fietsbob

The stationary back pad has to still be close , or you are pushing the disc sideways a lot, to meet it.

spare_wheel

The TRP spyre is not a conventional cable only disc brake -- it is an auto-adjusting dual piston design. The stationary back pad is one of the major flaws of mechanical disc brakes. It results in reduced pad and rotor life and requires constant pad position adjustment.

spare_wheel

Rotors often go out of true due to this deformation. It can be quite annoying if your brakes get a lot of use.

PatrickGSR94

Maybe someone should make a floating caliper design, which is what cars use. One pad is pushed by hydraulic force to meet the inner pad and push it onto the rotor, and that same force also makes the whole caliper slide back a bit so that the outside pulls the outer pad towards the rotor.

Should be as simple as making the bolts holding the caliper to the fork/frame go into greased sliding pins in the caliper.

Although fixed monoblock calipers with pistons on both sides of the rotor are definitely cooler on cars (but more of a pain to work on - twice the bleeding required), I'm not sure which would be easier/cheaper/lighter to implement on a bike - fixed hydraulic with 2 pistons, or floating with a single piston.

fietsbob

'Somebody should' is probably seeking kickstarter Crowd-funding right now , want to invest?

Magura's Gustav is the only single sided hydraulic brake. i've seen, and they are discontinued , now..
all the others are double acting ..

seen Gusset and IRD offering double acting mechanical discs
TRP giving it a go with their Spyre, a double acting Mechanical as well , now..

Chris_W

I don't know what you're talking about regarding the "auto-adjusting" feature of the Spyre - even though both pads move, you'd still have to adjust their location manually to compensate for wear.

Regarding the so-so review that I had read for the Spyre, here it is at BikeRadar.

GeoKrpan

I should have "as close". The difference in "closeness" is enough that noise is eliminated.

GeoKrpan

Someone should make a twin piston, servo action, self adjusting cable disc.

fietsbob

theres that 'you guys should' thing again..

BTW GK, TRP Hy RD is just that. twin piston, cable operated, pad wear self adjusting .. ..



servos, AFAIK need electricity to run, Ala Di2, what happens when there is no power?

spare_wheel

i had though they had some sort of spring mechanism but you are right about the auto-adjust.

PatrickGSR94

"somebody should" is just me throwing an idea around. It's not like I have the knowledge or resources to make it happen.

GeoKrpan

Drum brakes, in cars, use the energy of the rotating wheel to assist the braking, called servo assist. There is no electricity involved.

The OP says the TRP brakes are not a magnitude better than BB7s. I don't think I'd spring for them knowing that there are brakes that ARE a magnitude better.

fietsbob

for those Mystery-science theater 3000 fans
servo was one of the characters . tom servo..
https://en.wikipedia.org/wiki/Mystery...e_Theater_3000

might not be a common Thesaurus having that definition..


I have Scott Peterson SE cantilever brakes on my Camping-Touring Bike
their pads dragging on the rim once contact is made , pulls them further out on a Helical spiral.
coil return spring pushes the brake back up and around the helical core, fixed by bolt,
and friction, to the brake center boss .

They are relatively large and heavy, and on magazine reviewer's bikes ,
they were said to be too effective on the front, Sun Tour made a version of them,
and made it look better , but never made one for mounting ahead of the fork.

they did not sell well ..

as a Worker in Burly Tandem assembly shop, was source for mine .





Magnitude in first order is 10 X... so that would be asking a lot..

evidence of achieving that, would be picking gravel out of your face, I Suppose.

Jimi77

Nice review. Didn't even know these things existed.

PatrickGSR94

eh? I'm not really sure what you're trying to say...

webtwo

My old AMP MTB with AMP discs had a floating design. The brakes were operated by a traditional cable but the caliper had a small fluid reservoir. The entire caliper slid laterally on two pins. The only downside was that they would always leave a tiny amount of pad-rub on one side. If you listened carefully you could hear it squeak as you rode. I believe this happens on cars, but once you surpass a minimal speed, there is no sound. If you lightly squeeze your bicycle disc brakes, they will make noise while you ride slow, but not when you are moving faster.

I think that's why it didn't catch on.

fietsbob

Too bad , yours on your own from now on..

GeoKrpan

Magnitude is being used as a figure of speech, in this case meaning clearly better. I suppose car disc brakes don't have servo assist because they use a power booster for the hydraulic fluid. There's a lot of power in that rotating wheel. I would be great if some clever individual could harness it to increase braking power.

Andy_K 

Important Rain Update

So the rain has started here and I've gotten in a few rides on wet roads and a few in actual rain. Right now, I'm very disappointed in how these brakes are doing in wet conditions.

