Bikes do have different types of frames or chassis. The frame or chassis is like the skeleton of the bike or motorcycles. In this content, we will talk about the perimeter frame or twin-spar frame of the motorcycle. What is a twin spar frame? Or, What is the perimeter frame in bikes? What is the difference between a split trellis frame and a perimeter frame? Which type of frame is better for bikes?
What is Perimeter Frame in Bikes?
Perimeter frames are also known as Twin Spar frames. The alluded frame is one of the most common frames. Manufacturers place them on most conventional sportbikes. They are designed with Two spars (beams of metal) curved around the perimeter of the engine. Instead of being placed just over & under the engine. And this design & appearance brought in the name of the “Perimeter frame”.
It comes with two box-section tubes. The tubes have one end attached to the yoke. While the other end connects to the swingarm pivot. The latter keep in mind the connection is made in the shortest distance possible. In other words, this frame type is an intricate network of tubes decorated in a lattice-like pattern. It incorporates the engine under it. With integration, the engine becomes a part of this frame. Perimeter frames are indeed performance-driven chassis that offer more stability and rigidity.
What is the Benefit of a Perimeter Frame?
Perimeter frames are well suited for conventional sports bikes. Some motorcycle racing-based research generated the idea that the joining of the bike’s steering head to the swing arm in the shortest distance possible will enhance the rigidity tremendously. Perimeter frame emerged from this concept and executes exactly the same theme. Lighter beams with superior stiffness will do the job perfectly in this case. With two beams or two spars in usage, the name appeared as “Twin Spar Frame”. Those beams indeed surround the engine as they are destined for the swing-arm pivot.
Being wider than cradle frames, it offers far better performance even under heavy loads. Thus they are preferable for sports bikes. Moreover, the usage of exotic materials makes this frame more capable as well. Previously constructors used to make this with steel. But nowadays they have moved on and using lightweight aluminium to build it. As a result, the stiffness isn’t compromised but the frame gets lighter.
What is the Difference between Twin Spar and Trellis?
Twin Spar frame and Trellis frame, both have some similarities. But there are a number of differences between the 2 types.
| Twin Spar or Perimeter Frames | Trellis Frames |
| It forms wide and welded steel beams. Nowadays, come with the same shape but are made of aluminum. | Features an assortment of short-sized steel or aluminum tubes welded together. It forms a triangulated shape. Indeed, it is the strongest shape. |
| The manufacturing process is relatively complex. | Offers a simpler manufacturing system. |
| Relatively heavier than its counterpart. | Comparatively lighter in weight thanks to its hollow structure. |
| Able to provide good rigidity and strength but it’s less than the performance trellis frames provide. | The trellis frame offers even better performance in terms of rigidity & strength than the aforementioned frame. |
| You may notice such frames on the Honda CBR1000RR or Bajaj Dominar 400. | Many KTM bikes would offer such frames. |
Is a Trellis Frame Better?
It’s a highly popular frame. It comes with a unique combination of strength and lightness. Thus it offers improved handling and performance. The manufacturing is easier and also the maintenance. They can dampen the vibration and are compatible with high-performance bikes. Its disadvantages include costs, less space for other components, etc. Overall the trellis frames are better and popular.
