Author Topic: Decent cable disc brake callipers for Shimano STI levers  (Read 2504 times)

Decent cable disc brake callipers for Shimano STI levers
« on: May 07, 2019, 07:17:50 pm »
On my "touring" bike I have Shimano 105 5800 drop bar levers* and Shimano BR-R317 callipers. These suck for the following reasons:

- If you adjust them so they don't rub, the biting point for braking has the lever almost touching the bars
- The cable adjuster screw is too short, meaning any adjustment normally requires moving the cable bolt along the cable, sometimes more than once.
- Moving the cable bolt requires fighting against the very strong return spring on the calliper, with nowhere much to push it shut by while you tighten the bolt, meaning bloodied fingers.
- When you've got it all set up, braking performance is *generously* described as adequate.
- Every couple of hundred km you find the lever is touching the bars and you have to do the whole readjustment dance again.
- The bolt that holds the pads in can't be removed without disconnecting the cable.

All I want is braking performance comparable to rim brakes on the same levers. Do other brands' callipers work better? How does braking performance of HY-RDs compare, especially to real hydraulics?

I'll accept regular readjustment if I can get the biting point earlier in the stroke and/or better braking.

(* actually the left one is a 4703, because every cool kid needs a 33-speed bike)

mcshroom

  • Mushroom
Re: Decent cable disc brake callipers for Shimano STI levers
« Reply #1 on: May 07, 2019, 07:52:30 pm »
My Genesis has TRP Spyre brakes with 4700 levers. The braking isn't as good as the hydraulic discs on my MTB, but they feel decent to me, and I haven't had to adjust them anything like as often as you've had to.

How straight are your discs? Are the warped at all?
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robgul

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Re: Decent cable disc brake callipers for Shimano STI levers
« Reply #2 on: May 07, 2019, 07:56:11 pm »
I'd agree on the TRP Spyre brakes - I've fitted them to a couple of bikes I've built and they are pretty effective with the Shimano levers .... not quite as good as hydraulic BUT much less to go wrong!

Rob

Re: Decent cable disc brake callipers for Shimano STI levers
« Reply #3 on: May 07, 2019, 08:11:29 pm »
I too have Spyres on my road bike and haven't adjusted them in last 1100km if audaxes. They are due now. You can adjust them with a 3mm hex up to a point before you'd need to reclamp cable. Be aware that as they are dual caliper they can foul your front wheel spokes if you run a dynamo hub etc. I run a 160mm rotor and it needed a small bit of initial fettling to avoid spoke fouling.

I am more than happy with the braking , far better than my old rim brakes particularly in the wet. Plus I am no longer going through rims on a bi-annual basis.

My recumbent has the same brakes as well, work great.

Re: Decent cable disc brake callipers for Shimano STI levers
« Reply #4 on: May 07, 2019, 08:39:49 pm »
How straight are your discs? Are the warped at all?

Straight enough to not rub in the hydraulics on my other bike.

I'm not sure I'd grokked that double-sided mechanical callipers were a thing. The Shimanos are single-sided, which must play a big part in their finickiness.

Re: Decent cable disc brake callipers for Shimano STI levers
« Reply #5 on: May 07, 2019, 09:28:27 pm »
HyRds work OK but the bite point is usually about half way through the lever stroke and it often can't be adjusted to be less.  If you go about adjusting  them in the wrong way you will lose the "self adjusting as pads wear" facility and you will soon be left with no brake at all.  If you have a rear chainstay mounted caliper then water can very easily sit on the back of the MC piston and from there it will almost certainly  work its way into the hydraulic system.  Calipers of this type I have inspected internally have often been contaminated with swarf from the factory and contaminated with water in service.


Spyres are a nice idea but imperfectly executed;  however the notion that if both pads move the brake is intrinsically more powerful is a CoS. Furthermore the internal mechanism is a lot more complicated than it needs to be, and is not at all well protected from the weather; calipers that are used in all weathers soon develop rough-running bearings. The pad adjusting screws tend to work loose; they are only deterred from rotating by a small smear of blue threadlock and that doesn't work after a few adjustments.

