Fica a primeira review dos travões Shimano XT M785.

Estes travões foram beber a tecnologia da Shimano disponível nos XTR, colocando-a a um preço bastante mais convidativo ;)

Fica o artigo.

Shimano’s new XT M785 brakes are possibly the best brakes from Shimano that we’ve ever ridden. They combine almost all of the features of the M985 XTR Trail brakes — Servo-Wave lever design, calipers with oversized ceramic pistons, Ice Tech rotors and cooling-fin equipped brake pads — at a much more economical price and only slightly higher weight. Those needing to upgrade their brakes should definitely add these to their shortlist.

Ride performance

We tested the M785s with finned Ice Tech pads and a 180mm front /160mm rear rotor combination on a 140mm-travel trail bike. After a short break-in period, it became immediately apparent that these new XT brakes are something special.

Power is second to no other trail brake we’ve used, while modulation is also very good. The brakes’ high power requires a light touch, which takes a little bit of getting used to, but they’re not too grabby. Even on long, fast descents, braking requires only one finger. The system seems so good that those concerned with weight, or lighter riders, will be able to get away with a smaller front rotor, even on a trail bike.

The ice tech brake pads with cooling fins are said to cap brake temperature, which offers more consistent feel and better pad life:

The XT brake is available with or without cooling fins on its pads, but after riding with them, we’d say they’re worth the slight bit of extra weight

Our test system was equipped with all of Shimano’s heat management bells and whistles—Ice Tech cooling fin equipped rotors and alloy core rotors—which kept their feel smooth and very consistent. With other brakes we find ourselves constantly messing around with the freestroke or pad contact adjustments and the lever reach adjustments while riding—if they are tool-free—yet with the new XTs we set them and forgot about them because the feel stayed exactly as originally adjusted.

We were thoroughly impressed by shimano's xt brake; it offers xtr trail performance without the price and only a slight weight penalty:

The new brake features tool-free reach and tooled freestroke adjustments along with Shimano’s new ‘One-Way’ bleeding

The levers are easily adjustable for reach and fit a variety of hand sizes, while the tooled free stroke (pad contact) adjustment is more precise than on the previous XT M770 brake. Based on our initial testing, these brakes warrant BikeRadar’s highest five-star rating. However, we feel it’s prudent to reserve that award until we’ve spent more time on them.

Fit and finish

The new XT M785 lever mirrors the XTR Trail lever that Shimano introduced last year. The first change most will notice is the swap from a radial master cylinder to a barrel-type inline reservoir. This offers better oil flow and Shimano’s One-Way Bleed process, which is said to be quicker and more consistent than the old system. The lever is Ispec compatible, meaning that the clamshell-type handlebar clamp can also be used to mount your shifters.

The new xt brake serves to 'launch' shimano's first 6-bolt ice tech rotors:

The new XT brake serves to ‘launch’ Shimano’s first 6-bolt Ice Tech rotors

The increase in power over the M770 brake is down to three factors: the two-piece calliper with 22mm ceramic pistons, the Ice Tech cooling-fin pads and the three-layer (stainless steel-aluminum-stainless steel) braking surface found on the two-piece rotor. Unlike the original XTR Ice Tech rotor, the XT version will be available in IS six-bolt as well as Center Lock versions. Shimano offer two color options for the new brake: the pictured matte black anodized with chrome highlights or muted satin silver.

Even the weight is competitive, at a claimed 375g per wheel when equipped with a 160mm rotor and standard pads. While the US$209.99 package price ($159.99 per wheel for lever, caliper, line and pads, plus $49.99 per rotor, regardless of size) can’t be considered cheap, it’s good considering the performance the brake offers.

Manufacturers description

The Servo-Wave Deore XT hydraulic disc brakes continue to borrow from the features developed for XTR that provide huge leaps in braking and control. The new compact caliper with oversized 22mm ceramic pistons is combined with a lightweight lever for a brake that lighter yet packs 25% greater braking power when the ICE Technologies brake pads and rotor. The rotors have been proven to reduce temperatures of the rotor as much as 100% over a standard all steel rotor, and will be available in a 6-bolt pattern as well as the Shimano innovated Center Lock. Mechanics will appreciate the integration of the same one-way bleed that debuted on XTR last year.

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Para quem ainda não conhece, fica a dica!

Trata-se de um adaptador para iPhone que permite ler e registar os dados de todos os sensores ANT+ que tenhas na tua bicla!

