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bicyclerepairman.bsky.social
Bicycle Repairman
@bicyclerepairman.bsky.social
480 followers 88 following 1.6K posts
Was once told my bike was a "three-speed with five gears." Now posting actual bike repair #BR tidbits here on bsky instead of that other place.
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bicyclerepairman.bsky.social
Bicycle Repairman @bicyclerepairman.bsky.social · Sep 27
Google image search thinks these pictures are "visually similar"
The Cowardly Lion, The Tin Man, Dorothy, and The Scarecrow startled by someone outside of picture, from "The Wizard of Oz." C3P0, Leia, Chewbacca, and Han Solo startled by something outside of picture, from "The Empire Strikes Back."
bicyclerepairman.bsky.social
What's up with this weird DIY mod? #BR

I found this modification on a common, 1980's style 10-speed bike with fenders. My best guess is someone wanted more tire clearance at the chainstay bridge (or fender mount)?
View of inside surface of rear dropout. A common derailleur is affixed but the keyed threaded mounting plate, instead of slotting into the dropout opening, is installed backwards, with the mounting bolt passed through an extra hole drilled in the dropout. View of inside surface of rear dropout. A derailleur is affixed in the correct manner, with the keyed threaded mounting plate slotted into the dropout opening. The inexplicable extra hole drilled into the dropout is also visible.
December 21, 2025 at 6:42 PM
bicyclerepairman.bsky.social
It's as if 6mm x 1.0mm (M6) nuts suddenly need a 3/8" wrench: Half-inch pedals have evolved to have 15mm wrench flats, combining two measurement standards in the same part.

Some other bike parts have mixed-units dimensions, like 36mm x 24TPI.
bicyclerepairman.bsky.social Bicycle Repairman @bicyclerepairman.bsky.social · 3d
Your bike is retro if the 1/2" pedals accept a 9/16" pedal wrench. #BR

Most modern 1/2"-20 threaded pedals (to fit "one-piece" cranks) need a 15mm pedal wrench, same as most 9/16"-20 threaded pedals.

Bike parts with mixed measurement standards--why?
A rubber 1/2"-20TPI pedal, shown with a 9/16" pedal wrench correctly fitting the wrench flats.
December 20, 2025 at 5:45 AM
bicyclerepairman.bsky.social
Your bike is retro if the 1/2" pedals accept a 9/16" pedal wrench. #BR

Most modern 1/2"-20 threaded pedals (to fit "one-piece" cranks) need a 15mm pedal wrench, same as most 9/16"-20 threaded pedals.

Bike parts with mixed measurement standards--why?
A rubber 1/2"-20TPI pedal, shown with a 9/16" pedal wrench correctly fitting the wrench flats.
December 19, 2025 at 8:10 PM
bicyclerepairman.bsky.social
"Three-speeds" with five gears, animal edition.
rosemarymosco.com Rosemary Mosco @rosemarymosco.com · 7d
Animals with misleading names. I'm seeing this go around as part of a viral tumblr thread so I thought I'd reshare it.
A comic called Animals with Misleading Names. There's an electric eel labeled "not an eel". There's a mountain goat labeled "not a goat." There's a maned wolf labeled "not a wolf." There's a king cobra labeled "not a cobra. Also, snakes are typically self-governing." There's a peacock mantis shrimp labeled "Not a peacock. Not a mantis. Also, not a shrimp." There's a horny toad labeled "Not a toad. Only thinks of you as a friend." There's a mayfly labeled "active through the spring and summer." There's an eastern kingbird labeled "found in the west. Many birds do not recognize its authority."
December 15, 2025 at 4:57 PM
bicyclerepairman.bsky.social
Here's a tool combination I used VERY often during the Cotter Pin years. #BR

Since the shop had only one caliper gauge, having an inexpensive diameter gauge to carry around was invaluable. A miniature 1-meter long tape measure for checking frame sizes of display bikes completed the duo.
A cable/rope diameter gauge adapted for measuring cotter pins. The gauge is a flat stamped stainless straightedge with metric markings. In the center, a narrow triangular gap has graduations for measuring diameters. .A small 1-meter long tape measure is attached to the gauge via a keyring.
December 14, 2025 at 9:40 PM
bicyclerepairman.bsky.social
Meshing three gears together doesn't work. #BR #StuckGears

