psycholist

Starting with a screw on rear hub you can still use that, but you'll need new cranks and a 15T screw on sprocket (To give the most common ratio for a stock bike, if you ride a Mod you'll need a 12T screw on sprocket). Make sure the BB you have is long enough to have room for a FFW as well - certain combinations are known to have issues. I'm not too sure about the strength of the Dicta freewheels, but putting it on the front will load it slightly more heavily as the gear ratio multiplies up the torque seen by the freewheel, so if the freewheel you have already needs a lot of attention to keep it running it will need more on the front.

Do the same as you did for the back wheel. Assemble the spokes that run from the inside of the small flange first, then the spokes from the inside of the big flange (Lace these to the hole beside the ones you've already put in - for a front hub set these spokes as the ones that see tension when you hold the rim and spin the hub forward. The spokes from both sides of the hub should be more or less parallel with each other and the valve hole should be right beside one of the spokes with the other in the next spoke hole on the same side. Both spokes should be to the same side of a line between the centre of the hub and the valve hole - this means you'll be able to get a pump onto the valve easily. Then lace spokes that go from the outside of the hub flanges - I'd try 3X first, if the spokes seem too long (Don't judge this until you have all the spokes from one flange in) then try 4X, but unless its a 36 spoke wheel it's not going to be pretty. Use the longer spokes for the small hub flange.

There's one more fundamental very good reason for putting the magura mounts on the top of the seatstays - given very short seat tubes are the standard, there's no space to mount the brakes between the seat and chainstays with standard bolts anyway, especially if you factor in trying to get tools to it... Customising the frame with proprietary clamps for the brake pistons would be interesting but a serious design headache. Based on some of the clearance issues between Maguras and cranks thanks to small frames, wide rims and very thick CNC brake pads, using one of the longer DH BB setups could guarantee clearance between the Magura pistons and every crank on the market regardless of how far out the Maguras are. There are a few DH specific 83mm shell BB's around and thanks to Hollowtech II, you can pick whatever BB width you like provided you can get a BB axle machined to suit. You may need a wider rear hub to maintain the chain line, but building the frame to sit the hub off centre so you can build a dishless rear wheel into a 6 speed freehub would be very cool indeed - definitely need to get some CAD modelling together before you build something like that to check for chain/tyre interference...

I was debating this question a few weeks ago and thanks to a few emails to Tarty, I've more or less decided to go with dual disk stock bike. Now I need to decide whether to go with the +35 or the +60 GU frame, almost all the other parts have been chosen... The case for dual disk is down to the best performing Magura brake pads all being a faff to refill - unless you buy two sets of CNC backings to keep a reserve you have to wait for the glue to dry before fitting them, having quick wear rates on my rear magura (With most of them the faster the pads wear the better they work), faffing with the TPA mid ride to keep the bite point consistent, hold still not being perfect no matter what I do (So no better than the reputation disks have), the complete lack of modulation leaving no hope of adding manuals to my trick repertoire, the noise for everything except on/off braking, having to grind the rim to keep the brake working correctly, new version rim brake Magura levers being worse than the old ones and harder to fix in terms of the strength of the TPA adjuster and so on. It all adds up and it's starting to annoy me given I spend at least as much time and a lot more miles in much worse conditions on my XC bikes and commuter bike, but thanks to hydraulic disk brakes and full length gear cable outers I need to do nothing in terms of keeping everything in adjustment except slap in a set of brake pads every few months (Which takes a lot less time than removing Magura rim pads, levering out the old pads, cleaning the backings, gluing new pads in, sanding about 1/3 off the pads so they'll fit my bike and fitting them) and a drivetrain every year. The Hope trials brake seems to be the only consistently well regarded hydraulic option for use on the rear of a stock bike, though given how many seal kits Hope sell (I've never seen a Shimano or Magura seal kit for sale, but I don't know anyone who's ever needed one either), it may be a poorer long term choice than shimano or Magura, but I can't deny those I've tried work very well and the brake is designed specifically for trials bite and hold. For the front I'll probably go with a Louise as I'm happy with the one I have on the front of the current bike. Both will be 200 mm rotors... Looks like it'll run to about €1400 though, so it'll make for a serious christmas present to give myself ... I'm hoping to build it with everything black to fit with the stealth thing since it won't howl every time I pull the brakes...

