PMK

At the present time, and this will likely not change, there is no need for my stoker to have brake control. Her task is based on navigation and power output, along with having fun.

BTW, as good as Magura rim brakes are, when you run them with close tolerances on the rim clearance, the expanding fluid will bring the brake blocks closer causing rub on the rim. Possibly in extreme heat cases it could drag and / or lock up the wheel.

PK

fietsbob

guess I'm too slow to matter, so Im fine with them, could do a disc conversion,

all the mounts are there .

but when I got a Bike Friday, Pocket Llama, it has the discs on it ,
so the need went away..

which, Red Herring, is completely Un necessary, you dont have to set them up so damn close .

twocicle

My initial feedback regarding the TRP Spyre:

I received a TRP Spyre Alloy (non-SLC) yesterday. I ordered it via Amazon due to a better price than TRP direct. The TRP guy I spoke to claimed there was no way to order just the caliper or swap their smaller rotors for extra pads, etc, so I saw no need to pay $23 higher price + $6 shipping = $29 more from TRP than via Amazon.

Caliper weighed 158gm on my scale. With the mounting bolts, 170gm. The Avid BB7 with CPS washers and the longer mounting bolt required for that setup weighs 204gm. Diff equals a mere 34gm weight savings with this TRP. The Carbon TRP is only a few grams lighter, and as Ritterview found out perhaps the Carbon arm durability is suspect. TRP told me it was user error due to no front brake engaged! Shall we say SCAPEGOAT?!

As I already had a 203mm mount adapter from Avid (used with the BB7), I did not order another from TRP ($10 + shipping). The guy at TRP said the height of my adapter may be different, but AFAIK, Avid's is a Intl. Std. size and so I left it at that. Avid product catalog lists the same adapter part for either direct mount or CPS type calipers. Part #00 .5318.009.004 - "IS Bracket - 60 IS (Rear 200) Includes Stainless Bracket Mounting Bolts", so not sure what TRP was talking about. Hmmm, a running theme it seems.

On a positive note, the Spyre actuator arm spring seems quite strong, so this should provide a good feel at the captain's brake lever. If not, I will install a spring-over-wire helper as done many years ago on a weaker Avid model.

---

Next, is more about the 203mm Hope Sawtooth Floating Rotor since it was mentioned earlier in this thread.

This Sawtooth rotor has large rivets that sit very close to the braking surface area. With a Avid BB7 purchased in the last two years, the rivets on the rotor hit not just the pad tabs, but also the caliper body. Easy enough to break off the pad tabs, that works ok but the caliper body requires more work. Researching this online I found that many people have had to file down their BB7 caliper body in order to fit this rotor.

With the Spyre + Hope floating rotor, the pads clear ok, but again the rivets hit the caliper immediately beside the rearmost post mount. That would be an easier file job that the BB7, but still ends up being a caliper modification in order to use the Hope floating rotor.

Quality of the rotor was also suspect as it was not perfectly round, with a noticable high spot that prevented rotation through the Avid BB7. Also, the braking surface area is quite small top to bottom... IMO, too small for heavy use. IMHO, it is not worth trying to use this rotor with a TRP or Avid caliper. I returned the rotor whence it came.

If you want to use a Hope Rotor, I suggest the V2 instead. The rivets are much lower and not a factor, plus the brake surface area is larger. A vented rotor (2-ply) would be too thick and not fit between the Spyre pads.

mikebian 

So I just ordered the HY/RD for the rear wheel of my tandem. I bought a Shimano ice tec 203 rotor to go with it. Anyone have any thoughts on this? I am replacing a dura ace rim brake with this setup. What was the issue you had with the brake that you were thinking of adding an assist spring?

thanks

akexpress 

There is a lot of info in this tread about the Hy/Rd. My experience in a nut shell is the return spring in the hydraulic cylinder is not strong enough to fully retract a tandem length cable so the reservoir does not refill completely every time. This causes the system to not allow for pad wear on a long descent. You end up with minimal brakes at the end as the lever through is not long in the HY/Rd. Us and at least 3 others I know of have melted the aluminum core out of a Shimano Ice tec rotor. This combo may work well for normal riding but it is not up the task of long steep descents IMHO.

fietsbob

Sachs . years ago, showed a hydraulic brake line , the far end returned to be, functionally, a cable.

never actually saw one, in person, closed systems are so simple , as no heat needs be disbursed..
potentially a master cylinder on one end ,a hose and a slave cylinder on the other .
fittings on either end as if a cable .. multiply power by the cylinder size differential .

saw years ago in the Hostel Bike shed , while on tour, a hydraulic cantilever hybrid.
the slave cylinder pushed the transverse cable Up, actuating a conventional brake on the fork blades.

twocicle

Update to post #203 above.