BB7 ain't perfect either but works OK in practice, and the (simple) mechanism is easy to overhaul.  Pauls Klampers are worth a mention; they are available in three versions, one of which has an MA that is optimised for shimano STIs with NSSLR cable pull.

FWIW in your shoes I would

a) fit an inline cable adjuster
b) fit better quality/better lubed cables
c) ensure that the inline barrel adjuster had enough travel that I could unhook the cable from a slotted guide, or back off the adjsutement fully, thus facilitating adjustment/pad changes without disturbing the pinch bolt
d) fit better quality pads (eg sintered)
e) use a dial gauge to double check disc run-out.
f) double check the security of the hubs in the dropouts
g) check the disc mount is properly aligned and face it if necessary.

FWIW if the caliper and/or  pads can't articulate (and I think BR-R317 is like this) then a small misalignment will make the brakes terrible when new (hard-wearing) pads are fitted. It also seems to make the brake disc run out of true more easily than it would otherwise. It can even affect brake power after the pads have bedded in.


BTW apologies if this is obvious, but if the wheels use conventional axles/QRs it is quite likely that the axles can move slightly in the dropouts under heavy braking; this is only prevented by using internal cam or 'security' type skewers and even then they need to be bloody tight. If the axles are moving around even slightly, one common symptom is that the brakes rub almost incessantly  despite true-running discs and constant readjustment of the brakes.

One scheme I am thinking of trying with conventional  mechanical discs (using a symmetric pad ideally) is to use a hard wearing sintered pad on the 'fixed' side and to use a softer organic pad on the moving side. This may give the best of both worlds braking-wise, and may allow routine (mid-ride) adustments via the barrel adjuster only, since the fixed pad will be wearing at a fraction of the normal rate.

Most single-sided 'road' calipers allow the moving piston to move ~2mm if the total arm throw is used. Provided the initial setup is good and the  barrel adjusters allow enough cable travel, 2mm ought to be enough to allow the pads to be used up (whilst adjusting the fixed pad and barrel adjuster as necessary, without fiddling with the pinch bolt); most pads/brakes allow for (at most) ~1.5mm wear on the moving pad.

One more thing; if you temporarily (over) adjust the fixed pad inwards and use a fourth hand tool on the cable, you can set the cable in the pinch bolt quite easily, to give exactly the bite point you want on the brakes. Most fixed pad adjusters have a 1mm pitch on the threads, so backing the FPA out 1/4 turn gives 0.25mm clearance. The moving pad can be similarly calibrated so that the running clearance can be set accurately without a lot of trial and error.

cheers

zigzag

  • unfuckwithable
Re: Decent cable disc brake callipers for Shimano STI levers
« Reply #6 on: May 08, 2019, 10:49:24 am »
i've used these calipers with tiagra shifters/levers last year and did not have any of the issues described. rode about 4000km on them including sandy off-road and in the alps and they performed very well, the only attention required was to adjust the pads every ~500km, which was a 30s job. i have a suspicion they are not set up correctly, therefore giving the problems you describe. cables need to be cut(ground) square and lubed, brake pads have to be totally parallel to the rotor, rotors must be true etc.

Kim

  • Timelord
Re: Decent cable disc brake callipers for Shimano STI levers
« Reply #7 on: May 08, 2019, 06:42:29 pm »
One scheme I am thinking of trying with conventional  mechanical discs (using a symmetric pad ideally) is to use a hard wearing sintered pad on the 'fixed' side and to use a softer organic pad on the moving side. This may give the best of both worlds braking-wise, and may allow routine (mid-ride) adustments via the barrel adjuster only, since the fixed pad will be wearing at a fraction of the normal rate.

