Custom Ti All-Road: Geometry & 1x Clearance Log

[miker.the.biker]

Hey everyone,

I’m currently mapping out the geometry and spec sheet for a custom titanium 1x all-road/gravel frame that I plan to order from a Chinese builder (likely XACD) next year. Before I officially start the back-and-forth email process and get into the actual CAD drawing stages, I want to make sure my numbers are completely dialed and that I won't run into any classic clearance or manufacturing pitfalls.

The plan is a fast, clean, integrated 1x build around a traditional, level top tube silhouette.

My Fit & Main Component Specifications:
Saddle Height: 787mm (BB center to top of saddle)

Saddle Setback: -102mm

Handlebar Reach: 585mm

Cockpit: Integrated carbon handlebar/stem (100mm length / 420mm width) with full internal routing through an IS52 headset system.

Drivetrain: 1x setup running an AliX Pass Quest 48T 110BCD chainring on a Magene P505 spider power meter (24mm spindle).

Wheels/Tires: Elitewheels Gravel Pro carbon wheelset (24mm internal width) running 700x40mm tubeless tires.

Intended Frame Geometry:
Seat Tube Length: 600mm (Center-to-Top)

Seat Tube Angle (STA): 72.5°

Seatpost: 27.2mm diameter carbon seatpost with a 20-25mm setback (Elita One Master Series).

Why I'm Choosing This Layout:
With a 600mm seat tube, I'll have roughly 142mm of exposed seatpost to the saddle rails. I want to keep the classic, traditional look of a level top tube, and ~140mm of exposure gives me exactly enough exposed 27.2mm carbon shaft to flex and damp high-frequency road vibrations. Because my fit requires a deep -102mm setback, combining the slack 72.5° STA with a 20-25mm offset post keeps the saddle rails safely centered in the clamp.

Questions for the Chinertown Custom Ti Veterans:
The 48T Chainring vs. 40mm Tire Dilemma: A 48T ring is massive for a gravel frame. On 24mm internal rims, 40mm tires are going to stretch out closer to 41-42mm. For those who have done custom Ti builds with Chinese factories, what specific chainstay yoke design or dimpling instructions should I write into the order notes to ensure the chainring doesn't chew into the titanium stay while maintaining tire clearance?

IS52 Integrated Head Tube Details: I want fully internal cable routing. When the factory draws up the integrated IS52 head tube, what should I double-check regarding the internal bearing seats, transition spacers, and turning radius limits to make sure it plays nice with standard integrated carbon bars?

Front-Center & Stability: Given the slack 72.5° STA and my rearward weight bias, how should I approach the front triangle geometry (head tube angle/fork rake) to keep the bike tracking straight and stable on high-speed loose gravel descents?

I’d love to hear from anyone who has gone through the custom titanium blueprint process here. Let me know if you see any red flags or things I should change before I open up the conversation with the factory.

Thanks,
Mike

[Asco]

Questions for the Chinertown Custom Ti Veterans:
The 48T Chainring vs. 40mm Tire Dilemma: A 48T ring is massive for a gravel frame. On 24mm internal rims, 40mm tires are going to stretch out closer to 41-42mm. For those who have done custom Ti builds with Chinese factories, what specific chainstay yoke design or dimpling instructions should I write into the order notes to ensure the chainring doesn't chew into the titanium stay while maintaining tire clearance?

You shouldn't need to do anything other than tell them the specs you want. They will tell you if it's possible or not, but I really doubt that combination will be an issue.

My suggestion is to get the process started, the back and forth can take a long time.

[NormH]

Ditto what Asco said. But just FYI, here's Waltly's solution to my 1x 50t chainring request.

[miker.the.biker]

Thanks for sharing this drawing! It's helpful to see how Waltly handled the 50T 1x clearance with standard dimpled stays.

They used an aggressive 25.5x18mm ovalized press on that drive-side stay to get 103–104mm of radial clearance on a BSA bottom bracket. Since I'm using a wider T47 shell and targeting a 52T 1x ring, this gives a good baseline to compare how Carver, Titan, and XACD position their tube dimples versus using a 3D yoke.