One of the biggest debates in the bifold door industry is the lift cables vs straps debate. At Diamond Doors, we believe that cables are the safer and more reliable choice. That’s because our innovative cable lift system changes everything about how we view the cables vs straps debate.
What are three of the biggest points in the debate? First, that lift straps are stronger and more reliable than cables on overhead bifold doors, making them a safer option. Secondly, that straps are longer lasting, requiring less maintenance. And finally, that straps offer quieter and faster bifold door operation, making them a more appealing option overall. That may be true for some cables, but it’s not true for ours.
Why does it matter? The lift system is an essential part of the bifold door. Without a reliable lift system, the entire door fails, and that’s not something that we want to consider. That’s why we’ve considered every aspect of the lift cable design – and why we believe that it still comes out as the clear winner.
Let’s take a look at what Diamond Doors does differently and how it affects the choices we make when designing our overhead bifold door.
How Safe is a Bifold Door with Cables Instead of Straps?
When bifold door manufacturers talk about straps being safer than cables, they often refer to tensile strength and the risk of breaking or snapping during door operation. Let’s start with discussing tensile strength.
Strength of Lift Cables vs Straps
Tensile strength is the amount of force that a material can withstand before it breaks or is permanently deformed. In simpler terms, it is how much weight it can hold without becoming damaged or breaking.
The tensile strength of both cables and straps varies. Most bifold door manufacturers who offer lift straps provide a 3” nylon or polyester strap. The exact tensile strength will vary depending on the material used, but one manufacturer says that their straps are rated for 29 000 lbs.
In comparison, manufacturers who offer lift cables will generally provide a 1/4” cable with a tensile strength between 6 400 lbs and 7 200 lbs. (At Diamond Doors, our cable size varies depending on the door size and loads.)
Yes, straps are technically stronger. However, when we look at reliability and consider safety factors (Diamond Doors uses a 10:1 safety factor, which means that our lift system is rated to handle ten times more than the weight of the door), we still believe that cables win.
Reliability of Lift Cables vs Straps
When straps are damaged, their tensile strength is drastically reduced. This damage may come from a cut or tear, or even from everyday chafing and wear. Damaged straps are unpredictable and must be replaced at once.
Generally, cables are more durable and less susceptible to this type of damage, though they can experience similar issues, especially when repeatedly wrapping around sharp angles and corners, or rubbing against other cables. But here’s what Diamond Doors does differently.
Diamond Doors lift cables are an 18×7 cable design (meaning that they have 18 braids, with 7 strands per braid) with a flexible nylon core. In comparison, most competitors use a 7×19 (7 braids, with 19 strands per braid) cable. Our simple change creates a cable that is more flexible and harder to damage.
As further protection against damage, we’ve simplified our cable lift system. We’ve gotten rid of pulleys, sharp angles, and other moving parts. Our cables travel directly from the top of the door, across the “Y” pusher, down to the driveline. Our unique design also prevents cables from wrapping overtop of themselves and rubbing together, the most common cause of cable damage and failure.
Overall, our lift system design eliminates the normal wear and tear experienced by other designs, and provides a cable that lasts longer than other cables and lift straps. This means that our design requires less maintenance and makes a lift cable system safer than lift straps for bifold doors.
Are Bifold Door Lift Straps Faster than Cables?
Short answer? No, lift straps don’t make a bifold door any faster than a lift cable. Simply put, there’s a lot more to consider when it comes to opening rates than just straps vs cables.
The long answer is more nuanced. Lift straps often appear to open faster, especially as they near the end of their opening cycle. That’s because they wrap on themselves as the door opens, increasing the diameter of the wrap and speeding up the lift cycle. Cables don’t really do that, since their wrap stays more consistent.
However, that doesn’t mean the overall time to open is faster for lift straps. In fact, for most bifold doors, the total time to open doesn’t change between lift straps and lift cables. So what does affect the opening speed of a bifold door?
The three biggest factors are the gearbox ratio, sprocket reduction, and drum diameter. What does that look like in a practical application?
Gearbox ratio and sprocket reduction both affect the gear ratio of the door. A higher gear ratio increases torque but reduces speed. This is important for large, heavy doors. In comparison, a lower gearbox ratio reduces torque but increases speed, which is a great option for smaller doors. Drum diameter has a similar effect, where a larger diameter increases opening speed.
At Diamond Doors, our standard opening speed is 18ft/minute – the fastest opening speed in the bifold door industry. This isn’t just because of our lift cables, but because of our entire lift system.
Did You Know?
To increase the opening speed of larger doors, we upsize our bifold doors with a larger, more powerful motor. This means that there is increased torque to handle the load of the door and a faster opening speed to offer convenient door operation.
Other Advantages of the Lift Cable System
Lift cables aren’t just safer and more reliable. They also offer other benefits like low maintenance reliability and easy installation. Here’s what that looks like on our doors.
Low Maintenance Lift Cables for Bifold Doors
Like all other aspects of our bifold doors, we design our Diamond Doors lift cables as a low maintenance door feature. As mentioned earlier, our lift system design prevents the cable from experiencing the wear and tear that happens with other designs. This lengthens the lifespan of the door cables which means that they should never need to be replaced unless damaged by outside factors.
And unlike lift straps, lift cables rarely stretch after installation. This means that they don’t require regular tensioning. When they do need adjustments, this can be easily done at ground level with equipment that you already have on hand.
Easy-to-Install Lift Cables for Bifold Doors
If something does happen to your lift cables and they need to be replaced, it’s simple to do. Replacing lift cables takes only a few minutes of your time and can be safely done with tools that you already have.
Should You Choose Lift Cables or Straps for Your Bifold Door?
We’re not saying that lift straps are a bad option for your bifold door but lift cables with a properly designed lift system are the better choice. They offer increased reliability and low maintenance convenience. If you have questions that we haven’t answered here, reach out to our sales team and we would be happy to discuss it further.
