Shimano bicycles and bicycle parts

The reports, as CPSC published them

1. Hospital admission

   Made Aug 23, 2026 · , sent to the company Aug 26, 2026 · , published by CPSC Sep 11, 2026

   The product, in the report: The Shimano Ultegra Disc brake caliper is installed on a road bike to control the bike speed and bring the bike to a complete stop.

   I was riding a bicycle equipped with Shimano Ultegra Disc brakes. The brakes failed to slow me down. I crashed 6 broken ribs, broken nose, broken neck, bruised all over

   Model

   Ultegra

   Where

   Twentynine Palms, California: Street or Highway

   Who was involved

   Age 64, Male

   The reporter’s relation to them

   Self

   As this report names them

   Brand Shimano, made or sold by Shimano Inc

   How badly, in CPSC’s words

   Injury, Hospital Admission

2. No one hurt

   Made Jul 15, 2025 · , sent to the company Jul 18, 2025 · , published by CPSC Aug 1, 2025

   The product, in the report: Shimano DA 9270 Electronic 12 speed groupset. The culprit, is the FD-R9150 Front Derailleur

   1. Discovered a serious flaw int he Shimano DA 9270 electronic drivetrain system. This is Shimano’s flagship, and widely raced even by Tour winners such as [REDACTED], World Class cyclists, and countless US elite riders. Specifically, Shimano’s FD-R9250 Front mech has three serious flaws that can cause a crash, injury or death. The Dura Ace groupset is paired with a 54T front crank, and a 40rear. All lower tier groupsets do not accept anything like 54/40, but lower, easier gears. In this particular flaw, the FD-R9250 front mech may lose mounting support to the support bolt via two flaws. A supporting screw may lose contact with the bike downtube, thus moving wiggling in and outwards (which should not happen). In prev electronic gen, the actuator had way less force and this would not occur. In 9 10 11 speed mechanical, the actuator used a cable with a good leverage, again low force, it never moved. But the FD-9250 has the most force in actuator history, is compact, and unsupported.

   2. The worse design flaw is that the little black mounting bolt is a low tensile, nothing like a grade 5 to 12.9. In my case, 400 or so actuations weakened it and the cage fell a few times. The cage dropped on the 54T ring (as it would occur when the unit uses force to upshift) and intending to accelerate. Needless to say, that metal cage hitting a ring spinning at 100-110 RPM is a significant event. Razor sharp military reflexes saved me, because if you continue pedaling you will jam and crash. The shop replaced the original bolt with a higher tensile, Ultegra (prev generation), uglier but life saving. It has not moved since fall 2023 and 7000 kms.

   3. In addition, the front derailleur does not have a physical limit adjustment. it is done digitally. I also discovered that, if battery has an amperage fluctuation, or anything, it can reset the trim form, say -5 to +7, the chain will be thrown out during an upshift (40t to 54t), thus also causing crashes. In my case, lost a chain and was very lucky. Sept 2024, waiting and testing, I informed Shimano North America of their product design flaws. The original answer speculated that we may have mismatched components even though that it not possible with the electronic group set or the components do not talk to each other, and we had the images and application as proof.

   Filed with Canadian regulators, but the file went nowhere. Since more reports emerge of this very issue, US is the surest way top protect riders. Provided a cautionary tale to Shimano (DOJ vs [REDACTED]) that its riders include members of the Armed Forces, Law Enforcement, DOJ, Intelligence Community, and we understand exceptionally well how to protect the public and to support regulators and agencies. Shimano was cautioned in writing that, after the global crank recall (which also started with a group of dedicated riders including myself)) purposely withholding safety or reliability data is a serious liability, not the least, a series of indictable offences.

   This system is fast, designed for speed, high end fast bikes. 20-40 mph or 30-60 km/hour, accelerating, if it fails because of the 3 items above, it is a severe risk of serous injuries. In my estimate, all these parts (FD, bolt) should be recalled at no cost to the consumer, and replaced with safer units. As mainstream users adopt and increase mileage, all witnessed risks can have serious effects. A chain that is thrown out, or a Front Derailleur that falls on the rings, is just bad.

