was to throw 100% out of the window? It just changes the final number a little little. The actual value of the final number does not matter. It does not change the basic physics. I don't need to. As I have stated before it's a pointless exercise. I don't need to. As I have stated before it's a pointless exercise. I don't care what type of tyre it is. The equations don't care. This show just how pathetic your grasp of physics is. The tyre could be a tubbie' date=' tubular, MTB, road... The physics doesn't care. The physics holds true to all rotating bodies. We are talking about bicycle wheels, but it could be anything from a car's flywheel to a planet. You are obfuscating the issue by raising irrelevancies. Stop trying to shoot holes in the exact numbers (which you don't care about unless it suits you) and try to shoot a hole in my argument. I don't need to. This moronic insistence has been dealt with above. It just changes the final number a little little. The actual value of the final number does not matter. It does not change the basic physics. Not from me, because I respect them... jmaccelari2010-01-10 10:45:14

Johan - how can a guy like you be so dense? I gave you the figure. Give me any measurements and I'll generate another number. Use any number (or humungous, complex JB-ish hand holding numbers) you like. The physics ain't gonna change, boy. Now matter how much you'd like it to. I didn't formulate the equations. Some guys a lot more intelligent (and less childish) than you did. Are you now going to prove Newton wrong? What is your point? You're now just arguing for the sake of arguing. You were wrong to start off with. You blew your mouth off at Kiwi without understanding the issue and you're making a complete **** of yourself... Again - what is your point?

I have tried them on both MTB and road. MTB: useful and do provide a lot of protection. I have since gone tubeless and will state that that is the way to go if you can. Road: useless. I found the tyre liners eventually cut through through the tube due to the higher pressures road tyres are inflated to. More trouble than they are worth.

Schwalbe have discontinued them. Michelin are still making them. I suppose if you are looking for something to make your tyres more puncture resistant they might be worthwhile' date=' but there are other options (tubeless, slime tubes, ...) which might be "better". I can't answer "why" here - it's not something I can profess to have any knowledge or expertise of. I can only give my opinion and for me it looks like latex tubes aren't worth the benefit (they're probably also quite expensive?)... I suppose if you have a sub-6kg racing bike and are looking for somewhere to shave a couple more grams (and it's in the best place for energy saving - right on the extremity of a rotating mass) then they could be a good option! But I reckon they'd be a waste on my training bike. I'd rather buy some good Conti Gatorskins. The "other" thread has been really interesting, I must admit! It would be interesting for someone to get a couple and try them out.

Here's some nice info from Schwalbe: http://www.schwalbetires.com/tech_info/tire_tube My interpretation is that latex is more puncture resistant, but is a pain in the arse to use regularly... As for the rolling, I'll keep out of that one!

I think that Johan means the profile is not square, i.e. it's not just a simple drilled hole but one that has been bevelled to some extent to round the corners (or allow countersinking). The hole itself is still round! BTW, bits do exists to drill square (and pentagonal, hexagonal and other shaped) holes!!! http://demonstrations.wolfram.com/DrillingASquareHole/ They're based on something called a Reuleaux triangle... jmaccelari2010-01-10 02:59:20

Congratulations for the parent(s)!!! Mazel vot (as Jules would say...)

It makes no (zero) difference at a constant speed. The outer perimeter of the tyre has to do exactly the same speed as the bike when it touches the tar' date=' or else it would slip since it would be going either faster or slower than the bike. In normal riding, no slippage occurs so it must be travelling at the bike's translational velocity. Also the parts of the wheel at the rim have to all travel at the same speed or the wheel would be ripping itself apart (connected bits travelling at different speeds do not stay connected for long). This is true for each component at each radial distance (the angular velocity of all the bits everywhere in the wheel is the same, or the wheel rips apart). (The "confusion" here is that the reference frame you have chosen is the relative to tar one. It is correct that the relative velocity against the tar of the tyre at contact is zero, but it is twice the speed at the top - at the brakes. However, we cannot practically use this reference frame for investigating the rotational kinematics of the wheel. We could if we wanted to, but the equations would be horrifically complex - even to JB) (A way to illustrate this is that if we take a point on the rim, there is always a point directly opposite it travelling in the opposite direction, so the acceleration of these these two points as we see it in the cartesian reference frame "cancel" each other out - this is where the centrifugal and centripetal "forces" - known for this very reason as the "fictional forces" - come into play) (Mathematically, we say the angular velocity of the wheel at the contact point - tar - is: omega = v(trans) / r(contact) * sin(theta) Where in this case theta is the tangential angle (90deg), so sin(theta) is 1. You will note that when we have v(trans) we have omega. At no stage does this change and we have zero or twice the speed unless we are accelerating or decelerating the entire wheel in one piece) None. Zip. Zero. Nada. All energy at a constant speed goes into overcoming wind resistance, friction and potential energy (as well as powering your body). An aside: To do a "Bornmanism", I will ask - what is "beneficial"? To some it is an energy saving, but we have seen at least one person who is prepared to go for heavier wheels and use more energy, because he prefers the rolling smoothness (inertia) of his heavier wheels. There is a level of trade off and personal preference that comes into play. Of course, we would all notice a 1kg wheelset (Zipp 202s) versus a 3kg wheelset (el cheapo Pick 'n' Pay brand). But when we get to 200g, other factors become relatively more important. My tuppence. jmaccelari2010-01-10 00:24:50