Serrai – Custom Gravel Bike
Titanium, Carbon, or Steel
The Serrai is our custom gravel bike or cyclocross bike. Gravel riding has become one of the most popular sectors of the cycling world, and we are here to make you the best gravel bike you could ever imagine. The Serrai is built for cable or hydraulic disc brakes, up to 40mm tire clearance, and a tapered fork. When designing a great custom gravel bike, we focus on the fit and performance needs of each customer. If you are racing cyclocross, we will design your bike with more aggressive geometry than if you are doing long gravel grinder rides or races. Lennard Zinn has been designing custom bikes for cyclists of all sizes for over 30 years. In that time he has mastered the art of making a bike stronger and more durable than any other bike out there, while keeping it light and responsive. Durability is super important on a gravel or ‘cross bike since there is a constant amount of vibration and shock affecting the frame. We build gravel bikes with the proper balance of strength, durability and lightness depending on your specific needs. The Serrai gravel bike is designed for your ideal crank length so that you can finally achieve the level of fit and performance that you are looking for. The proportional length cranks, hand picked tubing, and Lennard’s unique compact frame design make this the perfect gravel bike for all cyclists. It doesn’t matter if you are over seven feet tall or under five feet tall, this bike will be built perfectly for you. The Serrai is available with custom cable routing for electronic shifting component groups, standard mechanical shifting systems, and also wireless shifting systems.
Frame Material Options
|Titanium is half the weight of steel, so we can build Zinn Custom Bikes for big guys with larger diameter tubing with a frame still lighter than steel, or we can build an extremely lightweight and compliant bike for smaller people. We specify the exact tube dimensions for each customer so you get the best balance of strength, stiffness, durability, ride quality, and lightness. Larger diameter tubing provides greater strength and stiffness for greater power transfer, yet still with amazing compliance for a comfortable ride that doesn’t beat up your body over a long trek. Titanium has enough strength and fatigue resistance to avoid the need for extremely oversized tubes, providing a compliant ride on rough surfaces that smooths out and absorbs road buzz and small bumps. Steel frames, with their smaller tubes, can be almost as compliant, but aren’t quite as comfortable. Titanium can never corrode, unlike other metals. It can be painted or – unlike steel or aluminum – can be left without paint, powdercoat or plating, so you never need to worry about scratches. Internal cable routing is simple because the insides of the tubes are naturally impervious to rust and corrosion. Unlike aluminum, titanium has a fatigue limit, so as long as the tubing is not stressed beyond this limit or damaged, it will never fatigue. Titanium can also flex three times further than aluminum and twice as far as steel without permanent damage.|
|The Zinn Cycles Carbon Fiber bike frames are a testament to our dedication to superior design and construction quality. For years, customers have asked us, “Why don’t you do carbon?”. And the answer was that it was too big of an investment to make molds for each one-off custom bike frame. The new style of fabrication that now makes a custom Zinn carbon fiber bike not only possible, but truly amazing, is changing the way custom bicycle customers, especially big and tall ones, think about carbon bikes. Each tube and joint is hand made and bonded together using state-of-the-art techniques and the highest quality materials. The layup and dimensions of each tube, as well as the frame’s geometry, are fully custom to Lennard Zinn’s design for each individual customer. We can “beef-up” or “lighten-up” any section of the frame, and we are making carbon frames for any size rider. Ultimate durability and extreme light weight has been realized on our carbon fiber bicycle frames, and every Zinn carbon bike frame comes with a lifetime warranty. We are excited about this addition to the Zinn line up and know that if you are big, tall, small, or anywhere in between, you will love a Zinn carbon fiber bike.|
|Steel is stronger and denser than titanium or aluminum, and the steel tubing we use has an incredibly high ultimate tensile strength, giving it unprecedented fatigue life under high loads. Zinn steel frames also offer a rider of any size great performance and versatility at a great price. |
While steel frames tend to be heavier than titanium ones, our TIG welding method with a single strengthening gusset under the down tube offers great strength and longevity while still maintaining a reasonably light weight, and they will last many times longer than aluminum frames would. A Zinn steel frame will provide a lifetime of great, responsive riding on your custom bicycle.
Bike fitting included with every Zinn bike frame
No matter where you live in the world, we will work with you to make sure the fit of your Zinn bike is absolutely perfect. We offer a full service in-house bike fitting for those who can make it to Boulder, Colorado and we also have detailed measurements instructions for those who cannot make it out for an in-house fitting. We are also happy to work directly with a bike fitter in your area, and we offer upgraded 3D bike fittings with Dr. Andy Pruitt at the Boulder RETUL Center.
Zinn Cycles Design Philosophy
Lennard Zinn has been designing and building great bikes of all types for big and tall cyclists, small women, cyclists with injuries, and everyone else since 1982. He is one of the few bike designers in the world that has dedicated his career to improving the performance and durability of big and tall bikes and bikes for women. He has also spent a great deal of time working with Dr. Andy Pruitt to design bikes for cyclists who have suffered from injuries, reduced mobility, knee problems, back problems, neck problems, and many other ailments. There are many more factors to building a big and tall bike than most people understand. It is not as simple as just scaling up a “normal” sized frame and calling it good. When you do that, several things happen to the bike. First, the stretched-out tubes become less stiff, which results in high speed frame shimmy. This is a scary by-product of a poorly designed bike. Second, the added material makes the bike heavier, especially if the builder tries to solve problem number one with just using thicker tubes. Third, without a fork with a long enough steering tube, the handlebars will be far too low for the tall cyclist, causing discomfort in the back, neck, wrists, and arms. Fourth, building a bike for a tall or small rider with average length cranks will make the rider feel unnatural while pedaling. Proportional crank length is at the heart of all of our custom bike designs. We offer cranks from 130mm all the way up to 220mm, so we can properly fit any person in the world, no matter their size. Lennard has developed great frame design concepts to address and solve all of these issues and more. A bike designed by Lennard Zinn will be stiff and strong, while remaining lightweight. It will not shimmy at high speeds, and all of the components will be proportional to the rider. Fit, performance, comfort, and durability will all be superior on a Zinn bike than a bike from any other designer out there. We guarantee it.
Make it a Travel Bike
Add S&S Couplers for easy travel
If you want your bike to be a travel bike, we can add S&S couplings to your frame. If you choose titanium or steel for your frame material, couplers can easily be built into the frame, making it an incredible travel bike that breaks down into sections and fits into an airline regulation travel case. We can do two or four couplers depending on the size of your frame. Bigger bikes need four couplers and smaller bikes can get away with just two. S&S Couplers do not reduce the strength of the frame one bit, in fact, it’s quite the opposite. The Couplings are so well made that they become the strongest point in the tube! Not all bikes can fit completely into an airline regulation case. Bikes like 29ers, Touring bikes with racks and fenders, and e-bikes may or may not fit completely in the case and will require a secondary bag or case to carry some of the parts. Contact us about building your bike with couplers.
Order a bike now
Excited about your new bike? While you are welcome to come to our location for a full fitting, it is not necessary. You can easily follow the instructions for submitting your own measurements by clicking the measurements button below. To start the order process, please click the button below to pay a deposit. We will contact you with further instructions. Once we have your measurements and deposit, we will create a CAD drawing of your bike for you to review.
Are you ready