Are you cutting a plate or laying up your own composite? The boosters I've seen have been cut from a plate. Massive strength benefits are available if the carbon fibres are laid up in the direction of peak stress within the booster. The possibility of making a custom cross section to increase stiffness would be there too, though you'd need a custom mould to autoclave it properly. Word of warning - if you're not wearing a proper face mask or cutting the CF under water, then make damned sure cutting in air is safe. Many CF types produce carcinogenic dust when you cut them...

What model are the brakes? If the adjustment is a result of the adjuster moving either loctite on the threads or some sort of locknutting arrangement (No idea if that's feasible) would be recommended. If it changes adjustment without the adjusters moving, something else must be moving. You'll probably have to dismantle the caliper to find out why though.

Spot on...

All depends on the type of carbon fibre used. I'm guessing the stuff here is a highly abrasion resistant aerospace grade designed for parts of planes that need to resist friction rather than high temperatures. It looks like conventional CF, namely fibres held together with a polymer resin, so I'm guessing they'd have burned away before hitting the 400-600 degC range performance car brakes get to. I'd guess these get killed very quickly by XC or DH use...

A lot of steerer's are a smaller diameter at the bottom to reinforce against the peak stress which occurs where the legs are welded on, so the star nut may jam before coming out the bottom depending on the fork. Some can be pulled out of the fork by putting a top cap on and tightening it against the fork, but the only way that definitely works is to drill the centre of the nut out and tap the sides of the stars with a punch to twist the sideways in the steerer so they can be pulled with a needle nose pliers or hammered out the top of the fork from the bottom.

The width is the critical thing for a trials rim. Once the tyre doesn't roll off the side of the rim even at low pressure with trials levels of loading then you're sorted. Adding a slightly bigger diameter just inside the rim walls to hold usually relatively slack XC tyre beads in place while keeping the centre of the rim a small diameter to keep tyre removal easy you're set. Choosing a slightly harder grade of aluminium to improve its ability to hold grinds or possibly texturing the rim walls from the factory would be nice, though trying to get people to agree on one level of grind would be a bit of a chore...

I've never heard of anyone trying the existing pro3 XC front hub for trials, so I'm guessing it's not common (And I doubt if I'm going out on much of a limb saying it's nearly certain to be strong enough already without a trials specific version), so I reckon it's the straight pull spokes that put people off. The weight difference for straight pull spokes is grammes in many cases, but the chance of walking into a bike shop and finding suitable straight pull spokes in stock when you get caught out is pretty low compared to the chance of finding normal spokes. It needs to be lighter than the existing hubs to compete on paper since current front hubs seem to be plenty strong enough. Getting the front hub colour to match the rear is probably the main selling point for these, but a standard flanged front hub to match the rear would sell better I reckon.

Vimeo is great apart from the skipping, hanging and juddering in playing videos even when the graphics say the buffering is complete... Only one of the three computers I use can play Vimeo reliably. All of them are fine with youtube. Playing Youtube videos on opera mini on my phone doesn't seem to work anymore though ... Here's the only good thing the guitar hero franchise ever spawned I'm pretty sure and an example of the sort of gems that form a vanishingly small percentage of the videos on youtube:

Try topping up the lever reservoir. It fixed some inconsistent bite on mine back when I bought it.

I'm pretty sure the sticky piston problem in Maguras is more down to the wiper seals being contaminated from the outside than the o-rings that seal the oil into the brakes causing the friction or anything to do with the fluid used (Unless it eats aluminium or rubber). A clean water bled brake will lose the water that gets to the outside of the seal through evaporation, and so will need topping up more often than an oil bleed or a water bleed with oil left on the seals.

