The M4 brake is one of Hope’s great success stories. What was originally devised as a no-comprise downhill racing brake has rapidly evolved into a lightweight high-performance do-anything stopper.
It can’t have taken Hope long to realise that the original DH4, 4 pot brake was barely heavier than their standard 2-piston models, so the DH4 lost substantial amounts of metal to become the Enduro 4; which this year gained the Mini lever, lost a bit more metal and became the M4.
So why did I buy the M4, rather than any other brake? Well firstly because it weighed less than the closed 2 it was replacing, cost the same, and was presumably more powerful. No contest. I also believed it was about time to try using an open system, after all, probably 95% of disc brakes sold are open systems. As far as selecting Hope over their competitors; quality, after-sales backup and parts availability leave everyone else standing: I recently bought Closed 2 replacement pistons as stock items from my LBS. Try that with any other manufacturer!
The quality of manufacture of this item hits you between the eyes. I actually wonder how they can produce them for only £130, when you examine the extent of the CNC machining. Fair enough, it is Hope’s decision to use CNC, and a cast or forged brake would probably be both stronger and cheaper, but whatever the pros and cons, you are certainly not paying through the nose for this level of quality. Both brake and lever are beautifully sculpted from billet, and perfectly finished. Engineering geeks will be drooling.
The mini lever is far more practical than the previous ‘pro’ lever. Only a 2mm allen key is required to access the reservoir, rather than a large adjustable, and it is also angled to lie level when the lever blades are at 45º to the bars. Laser scripting even indicates the fluid type to use. The blade is stiff, wide and hollowed out at the back. It is designed for use with the middle two fingers, with a wide sweep outwards providing the innermost finger with unrestricted access to the rapidfire trigger.
A quality bronze lever pivot incorporates two tiny allen screws, one to adjust lever reach and the second to lock it in place. The pivot is even dished to save weight!
The lever harmonises perfectly with rapidfire and their accompanying indicator windows. Finally, a two bolt clamp allows easy fitting to the bars, and the bolts are even angled to prevent any possible rubbing against knuckles. In summary, the mini lever eliminates all the tiny, annoying niggles with the ‘pro’ lever - even the niggles that you never even noticed. I can’t think of any possible improvements to the mini-lever.
The calliper is also beautifully sculpted, with no obvious excess metal left in place. Not only does the calliper sport four pistons (the leading and trailing pistons are different diameters), but also four totally separate pads. This gives more power as the leading edges of the pads provide the majority of the braking effect.
The pistons are hollow, with the open end towards the pads. This clever little trick not only reduces weight but also keeps the hot pads as far way from the brake fluid as possible. The pads are located on high quality screwed-in pins, with separate spring clips to prevent accidental loss. A 2.5mm allen key is required to unscrew these pins. The amount of effort that has gone into manufacturing even these pins is quite staggering – no corners have been cut anywhere in the manufacture of this brake.
A pathetic brass spring is used to stop the pads rattling, and keep them pressed against the pistons (more about that later).
I’m not sure who manufactures the pads for the M4, but the standard compound does not correspond to the EBC green’s of the Closed 2’s. The ‘standard’ pads are much more tolerant of mud and water than the old EBC greens, but still seem to wear at the same (very slow) rate. I believe they are quite a bit harder, with more metal content, as they can leave a rust mark on the disc if the bike is stored wet. They do also tend to squeal, but a soft squeal like a car brake, rather than a savage ear-piercing squeal that gets louder the harder you brake. This slight squeal (squeak?) doesn’t really bother me.
The first test of these brakes was a traverse of the Howgills, on a perfect (if windy) spring day. For the Bowderdale section the pads weren’t yet bedded in, so they gave me some slightly nasty moments. The lack of bite-point adjustment was niggling at first, after several years riding Closed 2’s. However, the descent from the Calf and Winder was a different game altogether. By now the brakes were fully bedded in, and the self-adjustment was bliss compared to the old closed system. There was serious amounts of heat generated on the final flanks of Winder, but absolutely no fade or pump. When stopping at the fell gate the pads stunk, and the disc was glowing blue. The disc was hot enough to melt a wet glove. But they still worked perfectly.
Despite the fact that the pad area is only slightly more than that of the Closed 2’s and the entire ensemble weighs less, there is perhaps 50% more power, and they cope far better with high temperatures.
At the moment (after about 3 months’ use) the brakes have developed a slight judder under heavy braking. It seems as if the brakes are too grabby, which sometimes results from contaminated pads / disc. However, even after emery paper / meths cleaning, they are not yet cured. My next step is to try chamfering the pads’ leading edges.
This is where the M4 has some drawbacks. Trying to re-fit all four brake pads, the two pins, and the brass spring is a task only possible by people with several extra limbs. There is also absolutely nothing to locate the pads, and they simply fall straight through if you let go of one. It is a good job that the pins have a back-up clip, as they are the only things preventing the pads from dropping straight out in use! Secondly, the brass spring performs an awful job of keeping the pads against the pistons. This means that one pad permanently clicked (like a freewheel) against the disc, and re-fitting the front wheel was almost impossible.
In my opinion, Hope should have retained the magnetic pistons of the Closed 2 brake, which guaranteed drag-free riding, and also made fitting new pads a doddle. After several rides, and no luck with adjusting the brass spring, I came up with 2 possible solutions. To either buy some magnets and glue them into the hollow pistons, or glue the pads to the pistons. This may sound drastic, but I have some high temperature silicon rubber glue that I bought to repair a Cateye stadium bulb. A thin smear on the back of the pads before fitting, operate the brake once, and leave overnight to set. I now get perfect retraction, the pads can still move around slightly (as it is rubber glue), and they can be pulled off with only fingers, leaving next to no residue. Mind, you this glue is both expensive and very special. It is loctite 5145 “tempflex” if you have an RS catalogue handy. Ad-hoc used of glues could results in some messy results, including the prospect of your brake actually catching fire!
The fact that I have to go to the extent of doing this, rather than Hope providing a satisfactory solution, is a minus point for the Lancashire boys.
Returning to plus points: The pads are sold in packs of four, for approx £20 with all fittings, (i.e. not twice the price of 2 pads). Red and gold pads are also available, but I’ve never seen any in the flesh. The ability of the standard pads to cope with winter conditions, and the brake’s ability to cope with tremendous amounts of heat, means that these specialist pads may not really be necessary.
The brake was supplied fully bled, but with a drastically over-long hose. After a nasty experience when renovating my Closed 2’s, I now realised the correct way to disconnect a hose. You need to slit the hose for about an inch lengthways at the end to be removed. Just pulling at the hose will result in the two layers of the hose separating, and probably a broken end connector. I then simply cut the hose down to length and reattached firmly. No bleeding was needed, which seems to be fairly normal provided you are careful not to dislodge any fluid.
One final safety feature is the twin layers of the hose. Unlike Magura HS33 hoses, there are composed of two layers of plastic, but most importantly with a layer of yellow Kevlar between. It is best to protect you hoses against rubbing with Spira-wrap, but this also provides an obvious visual warning that your hoses are almost worn through.
Lever perfect, calliper powerful and fade free, a few maintenance niggles.
Kevin Hodgson
June 2002
Last Updated 13-06-2002
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