Bicycle Mechanics - mounting fenders on non-threaded rear dropouts where nut interferes with small cog

I've switched my commuting frame from a 1980 or 81 Miyata (http://www.unc.edu/~cupery/pics/bikes/Miyata_commuter/) to a 1978 Schwinn Le Tour III. The Miyata head threaded holes in the rear dropouts for mounting a rack or fenders, while the Schwinn has holes but
a) the holes are not threaded
b) the holes are in-line with the rest of the (stamped) dropout, whereas on the Miyata the rack-mounting holes were flared outward from the (forged) dropout.

The problem here is that I can't mount the fender on the Schwinn because of its stamped, non-threaded dropouts. To secure the fender's stays, I need to use a nut to hold the bolt through the hole in the dropouts, and the nut on the drive-side gets in the way of the chain shifting onto the smallest cog of the 5-speed freewheel.
The hole in the dropout is far enough away from the hub's axle that if the chain starts out in the smallest cog it won't bump the nut, but then I couldn't shift out of the small cog (14t) into any of the larger cogs.

But now that it's rained here a couple of times, I really want to mount a traditional fender. I think I could do this using a zip-tie on the drive-side mount and just use the bolt and nut on the non-drive-side.
Any thoughts? Here's pictures of the Schwinn's stamped dropout, to give you a sense of how close the dropout and hole are to the freewheel and to the chain when it's on the small cog.

http://www.unc.edu/~cupery/pics/bike_parts/IMG_6636--LeTour_rear_dropout_back.jpg
http://www.unc.edu/~cupery/pics/bike_parts/IMG_6634--LeTour_rear_dropout_side.jpg
http://www.unc.edu/~cupery/pics/bike_parts/IMG_6632--LeTour_rear_dropout_rear.jpg

I think a ziptie might be your best bet. Or perhaps a p-clip on the seat stay.

The connection probably doesn't have to be that strong, right? How about grinding the head of the bolt down enough so it fits?

Stick the screw in the other way around, so the screw head is on the inside, nut on the outside. A flat-head screw might give better clearance as it will fit partway into the hole. Alternately, a button head screw might work well.

Sheldon "Countersink?" Brown

+-----------------------------------------------------------+
| A pessimist sees the difficulty in every opportunity; |
| an optimist sees the opportunity in every difficulty. |
| -- Sir Winston Churchill |
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Tap the hole?

Is the fender support long enough to allow you to mount the right support using the small bolt helping to secure the derailleur hanger? The right & left supports would be asymmetrical, but it should work.

It looks like a buttonhead bolt might give enough clearance if the nut's on the outside. Or as Sheldon suggests, maybe countersink the hole and use a flat head bolt. But if the buttonhead gives enough clearance, it would be the easiest solution. Here's a link to some pics I found doing a search for "flat head bolts." Check out the pic of the buttonhead bolt: http://www.aaronscapscrews.com/CapScrews.htm

Tap the hole?

noooo thats too easy we want to make it hard...;)

A thin buttonhead works. Grinding a tiny bit off the head works but it rusts quickly.

There's no reason you have to mount your stays to that hole. P clips or home made brackets allow you to attatch anywhere you like.

I think a ziptie might be your best bet. Or perhaps a p-clip on the seat stay.

ziptie ... that's what i do.

ed rader

A thin buttonhead works. Grinding a tiny bit off the head works but it rusts quickly.

Stainless steel screws solve that problem.

Tap the hole?
That's a 1/4" hole. Any bolt size that could be threaded into that hole would be too big for most rack legs or fender stays.

Sheldon "I Thought Of That..." Brown

P.S. Oil your chain!

P.S. Oil your chain!
Yup. I rode to/from church in the rain, twice, on Sunday and haven't re-lubed the chain yet since then. I hadn't noticed how bad it was until looking at the pictures.

Thanks for the advice, all, btw. I'm going to try using a flathead screw (the kind that come with Look cleats will probably be perfect for this, actually) with the nut on outside of the dropout first, and if that's too fat then I'll go with a ziptie.

Tim "I should have thought of these solutions myself" Cupery

That's a 1/4" hole. Any bolt size that could be threaded into that hole would be too big for most rack legs or fender stays.

Sheldon "I Thought Of That..." Brown

P.S. Oil your chain!


Drill out the rack too?

Ive got clearance for a 1/4" hole on mine....I think.. Ill look tommorow

The thin bolt heads are called "pan heads" you can get stainless, metric at the hardware store! You may have to loosen the wheel to get any bolt in from that side. Good luck!

A useful guide (http://www.team.net/www/morgan/tech/bolts/bolts.html)to bolt styles. The panhead one with a screwdriver slot should work.
If you have room on the inside of the dropout, a washer is always useful but if space is limiting, drop it. Use a washer under the bolt, a nylock bolt will not come lose
Put the rack next to the dropout with the fender stay outside to minimise the load on the bolt.

Weld the hole up, dill it out to x mm where x is the size of bolt which will fit the fender, tap the hole. now due to the damge you have done to the paint while welding sand blast the frame, powder coat it to the colour of your choice and rebuild which your well secured fender. OR use a counter sunk bolt inserted from the hub side of the frame.

Weld the hole up, dill it out to x mm where x is the size of bolt which will fit the fender, tap the hole. now due to the damge you have done to the paint while welding sand blast the frame, powder coat it to the colour of your choice and rebuild which your well secured fender. OR use a counter sunk bolt inserted from the hub side of the frame.


^^ This guy is a thinker.

Thats a good call, weld er up and drill er out.

At your corner Ace Hardware store, you can usually find something called a "binder post and screw" assembly, or just a "screw post." They cost next to nothing, and look like this : http://www.screwpost.com/index.php?cPath=O0_1 . They come in various diameters made from aluminum or steel, with threaded posts as short as 1/8".

Thats a steel frame, put an extra spacer on each side on the axle the width of the nut, spred the dropouts and slip it in place. You may need a longer axle though. Putting a spacer on each side will keep the wheel centered.

I used a stainless, button head bolt, inserted 'head-in, threads-out' on my Miyata three-ten, and never had the issue again. I carry too much djunque in a rack trunque to trust the job to a zip tie.

You might also try a (countersunk) cleat bolt and use an oversized drill bit to to countersink the inner bolt hole opening and buy a little more clearance, Clarence.

Weld the hole up, dill it out to x mm where x is the size of bolt which will fit the fender, tap the hole. now due to the damge you have done to the paint while welding sand blast the frame, powder coat it to the colour of your choice and rebuild which your well secured fender. OR use a counter sunk bolt inserted from the hub side of the frame.

if you're dragging out the welder, might as well just weld the fender strut to the frame and get 'er done thataway.

if you're dragging out the welder, might as well just weld the fender strut to the frame and get 'er done thataway.

If you're going to do all that why not just weld up a new frame with better clearance. :D :D

You mentioned the zip tie and it works for my friend Tony:

http://community.livejournal.com/bikepirates/2448378.html#cutid1

He also posts on here as Napalmandroses

At your corner Ace Hardware store, you can usually find something called a "binder post and screw" assembly, or just a "screw post." They cost next to nothing, and look like this : http://www.screwpost.com/index.php?cPath=O0_1 . They come in various diameters made from aluminum or steel, with threaded posts as short as 1/8".

A most elegant solution. mount it from the inside, and it needs only 1/16" clearance for a 1/4" screw post.
http://www.screwpost.com/product_info.php?cPath=1&products_id=3