psycholist

I build all my wheels (XC/trials/commuting etc.) with double butted spokes and the spoke nipples will round before the DB spokes will break too (Unless you go for something ridiculously lightweight - I'm talking about general DB mountain bike spokes). Double butted spokes build more durable wheels because they stretch more for a give spoke tension (Due to the middle having a smaller cross section), which means the rim can deform more before the spokes can go slack and progressively loosen. Trials wheels tend to fail from crashes and overload or the rim getting too thin to stay stiff from grinding, so the progressive loosening and fatigue failures you see in wheels with high mileage will be less of a worry, they'll just take longer to show up... This also means that just because you're replacing a worn out rim you don't usually need new spokes unless the spoke length is wrong.

More tension in the spokes means more load is needed to pop the rim into a pringle shape if it's loaded sideways as well as more vertical load needed before the spoke pointing towards the ground loses tension. If a spoke goes slack it will start to loosen, so the more tension the longer the wheel will stay true (Bending the rim notwithstanding of course). Unless the wheel is very slack you're not really going to notice the difference in power transfer, though on a slack front wheel with a disk you'll see all the pushing spokes go slack under heavy braking.

Just keep tightening the spokes - you won't break them. When you either can't turn the spoke key due to the spokes being too tight or the spoke nipples start to round then you've got the strongest wheel you can get. Unless your rim, spokes or hub is shite the spoke nipples rounding is the first point of failure tensioning a wheel. A target tension of 1000N is sometimes used for spokes too. To find the theoretical maximum tension the spoke can cary, go to www.matweb.com and look up the properties of the spoke material you're using (This is difficult because most spoke manufacturers won't tell you exactly what they use, but if you put 'drawn stainless steel' in as a asearch term you should be able to get a rough idea). Look up the yield stress on the material - the unit should be N/m^2 or N/mm^2 - If the unit is in Pascals (Pa) this is the same as N/m^2. Multiply this figure by the cross sectional area of the thinnest section of the spoke (The root of the threads on straight gauge spokes, the butted part on butted spokes) in the relevant unit (N/m^2 x m^2 = N or N/mm^2 x mm^2 = N) and you've got the maximum theoretical tension the spoke can carry. Built wheels are usually a fraction of this though thanks to the nipples rounding once you pass a certain tension (You can get around this by building the wheel in your frame and flexin the rim towards the flange the spoke you're tightening goes to as you tighten it), but you're hitting diminishing returns in terms of wheel strength once you go to that territory...

It would defeat the purpose of having ceramic coating on the braking surfaces of the rims in the first place, but it can be done, it just means you've paid twice the money for the same braking performance as a non-ceramic rim with a ground surface ...

Profit ...

Presumably you're talking about aluminium backings, these should be fine at domestic oven temperatures. As for the pad material, presumably you're removing it because it's worn out, so you won't use it again anyway... Another method I've seen suggested is to boil the pads in a saucepan of water. Try this if you're worried about the temperature of the oven. That's what I'll try first (After just yanking at the pad material in case removing it is that easy). I've about a mm to go before the backing hits the rim, so tonight's session should finish it off...

Tiny pic is a website that hosts photos http://tinypic.com/ The pictures have to already be on the internet before the forum can show them. You put the link to the web address the image is at in the IMG tag to embed it in your forum post.

If you're just replacing the lever you won't need to rebleed the brake - just make sure you keep a bit of pressure on the pushrod to the master piston in the lever body while the lever blade is off just in case the piston pops out. I have one of the Chorrillas TPA adjusters and a GU lever blade and they're OK. The Chorrillas rubs on the lever a bit when I'm adjusting it, but overall it's better than the OEM 2 finger lever anyway thanks to having more of a hook on the end. The tendonitis I was getting in my braking finger has eased a lot since I changed too, though a water bleed is probably a better way to reduce the strain from braking, but I kind of like having no maintenance at all to do on my brakes.

The old style Magura Evo mounts should work on pretty much any trials bike. The wider spacing used by a lot of trials frames to accommodate wide rims means you may not be able to use the new version of the Evo mount which has a brake booster behind as well as in front of the brake. The brake boosters that came with the old style Evo mounts will often rub on tyres wider than 2.3" unless you're really careful in setting them up. Have a look at the magura manual to see the details of the new system (You're not going to get the old system except for second hand I reckon) - see page 6 for some photos: http://www.magura.com/uploads/media/downlo...rakes__09_E.pdf Before 4 bolt fittings became standard I used Maguras on single bolt mountings without problems (Except one brake mount pulled off the fork I was using after about 2 years - given my Echo Urban fork snapped in 6 months and that's supposed to be designed for trials that isn't really a bad thing). With the grabbier brake blocks and ground rims most people run now there may be more risk of things going wrong, but given that the forum isn't full of stories of V Brakes ripping the brake mounts off, Maguras won't be any more damaging as they apply more or less the same force to the same frame mountings.

If you want thick shims (They're really washers ) try B&Q or any hardware shop. Then for fine adjustment the thinnest shims here: http://www.chainreactioncycles.com/Models.aspx?ModelID=356 For what you're getting the price is ridiculous, but aligning the disk is a job that you only need to do once if you do it right. Then the disk should work perfectly for years...