But making the gears wildly mismatched isn't helping.
Three gears of different sizes seemingly with their teeth meshed with one another. However, the gears and the tooth pitch are all different and the tooth engagement is very poor, so the gear set is very unlikely to be able to function.
December 2, 2025 at 9:45 PM
Reposted by Bicycle Repairman
villagebicyclecoop.bsky.social
Here's a cool photo of a tandem bike with a large collection of batteries between the two riders. It's an electric battery-powered pacing machine on an outdoor racetrack! (France, ca. 1898)
December 1, 2025 at 3:01 PM
bicyclerepairman.bsky.social
Inspect and correct any faults with rim strips when building or refurbishing a bicycle. #BR

YIKES--I found THREE instances of mis-installed rim strips on the same bike!
A front wheel from a kid's bike with the tire removed. The rim strip is partly skewed, exposing several spoke nipples. A rear wheel from a kid's bike with the tire removed. The rim strip is partly skewed, exposing several spoke nipples. The same rear wheel from a kid's bike with the tire removed. Part of the rim strip is also twisted!
November 24, 2025 at 11:31 PM
Reposted by Bicycle Repairman
mplsfietser.bike
Extremely bad news for everyone who rides a Rad Power Bike 😢
cpsc.gov U.S. Consumer Product Safety Commission @cpsc.gov · 28d
CPSC Warns Consumers to Immediately Stop Using Batteries for E-Bikes from Rad Power Bikes Due to Fire Hazard; Risk of Serious Injury or Death www.cpsc.gov/Warnings/202...
Rad power bikes battery
November 24, 2025 at 7:58 PM
bicyclerepairman.bsky.social
Trek Recalls Bicycles with Coaster Brakes and Replacement Rear Wheels Due to Crash Hazard

www.cpsc.gov/Recalls/2026...
Trek Recalls Bicycles with Coaster Brakes and Replacement Rear Wheels Due to Crash Hazard
Consumers should immediately stop using the recalled bicycles with coaster brakes and related replacement rear wheels and contact an authorized Trek or Electra dealer to schedule a free repair at the ...
www.cpsc.gov
November 17, 2025 at 8:40 PM
bicyclerepairman.bsky.social
Making the gears all the same color won't help. #BR #StuckGears
Three gears of the same size, with teeth of each gear meshed with teeth of its neighbor, against a blank white background. No gear can rotate given this arrangement. Image lifted from a shutterstock.com thumbnail.
November 17, 2025 at 6:00 PM
bicyclerepairman.bsky.social
A chainguard that works!
coolbikeart1.bsky.social Cool Bike Art @coolbikeart1.bsky.social · Nov 15
Actress Virginie Ledoyen shows a fondness for big fenders in a scene from the 1991 film The Children Thief (Le Voleur d'enfants)

Happy #BicycleBirthday, Virginie!
Born November 15, 1976
Photo featuring a woman sitting on grass between the wheels of an upright, old-fashioned bicycle.
November 15, 2025 at 5:05 AM
bicyclerepairman.bsky.social
For most nuts, use a box wrench or a socket wrench. Pliers may be used as a last resort--but you're going to cause damage. #BR
A saddle mounted on a seatpost using a common ratchet style saddle clamp. Both the clamp and nut are damaged. Detail of damage to saddle clamp. The clamp plate has deep gouge marks, while the knuckles on the nut are rounded off.
November 14, 2025 at 10:09 PM
bicyclerepairman.bsky.social
Each of these gears could turn freely, so no #StuckGears in this illustration!
A drawing of an electric light bulb but the silohouette of the bulb is made of multicolored drawings of gears in different sizes. None of the gears engages with any other gear. Image borrowed from a thumbnail at vectorstock.com.
November 13, 2025 at 3:06 PM
Reposted by Bicycle Repairman
davidzipper.bsky.social
An abbreviated history of car bloat, courtesy of @xkcd.com

