Author Topic: New wheel build - spokes rubbing disc caliper!  (Read 286 times)

New wheel build - spokes rubbing disc caliper!
« on: 06 August, 2022, 02:27:01 pm »
Just built a replacement new wheel 32 hole 700c Andra 321 disc rim, Sapim race spokes and a Kasai FS-FK5D 6 bolt thru axle dynamo hub

The outer spokes are lightly brushing against the Tektro hydraulic disc caliper ??? Spokes laced as per Shimano recommendation for front disc wheels - ie trailing/pulling spokes laying on the inside of the flange, leading/pushing spokes on the outside. The wheel is perfectly centred.

The Kasai hub measures 27mm from the axle end to the centre of the 70mm dia. flange.

The original wheel with no name hub measures 30mm from the axle end to the centre of the 56mm dia. flange - and unsurprisingly there was no rub and sufficient space between caliper and spokes.

Both hubs measure 10mm from the axle end to the disc flange face.

Before I ring Spa Cycles (who supplied the hub), any thoughts from the "panel"?

Kim

  • Timelord
Re: New wheel build - spokes rubbing disc caliper!
« Reply #1 on: 06 August, 2022, 03:25:53 pm »
Is the caliper centred on the disc?

Re: New wheel build - spokes rubbing disc caliper!
« Reply #2 on: 06 August, 2022, 03:32:03 pm »
I presume the spokes are laced - outer passes inside the inner on the last crossing.

Re: New wheel build - spokes rubbing disc caliper!
« Reply #3 on: 06 August, 2022, 04:13:16 pm »
Is the caliper centred on the disc?

Yes, when the new wheel was inserted the caliper was slackened and recentred - and done again to make sure :thumbsup:

I presume the spokes are laced - outer passes inside the inner on the last crossing.

Yep, 3X standard lacing, outers under 3rd inner

LittleWheelsandBig

  • Whimsy Rider
Re: New wheel build - spokes rubbing disc caliper!
« Reply #4 on: 06 August, 2022, 04:36:41 pm »
Shim the disc outwards a shade and reposition the caliper?
https://www.chainreactioncycles.com/mobile/hope-disc-brake-caliper-shims/rp-prod356
Wheel meet again, don't know where, don't know when...

Re: New wheel build - spokes rubbing disc caliper!
« Reply #5 on: 06 August, 2022, 05:27:55 pm »
Just measured the distance between the spokes on the 7 mile 'old' original wheel, and the caliper body ~4.8mm  :thumbsup: No worries there even with wheel flex.

Ok, the flange is smaller diameter 56mm as opposed the Kasai 70mm and the Kasai flange is 3mm nearer to the axle end. With both wheels the disc is perfectly centred in the caliper.

Shim the disc outwards a shade and reposition the caliper?
https://www.chainreactioncycles.com/mobile/hope-disc-brake-caliper-shims/rp-prod356

There's not a great deal of lateral adjustment of the caliper if I add some shims to the rotor though -

 - what's a safe gap between spokes and caliper?

ps the new wheel has D/B sapim spokes, so the rubbing area in question is in the thinner section of the spoke. The original cheapo wheel are plain gauge.


LittleWheelsandBig

  • Whimsy Rider
Re: New wheel build - spokes rubbing disc caliper!
« Reply #6 on: 06 August, 2022, 05:32:25 pm »
Provided the spokes don’t tinkle against the caliper while braking, cornering or riding straight, I don’t care what the clearance is. Generally 0.5-1.0mm clearance at rest is enough but YMMV. Does the spoke lacing move inwards or outwards when braking? Inwards is obviously best.
Wheel meet again, don't know where, don't know when...

Re: New wheel build - spokes rubbing disc caliper!
« Reply #7 on: 06 August, 2022, 06:51:36 pm »
Shim the disc outwards a shade and reposition the caliper?
https://www.chainreactioncycles.com/mobile/hope-disc-brake-caliper-shims/rp-prod356

Thanks Dave :thumbsup:  Spacers of all flavours ordered - as that seems to be the only option with this Kasai hub, this Tektro caliper and these front forks combo? Fingers crossed.

This is my first bike with disc brakes - and having built many scores of 'old skool' rim brake wheels, never had an unusual tolerance issue like this. And I can't help being grumpy and frustrated very occasionally. Not to mention spending £134 on a hub that might not? fit these particular forks/brakes combo ::-) Do I need to add habitual catastrophisation being a problem too ;)




LittleWheelsandBig

  • Whimsy Rider
Re: New wheel build - spokes rubbing disc caliper!
« Reply #8 on: 06 August, 2022, 07:46:12 pm »
Don’t forget disc size amongst your list. Sufficient clearance for a specific disc diameter might foul a different disc diameter.
Wheel meet again, don't know where, don't know when...

Re: New wheel build - spokes rubbing disc caliper!
« Reply #9 on: 06 August, 2022, 07:50:41 pm »
Don’t forget disc size amongst your list. Sufficient clearance for a specific disc diameter might foul a different disc diameter.

Aaaarrghh :hand:

Re: New wheel build - spokes rubbing disc caliper!
« Reply #10 on: Today at 03:45:53 pm »
Well, there was little clearance to play with there!

I had some 1.2mm washers and tried them yesterday = the rotor bolts fouled the inside of the fork 🤔

3 x packets of different thickness Hope shim washers just arrived from ChainReaction. The 0.8mm just means the domed bolt heads don't foul the forks and the spokes are ~1.5mm away from the caliper.

There is another packet of 0.25mm shim washers, but they come in packets of 10, so not enough to double up to 0.5mm - which would probably give equal-ish clearances. I'll order anther packet methinks.

I'm surprised at how tight these tolerances can be - admittedly between different manufacturers' components. Google suggests spokes hitting calipers is far from rare and probably asking for it if using large-ish flanged dyno hubs?

Heigh-ho fingers crossed all will now be well in Slope's new modern thru axle, carbon forked, disc braked biycle world with all black components :-\

Many thanks for your advices and inputs :thumbsup: