psycholist

Best way to remember which way to turn BB and pedals is that if you're pedalling forward and the BB/pedal bearings seize it'll unscrew the BB/pedals - this is not the reason the thread direction was chosen, but it's a good rule to apply. On the chain side of the BB, unscrew clockwise, other side anticlockwise (Standard thread).

I'll probably drive across Ireland this weekend to meet 2 others of the 5 or 6 trials riders in this country and hit Dublin ... I ride well over 90% of my trials on my own though. I find that with riding trials on your own you progress more slowly, but what you learn to do, you learn really well. The other issue is if you like big, dangerous lines, you're a lot safer if there's a group out, but that's definitely not my thing. I cycle for the physical and psychological challenge rather than for the adrenaline or the social aspect of it. It doesn't matter of there's a crowd watching or I'm completely on my own, it's all about finding difficult lines and getting them just right for my own pleasure.

This should do the job: http://superstar.tibolts.co.uk/product_inf...;products_id=31 Same as the Echo branded one only it's 2/3 the price ...

There is the option of taking out a loan if you're sure the money will get paid to you. I'm not a fan of people being given easy credit and try to buy everything with money I have, but I've just had a class weekend riding trials in the sun - if I'd been without a bike I'd have been going nuts...

If the brake has gone silent but holds less that sounds a lot more like something has contaminated the rim (Like your oily fingers transferring everything to the new frame). Try cleaning/regrinding the rim and sanding the brake pads.

Great to hear you're progressing. Getting to the back wheel is a headwrecker at first - I spent a lot of time getting used to it (But I took probably 2 years to learn to wheelie and still can't manual or stoppie for any length of time after over a decade trying). Unless your bike is really short you won't be able to lift to the back wheel by just moving your weight back, you'll need to carry some momentum from loading the front wheel back. I reckon it's definitely easier at first to get to the back wheel from an endo without trying to use a pedal stroke (Once you get good you'll probably never go to back wheel from an endo again though - for the pedal push to work you need to already know where the balance point is). Mess with your weight position on the bike while on the back wheel too - you can be all the way from having the bars against your legs with the bike nearly vertical (With practice you can kiss the front wheel on most bikes from this position) or by hanging right back with the front wheel barely a foot off the ground. Those positions and everywhere between them are viable balance points, so get used to that range of movement.

Trying endo drops on a kerb unless it's a decent enough height is very difficult to get a feel for. Once you get used to endos though just try throwing your weight onto the front wheel while the back is in the air and throw your weight backwards, aiming to have the front wheel off the ground before the back wheel lands. The easiest way to get onto the back wheel isn't far off the technique for the endo drops. Roll forward slowly, lock the front wheel and endo, then move your weight backwards as the back wheel drops and hold onto the back break hard, pulling back on the handlebars as the back wheel hits the ground. This will lift the front wheel up and get you to the backhop position. You'll find you can only hop backwards first, but with a bit of practice you can move your weight and the bike forwards or backwards in the air to allow you to hop in any direction you like. Adding pedal kicks is the next step ...

Definitely need to see if you can find blue adjuster knobs for the brakes. Looks sorted though ...

Try pumping the lever while bleeding fluid through the system. I had to do this before my master cylinder would fill when I was bleeding this type of brake. Older Maguras don't need half this messing, so I had to bleed mine a second time, pumping the lever before they worked ...

Don't forget the Hayes stroker uses DOT fluid, so you might need to change out seals to make it compatible with HS33 pistons. Also, since it's a disk lever the piston will almost certainly be quite a bit smaller than the Magura lever. Potentially more power, but at the expense of lever sponginess and having to set the brake pads up really close to the rim (Think how far disk brake pads have to move before they hit the disk)... Another problem you may run into is that since the lever is for an open hydraulic system and the Magura pistons are for a closed system there will be no option to wind in the brake blocks as they wear and the first part of the lever travel won't move the pads in at all.

With a steel frame you could always try to get it nitrided. Same coating as you see on drill bits, so very tough. I had an XC frame finished this way years ago (when steel was still the dominant frame building material), didn't clean it for months and it still was shiny as new under the dirt when I wiped it with a rag. Also it was almost immune to the effects of cable rub too... I'm guessing it's hard to find people who do this to items as big as frames, but hopefully I'm wrong - I'd love to do my DMR up like this...

Much easier to readjust and refit a QR wheel if it does move - A friend of mine has his bolted wheel come loose regularly when he comes up short on gaps and lands on the bashguard/crank. If he hasn't an allen key handy that's his ride over... You can replace QR's with anti-theft bolts (They go the full way through the hub like the skewer). Only get the ones with 5mm allen key heads - there a quite a lot of 4mm ones around and they never do up tight enough...

Use some trials specific brake pads. I went for years thinking the stock pads were fine, but the constant fear of the brake slipping out put me off trying a lot of gaps and lines. Rock green pads are good on smooth rims, but they're all shite as soon as the rim gets even slightly damp.

If it feels solid when the brake actually bites it might not need bleeding. Have you adjusted the bite point/reach to see if that sorts it? There's a threaded rod from the lever blade to the piston which you might need to wind in.

The stiffness of the rim will cover a lot of the shortcomings in spoke tension. If there are loose spokes then the wheel could be stronger...

Lofting is way too much work and you wouldn't end up with round wires unless you were using elliptical cross sections or possibly worse... The twisted wires are driven off their centreline as follows: Look in the help files for the trajpar variable. Basically it varies between 0 and 1 as you move along a trajectory. If you use trajpar with a relation to drive an angle change (Just type something along the lines of ANGLE = TRAJPAR*360*NUMBER_OF_TWISTS into the text box), you can sweep a surface along the previously defined curve (In 3 dimensions - I think I made a spline through a set of points dropped at random for that one) and make it spin around the trajectory as it goes. Then use the edges of the surface as sweep trajectories for round cross section sweeps normal to trajectory and you're there...

