BikeRumor, 2011
REVIEW: ASHIMA PCB PISTONLESS HYDRAULIC DISC BRAKES
posted by Tyler (Editor) - May 18, 2011 - 2pm EDT
This review has been a long time coming. WeÂve blown through two pre-production sets before receiving a third, production-level set of brakes, which weÂve tested under a number of riders over the past eight months. The first set leaked out of the box and never worked. The second set worked fine until we shipped them to Zach, after which they lost pressure and failed after a few rides. This last and final (and the only production version) set seemed to finally cure the ails that plagued them.
For the uninitiated, AshimaÂs PCB (PanCake Brake) is a completely different design from other hydraulic brakes. The caliper uses diaphragms to hold the pads rather than pistons, so technically there are no moving parts other than the lever and plunger. This saves weight and simplifies the design  these are the lightest brakes weÂve ever had come through our doors  but it also gives the brakes a feel unlike any other weÂve ridden.
Is that a good thing? Read the full review and find outÂ
WHATÂS IN THE BOX?
To be fair, we never received our test sets in production retail packaging, and in most cases they arrived from overseas in a heavily beat up boxÂ
which might explain some of the issues with the early versions. The final production version weighed in at a very light 197g front and 213g rear.
They also come with their very light AirRotors and the appropriately sized mounting brackets.
This is within 1g of the pre-production versions we received, and thatÂs with an ever-so-slightly longer cable for the rear:
One of the issues with the early sets was that we had to run the rear cable on the wrong side of the steerer tube. See that, along with the weights for each size rotor and mounting bracket in our original ÂUnboxed post. Since that post, Ashima has started offering sets for both hardtails and full suspension, presumably with longer hoses for the FS kits. Measurements arenÂt listed online, but I can say that the sets weÂve tested would not have fit a full suspension 29er bike. Each brake also comes with spare parts (banjo, hose fitting, tools, etc.) to help you make repairs or shorten the hose.
Price is about $169 per wheel, available through J&B Importers for the U.S.
HOW THEY WORK:
The hydraulics push directly into a diaphragm that doubles as the seal for the brakes. ThereÂs a hard, flat surface on the visible section of the diaphragm to push the pads evenly and firmly.
An exterior Âpipe carries fluid from one side to the other and aids in cooling. We never noticed any fade on long downhills. Note the pin that holds the pads inÂ
grab it good when pulling it off or it launches into space and is impossible to find. A normal cotter pin would be preferable.
The master cylinder puts the vacuum diaphragm cover on the inside edge, forcing the hose to come in from the side, which means the backside of the cylinder body. The body itself is made of an Âengineering grade plastic to save weight. The lever blade is pretty comfortable and easy to grab, and a small allen key adjusts reach. ThatÂs the only user adjustment offered.
The hose banjo on the back of the master cylinder forces a big gap between it and your shifter body. I was able to compensate somewhat by using SRAMÂs adjustable trigger on their X0 shifters, but it still cocks it backward more than normal and requires a bit of compromise. The shift lever placement was something we quickly adjusted to, but worth mentioning if youÂre ultra-particular about your setup. You could get around this by running them Moto or buying the Euro versions (flip flopped front/rear placement), which would put the banjo facing forward.
HOW DO THEY RIDE?
TYLERÂS REVIEW: I spent the most time on these brakes, about six months on the 2nd pre-production set and about the same or a bit longer on the production set.
HmmmmÂ
how to describe these. I feel I need to preface the next section with this: The brakes absolutely work, and for the right person, theyÂre probably just right.
If youÂve felt the rock solid engagement of ShimanoÂs new XTR brakes, these are the polar opposite. The AshimaÂs squish into action with a very soft lever feel. If you ever had SRAMÂs old 9.0 thermoplastic lever mated up to some Avid SingleDigit brakes on a hardtail, the feel is very much the sameÂ
itÂs mushy all the way to the end, even after the wheel is locked up and youÂre skidding. ItÂs just that thereÂs a bit of a disconnected feeling between the lever and the pad.
What that translates to in terms of braking performance is a rather smooth progression from start to finish, with more lever pull required to lock up the wheels, but you can definitely lock them up. On the trail, that means youÂre less likely to scrub off too much speed too quickly unless youÂre doing an Oh S&*t grab. For racers, that could be just the ticket as youÂre saving energy in the long run while still being in full control.
AshimaÂs rep, Wayne, says theyÂre great for DH, too, but personally, I think the power is more in line with XC riding. IÂve raced them, and the bikeÂs been ridden by myself and others in wet, cold, hot, dry, mountains, rocks, dust and dirt, and the performance never waivered. Also, I never had any squeal throughout the entire test period.
So, would I recommend them? If the placement against your shifters doesnÂt bother you and youÂre looking for something super lightweight, then theyÂre worth a shot. It doesnÂt take long to get accustomed to the brake feel and performance. The rotors themselves are pretty greatÂ
light, stiff and havenÂt seemed to warp any over time (IÂve used the same rotors from start to finish on this review, including on other bikes with different calipers).
Now, all that said, a couple of days before writing this review I found the rear brake lever like this:
This didnÂt happen during a ride, so either it fell against another bike in the garage (likely) or my kids tried to hang from it (equally likely). Either way, itÂs not wanting to go back in, so short of sending this back for repair, the rear brake is gonzo. Even if it could, a full bleed would be required to get them working properly again, so if this happened on the trail, you might be in trouble. So, I hadnÂt thought of it during the review, but a breakaway lever feature like on AvidÂs levers would be a welcome addition.
ZACHÂS THOUGHTS: I think the first thing that anyone should consider before purchasing a set of Ashimas is the brake feel. The Ashima PCB has one of the strangest lever feels that I have experienced, but I must say they work.
Obviously, my pair were pre-production, so everything has be taken with a grain of salt, but I have been told that even the production models feelÂ
squishy. Unlike most disc brakes that have a very positive engagement point when the pads contact the rotor, the Ashimas engage very quickly, but never firm up. Ashima states that this is due to the fact that they are a pistonless system, and therefore rely on a flexible membrane that expands when you pull the lever. As the membrane expands, it pushes up against the pad, which then contacts the rotor. The harder you squeeze, the more power it delivers, but it always feels muted at the lever.
Im Vorfeld der Eurobike hatte die Brake Force One für viel Aufsehen gesorgt und im entsprechenden Thema hattet ihr euch gefragt, was denn so dran sein würde. Genau das haben wir uns auch und also haben wir uns kurzerhand die Präsentation am Stand des Unternehmens angeschaut. Nachdem ihr die ersten Videos zu der Bremse schon im Artikel zu Tune gefunden habt, kommt hier nun ein größerer Beitrag rund um die Bremse, basierend auf der Präsentation von Entwickler Jakob Lauhoff:
