TRP Spyre/Spyre SLC

[Gattonero]

It was mentioned upthread that the supposed advantage of dual-piston over single-piston calipers is to avoid the very slight bending of the rotor that occurs with single-piston designs, and that this bending is in fact so slight as to not be a problem. That might be the case but I've never heard it mentioned before. The advantage I have heard claimed for them is that they avoid the slight rubbing that occurs constantly with single-piston designs. The drag from this is probably so small as to be barely measurable let alone noticeable, but the noise certainly is noticeable.

I've always found that the main problem with rubbing in Avid's, is due to the pads not staying perfectly parallel, due to the bad design of the spring.
But it's not a big deal, the brakes themselves are good enough and I don't think you will easily warp the rotor under normal use

[reohn2]

It was mentioned upthread that the supposed advantage of dual-piston over single-piston calipers is to avoid the very slight bending of the rotor that occurs with single-piston designs, and that this bending is in fact so slight as to not be a problem. That might be the case but I've never heard it mentioned before. The advantage I have heard claimed for them is that they avoid the slight rubbing that occurs constantly with single-piston designs. The drag from this is probably so small as to be barely measurable let alone noticeable, but the noise certainly is noticeable.

I've been using Avid BB7's(single piston design) for approx 7 years( five bikes two of which are tandems) and a approx 30K+ miles,my experience is that with an almost(approx 1mm run out) true rotor I can adjust out any rubbing with a bit of free play in the lever.
I've never had any problems stopping with these brakes even on a loaded tandem,in fact they're the best brakes I've ever used on a tandem.
I have a low threshold for squeaks/squeals/ticking or other noises from the bike and have been known to lube the chain mid ride if I felt it was a bit dry

EDIT:-one of the tandems is on 203mm rotors so more potential for running out of true but they need no more attention(which means hardly any at all)than the 160mm rotors on the other bikes.

[Brucey]

possibly you misunderstand the nature of the problem; regardless of what the instructions might say, ...

Excuse me, when have I said this?

I'm not quite sure what you are driving at here; if you misunderstand the nature of the problem, you are hardly likely to say 'I misunderstand the nature of the problem'....?

You say that people cause their own problems due to 'a lack of common sense', and imply that the brake failure so caused ought to be gradual.

Neither thing is the case.

It was mentioned upthread that the supposed advantage of dual-piston over single-piston calipers is to avoid the very slight bending of the rotor that occurs with single-piston designs, and that this bending is in fact so slight as to not be a problem. That might be the case but I've never heard it mentioned before. The advantage I have heard claimed for them is that they avoid the slight rubbing that occurs constantly with single-piston designs. The drag from this is probably so small as to be barely measurable let alone noticeable, but the noise certainly is noticeable.

Regarding the scraping sounds from some disc brakes; these are invariably caused by some combination of bad setup and a slightly warped rotor. Some calipers are certainly worse than others (e.g. because the fixed pad adjustment is awkward, or the pads don't always retract evenly) but the idea that having two moving pads will make a major difference to this simply doesn't bear close scrutiny.

When the brake is on, hard, the pads are pushed against the disc with a very large force (several thousand Newtons). The force required to displace the disc sideways by the running clearance (~0.2mm say) towards a fixed pad is a fraction of one percent of this, and this deflection is nowhere near enough to cause even a very hot disc to 'take a set' in that direction. [For example if you want to true a disc, it is usually necessary to push the disc edge about x30 to x50 more than this...].

Similarly the disc assumes a slight angle through the caliper if it is so deflected; however this is very slight indeed, about 0.2 degrees. This means that even a disc with a wide (~20mm) brake track will only be skewed by about 0.06mm top to bottom. in practice the pads soon accommodate to this slight angle and the loss of running clearance is negligible.

Looking at it from another perspective, regardless of various blandishments, hype and journalistic BS, it ought to be obvious that a mechanical caliper with two moving pads is not a perfect compromise, or at least doesn't give a significant advantage over other types; if that were the case, there would be many more such brakes on the market. As it is, there are dozens of brakes with fixed pads vs a tiny number with two moving pads.

BTW regardless of brake type, the #1 thing that causes rotors to warp in use is that they are badly made to start with. IIRC some makes (e.g. Hope) use accurate machining and a proper stress-relief heat treatment on their discs, which is why they tend to work better than the usual cheap crap you might otherwise buy.

cheers

[Gattonero]

possibly you misunderstand the nature of the problem; regardless of what the instructions might say, ...

Excuse me, when have I said this?

I'm not quite sure what you are driving at here; if you misunderstand the nature of the problem, you are hardly likely to say 'I misunderstand the nature of the problem'....?

You say that people cause their own problems due to 'a lack of common sense', and imply that the brake failure so caused ought to be gradual.

Neither thing is the case.

...

I have not misunderstood the nature of the problem, because the "problem" is how the brake works: you cannot expect a brake, whether is a disk or rim brake, to work indefinitely without adjustment.
Given that the Spyres can push the pistons only up to a certain extent, and this does happen gradually, it can only be user error. The brake pads don't wear overnight.
There is a constraint of cable pull ration and action of the arm in the caliper, this cannot go at will to give the user "complete maintenance free". The pads must be adjusted, this is not a "failure" of the design.

[Bmblbzzz]

possibly you misunderstand the nature of the problem; regardless of what the instructions might say, ...

Excuse me, when have I said this?

I'm not quite sure what you are driving at here; if you misunderstand the nature of the problem, you are hardly likely to say 'I misunderstand the nature of the problem'....?

You say that people cause their own problems due to 'a lack of common sense', and imply that the brake failure so caused ought to be gradual.

Neither thing is the case.

It was mentioned upthread that the supposed advantage of dual-piston over single-piston calipers is to avoid the very slight bending of the rotor that occurs with single-piston designs, and that this bending is in fact so slight as to not be a problem. That might be the case but I've never heard it mentioned before. The advantage I have heard claimed for them is that they avoid the slight rubbing that occurs constantly with single-piston designs. The drag from this is probably so small as to be barely measurable let alone noticeable, but the noise certainly is noticeable.

Regarding the scraping sounds from some disc brakes; these are invariably caused by some combination of bad setup and a slightly warped rotor. Some calipers are certainly worse than others (e.g. because the fixed pad adjustment is awkward, or the pads don't always retract evenly) but the idea that having two moving pads will make a major difference to this simply doesn't bear close scrutiny.

When the brake is on, hard, the pads are pushed against the disc with a very large force (several thousand Newtons). The force required to displace the disc sideways by the running clearance (~0.2mm say) towards a fixed pad is a fraction of one percent of this, and this deflection is nowhere near enough to cause even a very hot disc to 'take a set' in that direction. [For example if you want to true a disc, it is usually necessary to push the disc edge about x30 to x50 more than this...].

Similarly the disc assumes a slight angle through the caliper if it is so deflected; however this is very slight indeed, about 0.2 degrees. This means that even a disc with a wide (~20mm) brake track will only be skewed by about 0.06mm top to bottom. in practice the pads soon accommodate to this slight angle and the loss of running clearance is negligible.

Looking at it from another perspective, regardless of various blandishments, hype and journalistic BS, it ought to be obvious that a mechanical caliper with two moving pads is not a perfect compromise, or at least doesn't give a significant advantage over other types; if that were the case, there would be many more such brakes on the market. As it is, there are dozens of brakes with fixed pads vs a tiny number with two moving pads.

BTW regardless of brake type, the #1 thing that causes rotors to warp in use is that they are badly made to start with. IIRC some makes (e.g. Hope) use accurate machining and a proper stress-relief heat treatment on their discs, which is why they tend to work better than the usual cheap crap you might otherwise buy.

cheers

So thanks for the engineering facts. The marketing theory is completely different. What the marketers say, that I've heard (not from TRP specifically but around disc brakes in general) has not been about rotor displacement but about the immobility of the fixed piston, or rather its pad. As for the prevalence of single-piston designs, this if anything works in the marketers' favour; when you hear someone's discs rubbing, they are probably single-piston!

Of course it's not really individual cyclists that the manufacturers need to convince but the big manufacturers, as by far the bulk of their sales are OEM. In this regard, what matters is what Trek, Giant et al can be persuaded the world believes, or will believe next year! TRP's Spyres seem to be doing very well this year but that might be down to such mundanities as price and delivery of course.

[Brucey]

..... The pads must be adjusted, this is not a "failure" of the design.

I don't entirely disagree with you, but I do think that many of these designs are extremely poor. Dangerous, even. Plenty of people have been caught out by the various issues that arise, and there have been product recalls. Type b) behaviour (cropping up part way through the pad life in many cases) is pretty much unforgiveable, and is a sudden failure mode. Type a) behaviour can be sudden too, depending on how stiff the cable housings are and how fast the pads wear; you can have good brakes at the top of a hill and no brakes by the bottom.

At one time I had BB5 calipers on both an MTB and a Road bike. Just at the point where the BB5(MTN) caliper works best, the BB5(Road) caliper arm is about to stop dead in its tracks, leaving you with no brakes! There is no indication on the outside of the caliper that this is the case.... this is just plain daft!

there are lots of things you could do, for example

1) you could make is obvious where the arm stops by incorporating a stop in the caliper body, perhaps with a rubber buffer or something. [This would make it comparable to a V-brake, where if it is set badly or the pads wear, the yoke hits the pinch bolt, which is easily seen and understood.] Or

2) part of the caliper body that is usually covered by the arm could be painted bright red or something, so that when the arm is reaching the end of its travel, there is a visible indication that this is happening before it causes trouble.