Just for kicks, I picked up a 203mm Hope V2 Floating 2 Piece Rotor via Amazon. This one weighs 210gm which is some 30gm heavier than the Sawtooth (which failed my install test due to the rivet location being too close to the braking surface). For weight comparison: the XT RT86 ICE rotor w/the unique retention ring bits is 175gm, and the Avid G2 rotor I have on hand is 230gm.

The Hope V2 rotor has more arm/rivet clearance than the ICE rotor, and so no issue with hitting the disc caliper body of either the Spyre or BB7 (also misses the lollipop arms on the Avid pads). It may be the best option... doesn't melt or warp, and has large braking surface area.



Akexpress (Mark) has/had it installed with a TRP HyRd caliper as shown below. Perhaps more feedback from him:

Rambetter

I have found this thread to be fully worthwhile; I think I've read or at least skimmed every post.

Just found this linked from the TRP website: https://www.trpbrakes.com/userfiles/f...%20Rev%20B.pdf
It's regarding the issues described previously with the HYRD brakes.

Rambetter

Question regarding TRP Spyre from someone who has never worked on disc brakes before.

Is the 160mm Spyre package compatible with the rear of a tandem? (Seems from some literature that 160mm is front only, 140mm being for the rear, but I don't believe that.)

My frame is pictured below, and I'm seeing to it that all cable stops, the wheel/hub, and any other interface is correct.

Chris_W

TRP are only saying that you shouldn't use a 140mm rotor as a front brake. All other sizes are OK. The limiting factor for larger sizes is normally just frame/fork clearance. For a tandem, you should use as large a rotor as possible.

Sixty Fiver

As builders of tandems this is the kind of information I like to read... we are always looking to improve our product and have a bit of an obsession with brakes.

The boss is a big guy and is almost a small tandem team all by himself so his obsession with brakes is well justified.

justcrankn

You should get a 200/203 mm rotor- the largest that will fit in the frame.

Rambetter

Thanks. For the sake of simplicity, I ordered a 160 mm packaged TRP Spyre brake/disc.
Since I will be using this as a drag brake (actuated via down tube shift lever), and thus rarely so, I plan on just trying the 160 and seeing how it goes.
But I will keep the 200 mm in the back of my mind.

fietsbob

If your frame takes Any ISO disc mounting Bracket for a 200 ish mm disc,

then you can put the Spyre on it.

Chris_W

160mm would be too small when used as a regular brake on a tandem. The situation will only get worse when it's used as a drag brake (which I wouldn't advise anyway). Get the 200/203 mm rotor and the adaptor bracket, and don't even try it with a 160mm rotor, or it won't be worth the effort of putting it on - you'll cook that baby REAL fast.

Rambetter

My current plan of action is to use the 160mm that comes with the Spyre, and have that as a backup brake actuated via bar end brake lever.
Thanks for all the advice.
Still not sure if all the parts needed will come with the Spyre 160mm package (brackets for frame mounting).
If I went with a 200, the clear choice based on the info gained in this thread would be the Hope floating model - with that route what are all the additional parts I would need (for the frame mounting) besides what's in the Spyre package and in the Hope rotor package? I already have the wheel hub situation and actuating interface accounted for.

scycheng

Why would you want to use a rotor which is known to be suboptimal as a backup brake?