Desta forma podes tirar partido dos sensores da Garmin em que já investiste e usares Apps como o Fisica, o Endomondo ou o Runkeeper pro para seguires os teus treinos e a tua evolução. Podes ainda partilhar no Facebook todo o esforço de preparação de forma simples e prática.

Conto escrever mais um pouco sobre estas aplicações em breve aqui no BTTecos.com.

Wahoo Fitness takes the Apple iPhone to another level as a high-end training tool, by making it work with the ANT+ wireless protocol. This means that with the small ‘dongle’ inserted, the phone can pick up data from almost all top-end cycling and fitness gadgets.

This includes the heart rate, cadence and speed sensors made for Garmin’s GPS bike computer range, PowerTap and SRM power meters, and Nike’s running sensors. To showcase the data you can collect, Wahoo Fitness have their own free app called Fisica Fitness, and we tested this on a 3G iPhone with both Wahoo’s own speed and cadence sensor and HR strap, and the same devices from Garmin.

It worked seamlessly with all of them, and a PowerTap hub, thus marrying up Garmin Edge-like data collection and display to a seemingly endless supply of third-party apps. The full bike pack, which includes the cadence/speed sensor, HR strap and a weatherproof sensor case with dongle, will soon be available for about £150.

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A terceira parte…

Buyer’s guide to mountain bike suspension, part 3

Before suspension, which didn’t become mainstream until as recently as the late Nineties, mountain bikes were proper bone-shakers. On those old rigid-forked, rigid-framed bikes rough sections of track were exhilarating rollercoasters, but had you grimacing and your eyeballs rattling in their sockets.

When suspension was first introduced many riders turned up their noses at the ugly, heavy, flexy and very inefficient early designs. Nowadays it’s a different story; modern suspension bikes allow you to ride faster over uneven surfaces, further and for longer as they reduce impact and strain on your body. They smooth out ugly landings and save your bacon when you get out of your depth.

Suspension has two jobs on a bike: to keep the wheels in contact with the ground as much as possible to improve traction, and to cushion the impacts a bike deals with on rough terrain. If it’s not set up correctly, even a great suspension bike can feel like riding a mattress and really hold you back. Once you get your fork and/or shock dialled in, however, your riding will take a leap forward.

Suspension comes mainly in two forms: coil sprung or air sprung, although elastomers still get a look-in on low-cost forks. All suspension features compression and rebound damping to adjust the rate at which the fork or shock dives through its travel and returns. Cheaper shocks and forks may lack external adjustments, but it’s commonplace now for suspension to have at least external rebound controls.

Well set up suspension enables the wheels to follow the contours of the terrain by letting them drop into hollows and move around rocks and lumps. To do this, suspension is set up with sag – meaning your weight on the bike allows the bike to sit at a set point within the travel. Sag is usually set between a quarter and a third of the available travel.

Almost all forks and shocks share the same basic construction: a tube that slides inside a larger tube, with the spring and damping system contained within. Most forks are telescopic, and consist of two upper legs (stanchions) – joined by a crown – which slide in and out of a one-piece lower leg construction (sliders).

Most, but not all, forks have dedicated legs  (left or right) housing the damping and compression cartridges:

Rear shocks are a scaled down version, albeit with one leg, and in the case of coil shocks with the coil spring on the outside rather than inside (coil-over shock). As the fork or shock is compressed it squeezes the spring medium, which stores the energy then releases it as the fork/shock rebounds. Damping dissipates this energy and is used to finely control how the suspension behaves during compression and extension.

Fox anatomy fox’s float rp23 shock is the workhorse for most full suspension bikes on the uk trails:

Chassis

Forks and shocks are available in many shapes and sizes to suit the intended application, from cross-country racing to dirt jumping, and the rider. There are a number of standards to be aware of though, many of which may or may not be compatible with your setup.

Rear shocks are somewhat easier to get right – the frame has precise measurements that must be matched, such as shock eye-to-eye length, shock stroke and specific fitting hardware. Forks, however, have all sorts of differences. Modern fork steerer tubes come in three diameters: 1 1/8in (equals 1.125in), 1.5in and tapered from the latter measurement to the former (all beefier than the old 1in standard).

Which will fit your frame depends on the size of your head tube and headset. Tapered steerers are a recent development that combine the stiffness of the 1.5in width at the crown with compatibility with standard 1 1/8in stems, with hardly any weight penalty. They require a tapered head tube or special headset to fit.