3) [less related to this particular issue] Many brake pads have locating tangs on them, that protrude from the caliper body. I think that it should be mandatory for the caliper design to be such that it allows the pad wear to be viewed directly, but failing that, there is no reason why the tangs shouldn't be set so that when the pads are worn, the protruding tang ends will touch one another, giving a clear indication of pad wear.

When it comes to making things safe, one of the yardsticks used is to see if the people involved have acted 'reasonably' or not. This means that your approach ought to compare well with that used by others, and furthermore if there are things that you could easily do to improve things, you ought to do them. So (for example) if you make the least safe brake on the market, that could easily be improved upon, you may be deemed not to have acted 'reasonably' in failing to improve it. Judged by this yardstick, the makers of very many disc brake calipers could be viewed as having behaved 'unreasonably' IMHO.

cheers

[reohn2]

........ As for the prevalence of single-piston designs, this if anything works in the marketers' favour; when you hear someone's discs rubbing, they are probably single-piston!

But that's down to bad adjustment/maintenance,not the fault of the brake design.

TRP's Spyres seem to be doing very well this year but that might be down to such mundanities as price and delivery of course.

More than likely,and to probably make a dent in other manufacturers share of the market.
TBH it's no coincidence that Avid BB7's are regarded as probably the best cable disc brake on the market .

[Bmblbzzz]

Yes, it probably is largely down to poor adjustment or maintenance but TBH I think that is the result of bad design. The internet is full of people complaining about how hard it is to properly adjust their brakes. This applies to all sorts of brakes, not just disc brakes; anecdotally, cantis would seem to be the hardest. An awful lot of people find it difficult, fiddly, or non-obvious to adjust their brakes so that they work effectively, don't rub, wear evenly, etc. The only ones you don't hear any complaints about are drums and those Magura hydraulic rim brakes, which is probably because they're uncommon in Britain. Definitely something manufacturers should take on board.

[Brucey]

regarding drum brakes; I happen to think that SA drum brakes are pretty good pieces of kit. Not perfect, but pretty darned good. The designs that are presently made were originally refined to meet the needs of the post office, i.e. that they should cope with daily postie-use for several years without wearing out or needing constant fettling.

Before the post office went barking mad and stopped using bicycles, there would be at least 30000 bicycles that were in all-day, all weather use with such brakes; if there was an inherent problem with them, it would be known about!

It is a shame that if you go looking for bikes with such brakes fitted, it is difficult to find one that isn't made of gas pipe and comes with a bunch of other parts that you mightn't want. It isn't as if the brakes themselves are especially heavy, or would make the bikes to which they are fitted slow and unwieldy, yet that is how most such bikes are... all somewhat mysterious!

By comparison, using disc brakes (of almost any kind) for utility work would seem to be 'a bad idea'; probably you are just setting yourself up for an amount of unnecessary aggro in return for brakes that (on a good day, in the right weather, correct phase of the moon etc) might work slightly better....

cheers

[reohn2]

Yes, it probably is largely down to poor adjustment or maintenance but TBH I think that is the result of bad design. The internet is full of people complaining about how hard it is to properly adjust their brakes. This applies to all sorts of brakes, not just disc brakes; anecdotally, cantis would seem to be the hardest. An awful lot of people find it difficult, fiddly, or non-obvious to adjust their brakes so that they work effectively, don't rub, wear evenly, etc. The only ones you don't hear any complaints about are drums and those Magura hydraulic rim brakes, which is probably because they're uncommon in Britain. Definitely something manufacturers should take on board.

I don't think for one minute it's bad design.
IMO a lot of people don't take the trouble to learn how to maintain things,brakes are just one.
It's never been easier for someone with even a modicum of mechanical application with the aid of Youtube to learn how to maintain a bicycle,but in a throw away society people seem to expect lifetime trouble free use,then buy a new one.If people were as addicted to maintenance as they are to shopping their bikes would be much better.
When I use to fit UPVC windows and doors I always made a point before leaving the job,of explaining that the locking systems(particularly the three hook bolt door locks),needed lubing from time to time even showing the customer where and how by demonstration.
If I got a call back it in the first two or three weeks it was always the hinges needing slight adjustment after settling in,which was my job.
If the call came after a few months or longer it was always a lack of lubrication which I always attended but explained they needed periodic lubrication easily done with WD40.
I'm convinced some people look at something mechanical and just cover their eyes in fear and call 'someone who knows what they're doing' or pretend it'll heal itself and use it anyway until it breaks.
My SinL's Marin,which is used to commute lmost daily in all weathers,and has low end Promax Render discs.
I service the bike when he thinks it's either not stopping as it should or it's 'making funny noises',the chain is always drier than a dry thing in the desert in summer,little or no maintenance is the norm with this bike.
But the brakes do stop it surprisingly well even when the levers(drops) are almost touching the 'bars and the pads almost down to the backing .
I've just serviced it and fitted new pads so he'll need telling about how good they'll be when rides it and there's little free play in the levers.