Double butted will pretty much always outlast straight gauge spokes in a wheel. The main benefit is that the spokes in the wheel can maintain tension under load more easily. Here's why: A straight gauge spoke will stretch less than a double butted spoke for a given load thanks to the smaller cross section supporting the load in the thin section of the double butted spoke. Spokes in a wheel lose tension due to loads being high enough or spoke tensions being low enough that the spoke pointing towards the ground on heavy landings etc. will become slack, offering no resistance to the spoke nipple unscrewing, leading to the wheel losing more tension. Double butted spokes are stretched more in the wheel (If they're tightened to the same tension - if the straight gauge and butted spokes are carrying equal tensions, wheels built with either should be equally strong) therefore they require more deflection in the rim before they become slack. Double butted spokes still fail at the bend or the first spoke thread, exactly the same as straight gauge spokes, so the change in cross section does not make them any weaker than straight gauge spokes, while they should resist loosening better.

One way to practice the front wheel landing is to spend time doing a modified version of walking the bike sideways one wheel at a time with both brakes locked (You probably do this already for balance on narrow stuff), where instead of having both wheels on the ground for a split second as you transfer weight from the back wheel to the front or vice versa, you hop the bike between the back and front wheels so it follows an arc through the air as you weight shift. With a bit of practice you can weight shift to front enough to end up hopping on the front wheel from a standing start (Which is pretty much as far as you're ever likely to need to go ). Practicing this will get you used to the feel of landing on the front wheel without having to worry about the gap.

That's so cunning you could pin a tail on it and call it a weasel ...

I'm a big fan of vertical dropouts because you don't need to adjust the Maguras every time you tweak the chain tension. I'd build it with a FFW and Echo fixed hub with built in tensioner like my current bike. I'd like to see a disk mount on it too... Are those trialtech cranks? I notice there's no bashguard - is this because the freewheel rubs the BB with the bashguard fitted? I'm bashguardless on my trialtech cranks and 128mm Echo BB for this reason ...

For less aggressive grinds use a wider cutting disk and grind radially. For even less aggressive use a grinding disk edge on or flat side down for less aggressive again. After that a sanding disk with various roughnesses on an angle grinder or a power drill will give less again. I'd be interested in trying soft brake pads on various roughnesses of rims to see if there is a point where the brake bites and holds well but doesn't howl and gives some modulation when you want it and still works in the wet. There are so many permutations of grind, pad and conditions it'd take ages though.

If you want slightly more bite from hard pads like Kool Stops or OEM black Magura pads and loads of modulation for manuals at the expense of bite and hold then this might work for you. Unless the grinding wheel you have is ridiculously coarse it won't give you the sort of grind I like - I use a cutting disk on an angle grinder, giving deeper grooves in the braking surface to get an on/off brake with loads of bite and hold (The brake's got even better since I got some heatsink yellows too). The grinding pattern you need should be radial to the centre of the rim all the way around. Before trying any of this make sure you've got goggles and gloves on to be safe - hot chunks of metal will go flying and aluminium doesn't tend to spark, so you won't see them. My angle grinder is loud enough that I need ear plugs to use it - grinders tend to be a bit quieter.

Here's my bike packed for the London ride in March: The bike box I have is pretty compact (It's shorter than most cardboard bike boxes), so wheels off, disk rotor off and cable tied into the front spokes. Remove pedals, take handlebars off the stem, turn fork backwards and pile everything in. I used a marker to mark the handlebars (Use tippex if its a black bar) so I could put them back in the stem at the right angle. Make sure you put loads of padding on the ends of the axles, frame and fork dropouts etc. to stop them going through the box when the baggage throwers get their hands on them... A good plan is to put all the tools you need into the box as you use them to dismantle the bike - then you'll definitely have all you need to assemble it at the other end of the trip.

Is it actually a spanner like this one: http://www.unicycle.uk.com/shop/shopdispla...p?catalogid=797 If so it'll take hours to build a wheel ...

Ever tried building a 36 hole 20" rim? I'm not sure my spoke key will even fit between the spokes to tighten them come to think of it... I reckon 32 spokes are more than enough unless you ride flatland and spend all day rolling around on the sides of the tyres ...

Hard to judge from the picture, but if the diameter of the centre clamp is 31.8mm it's oversized so look for a 31.8mm clamp stems for it...

Magura blood or any other mineral oil (My personal choice is Citroen LHM suspension fluid because it's dirt cheap and more readily available - I bought 500ml about 7 years ago and still have about half of it and I bleed everyone else's brakes near me too) will work in a Magura. All Magura brakes are designed to run mineral oil and will be ruined by DOT fluid. Magura royal blood is supposed to have lower viscosity, making the lever less draggy to pull, like a water bleed, but I haven't verified this myself. Incidentally to get an idea of the difference between DOT and mineral oil (And why I prefer to work with mineral oil), shiny jelly sweets are made shiny by coating them in mineral oil, so basically it's safe to drink (But will act as a powerful laxative). DOT fluid on the other hand works well as a light duty paint stripper...

What brake is it - DOT 4 and 5.1 (DOT 5 is different again and incompatible with pretty much everything - It's unlikely anyone has this as the US military is the only significant group that uses it AFAIK) will eat seals designed for mineral oil and vice versa. If it's a Magura rim brake you can also bleed with water, but more maintenance is often needed to keep the brake running with water...

Or a 140mm disk, but that would be a really awful idea...

You can't uncut the fork steerer, so start with loads of spacers and move the stem around in the stack to find the perfect height. Then cut the steerer so only the spacers under the stem are needed...

My guess is you need to raise the handlebars on the mod if you're having trouble bunnyhopping but can hop other bikes. The only people I know with mod bikes are over 6 feet tall, so height isn't that big a deal, just get the stretch from the cranks to the bars right...