I encountered a BSO brake that employed a similar scheme:  Proper organic-looking pad on the moving side, and a simple piece of metal on the fixed side.  It worked appallingly, as you might expect, but it did technically stop the bike.

IME, the moving pad gets the bulk of the wear anyway, as light braking is performed against the flex of the disc.  Possibly an argument for the other way round?

(An advantage of the BB7 design is that pad wear adjustment is separate from cable adjustment.  Once the cable is bedded in, you pretty much never need to fiddle with it.)
Careful, Kim. Your sarcasm's showing...

Re: Decent cable disc brake callipers for Shimano STI levers
« Reply #8 on: May 08, 2019, 07:31:27 pm »
it doesn't take much load to cause the disc to flex ~0.25mm sideways so the difference in the pad wear in a well-adjusted brake is (IME) slight in most mechanical calipers. Maybe if you don't keep up with regular adjustments (thus forcing the disc to deflect further/with more force before the brake comes on properly), and/or   use centrelock discs (which are often laterally stiffer) things are different?

FWIW one of the brakes with the most 'brake on' disc deflection I have seen in recent times was a TRP spyre; the pad adjusters wouldn't stay put and the bike's owner had left them long enough that the disc got pushed over 1mm sideways when the brake was applied....

The attraction of having a hard-wearing pad on the fixed side is of most benefit in brakes that don't have a moving pad adjuster, only a barrel adjuster and a fixed pad adjuster.  Such brakes include many basic (but functional) models and includes models from Hayes, Promax, the OPs shimanos, and Avid  BB5,  which I have several examples of. I'd go as far as to say if you get a bike with OEM mechanical disc brakes on it, it is most likely that they will be of this type.   Being able to adjust the brake using a barrel adjuster on or near the handlebar, mid ride, is a fairly attractive proposition.

cheers

Torslanda

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Re: Decent cable disc brake callipers for Shimano STI levers
« Reply #9 on: May 09, 2019, 10:24:42 pm »
Quote
I encountered a BSO brake that employed a similar scheme

I have, once or twice.

In one case it was because 'me dad's a mechanic' and had assembled the brake with the pad inside out and in the other the pads were so worn that the friction material had gone completely and the fixed 'pad' was just the backing...
VELOMANCER

Well that's the more blunt way of putting it but as usual he's dead right.

Kim

  • Timelord
Re: Decent cable disc brake callipers for Shimano STI levers
« Reply #10 on: May 10, 2019, 12:33:54 am »
Quote
I encountered a BSO brake that employed a similar scheme

I have, once or twice.

In one case it was because 'me dad's a mechanic' and had assembled the brake with the pad inside out and in the other the pads were so worn that the friction material had gone completely and the fixed 'pad' was just the backing...

This didn't have a pad at all.  Just a flat-faced disc of metal with a thread on it for twiddling in and out - which I initially assumed meant that the pad was AWOL - but there didn't seem to be any obvious method of retaining it (perhaps explaining why it was AWOL?).  TBH, it went in the bin too quickly to give the matter proper investigation, as there was a Tektro IO with a seized adjuster just sitting in my spares box begging to be upgraded to.
Careful, Kim. Your sarcasm's showing...

Re: Decent cable disc brake callipers for Shimano STI levers
« Reply #11 on: May 10, 2019, 07:30:12 am »
confession; after years of disregarding them (mainly because of the bikes they are usually attached to),  I have actually developed a slight soft spot for the Tektro IO brake.  The reason for this is that having just assumed that they usually  worked reasonably well by accident (they appeared to have little in the way of features to allow misalignment tolerance) I actually bothered to take one apart and look at it carefully. 

 To my surprise I found that both pad seatings have a well-designed articulation which allows a couple of degrees of movement, and the position of the virtual centre of rotation and the breakaway torque  are such that the pads are unlikely to articulate accidentally. I've seen much posher brakes with worse arrangements.