As with forks, there are also a number of different types of axles. Most forks have 9mm quick-release (QR) dropouts, a carry-over from road bike technology. But in order to reduce flex, screw-through (also called through-axle) forks are becoming increasingly common. Like steerers, these require specific hardware, in this case a compatible hub.

The two main standards for screw/bolt-through axles are 20mm and 15mm, and hubs are available that can be converted between the two, and even from quick-release. Alongside the new axle standards, thicker, wider stanchions also increase fork stiffness and allow more precise steering, less twisting and reduced braking flutter, but the penalty for all this is increased weight.

Travel

Fork or shock travel – the total available compression – is typically between 80mm and 200mm (3-8in). More travel allows a softer spring rate and gives the fork/shock more time to deal with an impact, increasing the control over energy absorption. The amount you need depends on the intended use and what your bike is designed to handle, given its geometry. Check with the manufacturer before fitting new suspension so as not to invalidate your warranty or affect your bike’s handling adversely.

Springs

The spring stores the energy created when the shock or fork compresses. In cross-country forks it’s usually compressed air or it may be a metal coil. Air springs can be precisely adjusted to the rider’s weight and are lightweight, but air sprung forks can suffer from stiction (when the stanchions don’t slide smoothly in the lower legs because of flex in the fork) and resistance from increased sealing.

Unlike a coil, the spring rate increases as the fork compresses, known as progressive suspension, which can lead to the unit ramping up (becoming stiffer) at the end of the travel. Coil springs have an adjustable preload to set the ride height and sag, but the adjustment window is usually very narrow and often a change of spring is needed to get the desired results.

Damping

An undamped fork or shock would simply take the energy stored in the spring and fire it right back at you. Control is important, and that is achieved by forcing oil through ports and shims inside the stanchions to slow the action down.

Rebound damping is exactly that: as the fork or shock extends from a compression, it slows the rebound and turns the excess energy into heat as the oil is squeezed through the valves. Most forks and shocks will have an adjuster to precisely tune how fast you want them to rebound. Too much damping and the fork/shock will pack down (ie have less travel) over successive hits, too little and it will feel uncontrolled and bouncy.

Compression damping controls the fork/shock as it compresses, allowing it to react proportionately to different sized impacts. Slow-speed damping regulates movement such as brake dive, fork bob and excess compression in berms, while high-speed damping can prevent the fork/shock blowing through the travel (bottoming out) on big hits and drops.

Too much high-speed damping can be a bad thing, though – the oil pressure may build up causing a spike (when the oil can’t get through the ports or shims fast enough), which can be felt as a sharp knock. Sophisticated forks and shocks have shim stacks – thin washers that can bend out of the way – allowing the oil through and the fork/shock to move faster.

Lockout levers prevent the fork or shock moving, sometimes completely but many retain a little bit of travel to help traction. Lockout is useful on smooth climbs or road sections. Blow-off adjusters let you set the force of impact that will knock the lockout off to regain full travel. Not all forks and shocks have all these features, but the very least you need is rebound damping.