I think it's just the pads. When I first start riding in the wet conditions, everything's great. The brakes are quiet and performing well. After a while, how long depends on the conditions I think, they start to squeal under hard braking. No news there -- still not as bad as my BB7's were. What happens next though is totally unacceptable. Twice in maybe 6 wet rides I've had the brakes dramatically lose power.

It happened to me Tuesday on the way home. The morning was wet, but they worked OK. When I left work in the evening it was drizzling a bit and the brakes were squealing. A short way up the road I was riding in traffic, the car in front of me came to a sudden stop and I had to swerve to keep from hitting it because the brakes weren't grabbing. Once I was stopped I found that I could actually give the front brake a full squeeze and still push the bike forward and turn the wheel. Not cool! I nervously played with the brakes the rest of the way home (about 10 miles) and it seemed like by the time I got there the problem had worked itself out, like maybe some contaminants had burned off or something.

This morning it was raining as I rode in to work. I used the barrel adjusters to tighten up the cables before leaving the house (350 miles since installation) and coming down the hill from my house they were working great. But as I rode along I noticed that I was losing power. By the time I got to the office, I could push the bike with the front brake applied as above. I'll ride around the parking lot before I leave this evening and see how they're doing, but the forecast is calling for more rain and I don't feel confident about it. That's not supposed to happen with disc brakes!

Anyway, I plan to order new pads this weekend. Any body have any recommendations for Deore-compatible pads that do well in wet weather?

kingsqueak

You might have picked up some oil or diesel fuel from road water along the way.

Also, dumb question, but are you sure your cables didn't slip?

dynaryder

That's weird. If your pads are contaminated,then your brakes either shouldn't work right at all,or the contamination should have burned off and they'd be back to normal. It doesn't make any sense for them to be intermittent like that.

Any possibility that there could be leakage? Like maybe some brake fluid is leaking out then getting burned off? I'd pull the calipers and give them a close inspection. Also prolly wouldn't hurt to thoroughly clean the rotors and maybe pull the pads and give them a light sanding to clean the surfaces.

Andy_K 

I'm still at work, but I'm considering the possibility that this is user error. I was checking the TRP sight and apparently the barrel adjuster is mostly decorative (my interpretation -- they say it's for fine tuning cable tension). They say that if you turn the barrel adjuster more than 1.5 turns it will close off the hydraulic system and prevent it from adjusting for pad wear. So my theory is that maybe I had it mostly closed off before and by working the brakes neurotically I was able to squeeze enough fluid through to temporarily fix the problem but then today I inadvertantly shut it off completely and the brakes wore down enough in 10 miles to kill their performance.

If that's the case I'd still be shocked at the speed of the pad wear, but I guess sloppy conditions can do that. It does make more sense than my previous theory that the pads were getting contaminated somehow but then that was being corrected by repeated braking.

I completely tightened down the barrel adjusters and pumped the brakes a few times. If things work well on the way home, I'll slap myself and then post an update.

spare_wheel

I wore through 3-4 organic pads each year before I switched to sintered. I use the serfas ones which can be bought for $8-10 on sale.

Andy_K 

It ended up not raining on the way home, so I can't say anything 100% decisive, but the brakes were great (and quiet). I decided to go ahead and slap myself, and instead of new pads I'm ordering a cat-o-nine-tails for further self-scourging.

Andy_K 

So another day, another bit of dissatisfaction. The roads were wet this morning and it rained heavily on the way home. Braking response ranging from pretty good to scary bad. By the time I got home I was fixated on the idea that the levers were bottoming out.

Basically, I was getting to the point where the lever was making physical contact with my bar tape before the pads started to grab. Even when these brakes were brand new they required quite a bit of pull to get the brakes to engage, which was one of the reasons for my snafu with the barrel adjuster. Running out of lever movement, however, just seemed unacceptable, so I went back to the TRP website and looked for any scrap of information on what I could be doing wrong. Watching their installation video, I found something, and it's the barrel adjusters again!

So here's the scoop. The brakes have a little "lock-out" screw that fixes the actuating arm in place so you can tighten the cable. The TRP site says that this screw is the test for whether the hydraulic system is open or not. If you can't screw it in, then the system is closed and the pads won't self-adjust for wear. However, cable tension is apparently a pretty big deal. So what the video says you need to do is while you have the locking screw in the locked position, and after you've tightened the cable anchor screw, you use the barrel adjuster to increase the cable tension until there is no play in the brakes levers.

So I did that. Now the lever stops because the brake pads are fully engaged, not because they're hitting the handlebar. They're close to the handlebar, maybe 3-5mm from bottoming out, but at least that's not the limiting factor anymore.

I'm still not convinced these pads are going to be good in the rain, but the pads have plenty of "life" left in them. So I'll try it again tomorrow and see how things work now.