Cartridge Bottom Brackets from Harris Cyclery

The bike I usually have here at the shop is an older Giant OCR Elite, set up as a single speed with a White Industries ENO Eccentric Hub. With the hub rotated upwards, and with the shorter replacement fork I have installed, it uses short reach brakes, rather than the usual spec medium reach.  With 25mm tires, there’s not enough clearance for a normal fender under the rear brake.  Another problem is the lack of a chainstay bridge with the carbon rear end.  To mount the fender at the chainstays, I had to make this bracket, which attaches to the frame with the bottom bracket cable guide screw.

At first I tried to make one of these by flattening out a p-clip and bending it to the right shape.  It was far too flexible, so I made one out of the clamp band from a Shimano STI lever.  This just happened to be exactly the right size for my bike, about as big as a #10 p-clip, for reference.  You could make this bracket out of just about anything you could bend and drill two holes in.

Before

After

These are really (really) hard to bend, but eventually I got it into this shape, which is about what you see mounted on the bike above.  I made it so that it would press up against the frame when tightened down, so it wouldn’t vibrate. I don’t think it would work so well without being supported in the middle somehow.

Fitting this to the frame gives you your first fender attachment point, and a good reference point for your second.   To get the fender to fit between the chain stays without rubbing the tire I needed to cut some material off.  Make sure you line up the fender where you want to attach it to the mount, I used the third hole up from the end to extend the fender a bit below the bottom bracket shell.

I marked the fender around the chainstays as a guide to where I would cut the relief, while keeping it aligned with the bracket.

I then cut into the fender, removing a small amount at a time, and test fitting as I went.  It’s best to remove as little as you can because the fender gets weak quickly if you cut the sides out.  I used a pair of diagonal cutters to cut the fender, and a half-round file to smooth out where the fender contacted the stays.  Here’s what it looked like in the end:

Plenty of clearance to go around now, and no rub at the chainstays.  If you’ve got a steel or aluminum bike, and can’t fit the fender between the tire and chainstay bridge, try using a bracket and modifying the fender to mount it in front of the bridge.

Now that I had the fender attached at the chainstays, I could measure where to cut the fender in half to clear the seatstays and rear brake.  Make sure you take into account the shape of the bracket that clips on to the fender, it might extend a bit forward of where it bolts into the frame.  I didn’t do this, and have a larger gap in front of the seatstays than I needed to.  This design of carbon seatstay uses a normal recessed nut to attach the rear brake, so I was able to substitute it with one of the Sheldon Fender Nuts.  Here’s the hardware I used to attach the fender and brake:

The Sheldon Fender Nut works just like a normal recessed brake nut, except it has an internal thread that accepts a 6mm bolt.  I used a long 6mm bolt and a spacer to attach the fender bracket, like this:

I have no idea where this spacer came from, but it was just right.  The Sheldon Fender Nut anchors the brake caliper, then the spacer, the fender bracket, a washer, and the bolt attaches the fender to the bike.

To attach the rest of the fender, I made a bracket that comes up from the brake bolt, over the brake, and back down near the wheel to anchor the fender.  Here’s the part I used, the single stay from a Blackburn Rack:

I bent it using a vise and some pliers, and attached it in front of the brake behind the seatstays.  You should probably make this bracket and attach the fender to it, before attaching the brake and front portion of the fender, or you’ll just have to take the brake off again like I did.

It’s important to make sure you leave enough room under the bracket so it doesn’t rub on the brake at all.  I had to make mine go up pretty high to clear the triangulated arm of the Rival brake.

After this, I lined up the rear portion of the cut fender under the bracket, and drilled a pair of holes to attach it.  Using a center punch is really helpful when drilling holes in fenders to keep the drill from walking around.  I found a couple of short 5mm button head bolts with nylock nuts, and attached the rest of the fender.

There weren’t any eyelets at the dropouts, so I attached the fender stays to the seatstays with p-clips.  Make sure your p-clips are small enough to tighten down completely.

The finished product:

The fender almost looks like it belongs there.