Jargon buster

Suspension fork terminology

  • Adjustment dial(s): Also called top caps. Besides allowing external adjustments – including compression, rebound, threshold and travel adjustment among others – the top caps seal the top of the stanchions/air springs.
  • Air valves: Depending on the fork, these can be for the main or supplementary air springs, the negative air spring or platform damping adjustment valve. Keep clean and check the valve core is tight if you get a leak.
  • Axle: This can be a regular 9mm quick-release, 20mm bolt-through or 15mm bolt-through. Now quick-release bolt-through axles, such as RockShox’s Maxle and Maxle Lite (20mm and 15mm for 2011 forks) and Fox’s QR15 (15mm), are increasingly being seen on cross-country and trail bikes.
  • Bushings: Synthetic slider guides for smooth telescopic action between upper and lower legs.
  • Crown: The ‘hips’ that hold the fork stanchions and attach to the steerer tube.
  • Dropouts: Traditionally forks used slotted 9mm dropouts for quick-release hubs, but with the new 15/20mm through-axle standards compatible forks have a hole rather than slot to slide the axle into.
  • Fixing bolts: Extremely important fork end bolts that hold the internal spring/piston rods in place, stop damping oil leaking out, and the whole lower leg assembly falling off.
  • Fork brace: An arch (or sometimes a pair on brands like Magura or DT Swiss) that stops the lower legs moving independently by preventing torsional flex to ensure good tracking.
  • Lockout lever: Stifles oil and air flow through the compression or rebound circuits to lock a fork rigid –  handy for climbing or spinning on the flat. Most have a blow- off (sometimes adjustable) valve to stop unexpected hits snapping your wrists.
  • Negative spring: Helper spring that opposes the main spring to help overcome seal resistance.
  • Preload adjuster: Increases the initial spring resistance of coil and elastomer forks. If you’re using more than several turns, consider the next spring weight up.
  • Rebound dial: External adjuster for the rebound damping circuit. May be on the top of the fork leg or at the base and is normally red in colour. Increasing rebound damping slows down the speed at which the fork leg returns after each hit; decreasing rebound damping speeds it up.
  • Remote levers: Fly-by-wire bar operation of one or more of the fork leg/ crown mounted adjusters.
  • Seals: Multiple wipers and lubricating sponges vital for keeping insides in and dirt out. Clean and check for damage often.
  • Slider/lowers: The moving part of the fork made of cast magnesium or carbon fibre. Big generally means stiff (on freeride/aggressive trail forks), skinnier generally means lighter/more flexible (cross-country forks).
  • Spring: Provides the basic up and down motion in air (light and easily adjustable), coil (ultra smooth and reliable), elastomer (cheap) or a mix of all three. Can be in one leg or both.
  • Stanchion: Slippery upper leg so the lower leg can slide smoothly over it. Occasionally steel, mostly aluminium and ranging from 28-40mm diameter, increasing in stiffness and strength as width increases. Watch for scratching or corrosion as this will rapidly ruin seals.
  • Steerer tube: Aluminium or carbon to save weight, or steel to boost strength and reduce cost. Come in a variety of sizes, with 1-1/8in being the cross-country standard and 1.5in steerers standard for freeride or downhill bikes. Tapered steerers (which taper from 1-1/8in at the top to 1.5in at the fork crown) are common on all-mountain or aggressive trail bikes where both stiffness and light weight are important.
  • Travel adjuster: Various travel adjustment systems are used by different manufacturers to let you change the amount of travel either on the go or when stationary. This can be useful for effecting geometry changes for climbing or descending.  The adjustment can be stepped (such as 100-150mm), incremental (3mm per click) or infinite (free adjustment anywhere within the range of travel) depending on the system, while other forks can be adjusted internally (such as to reduce a 120mm fork to 100mm travel only).

Rear shock terminology

  • Air valve: Schrader valve used for adding or removing air from the positive air spring on air shocks. Normally marked with a ‘+’ on it. Keep clean and check valve core is tight if shock starts to leak.
  • Bottom-out bumper: Simple bumper to stop a harsh clang at full compression.
  • Coil: Metal coil spring on coil shocks. Can be steel or titanium (for light weight), straight rate or rising/ falling rate. Spring weight (in ft/lb) will normally be printed on the side as well as the dimensions.
  • Compression adjuster: Dial or lockout lever that controls the compression damping circuit.
  • Eyelet: 6mm or 8mm hole at either end of the shock.
  • Length: Shocks come in various lengths. It’s measured from eyelet to eyelet (eye to eye length).
  • Lockout / low-speed compression: A damping circuit that resists compression from low-speed inputs like pedalling forces.
  • O-ring: Rubber ring on shaft showing the ‘tidemark’. Helps accurate sag set-up by showing how much travel is being used when sitting on the bike.
  • Piggyback chamber: Extra damping or air spring expansion chamber mounted parallel to the main body. Used mostly on all-mountain and downhill long-travel air shocks.
  • Preload collar: Only on coil shocks. Threaded collar that can be used to add additional load to the spring for a stiffer start. If you’re using more than 2.5 turns from contact we’d advise you get the next spring up.
  • Rebound adjuster: Controls the rate at which the shock extends after compression. Normally coloured red but can sometimes be blue. Check your manual.
  • Seal head: Wiper seals designed to keep the insides in and the outsides out. Check for any splits, embedded grit or other damage before it scars the shaft, and clean regularly if the shock can be dismantled (most air shocks can).
  • Shaft: The moving part of the fork made of cast magnesium or carbon fibre. Big generally means stiff (freeride/aggressive trail), skinnier generally means lighter/more flexible (cross-country).
  • Shock mount: Normally just a sandwich of alloy spacers but can be a spherical rose joint to reduce sideways stress. Check width is correct for your bike, check for wear/rattle regularly and replace immediately if this occurs.
  • Sleeve: Air-tight can that contains compressed air acting as a spring. Some are adjustable to change travel or internal chamber dimensions, and therefore the shock rat

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