Quick check - servicing TRP Spyre mechanical cable disc

[LittleGreyCat]

https://www.trpbrakes.com/userfiles/file/SPYRE_Final_053113%281%29.pdf

This seems to imply that there is one fixed caliper and one floating caliper, although I read somewhere else that the spanky new thing about the Spyre was that it had two floating calipers.

Anyway, although the PDF is not quite as specific as I would like, I think that the following applies:
When first fitting

fit the housing with the bolts still a little loose
fit the wheel
turn the barrel adjuster on the cable fully in
self-align the calipers by pulling on the brake lever and holding it (or do you pull then release?)
tighten up the bolts on the housing
check
fine tune with the barrel adjuster and/or by winding in the pad adjustment screw in the outboard piston
Note: you may have to realign the caliper after moving in the outboard piston, presumably by going back to the top of this list
Fine tuning with the barrel adjuster is OK.

There isn't much guidance on further servicing, just on pad replacement.

I assume that before adjusting the pads by winding in the pad adjustment screw you back off the barrel adjuster on the cable as well as loosening the housing bolts and re-aligning the calipers using the brake lever. However it just doesn't say.

No real guidance on how to check that there is at least 8 mm of pad left - I recall Brucey saying a few words about the lack of wear indicators.

I did look in my trusty Park Tools Blue Book but it doesn't cover this (recent) brand of mechanical disc brakes.

Writing this out to check that my understanding is correct; this helps me with new technology.

As a footnote, how often should a "non mechanically minded" cyclist have disc brakes adjusted by the LBS?

[Brucey]

no need to loosen the caliper mounting bolts when adjusting Spyre/Spyke pads for wear.

SOP is to back off the barrel adjuster, then wind the pads in (both sides, i.e. two adjusters, ideally an equal amount eg 1/4 turn each) so that they are just touching the disc (easy if the wheel is turning with the bike in a workstand). Finally back the pad adjusters out until you have the bite point you want, no rubbing and the disc doesn't flex sideways when the brake is applied.


If the brake doesn't adjust well (with new or worn pads) and the disc is running true, then you may need to realign the caliper body, but if this happens then something has moved; probably the wheel in the frame.

The instructions are poorly worded and the brakes have a few real problems too; one is that the thrust bearings inside each caliper half are pathetically small and not designed/lubricated for the great British weather. Another is that the pad adjustment screws tend to turn by themselves which throws the brake out of adjustment.

cheers

[LittleGreyCat]

Thanks for the prompt response.

I've just been out (Baby, it's cold outside) and checked and there are adjusters on both sides.

So just as well that I posted the details for checking!

I'm assuming that if they turn their toes up it is relatively easy to replace them with BB7s?

[Brucey]

yes very easy to replace them.

Usually the thrust bearings just get rougher and rougher rather than fail altogether. It is also possible to add fresh threadlock to the pad adjusting screws; a fiddly job but it is possible.

NB by the time the thrust bearings are rough, it is too late to do much with them. You can strip the calipers down and regrease the bearings and that at least will stop them from getting much worse, but it is awkward to do and a lot of effort for very little gain. Ask me how I know....

cheers

[awavey]

well Im hopelessly non mechanically minded, but even I managed to replace the pads on the spyres on my bike.so Id say they are dead easy to replace I didnt muck around with the caliper at all, it was just the adjustment screws I had to unscrew far more than Id expected, just because the pads I was replacing were so worn down

[LinusR]

You can strip the calipers down and regrease the bearings and that at least will stop them from getting much worse, but it is awkward to do and a lot of effort for very little gain. Ask me how I know....

Both BB7s and TRP Spyres look like a pain to take apart and put back together.

I note you have a guide for the BB5/7s here https://forum.cyclinguk.org/viewtopic.php?t=118495

And there is a guide for the TRP Spyres here https://singletrackworld.com/forum/topic/psa-trp-spyre-rebuild-guide/

Having gazed at all those bits I'm minded to think that the cheapo hydraulic brakes (Shimano M365) on my MTB are simpler to maintain (fewer parts). Yes? But of course none of these calipers - cable or hydro - are actually serviceable, according to the manufacturers, but they can be stripped for some preventative maintenance.

[Brucey]

BB7 is simpler and more robust inside, is very easy to overhaul by comparison with spyke/spyre, and you can buy spare parts for BB7 too. So BB7 is a clear winner on that basis.

Most hydraulic brakes are bin fodder by the time they start to misbehave; you can't buy the spare parts and/or there are too many places where they are going to leak. A few you can buy spares for, rather fewer is it actually worth the bother. For example Avid and Hayes hydraulics, in UK conditions you are most often on a time consuming, expensive hiding to nothing trying to fix them; the chances are excellent that some part of the brake is so corroded it will always leak fluid.

cheers

[LittleGreyCat]

yes very easy to replace them.

Usually the thrust bearings just get rougher and rougher rather than fail altogether. It is also possible to add fresh threadlock to the pad adjusting screws; a fiddly job but it is possible.

NB by the time the thrust bearings are rough, it is too late to do much with them. You can strip the calipers down and regrease the bearings and that at least will stop them from getting much worse, but it is awkward to do and a lot of effort for very little gain. Ask me how I know....

cheers

Reading this makes me wonder what is involved in getting to the thrust bearings to add grease.

Presumably more than just removing the whole assembly and then the pads.

[Brucey]

Linus posted a link to one of the few online guides to Spyke/Spyre overhaul.

https://singletrackworld.com/forum/topic/psa-trp-spyre-rebuild-guide/

and it is a pretty fair effort. What isn't clear is that the 'spring' is that U shaped piece of steel that pushes against the moving pistons and it requires a mighty force to compress it. I think that you will only get so many goes at springing the actuating arm off the caliper and that the push-in covers which hide the arm fasteners will again probably only work a few times before they just fall out.

FWIW the three balls in the main actuating cam are smaller (and weaker) than those in a BB7 or BB5 caliper. In early model Spyres the balls could run out of the end of the ramps when the pads were worn (leaving you with no brake....); I dunno if this is a possibility with the revised version. But this isn't the worst part; the worst part is the thrust bearing that the moving pistons react against. BB7 is cleverly designed so that it needs no such thing but in the Spyke/Spyre there are two of these bearings (which use miniscule ~1.5mm balls in them) and these bearings run rough when there is the slightest damage to them.

There is sod-all grease in these bearings when the caliper is built in the factory and there is basically no weather protection; on a road bike it is bad enough but Spyke thrust bearings usually start to run rough on many MTBs before the first set of pads is worn out. Given that the stock pads are pathetic this means the bearings are laughable. In the link above the caliper is new. I have never seen one that isn't basically knackered inside. Obviously if you overdo it with the grease it can melt and come out all over the brakes. Another hazard is that the brake pad dust unavoidably mixes with the grease and turns into an abrasive slurry.

Having done both I'd say BB7 is about half as complicated, takes about 1/4 the time to overhaul, and you are about x5 times less likely to find something knackered inside. The only BB7/BB5 part that is routinely troublesome through neglect on a road bike is that the fixed pad adjuster can seize up if not regularly treated.

I suggest that with mechanical disc calipers in daily use, it isn't a bad idea to have a third caliper so that the calipers can be used on rotation, and overhauled off the bike. With organic pads a caliper could be overhauled every second set of pads but with longer lasting sintered pads maybe it would be best if this is done every set of pads.

cheers