   Model

   DURA-ACE 12 SPEED 9270

   UPC

   N/A

   Serial number

   N/A

   Bought from

   Euro Sports Ottawa

   Bought

   Sep 14, 2022, about then

   Where

   Canada: Street or Highway

   Who was involved

   Age 46, Male

   The reporter’s relation to them

   Self

   As this report names them

   Brand Shimano Dura Ace, made or sold by Shimano Inc

   How badly, in CPSC’s words

   Incident, No Injury

3. Hurt, no treatment

   Made Sep 13, 2024 · , sent to the company Sep 18, 2024 · , published by CPSC Oct 2, 2024

   The product, in the report: Shimano Ultegra CS-R8000 11-speed cassette. This is a chain-driven gear assembly consisting of 11 gears ranging from 11 teeth to 28 teeth each that installs on the rear axle of an 11-speed bicycle.

   The Shimano Ultegra CS-R8000 11-28T 11-speed cassette (rear wheel gear assembly) installed on my bicycle abruptly failed as I was riding up a steep incline in a standing position, causing the drivetrain (pedals and front and rear gears) to suddenly start freewheeling, which resulted in me losing my balance and forward momentum and crashing, resulting in injuries to my arms, legs, and back. Disassembly of the cassette found that the internal structure of the 19/21-tooth sprocket subassembly had broken in several places, allowing the subassembly to spin freely on the rear wheel axle’s free hub (I was riding in the 19-tooth gear when the failure occurred). The rest of the nine gears on the cassette were unaffected and continued to operate normally. I purchased and installed the cassette in March 2021, and at the time of failure it had been ridden 8,446 miles. I’m reporting this since I consider it to be a very dangerous latent condition. Had this catastrophic failure occurred while I was riding along a street instead of a bike trail, I could have potentially fallen into the roadway and been struck by a car. I reported this failure to Shimano’s warranty department on September 10, 2024, but have not received a reply yet.

   Model

   CS-R8000

   UPC

   Unknown

   Serial number

   Unknown

   Bought from

   Folsom Bike in Folsom, California

   Bought

   Mar 6, 2021

   Where

   Fair Oaks, California: Place of Recreation or Sports

   Who was involved

   Age 67, Male

   The reporter’s relation to them

   Self

   As this report names them

   Brand Shimano, made or sold by Shimano Inc

   How badly, in CPSC’s words

   Injury, No First Aid or Medical Attention Received

4. No one hurt

   Made Oct 2, 2023 · , sent to the company Oct 5, 2023 · , published by CPSC Oct 20, 2023

   The product, in the report: Shimano Dura Ace crank. 172.5 mm

   This concerns Recall# 23-294. My Shimano Dura Ace crank failed on the non drive side . Where the pedal screws in, a crack formed in the crank from the screw hole to the side of the crank arm. The lamination surface material broke off. It made a clicking sound with each pedal stroke for 4 months that I could not locate until it got worse and I noticed that when pedaling hard (climbing or sprinting) that the pedal flexed downward. The warranty had expired so I replaced it at my own cost.

   The previous crank (also Shimano Dura Ace) also failed, but in a different way. On the drive side the center four splines separated, allowing the crank to flex inward and feel spongy. It was under warranty and my local bike shop replaced it.

   In each case the crank had between 15 and 25 thousand miles on it.

   I was not injured, but could have easily been injured if I had not eased up on the pedals when the crank felt spongy. In the second case I finished my ride home using one foot since failure seemed imminent.

   Model

   Dura Ace

   Bought from

   Champaign Cycle

   Bought

   Jul 10, 2018, about then

   Where

   Charleston, Illinois: Place of Recreation or Sports

   Who was involved

   Age 65, Male

   The reporter’s relation to them

   Self

   As this report names them

   Brand Shimano, made or sold by Shimano Inc

   How badly, in CPSC’s words

   Incident, No Injury

5. No one hurt

   Made Aug 16, 2023 · , sent to the company Aug 21, 2023 · , published by CPSC Sep 5, 2023

   The product, in the report: Brake pads for a bicycle that are sold and packaged by an ebay seller as authentic Shimano brand parts.

