Kostya’s Custom BMX

Kostya kills it on a BMX.  He also tends to break his frames with surprising regularity.  So over the winter he worked with  Brian Kelly to make a custom one off BMX.  In case you don’t know who Brian is, he’s the man who designed the Cove Shocker, STD,  G-Spot and is now making custom steel frames.

 

From Kostya:

It started about 6 months ago, and was driven partly by curiosity, partly by financial need, and partly by a desire to try something new and challenging. At this particular point in time, I found myself inspecting my frames and finding hairline cracks along weld joints after, at most, six months of building them up fresh. This is entirely understandable, especially with frame weight going down and rider abuse going up, but I kept wondering if it was possible to build something stronger, something to last; not to mention, I really wasn’t in a position to drop $400 on a new frame twice a year.

Enter Brian Kelly, a good friend of mine who, over the last few years, has gotten into the custom steel frame building business right here in North Vancouver. We talked, one thing led to another, and the Maker Cycles BMX frame idea was born.  To simplify things, we decided to use an existing frame as a baseline for our dimensions. I was riding a Fit Aitken S4 at the time, and loved its geometry, so it became our datum. The 75 degree headtube angle, 13.25” slammed chainstay length, and 21” top tube were locked, but we played with the bb height (lowering it from 11.9” to 11.625”) and seat tube angle (going from 71.5 degrees to 70.5). This gave us a lower center of gravity and more effective top tube length (I’m real lanky, and can use all the room I can get).

For tubing, we kept it simple, using straight gauge 4130 True Temper steel throughout, with heat treated ¾” stays, and normalized front triangle (thanks to Jessica at Standard Bykes and Ian at Chromag for setting us up with the materials). What we did do is use thicker gauge walls (0.9mm on the top tube, 1.6mm on the down tube, and 1.2mm on the stays). While this did end up costing us a little in weight (the finished frame tipped the scales at 5.5 lbs), the hope is that this will go a long way in prolonging its life.

Fast forward a few months and we had all our geometry, computer models, materials, and other hoopla sorted out and were ready to begin building the thing.

Strange feeling to be standing in a shop and seeing the hard goods lying on a bench top… This became a bike in a month’s time.

First step (and by far the smoothest): the front triangle came together.

We opted for 0.9mm thick doublers at the top of the TT and the bottom of the DT for added reinforcement. Coupled with the thick walls on the tubes themselves, the front end is built to take a beating.

This concluded work on the front triangle, the easy part of the build. From here on in, it was on to the tricky welds and compound joining angles of the rear triangle…

Starting with some prep work, the stay ends were cut to length and capped.

A big thank you to Chris and Pete at North Shore Billet who let us use their machine shop to make the dropouts and bridges.

The dropouts are 6mm thick, allowing them to withstand repeated impacts on grinds without crimping.

We opted for a clampless seattube, partly for simplicity, partly to avoid the stress risers associated with clamp slots. Also, I haven’t ridden brakes in 2.5 years, so the frame is dedicated brakeless.

The BB joint proved to be mother of frustration. Lots of hair was torn in the process of getting this one done.

And at long last, voila! A complete frame was sitting on the shop table. Needless to say, I built it up the next day…

Many thanks to Jeremy at Ten Pack for the parts needed for the build! Complete bike weight: 25.1 lbs.

And went riding on it the day after that.

How will it hold? It’s responsive yet solid, and has yet to feel squirrely after a landing (not an iota of give on the sizeable 180 in the picture above). Time will tell, but for now I’m just really excited to be riding it. There are already talks of making a trails-specific frame with chainstay brake mounts… Who knows where it will go from here?

Kostya Chimkovitch