xkcd.com/3167/
November 12, 2025 at 8:37 PM
Reposted by Bicycle Repairman
rhyall.bsky.social
Currently above Michigan!
November 13, 2025 at 2:39 AM
bicyclerepairman.bsky.social
Knog Recalls Bicycle Lights Due to Fire and Burn Hazards

www.cpsc.gov/Recalls/2026...
Knog Recalls Bicycle Lights Due to Fire and Burn Hazards
Consumers should immediately stop using the recalled bicycle light and register at http://www.knog.com/recall for instructions on how to receive a free replacement bicycle light. Consumers should disp...
www.cpsc.gov
November 10, 2025 at 4:30 PM
bicyclerepairman.bsky.social
Making the gears in bright colors won't help them to operate. #BR #StuckGears
Three plastic gears of the same size, with teeth of each gear meshed with teeth of its neighbor, against a blank white background. The gears are colored red, blue, and green. No gear can rotate given this arrangement.
November 7, 2025 at 7:06 PM
bicyclerepairman.bsky.social
Someone tried to "stretch" this tire onto the rim! #BR

Hint: Tires are constructed to resist the force of inflation pressure. Therefore, they are designed NOT to stretch.
A 54-559 (26x2.125") tire removed from a wheel. The wire bead shows a sharp bend, likely caused by force-mounting the tire with a tire lever. Using proper technique, most tires this size can be mounted by hand without tools.
November 6, 2025 at 11:11 PM
bicyclerepairman.bsky.social
Lezyne USA Recalls Bicycle Floor Pumps Due to Serious Injury Hazard

www.cpsc.gov/Recalls/2026...

ride.lezyne.com/pages/pressu...
Lezyne USA Recalls Bicycle Floor Pumps Due to Serious Injury Hazard
Consumers should immediately stop using the recalled pumps and contact Lezyne for a free replacement pump, including shipping. Consumers will be asked to visit ride.lezyne.com/recall to register their...
www.cpsc.gov
November 6, 2025 at 5:58 PM
bicyclerepairman.bsky.social
A single loose bearing locknut can affect many things! #BR

The wheel:
-may not tighten properly
-may not center properly in the frame
-cannot be trued correctly
-may affect proper derailleur adjustment

Always inspect axle hardware on new bikes at assembly time, when it's easier to correct.
A rear wheel removed from a bicycle, showing the freewheel and axle and axle hardware. There is a noticeable gap between the spacer bushing and the bearing locknut (indicated by a red arrow). A callout pointing to the locknut says, "loose."
November 5, 2025 at 5:18 PM
bicyclerepairman.bsky.social
A possible cause of some brake failures: turning handlebars around too far. #BR
A kid's mountain bike shown with the handlebars turned almost 180-degrees. The cable on the front linear-pull brake is hitting the frame and forcining the noodle against the tension link, causing the latter to bend. Detail of the brake cable hitting the frame and causing damage. The ferrule has fractured and is no longer able to retain the cable liner or housing. The noodle has to be replaced. The tension link is also getting bent.
October 24, 2025 at 5:11 PM
bicyclerepairman.bsky.social
Can you see it? #BR

This "radial" spoke pattern is not built correctly.

Not a big deal on a kid's bike, but if you spoke a pro wheel like this, you're going to get called out.
A close-up of a wheel with large flange hubs and spoked in a "radial" spoke pattern--spokes on the same flange do not cross one another. This wheel is not correctly laced for a radial pattern. The camera is lined up with the wheel's axle, showing that one side is laced one spoke hole off. In other words, one flange has its spokes one hole "ahead" of the other spokes. A true radial spoke pattern when viewed from this perspective will have all its spokes appear to radiate radially.
October 23, 2025 at 7:19 PM
bicyclerepairman.bsky.social
POP QUIZ: What is a common cause of mysterious flats? #BR

Answer is tn the image [ALT] text.

Fun fact: Both these wheels are from the same bike!
A coaster-brake wheel from a kid's bike with the tire removed. The rubber rim strip does not fully cover the spoke nipples, which can puncture the inner tube, causing a flat. A front wheel from a kid's bike with the tire removed. The rubber rim strip does not fully cover the spoke nipples, which can puncture the inner tube, causing a flat.
October 14, 2025 at 5:00 PM