   I bought two sets of “Shimano B01S” brake pads for my bicycle on eBay from the seller “costto-bike” on May 25 2023: https://www.ebay.com/itm/385633357374

   I installed them shortly after purchase. I usually replace my brake pads every 6-12 months and have never had one fail suddenly before. Yesterday while riding one of the brake pads installed on my front brakes spontaneously completely failed, with the entire pad lining having slid clean off the metal bracket that it’s affixed to. I was luckily not going down a hill when this happened and thankfully not injured, but if I had been going down a hill I would have been. I believe the part was counterfeit after today looking at the packaging of the unopened set and noticing that the authenticity check label meant to be able to be pulled up to view a QR code is actually a single layer sticker with no QR code beneath: see description on Shimano website of how the label works: https://bike.shimano.com/en-EU/information/anti-counterfeit.html

   I contacted the eBay seller and they said their return policy is one month so all they can do is offer a $3 partial refund for the $24 purchase.

   Model

   BR-T615 PAD B01S

   UPC

   6 89228 40922 4

   Bought from

   https://www.ebay.com/str/costtobike

   Bought

   May 28, 2023

   Where

   Seattle, Washington: Street or Highway

   Who was involved

   Age 25, Male

   The reporter’s relation to them

   Self

   As this report names them

   Brand Shimano, made or sold by Shimano Inc

   How badly, in CPSC’s words

   Incident, No Injury

6. No one hurt

   Made Apr 27, 2022 · , sent to the company May 5, 2022 · , published by CPSC May 19, 2022

   The product, in the report: Shiman GRX 810 hydraulic brakes (likely also with other Shimano hydraulic braking systems)

   I am president of a local cycling team in [REDACTED] and have experienced a potentially hazardous situation with my Shimano GRX 810 hydraulic brakes. As is apparently well known to Shimano, when a rider changes brake pads, and is required to push the brake calipers back in, this process can create back-pressure through the hydraulic system all the way back into the shift/brake lever and rupture a small rubber diaphragm (part # Y0C578000). This can cause leaking of brake fluid and failure of the brakes which is usually unknown to the rider. I have contacted Shimano and sent a certified letter to their Vice President, but have not received a response.

   Model

   GRX 810 hydraulic brakes

   Bought from

   BikesDirect.com

   Bought

   Oct 1, 2020, about then

   Where

   Auburn, California: Street or Highway

   Who was involved

   Age 69, Male

   The reporter’s relation to them

   Self

   As this report names them

   Brand Shimano, made or sold by Shimano Inc

   How badly, in CPSC’s words

   Incident, No Injury

7. Hurt, care not known

   Made Apr 15, 2022 · , sent to the company Apr 21, 2022 · , published by CPSC May 12, 2022

   The product, in the report: Shimano Hollotech crankarms, including but not limited to their [REDACTED] models

   A friend of mine was injured when the crankarm of his bike snapped in half as he was accelerating, and as it turns out, these types of cranks have such a notorious reputation that a whole [REDACTED] account has been made cataloguing the failures of Shimano’s crankarms. [REDACTED]

   Model

   [REDACTED]

   Where

   Fairfax, California: Street or Highway

   Who was involved

   Male

   The reporter’s relation to them

   My Friend / Neighbor / Co-worker

   As this report names them

   Brand Shimano, made or sold by Shimano Inc

   How badly, in CPSC’s words

   Injury, Level of care not known

8. No one hurt

   Made Jun 19, 2021 · , sent to the company Jun 23, 2021 · , published by CPSC Jul 8, 2021

   The product, in the report: This is a Shimano FC-7800 crankset from 2006 installed on a custom titanium bicycle from Seven Cycles. Without warning the left side (opposite the gears) snapped while climbing a hill. The break was about 1 1/2 inches from the pedal. I was fortunate to retain control of the bicycle and thus was not injured, but based on Internet research, a broken crank often if not usually results in a crash and injuries.

