Bicycle TPU Inner Tubes: An Evaluation of Their Pros and Cons and Whether They're Worth the Use
An Evaluation of Their Pros and Cons and Whether They're Worth the Use
Although tubeless tires have become increasingly popular, many riders still opt for the convenience and lighter weight of traditional clincher tires with TPU (thermoplastic polyurethane) inner tubes, as dealing with self-sealing liquids can be a hassle. After more than a year of using various brands of TPU inner tubes, I've gathered some insights and experiences to share. Here’s a summary of the pros and cons of TPU inner tubes.
ADVANTAGE:
1.
This might seem obvious, but it's worth mentioning for those new to the game. TPU inner tubes typically weigh around 30 grams, with some ultra-lightweight models weighing just 25 grams. Compared to traditional 0.8mm butyl rubber inner tubes, which can weigh around 80 grams, TPU tubes save about 50 grams. Even when compared to super-light butyl options at 0.6mm thickness, TPU tubes still offer a reduction of around 30 grams. For example, the weight of the JIISO TPU inner tube is about 36 grams. Compared with other TPU brands, although JIISO is about 10g heavier, it uses a copper valve instead of a plastic valve. But the weight of TPU material is almost the same. The reduced weight is located on the wheel's outer edge, significantly lowering the rotational mass and providing a lighter, more responsive riding experience.
2.
According to tests conducted by the well-known tire rolling resistance website BicyclingRollingResistance, TPU inner tubes can lower tire rolling resistance compared to butyl rubber inner tubes. While they don't match the performance of latex inner tubes, some top-tier TPU models have rolling resistance data that is very close to that of latex tubes.
3. Portability
Due to their thin and lightweight construction, TPU inner tubes fold up to a very small size. This means that the space traditionally taken up by one butyl inner tube can now accommodate at least three TPU inner tubes. This makes them an excellent choice for long-distance and touring rides where carrying multiple spares is necessary.
4.
Due to the material properties of TPU, which offers good elasticity, a single size can cover the common road bike tire widths from 18-32c. Only some of the ultra-lightweight models may have specific size limitations, but overall, this makes using TPU inner tubes very convenient.
5. Durability
Despite their light and thin construction, TPU inner tubes have good resilience and provide some puncture resistance.
DISADVANTAGE:
1. Air Retention
The air retention of TPU inner tubes can vary greatly, even within the same brand and batch. Some may require re-inflation every one or two days, while others can hold air for up to a week. It feels somewhat unpredictable. Mentioning air retention issues leads us to the next point.
2. Valve Material
Leaks in TPU inner tubes typically occur at the valve. To achieve a lightweight design, most TPU inner tubes use plastic valves. The plastic threads do not provide the same level of airtightness as metal valves, so they often require adhesive to secure the valve core and ensure air retention. Many riders unaware of this might attempt to remove the valve core as they would with a metal valve, compromising the seal. Additionally, friction between the plastic valve and the rim can cause wear over time, leading to minor leaks.
3. Valve Connection
How to connect the valve to the inner tube has always been a challenge for TPU inner tubes. Early versions had insufficient strength at the connection point, which could lead to abnormal permanent deformation after use, increasing the risk of blowouts. However, this issue has largely been addressed through rapid iteration, and you'll find that newer TPU inner tubes have significantly reinforced valve connections.
4.
Plastic deformation is the permanent distortion that occurs when a material is subjected to tensile, compressive, bending, or torsion stresses that exceed its yield strength and cause it to elongate, compress, buckle, bend, or twist. We mentioned the term 'plastic deformation' earlier, and it's important to discuss how this affects TPU inner tubes as a whole. In common usage scenarios, this simply means that if a TPU inner tube is used with a 28c tire, it will stretch and become permanently larger, making it unsuitable for use with narrower 23c or 25c tires.
5.
There are several tips and considerations when installing TPU inner tubes. It's known that before installation, you should inflate them slightly to give them the desired shape inside the tire, but not too much, as over-inflating can cause excessive plastic deformation and potentially damage the inner tube. Recently, we came across a tip suggesting that when the valve is at the 6 o'clock position, the seam of the TPU inner tube should be positioned in front of the valve. This ensures a more reasonable direction of force, reducing the risk of pulling on the seam and causing leaks. Additionally, when removing the tire, you need to be very careful with the tire levers. After deflating the tire, the TPU inner tube tends to stick to the inside of the tire, and if you're not cautious, it's easy to damage the TPU inner tube while levering the tire off.
6. Temperature Sensitivity
TPU material has relatively poor heat resistance, so if you're using rim brakes and plan to descend long hills, it's not recommended to use TPU inner tubes due to the risk of overheating and potential failure. Additionally, TPU inner tubes are sensitive to temperature changes, so in hot weather, it's advisable to reduce the tire pressure slightly.
IN SUMMARY
TPU inner tubes offer tangible improvements to clincher tires, with the main issues centered around airtightness and leakage. Manufacturers are addressing these concerns through rapid product iterations. While there are still some minor issues with TPU inner tubes, the price point makes them a non-issue. They are nearly as affordable as butyl rubber inner tubes, making them highly cost-effective.