Installing a chainguard on a bike with derauiller

Question

My pants always get caught in the chain (and wearing shorts is not an option). However, it seems that it's impossible to have both a derailleur and a chainguard so what is the solution?

• Can I just lock the front derailleur in place and slip the chainguard past it. (locking the bike in top gear?)
• Do I have to remove the derailleur entirely, by breaking the chain?
• Can I just remove the smaller front gears and lock it into third? How difficult is this? Do the gears just pop off or is there more to it?
• Does anyone make a metal chainguard so large that it could encapsulate both the derauiller AND the front crankset. (a preferred solution, but not easy to find)

Example of a chainguard to protect the pants from getting ripped. It also proctects the rider in case of a fall so that the gear teeth don't puncture the leg. (It happened to me and is just as nasty as it sounds! Gear teeth are dirty.):

Note: The winning answer will suggest a chainguard that covers both the top of the chain and the crankset (as seen in the picture above). Suggestions of tying, clipping or banding pants are not an answer to the question being asked. However, an answer that involves modifying the bike in some way to accommodate a chainguard will be accepted.

Answer 1

This StackExchange site has its limitations, in that product recommendations are not allowed because of regional differences and products/pricing going obsolete. However I think the answers are no you don't have to break the chain, remove the derailleur or lock off any gears. Products exist but are quite unusual so you will have to do some searching online or in bike shops in your local region.

Using Google, I found a couple of examples. The first one I got to a website which sells chainguards and browsed through the ones which say compatible with a single gear, and discovered some which say compatible with a triple ring like this style:

Another Google search along the lines of "chainguard triple derailleur" and I found this image, which has a more conspicuous allowance for the derailleur to remain fitted and usable:

Answer 2

In a way, the front derailleur already is a sort of chainguard device as it restricts chain movement. A correctly set up front mech makes an extra chain guard redundant, and clutch devices found in modern rear derailleurs that control chain tension even more make it even less needed.

Standalone chain guard devices are mostly needed for two reasons, and predominantly in more technical mountain biking disciplines such as enduro and downhill, where chain really flies like crazy:

1. The bike is a 1× system with a single front chainring, thus no front derailleur.
2. The chain guard is combined with a bash guard device meant to protect the front chainring from rock strikes.

It is unclear what type of chain guard you are trying to install, please clarify, but the most common type these days looks like this, and it is certainly not compatible with a conventional front derailleur:

There are however other types of chain tensioner devices, both DIY and commercially solved, that would allow you to reduce chain movement while being compatible with a front derailleur. E.g. from here:

Or something like a small red wheel below the chain on the picture below. Here you also see a 2×-specific bash guard mounted to the spider:

• Can I just lock the front derailleur in place and slip the chainguard past it. (locking the bike in top gear?)
• Do I have to remove the derailleur entirely, by breaking the chain?
• Do I have to remove the smaller front gears? Is this possible?

All these options suggest that you want a single front chainring. It is possible, but will most likely require upgrading the whole drivetrain, including rear derailleur and cassette (not a cheap way), or tinkering and making compromises with existing drivetrain (requires a bit of a knowledge or time).

Having a single front chainring opens some options for installing a chain guard. Keep in mind frame compatibility issues: you cannot install an ISG-typed chain guard on a frame that lacks mounting tabs for it. However, a modern combination of a so called narrow-wide single front chainring (seen on the first picture above) and a rear derailleur with a clutch device is enough to retain the chain on their own. Unless you absolutely cannot allow a chain drop, you won't need a chain guard in such case.

Answer 3

The (imperfect) solution for derailleur systems is a protector ring, which is also called a "chain guard". Though it's missing from your crank set, chances are that a matching guard does exist; look into it. See those four empty bolt holes near the outer circumference of the large chain ring? That's where the chain guard is attached. Basically it just has to have the right bolt circle diameter, and overall radius. If you have that type of chain guard, and also do something to bind your loose pant leg to your leg, you shouldn't have any problems.