   Shimano FC-7800 Dura Ace crank arm on high-end bicycle snapped without warning

   Model

   Dura Ace FC-7800

   UPC

   None

   Serial number

   None seen

   Bought from

   Bicycle John’s assembled the bike

   Bought

   Oct 20, 2006

   Where

   Sun Valley, California: Street or Highway

   Who was involved

   Age 67, Male

   The reporter’s relation to them

   Self

   As this report names them

   Brand Shimano Dura Ace FC-7800, made or sold by Shimano Inc

   How badly, in CPSC’s words

   Incident, No Injury

9. No incident, no one hurt

   Made Feb 15, 2021 · , sent to the company Mar 5, 2021 · , published by CPSC Mar 19, 2021

   The product, in the report: Road Bicycle: Shimano 10 Speed Dura Ace Crank arm broke in half. Lucky I was not killed or injured.

   Bicycle: Shimano Dura Ace 10 Speed crank arm broke in half. Its lucky I was not injured or killed.

   Model

   FC-7800

   UPC

   N/A

   Serial number

   N/A

   Bought from

   Wheel Power Bike Shop

   Bought

   Jan 2, 2005, about then

   Where

   Fairfax, Virginia: Home/Apartment/Condominium

   Who was involved

   Age 63, Male

   The reporter’s relation to them

   Self

   As this report names them

   Brand Shimano 10 speed crank arm (Dura Ace), made or sold by Shimano Inc

   How badly, in CPSC’s words

   No Incident, No Injury

10. No one hurt

    Made Aug 7, 2019 · , sent to the company Aug 15, 2019 · , published by CPSC Aug 29, 2019

    The product, in the report: Shimano |,pde; Ultegra 6800 series road bike crankset.

    The Shimano Ultegra 6800 cranks on my road bike failed. The crank cracked at the spindle. This created a potentially hazardous situation as if there was a complete failure, which was sure to eventually happen, a crash was likely to occur. The crack was picked up by my local bike shop. There seem to be a lot of reports of failures of this particular crank. It should not fail during normal usage. My bike was never crashed or damaged. These cranks should be recalled and replaced. They are not safe. There was no “incident” as I did not crash.

    Model

    6800

    Bought from

    Fusion Cycles, New Jersey

    Bought

    Sep 3, 2016, about then

    Where

    Demarest, United States: Home/Apartment/Condominium

    Who was involved

    Unspecified

    The reporter’s relation to them

    Unspecified

    As this report names them

    Brand Shimano, made or sold by Shimano Inc

    How badly, in CPSC’s words

    Incident, No Injury

11. No one hurt

    Made Feb 20, 2017 · , sent to the company Mar 23, 2017 · , published by CPSC Apr 13, 2017

    The product, in the report: Bottom bracket that connects the crank arm to the bottom of the bicycle. Had it installed by my local bicycle shop on October 4, 2010.

    Riding my bicycle when the crank arm broke off of the bottom bracket. I was going slow up a hill and did not get injured. However, had I been going faster I could have been seriously injured

    Bought from

    Bike America

    Bought

    Oct 4, 2010

    Where

    Raymore, Missouri: Street or Highway

    Who was involved

    Age 58, Male

    The reporter’s relation to them

    Self

    As this report names them

    Brand Shimano, made or sold by Shimano Inc

    How badly, in CPSC’s words

    Incident, No Injury

12. First aid

    Made Sep 20, 2015 · , sent to the company Sep 28, 2015 · , published by CPSC Oct 13, 2015

    The product, in the report: Shimano Ultegra FC-6650 10 speed crankset 175mm arms 50/34 compact

    Sudden catastrophic failure of a Shimano Ultegra compact crank that was used on my 2007 Cervelo R3 bicycle. This was the 50/34 Ultegra 10 spd crank that came with the bike when I bought it in August 2007. I have had no prior issues with the crank and had bottom bracket replaced twice, most recently 15 months earlier. As you can see it failed dramatically. On 12 September 2015 I was riding uphill on hwy 39 at about 8-10 mph in the San Gabriel mtns and got to a switchback I had been on countless times in the past (and earlier in the same day) when out of the saddle the crank suddenly failed with zero warning and I tumbled into the road. I am 6’1” and weigh 188lbs. The bike has never been in any sort of major accident and that pedal has never been hit hard in any kind of mishap. No one other than me and shop personnel have ever ridden the bike. Other than scrapes I was unhurt. I include photos with the crankset if a subsequent page of the report will allow me to do so.

