← Matthew Tse

Custom Ti-Bike Part II — Design

My last post detailed the initial ideas for my titanium build, this post jumps a few weeks forward (full of intense delibration and decision-making) to initiating contact with a manufacturer and going through the design process.

Selecting a Manufacturer

There are three main titanium manufacturers in China that are willing to fabricate one-offs for western customers, Titan, Waltly, and XACD. I sent an inquiry to all three to get a price quote and to feel them out.

XACD

XACD is the oldest, they've been doing custom titanium bicycle frames for over a decade and for awhile they were the only ones doing it. That presumably means they have the most experience, and perhaps the highest quality. I had read that they were the only one of the three who did double-butted tubing, but that has changed recently since both Waltly and Titan offered that feature to me for an additional fee. In general, XACD would most likely be able to accomodate exotic requests, like a titanium-carbon hybrid, but they'd also probably charge quite a bit extra for it.

Their main caveat is their point of contact, the infamous Porter. He's gotten quite a few negative reviews as being impatient and rude. Although some other reviews appreciate his promptness and directness that push the process along as fast as possible.

My own brief experience with him wasn't bad. After sending my initial inquiry, he responded within hours with a full invoice and asked for a downpayment. I felt quite rushed!

Waltly

Waltly is a relative newcomer compared to XACD, I believe they've been fabricating frames for less than a decade. The frame designer you work with is Sumi or Amy who are both very polite and helpful. Quite a few of the custom builds on Spanner were done by Waltly, which inspired some confidence.

Titan

Even more of a newcomer, Titan has only been in business since 2012 or so. There are also quite a few builds on Spanner by Titan, although there is a very negative experience from one customer. With Titan, you work with Eric, who is also very polite and helpful.

Choice

I ended up choosing with Sumi & Waltly Titanium. The price was marginally better than the other two, but mainly I felt that Sumi was really helpful, quick responding, and would carefully guide me through the frame design process. I also saw many successful builds on Spanner (1, 2, 3) that were quite similar to mine, so I knew they were capable of building a quality frame based around my feature set.

My second choice would have been Porter & XACD, but I felt a bit intimidated. I knew that the frame design process would take several iterations. I predicted asking a lot of questions, wavering back and forth on decisions, and changing my mind as I educated myself about frames. Although Porter might accommodate these requests, I wouldn't feel comfortable and I could imagine him rushing me forward through te process. As for Titan, I didn't get very prompt replies from Eric, which was a negative predictor of how the overall experience would go.

Bike Fit

Since I was spending so much time and money on a custom frame, I really needed a proper bike fit to dial down my exact geometry. I Googled for bike fitters in San Francisco, and initially scheduled a fit with Bespoke Cycles, but canceled and went with 3D Bike Fit instead. From reading reviews and the website description, I just had a feeling that 3D Bike Fit would offer me a more comprehensive service.

What followed was a three plus hour session where my body was closely examined for measurements, flexibility, and reach. Towards the end I was videotaped pedalling on a retul bike machine to figure out the perfect geometry for my riding.

retul

Having fun on the machine :)

I finished the session with critical dimensions in hand, stack, reach, crank length, drop bar dimenions, saddle type, etc. Besides that, I also got some other things beyond what I expected, but I also paid a lot more than I expected.

Unexpected Benefits

Unexpected Costs

Frame Design

Once I had my bike fit complete, I was ready to begin the frame design. I paid a 30% down payment to Waltly via paypal, and eagerly awaited my first CAD drawing from Sumi.

Iteration #1

waltly-drawing-one

The first drawing Sumi sent me had the general idea, but several things were off and several things needed to be clarified. I tried a few different communication methods, and found diagrams and technical terms to be the most effective. Sumi's English is okay, just about good enough to fabricate a frame with an English speaker. It's a bit like playing reverse Mad Libs, where she has full understanding of technical terms but is missing the transition words in between them.