If you need to use the disk brake because your rim brake is smoking, a smaller rotor like a 160mm rotor will be smoking very quickly also. We've warped our one piece no-name 200mm steel rotor coming off a small pass in the mountains. Don't even want to think what would happen with a 160mm rotor.

akexpress 

I have set my HY/RD up multiple times like this however the spring in the caliper is just not strong enough to fully retract the actuator on a tandem length cable. My cable run is very good with quality compression less housing and new cables so that is not the problem. I also think for some reason the problem is exasperated as the caliper heats up. The problem is that if they system does not retract fully every time the piston position does not allow for pad wear and the brake becomes useless. Bike brake calipers use a square seal on the piston that when functioning correctly slowly moves the piston toward the pad as the pads wear to keep the braking the same as pads wear. This is one advantage of a hydraulic system over mechanical if all is functioning correctly.
the Hope V2 floating rotor 203mm is now my rotor of choice. I have gotten it very hot and it does get noisy but it quickly quiets down as it cools and has never warped. I now have them on 3 tandems all with good results. IMHO anything less then 200mm is looking for trouble on a tandem, especially with only one disc brake however your results may be different.
Mark

fietsbob

OK Spyre, after using Avid BB7 or ... another versus comparison

as I see advantage to the Avid

is every small internal part is in the QBP catalog , if needed

folks like the TRP ones Better ?

twocicle

The reason you see so many BB7 small parts in the catalog is because those parts have needed to be replaced for one reason or another (ie: lost, broken, melted...).

Conversely, the only Spyre parts you should need to replace are the pads, and since those are replacable with any Shimano Deore M525/M515 compatible pad, finding spares is not a problem. Plus the Spyre has dual pistons to push the pads from both sides vs. 1 piston on the Avid. It's still a relatively new brake, so time will tell how it holds up over the long term and heavy "abuse" by some teams.

waynesulak

When the diameter of a circle is changed many people misjudge the dramatic increase in volume or circumference.

160mm diameter circle has a circumference of about 502 (160*3.14)
200mm diameter circle has a circumference of about 628 (200*3.14)
That is a 25% increase in brake surface area at the edge of the disk.
In addition there is an increase in leverage with a larger disk.

and kids tell the geometry teacher they will never use that stuff!

fietsbob

I'm talking the dealer's catalogs, Im not a computer programmer.

Campagnolo used to ship a little display case with
a ring bound catalog number 17 on the customer side ,

and a lot of small parts drawers on the shopkeeper's side,

and nobody in C&V disses the Campag stuff for having had spare parts available.



BTW in the shop we dont bother , just replace the whole thing, it's the Shimano Way.
from their site:
Oregon Coast, the orignal pads have to go immediately..


Ill ask again in a couple years , since the TRP stuff is just out this year. No time in service.

Chris_W

I'm not sure how that helps - the circumference is a linear function of the diameter, so the relative difference is the same (200 = 1.25 x 160 and 628 = 1.25 * 502). I would expect that heat dissipation from the surface is also a linear function of surface area, and leverage tends to be a linear function too, I believe. So where is the non-linearity that makes the 200mm rotor more than 25% better than the 160mm? I also have a feeling that there should be one there somewhere, but I'm not sure where.

Rambetter

The area of a disc increases with the square of the radius (so non linear).
But in the above statement, by "disc" I mean a mathematical concept. Like a frisbee without a hole.

But there are two reasons why such a mathematical statement might not be relevant.
First, the contact area width with the brake pad (what length along the radius the brake pad touches) stays the same.
Second, with most discs the center section has arms so is mostly hollow (so the surface area does not increase with the square).

But of course the braking surface area still seems to increase linearly with the radius, as does the leverage. Note that the speed of the metal disc flying next to the pads also increases linearly. I think the speed/leverage cancel each other out. Perhaps only important if leverage is really too small. Probably heat dissipation is the really important concern.

waynesulak

My response was intended to point out that increasing the disk size may be more beneficial than expected:

Increasing the diameter by 20% increases the circumference by more than 20% or approx 25%. Many people do not expect this and would think a 20% increase in circumference to result from a 20% increase in diameter. Those people with some math background find this relationship intuitive but I have run into many that do not.

I believe that since the interior of the disk is not involved the circumference is a good indicator of the mass available to store heat. If we were concerned about solid disks then the area of the disk and not the circumference would be relevant and the change more dramatic.