Dropout Modification - Vallie Components - bicycle part and accessory design

So this August was all about dropout modification. I have mixed feelings about August every year. The start of the month is when I celebrate my birthday, but quickly after that summer wraps up, depression sets in, and its fall again. This year I tried to make the most of it while working almost daily.. Anyways, here are a few of the results.

First up was Mitchell's Rocky Mountain. This bike is sort of timeless around here. You will see them everywhere from the shore to the bike rack outside of MEC; signature top tube seat stay junction, just begging to be hammered on. Well.. now Mitchell will be able to hammer a little harder thanks to the stopping power of disc brakes:

The ISO mounting jig I made worked like a charm, but I had a small amount of trouble TIG welding so close to brass. Its straight and solid though, so I have no worries about sending Mitchell down a mountain with it.

The next project up was a little more involved. It was dropped off at Mighty Riders with the instructions 'Whatever it Takes'.

The bike is the Mighty Rider's team captain Savage's winter trainer. An aluminum Fetish Attack frame with a carbon CX fork, front disc brake and heavy ass Specialized tri-spoke on the rear. Savage is a big guy who runs a big gear, and seems to kill bike parts faster than most. He has been laying down miles on this bike every winter for the past 5 years or so. Mighty doesn't do rollers or trainer riding. When I first looked at it, it was caked in a sludge that required a chisel to remove from the powder coat. The chain barely sat on the teeth of the rings, and pretty much every bearing was loose. Gross.

On to the project.. Savage is tired of wearing out chains. I guess he must go through about one a month each winter. He had the bright idea to go to a Gates carbon belt drive. I feel like I tried to talk him out of it. The frame is aluminum, it will never work, you're just going to snap belts blah blah.

He didn't listen. I'll let the photos show how I went about this problem:

Here you can see how his chain ring looks after last winter. click on the image for larger grossness.

dropout scale

Here's what the dropouts look like after clean up with a chisel and stainless track nut plate removal.

After some careful measurements, this is what I came up with. A piece of 1/4" stainless milled to fit the existing dropout recession, using 4 of the holes already in the bike, and having 3 bolts total per stay. My strength analysis modelling shows that this solution is just as stiff as the original aluminum dropout. .. but will it actually work?

Yesterday I hit up DMT and rented the use of his Tormach for a few hours.. One scrapped piece of stainless later (good thing I bought two!) this is what I was left with:

That doesn't show the step at all, but this is what was left after the centre hole drilling.

Next up was hole clean up, drilling to size and tapping. The three M4 bolt holes are tapped in the plate, and the three M5 bolt holes will be tapped in the bike. I bolted it up to the bike, and used the bigger holes as guide holes to drill the frame.

Tangent:

Also in the above picture is a Broakland thread-on to ISO adapter. This thing will be required to mate a Phil Wood Gates cog to the specialized tri spoke. Wacky? Yes. As far as I knew up to a few days ago, there was no such thing as a thread-on Gates cog in existence. None of our suppliers list anything like that. Just 9 splined, or Alfine splined. Then out of sheer coincidence, I was led to baseurban.com, as they've got a new distributing studio/boutiquey thing in town.. and guess what, their bikes have a thread on Gates cog! Dammit! I emailed them about parts availability, and they still haven't replied. I guess they're just getting this thing off the ground and probably only have a couple of the belt bikes in stock. I still can't believe that the part I want exists in my city! I thought this was going to be the first Belt fixie in Vancouver! Oh well..

Here its looking a little softer, sitting in my soft jawz. The corners have all been cut off and chamferred with a hand file, and the M5 holes are counter sunk. Just about there... I'll spare you the gory details of the next step.. but for me, it was the scariest one. Hacking Savage's bike in two. A fetish attack has no chance against a fresh 24 tooth-per-inch blade.

Here's the final result (click for bigger):