UCI Bike Builders



UCI Bike Builders is a senior project devoted to the design and manufacturing of bicycle frames. In the past, the project has functioned as a UROP grant-funded project, where a traditional steel lugged bike was developed. In order to manufacture this bike, a modular welding jig was designed and machined in-house. The project is currently brazing this traditional steel bike using oxy-acetylene. The 189 portion of the project is focused around developing an additively manufactured weldless bike which will utilize multiple materials. This bike is experimental in nature and allows for greater customization while also reducing assembly time. The bike will utilize off the shelf carbon tubes which will be connected using custom additively manufactured titanium lugs. The carbon tubes will be fixed to the lugs using a two part epoxy and fishing wire will be wrapped around the ends of each tube to ensure concentricity at the mating surface. Tolerancing will be extremely important in determining the strength of the joint. The 3D-printed lugs will have to be post-processed in the machine shop to ensure accurate tolerancing.

UCI Bike Builders provides engineering students an opportunity to develop a system of mass-producing custom bikes that is cost-effective, sustainable, and time efficient. Testing on completed frames will be conducted using industry standard methods for bicycle frames. This involves fixturing the bike vertically and exerting a load on the front axle.


  • Manufacture and test a custom weldless bike frame by Summer 2021
  • Adhere to industry standards for frame tolerances and structural limits
  • Design a system of manufacturing with costs below industry averages
  • Organize documentation for future teams seamlessly expand off of previous work
  • Finish welding/brazing on traditional steel frame


This quarter the team has been able to create a complete front triangle design in CAD that is parametric and can be easily adapted to different rider geometries. Carbon fiber tubes have been purchased by Rockwest Composites who were able to closely match our design requirements with off the shelf inventory. Metal additive manufacturing has been kicked off, starting with a prototype frame printed in AlSi10Mg. The final material will likely be titanium. 

Looking Forward

With such a large project, it proved difficult to manufacture a finished product in only 10 weeks. For this reason the project will likely roll into the next academic year. A list of things that need to get done before the protoype can be assembled can be found below

  • 3D print the Headtube and Seattube lugs in AlSi10Mg
  • 3D print the softjaws for each milling operation out of PETG 
  • Create gcode for the Haas CNC Mill and cut lug diameters to spec
  • Glue all pre-cut tubes and post-processed lugs together using the welding jig as a fixture for alignment.
  • Fillet braze a rear triangle using Paragon Machineworks 'Rear Round' dropout kit

High Definition Photos

Full Sideview
Headtube Lug Closeup
Welding/Assembly Jig
Machined parts for the Jig

Midterm Presentation

PDF Slide Deck

Team Contacts

Felix Slothower e. fslothow@uci.edu

Tony Drabeck e. adrabeck@uci.edu

Trevor Tuck e. tuckt@uci.edu


Prof. Lorenzo Valdevit

Benjamin Dolan

Tyler Schuldt

Fabio Bressan

Project status: 
Academic year: 
Spring Video: