tuolumne

I had to through-bolt the rack on my new commuter as the heavy load I usually carry caused the threads to strip on the aluminum rear drop-out. The load is a bit eccentric as this bolt also supports the fender. I currently am using a pan head machine bolt (approximately 1/16" deep head), but this is still too much to allow me to use the smallest cog. Any ideas? Are there any bolts out their with a thinner head. Thanks.

Rowan

You could, perhaps, rethread the hole in the aluminium with a metric tap and use a slightly larger bolt. Taps are pretty cheap. You will, however, have to lubricate the tap as you do it with kerosene.

You might see if the bolt that secures a jockey wheel on a rear derailleur is long enough. Finding the correctly sized nut might be a challenge, however.

AndrewP

Make sure the fender struts are mounted outside the rack.

MichaelW

Maybe put the panhead of the bolt on the inside and use some nylock nuts and washers on the outside over the fender struts.

ridelugs

take off the smallest cog. replace it with a spacer.

cooker

This might be bad advice because I don't know if it would damage your frame, but would it work to put an extra washer on the axle outside the cone locknut on the cassette side (EDIT: or actually, both sides, see next post), so the rear drops are spread a couple of millimeters wider? On a steel frame it wouldn't be a problem.

moxfyre

I'd say that's worth a shot! You would want to put a washer of the same thickness on both sides of the axle, so that you don't mess up the centering of the rear wheel.

On an aluminum frame, I've successfully used a 130 mm hub in 126 mm dropouts for over a year with no problems. Lots of folks doing that. With a steel frame, there's no worry, you could squeeze it open an extra 10 mm (though it would be a pain to get the wheel in and out).

tuolumne

I don't have enough travel in my disc brakes to add a washer. I'm not a huge fan of disc brakes, this bike is fairly new to me. However, I was very glad to have them yesterday in the pouring rain...those will stay. I already have the pan head in as shown. The chain just barely rubs in the smallest gear causing vibration, so I quickly upshift when I forget. Hopefully it won't grab because this gear is only used at high speeds. I would worry about stripping the threads again if I tap it out with the eccentric load. I can't swap the fender to the outside unfortunately. Here's a picture...good ideas so far; maybe someone will come through with something that is feasible. Thanks.
CROP-DSC04467.jpg

Resized_DSC04467.jpg
By the way, how do I upload pics larger than 100kb? Do they need to reside on another web site somewhere? I guess I'm out of luck in that case.

moxfyre

I don't have a good solution for you, I'm afraid. I find that style of rack eyelet to be kind of annoying because it puts the threaded hole so close to the cogs

If you want to put photos larger than 100kb on here, you have to put them on an external site and link to them like this: [img]https://some.site.com/path/to/your/image/file.jpg[ / img]. There are lots of places to get free web space with minimal hassle, e.g. Google Pages or Yahoo Geocities.

Little Darwin

First, I don't see why you can't put the rack inside the fender. And you should always try to put the item exerting the most force closer to the fulcrum (the dropout in this case).

What I would do is to get a flathead bolt and countersink it slightly using a drill or dremel to create the bevel on the inside of the dropout. Just go far enough to clear the chain, and ensure the bolt fits the hole diameter as closely as possible. I would also consider drilling out the hole to accept the next larger bolt while I was at it. For best support, I believe the bolt should not have any play in it... it should just barely slide through the hole.

EDIT, I have seen bolts with very thin heads, but I don't know a source... unless you can find one at the local hardware store, which I assume you have checked.

Rowan

Why don't you feel confident in tapping out the hole to the next sized bolt? It really is a very simple and quite quick procedure.

Little Darwin

Another thing to try... flatten out the pan head with a dremel, file, grinder or sandpaper enough to clear the chain... It doesn't need to be much if the issue now is just some minor rubbing.

mechBgon

You could also countersink the hole from the inboard side, then use a bolt with a cone-shaped head (I forget the proper name for them, but think of the head shape of a typical drywall screw). It would be able to sit completely flush with the inside face of the dropout. Use good strong Grade 8.8 or better bolts if you can.

cooker

You can see that the fender strut runs pretty close to the rack support. It would somehow have to wrap around it to go on the outside.

Grand Bois

That's not a pan head screw, it's a round head screw. A pan head screw has a lower profile and socket button head screw has a lower profile yet:

https://www.boltdepot.com/dimension.a...25&cs=82&cm=19

I wouldn't do anything to the dropout that cound possibly weaken it.

Ray Dockrey

I would try a countersunk machine screw. You can find them about anywhere. Because it is countersunk it will sit further down into the whole. It also has a flat head which should give you further clearance.

AndrewP

You can bend the fender struts around the rack struts just as you have bend them to clear the disc brake. There are lower head bolts available, without resorting to countersunk. You can also use a Dremel or file to lower the head on the side where the chain rubs against it

SerottaK

Take the screw out and file two flat spots so that a wrench can be used to tighten it. Then file the head of the bolt down so it does not interfere with the chain.

tuolumne

Thanks for a host of great ideas. I did file down the head over the weekend and have my gear back. The bends required to get the fender strut on the outside would render it too short to reach the support.

xB_Nutt

You probably don't need this anymore, but if you run across similar problems in the future or just want a source for some great stainless steel metric hardware, these guys are great!
https://www.fastener-express.com/inde...S&Category=297

masiman

If you could find one, this is another idea. Find a set screw to replace your machine screw. You would not have to do any filing. I have only seen them in hex and flat drive but apparently there are other types. You could put the set screw in as flush as you like. I could not tell from your pics if there is a nut in use but I am pretty sure you are using one.

https://www.engineersedge.com/iso_set_screw.htm
https://icrank.com/cgi-bin/pageman/pa...source.htm&t=2

Good Luck