The brakes are of course imperfect in other ways but (IMHO) there isn't such a thing as a perfect mechanical disc brake and there are workarounds for most of these other shortcomings.

One of the things I intend to experiment with is a revised cable mount (e.g. the other side of the pinch bolt) and running them with NSSLR levers. 

cheers

S2L

Re: Decent cable disc brake callipers for Shimano STI levers
« Reply #12 on: May 10, 2019, 08:35:13 am »
I've tried most of the cable operated disc calipers... the most convincing were the Juin Tech R1, which are semi hydraulic... easiest to set up and adjust for pad wear, best braking action and competitive price.
Never really got on with the HyRD and whilst Spyre are good, I find they tend to seize fairly easily if not constantly cleaned and maintained. BBR7 are very average and Hayes are crap

Re: Decent cable disc brake callipers for Shimano STI levers
« Reply #13 on: May 10, 2019, 08:46:33 am »
its worth noting that 'road' disc calipers fall into two main categories; older designs (which are designed for the 'old' cable pull) and newer designs (with slightly higher MA) which are meant to be compatible with NSSLR cable pull.

Some of the older designs can feel very wooden when paired with current shimano STIs (which have NSSLR cable pull). Others have MA to spare, and are OK provided the rest of the system is well maintained.   If you try and use some more recent designs of caliper with 'old' levers (which includes all current SRAM and campag road levers) you can get a very powerful brake but it may come with other problems like reduced running clearance late bite point, constant readjustment required, etc

In terms of brake power, provided the caliper MA is about right, and the pads are OK/bedded in, most brakes can be adequate. The differences lie in the detail of modulation and how easy the brake is to live with in the long run.

cheers

Re: Decent cable disc brake callipers for Shimano STI levers
« Reply #14 on: May 10, 2019, 10:56:42 am »
confession; after years of disregarding them (mainly because of the bikes they are usually attached to),  I have actually developed a slight soft spot for the Tektro IO brake.  The reason for this is that having just assumed that they usually  worked reasonably well by accident (they appeared to have little in the way of features to allow misalignment tolerance) I actually bothered to take one apart and look at it carefully. 

 To my surprise I found that both pad seatings have a well-designed articulation which allows a couple of degrees of movement, and the position of the virtual centre of rotation and the breakaway torque  are such that the pads are unlikely to articulate accidentally. I've seen much posher brakes with worse arrangements.

The brakes are of course imperfect in other ways but (IMHO) there isn't such a thing as a perfect mechanical disc brake and there are workarounds for most of these other shortcomings.

One of the things I intend to experiment with is a revised cable mount (e.g. the other side of the pinch bolt) and running them with NSSLR levers. 

cheers

The failing I had (still have) with the IO is that the body is too fat to fit onto an ISO-PM adaptor, at least for 160mm. Other than that I liked it but it was my first disc brake and I am easily pleased (it went on a PM fork).

Re: Decent cable disc brake callipers for Shimano STI levers
« Reply #15 on: May 10, 2019, 12:38:17 pm »
It can be done but I think the adaptor is a special one



because there is more clearance, at the rear there is no problem and at the front there is no problem for larger discs, but for 160mm disc at the front you need a slim adaptor

cheers

quixoticgeek

  • Mostly Harmless
Re: Decent cable disc brake callipers for Shimano STI levers
« Reply #16 on: May 10, 2019, 05:08:21 pm »

I've done about 16Mm with my TRP Spyre's now, and had you asked me 2 weeks and 2Mm ago, I'd have recommended them with out hesitation as being excellent.

However, the last couple of weeks has changed this slightly.

The stock pads that come with the bike are much better than any after market pad I've tried so far (nuke proof and uber bike so far). Despite bedding them in, the nuke proof pads I put on just before RatN, were pretty useless. Things improved a little once I degreased the rotor at 860km, but they were never great. At about 1450km, I backed off both pad adjust screws, loosened both bolts holding the caliper, grabbed a big handful of break lever, then tightened the bolts, then adjusted the pad adjust screws, effectively doing the standard procedure when you fit the brake. This helped a little, but again, not great. I basically did the whole of RatN with only a front break. Limburg was rather more exciting than I'd like...