    Model

    Shimano Ultegra FC-6650 10 speed crankset

    Bought from

    bike Wave

    Bought

    Sep 3, 2007, about then

    Where

    above Azusa CA, California: Street or Highway

    Who was involved

    Age 57, Male

    The reporter’s relation to them

    Self

    As this report names them

    Brand Shimano Ultegra, made or sold by Shimano Inc

    How badly, in CPSC’s words

    Injury, First Aid Received by Non-Medical Professional

13. No one hurt

    Made Sep 14, 2015 · , sent to the company Sep 22, 2015 · , published by CPSC Oct 6, 2015

    The product, in the report: Shimano BR-785, hydraulic disc brakes

    I bought a bike with Shimano BR-785 hydrolic disc brakes. Twice the brakes have failed because the brake fluid has leaked out of the brake during a ride. Both times I was descending a mountain for an extended period for about 1500 feet.

    After the first incident my rear brake was replaced by the manufacture Shimano for free. I was told this has happened on multiple bikes for customers of that bike shop.

    After the second failure, this time the front bike brake, again on a long mountain descent of about 1500 feet occurred. I took the bike into the bike shop and the mechanic said the same problem was happening for the front brake this time. They also again stated that I was not the only customer having this problem, and that they were running into problems getting Shimano the acknowledge the problem.

    The problem seems to come on pretty quickly. So it’s not possible to judge the bike has brake problems until an actual descent has started and the fluid leaks out sufficiently to cause a loss of braking power in the middle of the descent.

    My concern at this point is that a defective product is out on the market and the failure of the brakes could cause serious injury and death. I wouldn’t be reporting this had there been one failure. Having two failures and hearing that other customers are also having the failures makes me wonder if I should be using the product at all, and that this is a larger problem and people are going to get injured and killed before something is done about the situation.

    Model

    BR-785

    Bought from

    Mikes Bikes, California

    Bought

    Aug 1, 2015, about then

    Where

    Sunnyvale, California: Place of Recreation or Sports

    Who was involved

    Age 60, Male

    The reporter’s relation to them

    Self

    As this report names them

    Brand Shimano America Coorperation, made or sold by Shimano Inc

    How badly, in CPSC’s words

    Incident, No Injury

14. No one hurt

    Made Nov 22, 2011 · , sent to the company Dec 1, 2011 · , published by CPSC Dec 15, 2011

    The product, in the report: Shimano WH-RS10 road bike wheels These are inexpensive wheels that come on many new bikes.

    My 2009 Fuji Roubaix RC road bike came with Shimano WH-RS10 wheels. These wheels in fact are on many new bikes. After a recent ride and inspecting those wheels I noticed a crack in the rim perpendicular to the spoke. On removal of the wheel and careful inspection there were breaks at 9 of the 20 spokes in that rear wheel. The wheels have considerable use but should not fail in such an unsafe way. I sent these wheels back to Shimano to impress them that this is a serious safety issue. I’m tired of products being designed to the point that failure occurs in the worst possible way. I have been told by the bike shop that returned them for me that the problem occurs frequently with these wheels. Also these wheels are still on bikes sold today. It is said that a new generation wheel will have re-enforcement rings at the point the spoke enters the rim. But the public should be aware the RS10 is dangerous!

    I think Shimano will send replacement wheels although that was not my intention.

    Model

    WH-RS10

    Serial number

    bike IF80500775

    Bought from

    Performance Bike

    Bought

    Apr 19, 2009

    Where

    Durham, North Carolina: Other

    Who was involved

    Unspecified

    The reporter’s relation to them

    Self

    As this report names them

    Brand shimano, made or sold by Shimano Inc

    How badly, in CPSC’s words

    Incident, No Injury

CPSC’s disclaimer

Sources