Here's an easy one to start with (Though maybe not as easy as it looks ): A C60 Atom - built using the assembly functions, so the program calculates all the angles to make it work: A light bracket for high power LED's for night XCing (Built in my garage): A thermocouple mounting into a flow test rig - extra marks for working out how I drew the twisted wires ... A test rig we built ages ago in the lab - replaced by a simpler one now... And in conclusion I think I must like bright colours ...

Most long term wheel durability issues are down to whether the wheel is stress relieved or not after it has been tensioned. Two wheels built from the same parts with the same lacing and the same spoke tension will show massively different rates of spoke failure if one is stress relieved and the other isn't. Modern manufacturing techniques have made material quality much higher, so even badly built wheels with good spokes in particular can last pretty well... If the spokes are obviously slack or the wheels fail through overloading rather than fatigue, you're dealing with a whole other problem of course...

Sweet CAD models - Some of those engines are almost big enough for the average American pickup truck ... I presume they're marine or stationary engines? What company are you working for - Perkins are the only company I can think of in the UK that do engines that size? ProE is my CAD package of choice too. You must be on a pretty serious computer to run models like that (and not spend most of your day waiting for the PC to catch up) though .

The fall off in stress in the spoke pointed downwards is due to the rim being bent flat at the point where it contacts the ground, bringing that point in the rim closer to the hub centre. This local bending in the rim is the reason the downward pointed spoke sees such a huge tension change. The hanging effect such that it is is much less because all the spokes pointing to the upper half of the rim will have to see a stress change in order for the hub to move downward relative to the rim (Without a point force to bend the upper half of the rim locally the change will be massively less than seen by the single lower spoke pointing downwards). Radially laced wheels will show the effect of stress reduction in the bottom spoke more strongly as only one spoke will point straight at the ground for any given wheel position rather than for tangentially laced wheels where there will be several spokes pointing in about the right direction that share the load. Radial wheels show better lateral stability (Smaller angle between the hub axle and the spoke means the cosine component of the spoke stress is higher). Radially laced wheels are statically indeterminate under disk brake/pedalling loads (Spoke tension will skyrocket as the wheel tries to resist twist between the hub and rim) and will loosen more quickly if the spoke tension is too low as the side forces the spokes see where they cross each other act to resist unscrewing at the spoke nipple (Not sure if this is a very significant effect though). I haven't time to take spoke by spoke values off this, but if this thread is still running in a couple of days I'll have time to work on it then.

Here's the model I did ages ago - I only have a printed report from the more recent solid model based work... The circles/squares around the beams show their assumed cross section. The model was only fed an approximate cross section for the rim. Te stress plot is for the case where the wheel is loaded by the bike + rider weight only. Note the spokes pointing downwards lose stress while the rest stay quite even. This is consistent with other work done in the field. Most people assume that the hub hangs from the upper spokes, when in fact due to the prestress in the spokes before loading, the only significant stress change is for the downward spokes to lose tension (All other spokes gain a small amount of tension - not visible in the result plot as it's much less than the change seen on the downward spoke.

What FEA package are you using? I had a student this year analyse the stress in a bicycle wheel using Abaqus - he took it several notches beyond the 2D simulation in 'The Bicycle Wheel' by Jobst Brandt ... Some boundary condition issues in setting prestress in the spokes though. I built a proMechanica model of the same thing years ago and it worked very well, but won't deal with plastic deformation... Next year I'll see about modeling the stress relieving process (Plastic deformation in the spoke/hub interface) for another project .

The wheels I got on my bike from Tarty are the first set of wheels I've bought mail order that I haven't needed to disassemble and build properly myself. They even lined the hub logo up with the valve hole, which is unnecessary, but I always build mine that way ... I stress relieved the wheels when I got them (4 months ago) and have done no trueing yet. The wheels are now slightly off true, but not even to the degree that it affects the Maguras yet... I'm about 14-15 stone and not the smoothest rider on the planet, though I don't usually do for wheels...

From what I've read elsewhere 180mm is pretty much the minimum for a front disk on a 26" bike. If you look at the ratio between wheel diameter and disk diameter, a 160mm disk on a 20" wheel will have the same leverage as a 208mm disk on a 26" wheel. I run Maguras though, so I've no specific experience on disks for trials (My XC bikes are all disk braked though). I used an average front brake for years on my trials bike (Kool stops on a grind), but went with trials specific brake blocks and a grind on the front for my new bike. The difference having all that power available to the front brake makes is unbelievable - the extra confidence on front wheel moves has allowed me to commit to bigger (Though not actually big) stuff and do it all clean. I thought my front braking was fine as it was until I upgraded it though. Only downside is that both brakes are noisy as hell, so I can't drag them down hills without deafening everyone around me... This (And that I haven't landed on the front dropouts in quite a while) is pushing me towards fitting a disk up front... If you're getting a cable disk, fit a really good cable, doesn't matter how good the lever and caliper are if the cable is grindy and sticky...

Pretty much anything from Shimano will be fine. They get lighter as you go up the range (And you get more depressed when you take chunks out of them in crashes if you go for more expensive ones). As for anti-theft skewers, I think Outland (Raleigh's component brand) do them. The cam is the mechanism that puts tension on the skewer as you close the handle. They're visible and exposed on Hope (And a lot of other skewers), but on Shimano ones they're hidden inside the end of the skewer, so less affected by dirt and crash damage.