Until I fitted the new pads, they have been brilliant. You need to know to adjust the pads as they wear, but that's really easy if you carry the right tool (I carry a 3mm allen key just for this).

J
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FifeingEejit

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Re: Decent cable disc brake callipers for Shimano STI levers
« Reply #17 on: May 10, 2019, 06:31:07 pm »
Pads appear to be the old Shimano M515 pad pattern, and looking at the list on Uber's site all TRP pads appear to be copies of Shimano patterns.

TRP list Semi-Metallic and Metallic compounds on their website.
Which compounds did you get the Nukeproof and Uber pads in?

I note that they don't list the TRP ones as Road Disc Pads; compounds aimed at the more constant application and higher temperature usage of MTB riding?

Re: Decent cable disc brake callipers for Shimano STI levers
« Reply #18 on: May 10, 2019, 11:15:38 pm »
the other possibility is that, over time, the cables and/or  internal mechanism of the brake calipers have gone bad, thus making any replacement pads seem somewhat underwhelming.

 FWIW the internal mechanism in spyres contains x10 more balls than BB5/BB7 and it is vulnerable to corrosion, not being weatherproofed in any way whatsoever.

cheers

S2L

Re: Decent cable disc brake callipers for Shimano STI levers
« Reply #19 on: May 11, 2019, 07:09:56 am »


 FWIW the internal mechanism in spyres contains x10 more balls than BB5/BB7 and it is vulnerable to corrosion, not being weatherproofed in any way whatsoever.

cheers

True... the bearing gets notchy fairly rapidly

Re: Decent cable disc brake callipers for Shimano STI levers
« Reply #20 on: May 11, 2019, 11:16:07 am »
Two winters have killed my TRP Spyke, now needs frequent adjustment and feels rough.  Not sure what to replace it with, I like the BB7's on another bike but the TRP's fit better with the rack. I haven't noticed any braking difference between them.

S2L

Re: Decent cable disc brake callipers for Shimano STI levers
« Reply #21 on: May 11, 2019, 03:33:15 pm »
Two winters have killed my TRP Spyke, now needs frequent adjustment and feels rough.  Not sure what to replace it with, I like the BB7's on another bike but the TRP's fit better with the rack. I haven't noticed any braking difference between them.

Juin Tech R1... little known company, but excellent brakes... I've had them for a couple of years on my all year commuting bike and they've been fit and forget

fboab

  • It's a fecking serious business, riding a bike
Re: Decent cable disc brake callipers for Shimano STI levers
« Reply #22 on: May 11, 2019, 04:44:16 pm »
I need a replacement caliper for the 140mm discs on the front of my 'cross bike. It came with BB5s (shit) I upgraded to BB7s (better) and it currently has Spyres (best- of the 3).
We've been trying to reduce range and are standardising to Spyres across the fleet- but like Phil W the Spyres foul the spokes when I run with a dyno hub. Fettling does not evade the problem- at 140mm I just can't get the caliper away from the spokes.
That Juin Tech R1 has a minimum rotor size of 160mm.

Any other suggestions?
TSS is not Total Sex Score, Chris!

Re: Decent cable disc brake callipers for Shimano STI levers
« Reply #23 on: May 11, 2019, 04:50:09 pm »
are you stuck with 140mm discs then?

cheers

fboab

  • It's a fecking serious business, riding a bike
Re: Decent cable disc brake callipers for Shimano STI levers
« Reply #24 on: May 11, 2019, 04:52:27 pm »
Stuck with 140mm rotor on the front- surely the caliper mount position reflects the rotor size?
TSS is not Total Sex Score, Chris!