Wheelbuilding - front wheel spokes touching disc calliper

LavaLavaDome

I've built a set of disc brake wheels with dynamo and sapim race spokes. They are 650b. I don't think I've got the bracing right on the front wheel as the nds outbound spokes are touching the brake calliper. I've checked the dish and it's fine. The j bend is slightly standing away from the hub flange.

Any advice on how I can remedy?

Monty Dog

If the interference is marginal / just touching you could try putting spoke washers on the inside of the flange to pull the heads-in a little?

cycleclinic

pics would help alot here. It could be the way you have laced the wheel. I have never had this problem to solve. It will also depend on the caliper . So there could be a number of causes.

svetty

LavaLavaDome wrote:

I've built a set of disc brake wheels with dynamo and sapim race spokes. They are 650b. I don't think I've got the bracing right on the front wheel as the nds outbound spokes are touching the brake calliper. I've checked the dish and it's fine. The j bend is slightly standing away from the hub flange.

Any advice on how I can remedy?

Heads in or out??

Nick Payne

I have two front wheels for my 650b disc bike, one with normal hub (DT Swiss) and the other with a Shutter Precision dynohub. I notice that the spokes on the dynohub run much closer to the disc caliper than on the other hub - they don't actually touch but there is only a fraction of a millimetre clearance (SRAM Force flat mount calipers).

If your spokes are actually hitting the caliper, there are some options:

1. If it's a 6-bolt hub, use some rotor mount shims to move the rotor out from the hub slightly, and move the caliper to suit.
2. Lace that side of the wheel with small blade spokes such as CX-Ray or CN aero424 or equivalent - the spokes being only 0.9mm thick where they cross will gain you some additional clearance.
3. Build the wheel with all the spokes on the caliper side being heads-out.

LavaLavaDome

Hi guys, thank you for your responses. I've gone back to this. My problem seems to be with the J bends not sitting flat on the hub flanges. The front is an SP Dynamo hub with Sapim Race spokes. I've tried to push them flat against the hub flange with a screwdriver. Any advice on how to do this properly would be appreciated and then I can properly tension the wheel. This seems to be the part that I missed out on in wheel building classes! Also, if anyone has experience of building with this hub and spoke combination and usually use spoke washers I'd be interested to know. I would rather not take it apart. I'll post a picture.

LavaLavaDome

Here is a pic: https://imgur.com/9NVtbWD

redvee

Give the spokes a little tension then press down on the rim with the hub supported and you should get some light tinging from the spokes as the tension is relieved, another thing to try to seat the heads better is the use of a soft mallet on the spokes at the hub.

ugo.santalucia

your spokes sit fine... there is clearly an incompatible caliper with your hub

LavaLavaDome

redvee wrote:

Give the spokes a little tension then press down on the rim with the hub supported and you should get some light tinging from the spokes as the tension is relieved, another thing to try to seat the heads better is the use of a soft mallet on the spokes at the hub.

OK - thanks. I have been doing this stress relieving but I don't think I did it enough after every tighten. I did it incrementally last night and I have got the elbows closer to the flange. I am now up to the recommended tension for the rim but the elbows are still slightly away from the flange and the crosses aren't braced properly.

I'm a bit worried about hitting the stokes with a mallet. I do need to do something though as I need to get the spokes up to tension

LavaLavaDome

ugo.santalucia wrote:

your spokes sit fine... there is clearly an incompatible caliper with your hub

It's TRP Spyre. They work great with another set of wheels I've got so I don't want to change them, if possible. The hub is SP Dynamo. I really hope that I can get them to work together.

ugo.santalucia

LavaLavaDome wrote:

ugo.santalucia wrote:

your spokes sit fine... there is clearly an incompatible caliper with your hub

It's TRP Spyre. They work great with another set of wheels I've got so I don't want to change them, if possible. The hub is SP Dynamo. I really hope that I can get them to work together.

Not uncommon with the spyre... double piston make them wider... it was an issue already 5 years ago

g00se

What size rotors are you using? Just a layman on this but I'm wondering if you are using 140s where 160s may move the callipers further away?

LavaLavaDome

g00se wrote:

What size rotors are you using? Just a layman on this but I'm wondering if you are using 140s where 160s may move the callipers further away?

160

LavaLavaDome

I'm making good progress, I think. I won't get a chance to do them properly and refit them to the bike until Wednesday or Friday, unfortunately. I want to get the shoulders flat against the flanges so that my caliper fits properly without the need to shim the disc. I'm going to try the soft mallet technique. Thanks for all the replies and help.

LavaLavaDome

https://imgur.com/a/fC5E6

LavaLavaDome

Just to update you and for anyone else struggling with this problem, it is all sorted. No shims or re-lacing wheels needed. I moved the dish ever so slightly (rim to the right) and gave spokes more tension. Slightly more than recommended by the rim manufacturer but I think they will bed down. I've been out on various rides and checked the true of both wheels and they have stayed true and there doesn't seem to be any flexing and no spokes hitting the caliper. I'm really chuffed with the wheels and they feel great to ride. This was a great project and really satisfying to finish it. Thanks for all your suggestions and help. Appreciated.

timothyw

You can work around this with the spyres by turning the outboard pad adjuster in a few turns before mounting the caliper (and ensuring that the inboard adjuster is all the way out).

You might struggle if the pads are very new.

Difficult concept to explain, but the idea is to move the point at which the pads meet towards the wheel (and so move the body of the caliper away from the spokes).

You can also work around this by using a asymmetric rim of the type commonly used on rear wheels - this will move the spokes slightly away from the rotor and give better spoke balance as a bonus.

LavaLavaDome

TimothyW wrote:

You can work around this with the spyres by turning the outboard pad adjuster in a few turns before mounting the caliper (and ensuring that the inboard adjuster is all the way out).

You might struggle if the pads are very new.

Difficult concept to explain, but the idea is to move the point at which the pads meet towards the wheel (and so move the body of the caliper away from the spokes).

You can also work around this by using a asymmetric rim of the type commonly used on rear wheels - this will move the spokes slightly away from the rotor and give better spoke balance as a bonus.

I tried everything with the spyres, including shims and spacers -moving the caliper slightly away from the fork, adjusting the pads etc. I wasn't happy with any of the results and found the solution with the wheel.

Great advice on rim type. If I build another disc dynamo I'll definitely look into this and look into slimmer spokes. This build is for a light tourer so I wanted solid spokes so I was a bit scuppered. I'm not up for lacing the wheel in a different pattern with all inbound spokes, particularly for this build, so this option was out.

Thanks for your suggestions.