The Bicycling Thread

[wildbears]

TPU Inner Tubes and Rim Brakes

TPU (thermoplastic polyurethane) inner tubes can be used with rim brakes, but there are some considerations related to heat. TPU tubes are generally more heat-resistant than butyl or latex tubes, but they can still be susceptible to failure due to excessive heat buildup during extended or intense braking.
Here's a more detailed explanation:
Heat Resistance:
TPU tubes have a higher melting point than butyl or latex, making them a better choice for rim brakes where heat can be a concern.
Rim Brake Considerations:
Rim brake friction can cause heat buildup, and some TPU tubes are not recommended for use with rim brakes due to this heat.
Rim Material:
Carbon rims are more likely to heat up than alloy rims, potentially posing a greater risk to TPU tubes if they are used with rim brakes.
Braking Habits:
The extent to which you use your brakes, especially during descents, can affect the heat buildup in the rims and the potential for tube failure.
TPU Tube Brands:
Some brands of TPU tubes are specifically designed for rim brakes, while others may be more suited for disc brakes.
Test and Testing:
Some manufacturers, like Continental, have tested their TPU tubes for heat resistance in rim brake applications.
In summary: While TPU tubes generally have better heat resistance than butyl or latex tubes, it's crucial to consider rim material and braking habits when using them with rim brakes. Some TPU tube brands are specifically designed for rim brakes and may be a better choice if you engage in frequent or intense braking.

AI Overview on Google

[955i]

I hit over 100kph coming down the south side of Col d'Izoard in 2015. Didn't touch the brakes for long stretches at a time!

[wildbears]

I've never been anywhere near that speed! Did come down the east side of the Rockies from the Continental Divide into Estes Park. Just enjoyed the scenery including mountain goats and coyotes. I was on a rented Gio Torino. Nice bike.

We put a down-tube-lever-actuated brake (drag brake) for long descents on our tandem with rim brakes. Just acted on the back wheel. OTOH, tandems are known for overheating of the rims with tube failures and loss of braking power.

[wildbears]

[955i]

Unfortunately, this is truer than many might believe.

[wildbears]

Under revision

[955i]

Art, not science. I am ham-fisted at this stuff and seem to lack "the nack" required!

[wildbears]

On September 17, 1946, British industrial designer Benjamin Bowden unveiled his revolutionary Spacelander bicycle to an intrigued public, capturing the imagination of a post-war generation with its futuristic design. Originally called the "Classic," the bicycle was created for the "Britain Can Make It" exhibition in London, a showcase of modern British design and manufacturing potential in the aftermath of World War II. Bowden’s bike stood out instantly—it looked more like a machine from a science fiction film than a traditional two-wheeler, with its flowing lines, integrated headlamp, and streamlined fiberglass body.
Bowden’s design was well ahead of its time, both aesthetically and technically. The Spacelander featured innovations like an enclosed drive train and lightweight construction, aimed at providing a smooth, clean ride. Its bold, organic shape reflected the era's growing fascination with space exploration and atomic-age optimism. While the prototype stunned audiences, practical manufacturing hurdles in postwar Britain prevented its immediate mass production, leaving the Spacelander a dazzling but unattainable vision for many years.
It wasn't until 1960 that the Spacelander was produced in limited numbers in the United States, though it struggled commercially due to its high cost and unconventional look. Today, however, the Spacelander is celebrated as a design icon—an emblem of mid-century innovation and daring creativity. Benjamin Bowden’s vision remains an inspiring reminder of how design can dream boldly, even if the world isn’t quite ready to catch up.

[wildbears]

We recently saw a fiberglass version of the Spacelander at the Cincinnati Art Museum.,.

[955i]

They look very cool. The differences between Bowden's original and the Cincinnati example are small but interesting. The steering stem and handlebars are more traditional in the later version. I like the dual torpedo headlights in the Cincinnati version, too.

[wildbears]

The Cincy bikes are on loan from the museum in New Bremen Ohio. A total of 20 on display.

[wildbears]

Think the propeller is just for fun, not wind speed.

But I've thought about having a head-wind, wind-speed indicator.

[wildbears]

Tom Pidcock...World's Best Descender.

[955i]

I am the fastest descender among my riding friends. They think I'm nuts, but I'm not really. Many hours of motorcycle racing on 350cc bikes hones your skills at maintaining cornering speed, while leaving a margin for slight errors in judging an apex or exit. You don't just point and shoot.

I'm going to send this video to my riding buddies so they can see what real descending can be like. Pidcock is an apex predator in this discipline. Putting out 400 watts on the exit of corners sure doesn't hurt either!

Pidcock rivals my favorite: Il Falco - Paolo Savoldelli. In 2005 he ripped down the side of Colle della Finestre on the way to Sestrieres to win the Pink Jersey. (Same route as this year. Good on you Yates!)

[wildbears]

[wildbears]

[wildbears]

When spinning the pedals, it helps some cyclists to consciously lift the knees before starting the down-stroke. That is, focus on the knees rather than the feet. Lift, don't pull. This engages the quads and the qlutes that are stronger and have more endurance than other muscle groups. It allows an earlier pedal down-stroke (starting at 3 o'clock rather than 4) and promotes pedaling in circles rather than squares.

This technique allows the rider to shift up 1 or 2 gears without a perceptible increase in effort.

Remember toes down, knees up.

(NOTE: I point the feet at the pedals, not above or below, to dive into the pedals, rather than a slide forward motion, in preparation for the down strokes.)

Added Video Information... https://www.youtube.com/watch?v=QkYtOCrCAi0

[wildbears]

Dec 11, 2025, https://www.youtube.com/watch?v=QkYtOCrCAi0

[wildbears]

Did a short, but hilly ride yesterday. Starting temp was 98. It was actually cooler moving down the road than standing next to it in the sun.

[wildbears]

Shades of Rollie Free....

[wildbears]

[wildbears]

Who knew Robin Williams was an avid cyclist?

[wildbears]

[wildbears]