Originally Posted by
Trevtassie
Are we talking the same BB7 here?
The one with a fixed caliper and adjustments for both pads because one piston is not floating? The one were the moving pad distorts the disc over on to the fixed pad, ie there's NO floating piston in the BB7, not even a floating caliper, which is what a single piston disc brake should have.
You seem so sure about that I'm assuming you've taken apart a BB7. So you know about the floating pad contact piece that isn't attached to anything and is thus floating? Piston, contact piece, serves the same purpose. It allows for slight change in pad orientation making better pad contact.
And the CPS washers that the Spyke doesn't need, because it's not a single piston fixed caliper, so it doesn't wear the disc unevenly and thus doesn't need CPS washers (best you send a strongly worded email to Shimano and ask them why the don't supply CPS washers with their twin piston calipers?) The set up instructions for the Spyke are: Loosely fit caliper, adjust each adjusting screw evenly with a 3mm allen key, to get the pads close to the disc, tighten the cable adjuster to lock on the caliper, tighten mounting bolts, loosen cable. That's it, by design, like all twin piston calipers, the body is already in alignment with the disc. A hell of a lot less than trying to align a BB7, especially with worn pads and discs, where you need to decide which pad you are going align parallel with the worn disc surface, which will always have a slight taper because the caliper and psitons are fixed and the disc flexes.
That's not what the CPS washers are for and honestly all mechanic disc brake systems could benefit from them if the caliper mounting surfaces have not been machined to spec after you bough the frame / bike.
Also with BB7 you always align the non moving pad with the rotor since the moving has a floating piece in there which allows for the pad to contact the rotor evenly. If the BB7 has been adjusted properly so that there's almost non perceptible bending of the rotor when brakes are engaged the pads or the disc should not wear unevenly. In all my years of BB7 use have I ever seen an unevenly worn rotor. Maybe if one were to use the soft shimano rotors with metallic pads (which one should not do) could that perhaps happen.
Furthermore BB7's are set and forget until the pads have been worn out. Then you replace the pads and you won't have to touch the caliper. But if you do have to take the caliper off for whatever reason align with the non moving pad because that's what happens automatically if you follow the very simple mounting instructions.
It's true that the BB7 does require a click or two every once in a while to adjust the non moving pad towards the rotor. But to me that's as big of a hassle as using a barrel adjuster to adjust spyres, ie. a complete non issue.
And the fact that neither the BB7 or the Spyke have seals on the inside of the piston(s) next to the rotor so both can get water inside easily and both need basic servicing, with the adjuster of the fixed piston of the BB7 regularly seizing up so you need a torx driver to adjust it? The BB7 only has a seal on the outside of the actuating shaft. I'll give you that TRP should put a little more grease on the anti friction ball race from new (which the BB7 doesn't have, thus contributing towards that spongy bending the disc feeling they have) but neither caliper has a way of stopping water from coming in from the disc side and getting into the cam area.
In the case of BB7 it doesn't matter nearly as much whether it has seals on the inside or not. The distance water will have to travel inside a BB7 to reach bearings is longer than with spyres and also less open. I'd also not consider the inside as much of a risk as the outside as there's usually heat evaporating the water getting in. That being said with spyres the inside distance towards the mechanism is shorter than with BB7 and thus a bigger risk. With the spyres the complete mechanism of bearings / sliding surfaces is maybe 2mm from the outside world with a visible gap leading to them with no seals whatsoever. This is on the outside of the brake. So with Spyres there's two viable water ingress ways one of which is extremely viable since it's essentially a gap water can just flow in.
The fixed piston of the BB7 is a bit tight sure, but that's also a blessing since the pad adjuster won't move on its own as with spyre which only uses a flimsy threaded screw.
And did I mention that TRP does not like you taking apart the spyre? Do you carry a full Torx set on tour? I don't. The biggest piece I have is a T30 and the Spyre requires a T40 to do maintenance on. Also a bench vise is recommended. a bb7 opens up with basic tools
As to the spongy disc bendy feel you've experienced with BB7, I wonder whether your BB7's have been properly adjusted. The BB7's I've used (both mountain and road) don't flex the disc all that much since the inside pad rests almost in contact with the rotor so there's maybe 0.1mm of flex when the brake engages. If you search the wide world of the internet the general consensus seems to be that BB7 has a crisp feel whereas the spyre is generally considered to be the spongy brake, which is my experience exactly.
From the point of view of being able upgrade the discs, the BB7 is a dead end in anything other than disc size because it flexes the disc sideways, so no aluminium center rotors. It needs thin flexible discs.
I completely fail to see why this is an issue except maybe in terms of fashion sense. Rotors are also pretty generalized in terms of thickness, but I prefer the thicker ones as they eat more heat than thinner ones.
I have both TRPs and BB7 on my touring bike. TRP on the front and BB7 on the back,and the front was previously a BB7 so I could compare the two, on the same bike under roughly the same conditions (the BB7 had a 160mm disc however). The feel of the TRP is heaps better.
I suppose feel is subjective. I far prefer the crispness of the BB7 over the sponginess of the spyre.