disc brake caliper rubbing against spokes

[Brucey]

if you just want more power there are lots of ways of achieving this;

in no particular order, you can:

1) Increase the MA of your braking system.
2) Use friction material with a higher coefficient of friction.
3) Increase the disc size
4) Lower any parasitic losses between the brake lever and the brake caliper.

Note that increasing the pad size is not on my list because it isn't really guaranteed to do anything.

[Cyckelgalen]

Thanks Brucey, that sounds pretty conclusive, and consistent with Cyclotheorist's experience upthread, no difference between the Hayes and the Spyres despite the latter having pads twice as big (and dual piston actuation)

Gaining some MA would require swapping levers, I use brake-only Tektro RL340, which seem fine. Different levers may open another can of worms, cable pull compatibility etc.
Not sure that my fork or chainstay can take more tan 160 mm discs, It's a Trek 520 with a steel fork.
The easiest way to go is 4), upgrading to compressionless housing.

Hayes CX are very fine, simple single-piston brakes. These type of brakes have all the moving parts outboard of the rotor and not likely to rub on the spokes on any wheel. Nothing wrong with sticking to these more basic type of cable brakes, since the hyped double piston design (Spyres/Spykes) doesn't seem to have any additional benefits.

[Brucey]

there are very few bikes where a 160mm disc can't be traded for a 180mm one and a simple adaptor is all that is required to revise the caliper position.

[AndyB1]

I also have a Spyke front calliper that is close to the spokes - but how close is too close?
The bike is a steel framed tourer with 26 inch wheels, a shimano HB-M525A hub, stainless spokes about 1.9mm diameter, all pretty standard stuff.
The spoke / calliper gap is 1.5mm.
Absolutely no problems over 3000 miles, but is this gap big enough?

One fix I am trying with the Spykes is to use blue hylomar jointing compound on the 3mm adjusting screws that kept backing off. Hylomar stays gooey so I hope it will still keep the screws in position after any adjustments. All OK so far after the initial adjustments and 400 miles. From new the screws had locktite but once they were adjusted this loosened off so was useless.

[Brucey]

I think you can use PTFE tape on those pesky screws. I also think that blue hylomar might not survive if the brakes get really hot.

[Cyclothesist]

I think you can use PTFE tape on those pesky screws. I also think that blue hylomar might not survive if the brakes get really hot.

Does that work on the Spyre pad adjuster threads too? So far I've not had a problem with them but there are a lot of reports of them becoming too loose to hold their position once the threadlock gives up. Another thought is to drill and tap a threaded hole in the caliper to take a locking grub screw, but that may not be practical or a good idea. I'm hoping the PTFE tape is a goer here.

[AndyB1]

Hylomar is rated up to 250C, I do not know how hot brakes get? If rated to 250C it will be OK to a bit higher.

I do know I could not successfully wrap the 3mm adjusting screws in PTFE tape - dental floss maybe?

Same adjusting screws and same problem on Spyres and Spykes - I think their only difference is the cable pull required.

But how small can the spoke / calliper gap be???

[Brucey]

i think the adjusting screws are indeed the same between spykes and spyres. Good luck with the PTFE tape!

[JohnR]

The spoke / calliper gap is 1.5mm.
Absolutely no problems over 3000 miles, but is this gap big enough?

I would say that it is. What's going to change to reduce it and cause the spokes to hit the caliper? IIRC, I've got a wheel where I used 1mm thick washers to move the rotor out because the spokes were rubbing on a Spyke caliper.

[AndyB1]

Good point JohnR - the gap SHOULD not change…….except on the day when the stars align, the front bearings are a little loose and the forks and wheel flex as I hit a bump!

[Brucey]

I would have said 1.5mm is more than enough for most folk. 'A miss is as good as a mile' they say.....Also, I would expect your RD to be closer to the spokes than that, in bottom gear. Normally, there are clear signs of intermittent contact before anything really serious occurs. If you want more clearance without moving the disc, selective use of bladed spokes may do it.

[AndyB1]

A rear wheel lock up worries me much less than something in the front wheel, but I think you and JohnR are right and 1.5mm is enough.

A friend face planted a couple of weeks ago, not cycling, but the damage to his face has made me think how I can avoid a similar accident when cycling. Assessing possible dangers by TEM (Threat and Error Management) may seem a bit wacky but the basics are that once you see something that might be dangerous you then assess if it actually is a threat, and if so work out how to best deal with it.

[AndyB1]

TRP who make the Spyke callipers say the minimum gap is 1.0 - 1.5mm. I had not told them what the gap was on my bike.

The Hylomar is still holding the adjusting screws steady. I tweaked one screw a hundred miles ago and it felt nicely stiff and has not come loose. I guess at brake pad replacement time I will just clean the screws and apply another match head of Hylomar.

[Cyclothesist]

You've TRP and Brucey saying the same for minimum clearance so that's reassuring.
Hylomar has a few products. Which one are you using?

[AndyB1]

Yes, good that thoughts agree on this.

Hylomar Universal Blue non setting jointing compound. Rated to 250C (PTFE tape rated to 260C).
Last time I bought any it came from Halfords.
In the past I have used it on metal - metal joints, eg motorbike rocker covers.
But please make your own decision about using it.