from Rookie’s keyboard,
Hello, friends
This will be a blunt post. Some will like it. Some will hate it. But I think that sometimes we need to have a firm opinion instead answering everything with “it depends”.
Here’s the deal – I’d never run a derailleur guard on any of my bikes.
Why? Well, take a pen and a piece of paper as this will be a long one.
Here are the reasons:
Bicycles Have Derailleur Hangers
Rear derailleurs attach to the frame via a derailleur hanger made of soft aluminum. The chosen material isn’t accidental or a cheap attempt to save money.
It’s purposefully selected as it turns the derailleur hanger into a strategic point of failure.
During a fall, the soft aluminum hanger will bend before the chainstay and the actual derailleur. This prevents stress transfer to the frame.
On a long trip, high-IQ cyclists carry a spare derailleur hanger with them in case the original is ruined in an accident.
And if you have a damaged hanger, don’t throw it away. Once at home, you can straighten it with a derailleur hanger alignment gauge.
There are also universal derailleur hangers that can be used on any bike (at least temporarily). Get one if you have a long trip ahead.
High End Derailleur Have Low Profiles
The more expensive rear mechs have a low profile. The “tucked-in” position reduces the chances of hitting or catching an external object (e.g., a branch).
A classic example would be Shimano’s line of Zee derailleurs designed for “heavy-duty” mountain biking.
Derailleur Guards Grab Things
Derailleur guards protrude and sometimes grab external objects – a strong reason for off-road riders like me to avoid this piece of equipment.
If a branch slides into the derailleur guard, the chain may pull the stick closer to the rear wheel and eventually into the spokes. And once the wheel is blocked, the outcome could be….well…painful.
Derailleur Guards = Extra Weight and Drag
A derailleur guard adds 80-160 grams to a bicycle. I admit. It’s not a lot, but it may matter to some weight weenies out there.
Another downside of derailleur guards that may trigger the same group of cyclists is the extra drag that this little cage adds.
The effect is very small, though. Even a pro cyclist won’t notice it.
Derailleur Guards Just Aren’t Cool
Derailleur guards are not part of the hot bike accessories. They’re considered weird, non-professional, and unnecessary. An advanced rider who uses one could be ridiculed.
If you want to receive bonus points for the looks of your bicycle, avoiding derailleur guards makes a lot of sense.
A Derailleur Guard Offers Only Limited Protection
A derailleur guard protects the rear derailleur mainly from lateral falls and side hits to the body from objects with a large surface area.
A small branch or a rock could still hit the low pulley and the cage of the derailleur from below.
Also, derailleur guards offer protection only from low-impact hits. During a serious collision, the guard is very likely to bend and hit the derailleur.
Therefore, derailleur hangers are required even when the bike has a derailleur guard because they further minimize the negative consequences of a crash.
Derailleur Guards May Damage The Frame
If a derailleur guard is mounted directly to the frame it could harm the rear triangle by applying nasty twisting force to the right chainstay.
Aluminum and carbon frames are the most likely to be hurt from the impact because they are less elastic than steel and cannot be rebent into proper shape.
Having said that, the chances of this happening are not as high as some may claim because high-quality frames are strong. Moreover, the axle of the rear wheel stabilizes the chainstays.
If you apply lateral pressure to a chainstay, it could easily bend if there’s no axle in the dropouts to stop it from moving to the opposite side. But when the rear wheel is in, the chainstay has a harder time caving in.
Ok. There is a little bit of usefulness, but only in the following situations:
On a kids’ bike
Derailleur guards could be useful when mounted on a kids’ bike because children tend to throw their bicycles around.
On a rented bike
Public bicycles used by multiple people could benefit greatly from another layer of defense because clients often treat them as disposable machines.
A little extra protection to an already fragile area could be beneficial.
On a touring bike
Touring bikes are potential candidates for derailleur protectors due to the high level of abuse.
A side fall of a loaded bike could harm the derailleur and kill the pedaling efficiency of the machine instantly.
And since derailleur guards are supposed to help precisely with side falls, some bike packers found the accessory helpful.
Another situation when a guard could help a touring bike is during transportation. If you’re traveling with your touring bicycle on a train, for example, the derailleur could get hit accidentally by another passenger or their luggage.
When Transporting a Bicycle on a Plane
Experienced bike travelers recommend adding a derailleur protector to the bike when transporting it via plane. The extra protection reduces the risk of derailleur damage if the baggage handlers aren’t very careful.
Some of the more expensive bike bags include a protector, but many cyclists are buying an aftermarket one because the stock ones don’t always cut it.
The Bopworx detachable guard is one of the popular products used for this purpose.
Until next time,
Rookie
Leave a Reply