waltly-drawing-one-annotated

The first annotated drawing I sent back

  1. flat-mount, not post-mount disc brake
  2. please provide a picture of the dropout, is the hangar replacable?
  3. the internally routed cable only shows the beginnings of a guide tube, is it just a hole with an entrance or does the tube extend all the way? This would come back to bite me later on.
  4. 607.3mm reach is too low, I asked for 610mm
  5. increase the angle of the downtube barrel adjusters to 90 degrees
  6. move the entrance of the rear brake cable routing to the underside of the downtube. I thought it looked cleaner to have all cables on the underside, it looks weird to have a cable randomly going in on one side of the downtube.
  7. remove some of the fender/rack mounts. It's overkill, I'll reuse the same mount for both fenders and racks.
  8. straighten the seatstay since no curve should be necessary with a flat-mount
  9. change the cable stop from a zip-tie based stop to a hollow cylinder type
  10. What is the second 4.5mm diameter hole for? Sumi explained that this was a drain hole to prevent fluid buildup. it's nice that they generally know what they're doing so they'll put the important stuff in even if I don't explicitly specify it.
  11. please confirm that this is a 68mm English Threaded BSA bottom bracket

Iteration #2

waltly-drawing-two

Much closer, but still needs more tweaking.

waltly-drawing-two-annotated
  1. I had to repeat asking for a 610mm stack. It turns out this couldn't just magically increase from 607mm to 609mm, other frame parameters needed to be adjusted to make it happen. I asked for the bottom bracket drop to be reduced, and the headtube length increased to get it to 609mm
  2. I asked for an hourglass shaped headtube that I found in another one of Waltly's frames.
  3. reduce the seatstay tubing diameter from 19mm to 16mm. I saw many other builds using 16mm tubing, so I figured I'd save some weight and give the bicycle a sleeker thinner tube aesthetic.
  4. let's try a 34.9mm diameter top tube to reduce flex
  5. increase the chainstay length to 425mm. There's a bit of a controversy going around in the bicycle frame building world about chainstay lengths. The general consensus is that longer chainstays result in a more stable ride, and shorter chainstays result in a more agile ride (and marginally better weight). Some frame builders unpopularly believe longer is strictly better, a shorter chainstay doesn't make you more agile, just less stable. I decided to trust the unpopular opinion because it made sense to me, and at the end of the day I was only asking for a <1cm difference.
  6. readjust the positioning the barrel adjusters and internal cable hole

Iteration #3

waltly-drawing-three

Almost perfect

When I previously asked for a 34.9mm top tube, I didn't realize Waltly would have to taper the end of it in order to match the 31.8mm seat tube. I was okay with the large thick downtube being tapered to fit the bottom bracket, but a tapered top tube seemed to look funny to me. So I back-pedaled and asked Sumi to switch it back to a 31.8mm top tube. I hoped this double-butted frameset wouldn't be too flexy for me.

Iteration #4

waltly-drawing-four

Final iteration

The only difference here was the aforementioned top tube diameter. I signed off on this and offered to pay the remaining 50% down payment that Waltly specified on the invoice. Sumi said no need for the additional payment, Waltly would begin the frame construction. I think from my fastidiousness, Sumi was fully confident that I was really serious about this frame, and so she saw no need for an additional down payment :). I now had a few weeks of quiet to eagerly await my frame. In the mean time, I worked on the logo files, which I could supply later since the logos aren't applied until the entire frame is complete.

Logo Selection

I spent the next few weeks brainstorming what kind of logos I wanted. I again perused FireFly's tumblr for ideas. I wanted something subtle, technical, and with some unique meaning for myself. I briefly considered embroidering my name on the top tube, but honestly I'm not super proud of my name. "Matthew" is an extremely common first name, and my last name, "Tse" is far too short and just as common—at least in Asia. I eventually came up with:

Headtube — I had the great idea of putting the periodic table symbol for Titanium as the head badge. I couldn't find a suitable image online, so I made my own custom elemental symbol. Every bit of type on this symbol is custom font and size selected.

headtube-logo

Top tube — I settled on "Titanium | 3Al2.5V" to indicate the particular alloy this frame was made out of. The font used is Google's Roboto, which I thought looked particularly good as a bike logo.

ti-alloy-logo

Down tube — This is where I put a personal touch in. A pair of literary references from my favorite science fiction books. Also in the roboto font, but bolded and italicized.

bluespace-logo gravity-logo

I ended up using a free cloud based editor, gravit.io to create the logos. I then asked a designer-savvy friend of mine to convert them into the .eps files requested by Sumi.

Final Component Selection

Once the frame was done, I began finalizing and ordering all the components. My general philosophy was to spend a bit more on things that mattered, like the groupset, or contact points such as the saddle and pedals. And I'd skimp on things that don't need to be high quality, like cheap $17 shipped from China eBay aluminum handlebars.

The upcoming followup: Part III — Build, details the arrival of all parts and the construction of my bicycle.