light, responsive, predictable

lacks a bit of power on long downhills

For normal XC use, with few hills, this brake is very good! It's light, it's got plenty of power for normal use, and they look cool offcourse. I ride a lot in muddy and wet conditions (extremely muddy in winter), and I prefer these disc brakes above V-brakes ANYtime. I have been riding them for over a year and haven't experienced any problems.

I've also tried them on more steep, and speedy downhill courses in Belgium, and they could use a bit more stopping power with 60kph+ over rocky terrain. So I'm thinking of changing the discs for one size larger,: 18,5 cm instead of 16 for example, NOTE!! THIS INCREASES THE STOPPING POWER BY 45% !! YES, 45%!!!!!!! pure and simple physics. Simple, CHEAP, and works very well.

Test do show different results with regard to the oil reaching its boiling point.
Some test show its not a problem, others say it is. I haven't experienced it so I can't comment on it. But again: change the disc size! One size larger prevents the overheating of the brake! (probably, but should improve things certainly).

You buy something which suits your riding stile. The B4's aren't advertised as downhill brakes, but XC, so use them accordingly. For XC use, they are one of the lightest on the market, and work like a charm...

Thumbs up for Formula!

Similar Products Used:

several others

lightest disc brake system, great looks, low maintenance, better than any v-brakes i've tried

smallish rotors, finish on lever reservoir wears off

Other reviews i,ve read claim these discs to work poorly, but i've never had a problem with mine. Parts are easy enough to get should you need them and set up and maintenance is a breeze. Other systems with bigger discs obviously mean more power but at a usually big weight increase. My bike is set up for x-country riding, not downhill, and I have yet to need stronger brakes for this riding. Also, there is no way any v-brake system will work better than these in muddy and wet conditions (i.e.scotland).

Similar Products Used:

hope mini, hope c2

lightweight, looks saucy, lightweight, better than v's, oh, and lightweight too.

flimsy rotors, gay reservoir covers.

Nice brakes, good power after break in although not as sharp as Hope's. I haven't had the noise other people have complained about but then I do try to keep them clean (that means keeping your mate's dick beaters off the rotors as well)
The rear seems better set up than the front, strangely, and also during a rather tough ride the front rotor warped and began squeaking on the pads when pedalling (it was still ok to stop with though)
I couldn't / didn't want to mess with it :as it looked bent as a boxing day turd (or thanksgiving doody if you're in the US) but the bike shop sorted it for me on the first service.
Overall I would still choose these over anything else (just)
Hope's are great looking but seem a bit snatchy on my mates bike.. a cross between these two at the price of Clark's mechanicals would be ideal.

Similar Products Used:

hope minis

Light weight. Ample power. Consistant performance. Supported in N.America by The Brakemeister himself - Thorsten.

Hmmmm......ahhh.....errr.....I can't think of one. I'd probably have to say that it was all the little o-ring seals on the connectors - but they do provide total no seepage sealing.

These brakes rock - nice power, awesome smooth modulation, leak-free operation, great looks and probably above all - their light weight. V-brakes don't have much going for them now that B4's are on the market. V's only had one slight advantage until now - weight - and this is almost non-exsistant now. Cost be damned - I want good brakes.

They are marketed in N.America by Thorsten (formula@khsbicycleparts.com), KHS Bicycle Parts and ThorUSA (all the same company) and their committment is total.

The levers feel very nice, the lines and fittings are sturdy and you have a great selection of rotor sizes for tailoring the brakes for your terrain. They come standard with 160 front and 140 rear rotors plus 185 front, 160 and 185 rear for those who are heavy and ride steep terrain.

Now no-one should complain that they ran out of brakes. The standard brakes (160/140 rotors) are XC brakes for normal people and racers.

I've had my brakes for six months without a problem.

Great brakes - Formula & Thorsten, take a bow!

G. Bob

Similar Products Used:

Magura Louise, Clara, Julie.

superlight, looks killer. Thorsten service.

difficulty dumb-ass bikeshop mechanics have in bleeding them. difficulty getting spares from a bikeshop (tho this is fixed by simply getting the stuff over the web).