O-ring seals tend not to be strongly pressure energised seals (that is the higher the pressure they resist the better they seal), but up to a point they behave this way in terms of being shoved to one end or other of the slot the o-ring sits in by the pressure they're seeing and being flattened by the brake fluid pressure, which forces the o-ring to press harder against the inner and outer sealing surfaces. I'm guessing (I haven't measured) for most bike applications where an o-ring slides in a given piston bore diameter, the pressure it can resist is more of a function of the difference in diameter between the piston and the o-ring pressed into it without having to worry about dynamic effects. As you go to higher performance o-rings at higher pressures I think the pressure energising behaviour will become important though. What this means though there's always a sealing pressure between the o-ring and the surfaces it touches, so no leaking occurs in static conditions either except through diffusion, which is very very slow. If the seal rolls slightly as it changes direction it will carry very small amounts of oil onto the piston surface, and I'm guessing this is what o-rings rely on to stay lubed. This provides part of the restoring force that helps retract disk caliper pistons when the lever is released (This is the case where the o-ring doesn't slide when the deflection is small, instead being able to roll on the piston surfaces). Pressure energised seals are found in the oil seals on suspension forks/rear shocks, where cutting friction/stiction is more beneficial to performance (As well as the seals needing to resist sudden high peaks in pressure). These seals can be recognised by their 'u' shaped cross section with the open end of the 'u' exposed to high pressure from within the fork, forcing the seal to expand inwards onto the sliders and outwards onto the fork legs to improve the seal (At the expense of higher sliding friction) but only when there is a high pressure to be sealed out. For braking systems on bikes the pressures and movements the seals see are small enough that there's no great benefit to cutting seal friction and considerable expense in trying to make small enough pressure energised seals to fit lever pistons, so o-rings are the chosen solution. Water is an excellent lubricant due to its strong surface tension and low viscosity (Low viscosity means it supports higher shear rates, and therefore allows bigger speed differences between lubricated surfaces for a given force applied to move them and a given gap filled with lubricant - think the difference between using oil and heavy grease in a Chris King). The low viscosity is also what makes a water bleed brake feel more responsive as it takes less energy to drive water through the narrow orifices within a brake system than it takes to drive mineral oil through. Water is let down by the fact it evaporates when left in air, so its lubricating effect is short lived unless it keeps getting replenished (Which would require a sustained leakage from the brake seals and is therefore a bad thing for a consistent brake). This is why it's a bad idea to completely clean all the oil out of a Magura before a water bleed. The oil will stay coating the surfaces, including sealing surfaces without evaporating away, keeping everything lubricated regardless of what fluid is used as well as providing a barrier the water has to diffuse across before it can get through the gaps in a seal to evaporate out. The other down side to using water is that drops of water on a surface can form part of a galvanic cell, leading to accelerated corrosion - a major issue if it's used in contact with non-stainless steels for example, as well as a cause of crevice corrosion in aluminium. Gravel behaves in exactly the same way as all fluids used as lubricants, but at a scale we can see more easily. It allows two surfaces to slide over each other with less friction by allowing the gravel to roll between the surfaces (Gravel behaves in a manner more like a rarified gas flow than a liquid flow, but the principles are the same). In liquids the rolling is less evident unless you're dealing with turbulent flows, but the idea of supporting a difference between the speeds of two surfaces using a velocity gradient in a fluid held between them is the same (Look for Couette flow on Wikipedia for this behaviour). As for the mineral content of water - I'm guessing after getting rid of the oil in sealing surfaces of the brake it's the single biggest contributor to the variation in people's long term results using water bleeds in their brakes. AFAIK acidic water is probably pretty ok with aluminium pistons as quite strong acid dips are used to passivate (oxidise) aluminium to stop corrosion in the first place, so an oxide covered aluminium surface won't really notice a weak acid (The seals are also likely to be fine with this). However if you look at previous threads you'll see alkaline solutions (Caustic soda/NaOH) are used to strip anodising (Which is just a thick layer of dyed aluminium oxide) from bike components. Tap water is pretty much never acidic (The latin origin of the word acid is from 'acidus' (Or something similar), which means 'sour', which will probably explain why tap water tends to have a pH slightly above 7 or pretty much always between 6.5 and 8.5 to make sure it's not sour tasting, though apparently if water has too high a pH it starts to taste sour too). For this reason people in hard water areas may see damage in their brakes quicker than those in soft water areas, but I'd say it's still slow. Carbonates carried in the water (Hard water) forming a scale in the brakes is less likely to be a cause of failure as there's a finite volume of water in the brakes, so unless they're bled repeatedly, there won't be enough of these compounds to leave significant deposits. Using boiled water is a good idea from this point of view as well as because it removes all the dissolved gases in the water, preventing them from being able to precipitate out of the brake fluid after the bleeding is done (Again this is rarely a problem anyway though may show up as spongy brakes that get better over time if you leave the bike in the car on a very sunny day for example). Probably way too much for a Friday evening, but the weather's shit here at the moment ...

If you run V8's go for slightly harder soled shoes (Asics runners work well). If you run cage style pedals skate shoes or trials specific shoes are better.

Bleed from the lowest point to the highest - you'll probably have to put the caliper on its side to get all the air bubbles out of the caliper. Try pumping the brake, releasing the lever suddenly to help bring bubbles to the top of the system before starting the bleed.

Scrub the rotor in soapy water, rinse to remove the soap and dry in clean tissue. Remove the pads and run a file/sandpaper over the braking surface until there's no visible black stuff left (Possibly wash the pads first if the contamination is on the sides of the braking material too). Wash the caliper so no oil is left on it, drying in clean tissue again. Reassemble everything and follow the usual procedure for breaking in the brakes (Lots of hard stops/rub in mud into the rotor between hard stops).

There may be too much grease on the stem to allow it to clamp tightly enough on the steerer. This is a particular problem with stems that have a very long clamp on the steerer. Check also that there's a gap between the top of the fork steerer and the star nut cap - if there's no gap then it can't tighten more.

The air rifles could be very useful for dealing with everyone who asks me to do a wheelie - Double tap anyone who asks for a backflip just to be sure ...

I'm currently giving serious thought to building up a dual disk bike too. I've never found a brake setup with maguras that holds every time and in all conditions. I've tried smooth rims (Brilliant in the dry, quite noisy, but lethal as soon as it gets damp), currently run a pretty harsh grind and TNN pads (Not quite as good on bite and hold as heatsink, but slower wear rate), reasonably good in the wet, but serious wear rate on the pads (Have to fiddle with the TPA a couples of times on long sessions), insanely noisy and will still slide sometimes when I come up short on back wheel landings. The current design HS33 levers seem a lot less solid than the old design too, so less reassuring in use. I'm running 203mm Louise on the front and that bites and holds very nicely, but again isn't 100% reliable, but seems close enough to the HS33 in terms of bite and hold with the benefit that I don't have to mess about with the TPA, pad position, glueing pad refills, lazy pistons or deafening noise to get a brake that's about as good. The disk also has some modulation, so I might even be able to learn to manual without deafening myself... Does anyone rate disks other than the BB5 and 7 and Hope trials disk for rear wheel use? I prefer mineral oil brakes to cable and DOT fluid ones (Purely because mineral oil is safer to deal with while cable disks don't automatically adjust for pad wear). Anyone tried Shimano XT servo wave or Magura Louise on the back of a trials bike?

A friend of mine bought a casio digital camera recently which can record video at 1000 frames per second... Trials stuff looks mental on it - the high frame rate is achieved by only recording to a small part of the camera CCD, but the image size is still fine for internet distribution. It's not really in your budget, but expect features like that to trickle down over time ... The OP never specified whether a still of a video camera was required either. Lens quality and light sensitivity are much more important than the number of megapixels the camera has, so don't be fooled by high megapixel counts. My phone camera for example has a very small lens, and as a result even though the photos are 3.2 megapixel, detail isn't captured to that resolution unless you hold the camera steady and take the picture in bright sunlight. If I were you I'd look for a reputable manufacturer and brand name lenses (Make sure the zoom figure claimed is optical rather than digital zoom too - any image editor will give you the same as digital zoom with the final picture) before worrying about the image resolution anyway.

Very like tubeless in cars. The rim is sealed (Spoke hole don't go the full way through it or a sealing rim tape is used), the valve clamps into a hole in the rim to keep the rim sealed and the tyre bead on each side pops onto a ridge in the rim under air pressure as you inflate the tyre. Usually a latex type rubber solution is added to seal small holes in the tyre as they form to keep the tyre inflated.

I run tubeless on an XC bike and based on my experience with them there there's no way I'd try running them on a trials bike. I've had the front tyre lift from the rim (And spit air and sealing goo out) on hard corners, which are nothing like as hard as say hopping 90 degrees to front onto a ledge, and that was at 30 PSI. I've also pinch flatted a tubeless rear tyre (though it was a conti and they have very thin sidewalls) when I hit the edge of a step with 35-40 PSI in the tyre on a full suspension bike - the landing was way lighter than I land the trials bike on similar edges too. So basically it's more likely to drive you mad or cause you to crash than help on a trials bike. I've also not noticed any difference in drag or grip comparing tubeless to tubed tyres (Including the same tyre run with and without a tube), so hard to justify for that use too. The sealing goo I think does stop a lot of the annoying small punctures you get from thorns riding XC, but won't seal a proper hole. It also brings the weight of a tubeless tyre (Heavier than a standard one because of the butyl layer added to allow them to seal) + goo to about the same as a tubed tyre. I have run some standard tyres tubeless with goo though, so that's where some weight can potentially be saved... To make it work on a trials rim you'll have to go with the ghetto tubeless setup - slit a 20" tube around the outside, stretch it over the rim and use the valve of this tube to put air into a tyre you seal onto the outside of the tube with tubeless sealant...

If you're looking for one exercise that will pretty much certainly sort out arm pain, try pushups... Here's a fun (And by fun I mean painful) training regime: http://hundredpushups.com/