Drilling My Fatbike Rims…

15 05 2012

Sharon’s front Pugsley wheel…

I’m [slowly] working on building up Sharon’s Pugsley from the parts Kurt gave me. The frame has been powder coated and new headset installed. The next move was cleaning and drilling out her Surly Large Marge rims. These Large Marge DH rims are heavy – very heavy, but they are paid for so rather than replace them I decided to drill them out.

Just a reminder where we started…

I’ve got Sharon’s front wheel drilled out and looking back I gotta say this is not a DIY project I would recommend unless you are totally motivated to get ‘er done. It’s noisy, messy [you’ll be covered with tiny metal shards] and you can potentially trash your rim. If you own some fat rims and want to drill them fair enough. I’ve warned you!

I’ll finish her rear rim, but I won’t drill out my Surly Large Marge DH rims. I have enough leg power that it’s not vital and when the time comes I’ll just buy some new single walled Surly rims that are already cut out. When I can afford it the price will be worth the hassle I’ll save plus I’ll use light weight hubs for a really killer weight savings and keep my old Pugsley wheels for heavy duty use.

Sharon won’t throw money at bikes like I do [silly!] so one set of wheels has to do it all.

The hole saw – your friend…

I have very few powered tools so here is what I drilled out the rim with:

  • electric drill
  • small drill bit for pilot hole
  • 1.5″ hole saw attachment
  • marking tool
  • ruler
  • dremel tool with grinding bits
  • needle nose pliers
  • eye protection
  • 6 ice cold Mexican beers and a fresh lime

Yikes!

This wheel has been used a lot over several years so I gave it a once over only to discover the aluminum spoke nipples are corroded to the point of self-destruction. I replaced a few with bronze nipples, but at some point this wheel will need to be totally rebuilt.

Oh well. You aren’t riding hard if you aren’t breaking things…;)

Measure and mark…

First thing I had to do is pull the tire, tube and rim tape. Then I marked halfway between the spokes along the centerline of the rim.

Drill pilot holes…

Next up drill a pilot hole at each mark.

Test fitting the hole saw…

I had room for a 1.5″ hole between the spokes.

Raw hole cut into rim…

Start the less than fun process of cutting out holes. This will generate a ton of tiny metal fragments so do it outside if you can or at least not in the living room on your lovely deep shag carpet…=-) I braced the wheel up against the steps of my deck while cutting out the holes. You can use a wall or work bench. Other folks have built jigs to hold the wheel or put the wheel into a fat bike frame that was secured to something else.

Upgraded hole saw…

I foolishly bought the cheapest hole saw at my local hardware store when I started this project. It lasted about halfway through the first rim before it was toast. So I went back and got a better quality hole saw which should get me through the second rim. As soon as you notice the cutting performance of your saw changing swap in a new one.

Holes cut…

Cutting the holes is not tragically hard, but I’ve done more fun DIY bike projects.

Rough edge…

Once the holes were cut I used a dremel tool to smooth out the rough edges. I may use a round file for wheel #2 as it was hard to maneuver the dremel around the spokes.

Smooth edges…

These rims are old and this bike will actually get ridden so I didn’t waste a lot of time trying to make it look bike show perfect. Note the self-destructing middle spoke nipple.

Weight savings = ~200g…

I collected all the big bits of metal and weighed them as 195g say ~200g savings for both rims with all the smaller bits included.

Truing the wheel…

After all the cutting and grinding was done I replaced some corroded nipples and gave the wheel some love. I’m not looking for perfection. I just don’t want the wheel to exploded mid-ride.

I should note that given the double wall construction and amount of material used in these Large Marge DH rims I don’t think the drilled out holes will compromise their strength in any meaningful way. Big guys are rocking the single walled cut out Surly Marge Lites so we shouldn’t have an issue.

The purple pugsley starting to come together…

It took me a solid afternoon of futzing with this one wheel to get ‘er done. I’m not fast at these sorts of projects so you may do better.

I threw some white duct tape in the rim to cover the new holes so I could mount the tube and a skinny 3.8″. Sharon will probably come up with something a bit more “pretty” at some point.

Front done…now for the rear rim…

So a few warnings:

  • don’t hurt yourself [wear eye protection]
  • don’t mistake the valve hole for a pilot hole and cut it out
  • don’t get too enthusiastic pressing down on the hole saw or you can take out a couple spokes