[reohn2]

By comparison, using disc brakes (of almost any kind) for utility work would seem to be 'a bad idea'; probably you are just setting yourself up for an amount of unnecessary aggro in return for brakes that (on a good day, in the right weather, correct phase of the moon etc) might work slightly better....

cheers

Our Cannondale tandem fitted with BB7's/203mm rotors,for the first three or four years of use it was the winter tandem and saw regular use in all weathers,after particularly wet /mucky rides it was hosed down and and lubed(chain mechs and brake adjusters)with TF2 and GT85,which normally took all of 10minutes.
I've never had brakes that needed so little maintenance or attention,it's that bike that sold me on discs.
I've never had drums so can't comment but I've absolutely no complaints about discs.

[Brucey]

The promax render is a good case in point; this is an MTB caliper, not unlike a BB5 in most respects. Similarly there is another model 'promax render R' for road bikes which will be subject to the issues that I have previously described. I don't know which behaviour a render R caliper will manifest exactly, but it is unlikely that it will be type c). If you were used to the MTB model, you might well set the R model up in such a way as it would work only for a very short period of time before becoming dangerous.

I agree many people don't set their bikes up properly but there is definitely an element of bad design in many of these systems.

cheers

[Brucey]

Our Cannondale tandem fitted with BB7's/203mm rotors...it's that bike that sold me on discs.
I've never had drums so can't comment but I've absolutely no complaints about discs.

tandems are a different kettle of fish, but how many miles and how many rides was that, do you think? IME it doesn't matter if you do a day ride or a single commute, the amount of salty crud that gets thrown on a bike in the winter is about the same.

The only ways found to stop bikes from dissolving in winter commuting were to

1) wash my bike every ride (fine for a leisure machine, a PITA otherwise) or
2) to lather everything in waxoyl or similar.

Commuting bikes are used, abused, (not washed every ride!), parked carelessly, knocked about by other folk whilst parked... In these conditions disc brakes go wrong all the time. LBS scrap bins are (relative to the number in use) full of disc brake parts from bikes where the brakes stopped working properly for some stupid reason or other. By contrast drum brake failures are very rare.

cheers

[reohn2]

The promax render is a good case in point; this is an MTB caliper, not unlike a BB5 in most respects. Similarly there is another model 'promax render R' for road bikes which will be subject to the issues that I have previously described. I don't know which behaviour a render R caliper will manifest exactly, but it is unlikely that it will be type c). If you were used to the MTB model, you might well set the R model up in such a way as it would work only for a very short period of time before becoming dangerous.

I agree many people don't set their bikes up properly but there is definitely an element of bad design in many of these systems.

cheers

SinL's are the R model (drops,Shimano 9sp Tiagra STI's)

[reohn2]

tandems are a different kettle of fish, but how many miles and how many rides was that, do you think? IME it doesn't matter if you do a day ride or a single commute, the amount of salty crud that gets thrown on a bike in the winter is about the same.

Twice a week minimum regular,between 300 and 400 miles per month.

The only ways found to stop bikes from dissolving in winter commuting were to

1) wash my bike every ride (fine for a leisure machine, a PITA otherwise) or
2) to lather everything in waxoyl or similar.

Agreed,as a good regime.

Commuting bikes are used, abused, (not washed every ride!), parked carelessly, knocked about by other folk whilst parked... In these conditions disc brakes go wrong all the time. LBS scrap bins are (relative to the number in use) full of disc brake parts from bikes where the brakes stopped working properly for some stupid reason or other. By contrast drum brake failures are very rare.

cheers

Both SinL's who commute regularly by bike don't do maintenance very well if at all(I do it ),both bikes are filthy when I get hold of them once every two to three months,both bikes* do a 7 mile each way flat commute,one has the Promax discs,the other has V's,off those two examples I know which I'd chose,it wouldn't be V's.
TBH salt doesn't seem to be a problem,when I wash the bikes off other than scratches to the frame and scuffs to pedals,etc their bikes come up quite nice.
As i said up thread for that application I've no experience of drums but I suspect they'd be much better from a low maintenance POV

*A Dawes Discovery 601 the other's a Marin don't know the model but it's a mid range CX model