Disc Rack Mount Clearance

[mrjemm]

Hi all.

I have a frame with disc brakes that I'd like to put a rack on. Yup, we've all heard this one before, and it is one of those troublesome ones with the caliper outside the seat stay... Thing is, it has a rack mounting threaded hole, and I have a rack designed for such set-ups- with spacers built in, but, the hole is right next to a weld, so the spacer cannot sit flush.

All I can think to do, is to file the edge of the spacer on the rack so that it can sit flush to the mount, but I wonder if that would compromise it's strength.

Any thoughts? Thanks, Jem.

[531colin]

That's awkward, isn't it?
The load on the bolt will be down, of course, so you want the bottom half of the spacer in good contact with the dropout, and I think with a stand-off to get the rack past the disc caliper you really want an M6 bolt.
How about drilling a new hole between the existing hole and the caliper bolt? I don't think the rack would be noticeably lop-sided......

[mrjemm]

Thanks Colin. That may be the way to do it, but before I do anything drastic, will keep thinking about this. I suppose in a similar vein I could make the hole in the rack spacer a bit bigger and replace the disc caliper mounting bolt itself.

[531colin]

I think I would like the caliper all alone on its own bolt, but that's instinct rather than engineering!

[mrjemm]

Maybe if I am very careful with a large drillbit, I could perhaps remove some of the weld bead somehow, so it could sit flush as intended.

I think the rack is the Topeak Super Tourist DX, but maybe an older version- http://www.topeak.com/products/Racks/Su ... rRack_disc

[JulesDawes]

I had a similar problem on my wife's bike with the topeak disk rack as well, I filed the corner off the ally rack leg until it fitted, if you do it carefully, a little at a time, you should be able to get a fairly good fit with the weld shape which will aid in the strength department.

She has used the bike and rack for about 18 months loaded with rack top bag and occasional heavy pannier use for work, and has suffered no problems.

Hope this helps.

[Brucey]

what frame is that? Did it always have disc mounts?

BTW the correct tool for dressing that weld bead out is a device known as a burr grinder. You might (eventually) do it with a dremel tool but it would take ages.

I quite like Colin's suggestion of an additional hole, and yes, an M6 would be better if you must use a standoff of some kind.

cheers

[mrjemm]

06 Orange P7 that I've been fiddling with. Yup, I believe it did always have the disc mounts. I'll have a look into burr grinders online.

Thanks for that Jules, may end up doing that.

Don't plan to use it very heavily loaded, but it would be nice to be able to rig it properly. Lots of mounting facilities on the forks though, being Surly Troll ones with many fixtures.

And yes, that's a lady specific Brooks on there at mo, just for the effect really, and to feel if the bars'll work, which feel like they may do better on here than on the Vaya they came off!