Addendum: After putting this article together I was able to put a front fender on, by just cutting the front of the fender past the bracket off, and using a Sheldon Fender Nut to attach it to the back of the front brake.  I get some spray splashing back from the underside of the fork crown, but not that much.  If it gets to be too annoying I’ll probably build a bracket similar to the one I used on the rear.

This morning I read a post on Bike Forums about a custom Shimano freewheel made by sciencemonster in a close ratio plus bailout style. Inspired, I decided to see what sort of gearing you could get out of just two different freewheels we had here in the store, the HG37 13-28 7s Freewheel, and the HG37 14-28 7s Freewheel. Shimano hasn’t made a freewheel with a large cog smaller than 28 teeth in a long time, and with some cogs from these two freewheels, you can put together a freewheel with a low gear of 24 teeth.

J.A. Stein locking lockring pliers.

The newer Shimano 7 speed freewheels use a right-threaded lockring to hold all of the splined cogs on. The easiest way to get the lockring off is using a cog vise to hold the freewheel in place, and go at it with the lockring tool of your choice. The notches on these lockrings are pretty narrow, and they both have a larger radius than a track or bottom bracket lockring, so I had the best luck getting them off with a plier-type lockring tool. I used Stein’s locking lockring wrench, Hozan makes lockring pliers that would work ok, or you can make one yourself by grinding teeth into a pair of slip-joint pliers.

14-28 vs. 13-28

When you take both freewheel lockrings off, you can see the difference in diameter between the 14 tooth and 13 tooth freewheel cogs.  The different diameter splines limit the changes you can make to the gearing on these freewheels without some serious grinding.

14T freewheel body vs. 13T

The cogs and spacers should slide right off. The 14 tooth freewheel body has two different splines, with outer diameters of about 43mm and 50mm. The upper spline holds four of the cogs, and the lower spline holds three. The thirteen tooth has an additional 41mm spline pattern, which holds the top two cogs, leaving two on the middle spline, and three on the bottom.  Your new inventory of cogs is as follows:

Large Spline

• Two 28T
• Two 24T
• One 22T
• One 21T

Medium Spline

• One 20T
• One 19T
• One 18T
• One 17T
• One 16T
• One 14T with spacer

Small Spline

• One 15T with relief
• One 14T with spacer

Large spline pattern differences.

For a reason obvious only to Shimano, the two freewheels use a slightly different large spline pattern.  One of the splines opposite the square spline on the 14 tooth body is offset clockwise slightly.  You’ll need to grind or file a small amount of material off of any large spline cog you want to install on the other freewheel body.

Modified 22T cog on 13T freewheel body.

The first custom freewheel uses all cogs but the 28T from the 13T freewheel, substituting the modified 22T cog from the 14T freewheel. Keep the spacers in the same order and orientation as the original freewheel, just remove the 28T, and install the 22T from the other freewheel after the original 24T.

13-24T Custom Freewheel.

This gives you a not unreasonable 13-15-17-19-21-22-24 range.  Just reinstall the lockring as tight as you can reasonably make it.

Another option makes use of the two spline body to make a 14-24T freewheel with a little bit different spacing.

Modified 21T cog on 14T freewheel body.

Use the 24T and 22T cogs from the original freewheel, then add the silver 21T, 19T, and 17T, then the original 16T and 14T.

14-24T Custom Freewheel.

This gives you a 14-24 freewheel with a spread of 14-16-17-19-21-22-24. Again, tighten the lockring down before using. There are a few other combinations you can make with these parts, but the splines are pretty limiting. If you ever wanted a 7 speed freewheel with a range of 13-15-19-20-21-22-28, this is probably the only way to get it with new parts.

13-15-19-20-21-22-28 At last!

Both freewheels needed for this project are available at Harris Cyclery. We can’t make a custom freewheel for you, nor can we get any of the Shimano freewheel cogs separately, but we do sell the 13-28 7 speed freewheel and the 14-28 7 speed freewheel necessary to make your own.