All the bikeshops i spoke to had no idea about bleeding these brakes. my bike went back 3 times, they ended up stripping out the little torx screw (plastic version) and inserting a water bottle bolt of all things - like i wasnt going to notice?!. F*ckwits. Bought the upgrade kit from thor in the US to metal screw, new reservoir cap etc, got the bleed nipples etc and did it myself. piece of cake. I'm 85 kg and use my bike for freeride - have absolutely no trouble with power, drag, fade etc - even on long technical downhills, and even with the 4" rear rotor. Anyone who is having trouble should try working on it themselves. The other reviews suggesting these brakes are crap havent put in the effort: besides the formula site; also consider the following sites. http://www.windwave.co.uk/Pages/newsiteformulab4bleedinstructions.htm get the upgrade kit to metal torx screw: http://www.thorusa.com/
if it gives you any perspective - after the bike shop debacle i bought some xt fourpistons from ebay, but after getting the thor kit and bleeding the B4's up, i havent even taken the xt's out of the box. back to ebay for them!
PS formula service is crap, never got a reply from them - go to thor

Similar Products Used:

Hope DH4's
Shimano Deore
Hayes Mag
Hayes HFX

Weight? Handlebar clamps

Cheap plastic parts, lack of US service

In general: They rubbed from when I got the bike - never could get them tuned. When they heated up after short downhills (1-2min) they would squeal for the next 1/2 hour.

Now - about the plastic in the parts:
First - there is some plastic lever retention thing that broke off, so I was running a ghetto-lever with a rubber band keeping it from extending too far.
Then - Hanging it for the winter, all the fluid leaks from another plastic part - the resevoir lid.
Finally - the plastic bleeder screw twisted apart from minimal torque with a torx bit.

I ordered a set of Avid mechanicals today.

Avoid these if you don't have your own personal Itallian mechanic to tune them. I would rather have an extra 50 grams and some metal parts instead of plastic bits.

In all fairness, even though they are junk if they worked when I left for a ride, they still worked at the end of the ride. I was never stranded brakeless, and they always stopped me. For that they get 2 chillis instead of snake-eyes.

light weight, pimpy gold, cute looks

dont use for downhill, because of the light weight build strength starts to dissapear after a while even with new pads

these brakes are ideal for xc but as i have been getting faster at dh and doing higher and faster drops and decents they have been too weak. they have taken a couple of knocks though not bad for an xc brake.

i work in a bike shop (bicyclechain.co.uk) and one of my collegues has successfully mated a b4 caliper with an old hope sport lever WHAT A DIFFERENCE! this improved the power by 200% they now feel like hayes...

Light, powerful, good value

Like all discs need careful set up and 'running in'

Many of the gripes indicate some 'set up' issues, take the time to do it right (same as all discs) and they will reward you with good performance. They are damn light and poweful.

Similar Products Used:

only Vs

Lightweight, cool looks!!

price!

This discs rocks!! they squeal a lot at the beginning but its normal when breaking in... still good enough for the weight @ 700 grams (f/r set)...quality built, encountered little probs at 1st but the shop had good service and was able to help me and set the discs perfectly!!!

Similar Products Used:

Avid Mech discs, Shimano XT

It came on my bike. Light. I like the feel and modulation. Decently durable.

Only decently durable. Little to no support due to it not being a common product.

Great brakes if you're handy and don't mind waiting for parts or the squeeling. I like ther modulation and power, everything I need for XC. Have been working for 3 years (2 racing) will little to no maintenance. I don't mind the squeeling as I don't need to shout to slower riders as I come up on them ;)

Little story about the infamous dogbone. I finally lost mine at the most in opportune time. Race the Rockies adventure race in Canmore. At the top of a mountain. First the piece of plastic the dog bone fits into on the lever broke (age I guess) so teh lever kept falling away. Then it happened to fall away on a rocky section at the top of a mountain and the dogbone fell out and was gone forever. The net result....20 minutes of downhill with the rear brake only, white knuckles, praying to make switchbacks and a right forearm 20% larger by the time I hit the bottom.

Do I recommend these brakes, only if you get a good deal on them, the service network just isn't there. Replacement parts took 4 weeks which is unacceptable. I plan on buying XT hyrdos, hope minis, something to go dual hydro in the next couple months.

Similar Products Used:

None, just V brakes.