Paul Chain Keeper

The Paul Chain Keeper is a chain retention device for 1X single ring drivetrains. It’s available in models to either clamp on a seat tube in place of a derailleur (shown here), or mount on an external bottom bracket. The seat tube version is available in three sizes to fit 28.6mm, 31.8mm, and 35.0mm seat tubes. The external bottom bracket model is intended for full suspension frames, carbon fiber frames, frames with eccentric bottom brackets, and frames with non-standard tubing.

Not all 1X set-ups require a chain keeper. If you’re doing a conversion, my advice is to give it a try sans keeper for a week or two to see if chain derailment is going to be an issue. Drivetrains set-up with good alignment and high tension may never throw a chain, particularly if the shifters are indexed and the bike is only used on relatively smooth, paved roads. But, if you plan on riding your bike on dirt trails, or if you’re an aggressive rider who hops curbs and so forth, a chain keeper of some sort is definitely in order. I decided to install the Paul Chain Keeper on my bike because I occasionally ride dirt trails, and I sometimes hop curbs when transitioning from bike lanes to off-street paths.

The Paul Chain Keeper works as advertised; with this unit installed, your chain will not derail, period. The fit and finish are excellent, and like all Paul components, the Chain Keeper is manufactured right here in Chico, CA, USA.

I purchased my Paul Chain Keeper at The Bicycle Business in Sacramento, CA (thanks, guys!). They can also be ordered directly from Paul in Chico.

The Bicycle Business
Paul Component Engineering

Note: The Bicycle Business is a sponsor of this website.

24 Responses to “Paul Chain Keeper”

  • CHenry says:

    Rohloff makes one also, but this is much more elegant.

  • Ted S says:

    This is an extremely reliable addition for your 1X build. After a periodic chain jumps on my 1 x 9, I installed the Paul Chain Keeper, which completely solved the issue. It works so seamlessly that I keep forgetting that it is there!

  • David says:

    I use an old front derailler. It gets the job done and it’s a lot cheaper.

  • Alan says:

    The Paul Keeper, because of its design and position, completely locks the chain on the chainring while still providing enough clearance to not rub throughout the full range of a 9-speed cassette. Derailleurs sometimes work fine as keepers, but depending upon the model and set-up, they may rub in the lowest and highest gears. Of course, a person can leave the shifter on to adjust the position of the derailleur, but then it’s not really a 1×9 conversion. :-) Also, a derailleur will certainly catch the chain in the case of a derailment, but it may not actually prevent the chain from dropping off of the chainring in the first place, particularly if it’s a model with a wide cage.

  • geoff says:

    Thanks for this great review! Anyone with a Dahon folder equipped with a plastic chain ring guard will want to know about this. Because – someday – you will break the guard and you won’t easily find a bash guard to replace it. I’m getting one of these.

  • geoff says:

    No, forget it…. Dahon seat tube is 39mm… too fat.

  • Alan says:


    If your Dahon has an external BB, the model designed for bikes with oversized seat tubes might work.

  • David says:


    I adjusted the limit screws to move the derailler to the appropriate position side-to-side to clear the whole range of gears in the back without needing a cable or lever. I also slid it down the seat tube so the chain rides near the top of the cage. This constrains the chain to the ring laterally as well as vertically, much like the Paul, without rubbing since the upper part of the cage is larger than the lower part.

  • Lovely Bicycle! says:

    This is a good idea, but I wish they had something more classic looking; this will look out of place on a vintage-style Porteur for instance.

  • Alan says:

    @Lovely Bicycle!

    Yeah, most of Paul’s products have a modern-ish look, probably because they’re CNC machined from bar stock. Even his brakes, some of which are closely patterned after old designs, have a high tech look to them (IMO). I don’t think this is a bad thing, but aesthetically they may not be a good match for some of the bikes featured on your blog.

  • Bee says:

    i have one of these on my cyclocross bike, and I love it. however, a word to the mechanically challenged – it can really be a bear to install, especially if you don’t have a wrench that can apply force at an angle (rather than straight on). a rachet or a ball-tipped allen works well.

  • Alan says:


    It must depend upon the bike; as you can see in the third photo, there was plenty of clearance on my LHT to install the chain keeper using standard allen wrenches.


  • Scott Wayland says:

    More beautiful Paul gear. Love my Thumbies!

  • DRikardo says:

    My thumbies too!

    Beautiful cranks, any idea where one could buy these??

  • Nico says:

    I like the looks of this. Very clean. Is that spot of grease on that chain I see? :)

  • Alan says:


    “Beautiful cranks, any idea where one could buy these??”

    Those are Sugino RD2 Track cranks. They come in either a satin or polished finish. Those in the photo are polished. I purchased mine at Gold Country Cyclery in Shingle Springs, CA. You can also get them at The Bicycle Business in Sacramento. Both are sponsors of this site – click on their banners in the right hand column for more information.


  • Alan says:


    “I adjusted the limit screws to move the derailler to the appropriate position side-to-side to clear the whole range of gears in the back without needing a cable or lever.”

    Thanks for the info…

  • Fergie348 says:

    Alan, your bikes are entirely too clean. We’re starting to wonder if you ride them at all..


  • Alan says:


    “Is that spot of grease on that chain I see? :)”

    It’s actually wax:


  • Rick says:


    I understand: the biggest drawback to being a friend of Alan’s is how shabby your bike looks when you ride alongside him; still, all things being equal, my wife and I can easily overlook that shortcoming because of the spectacular culinary talents his wife has! Lol!

    (In the meantime, ask him to explain to you how he cleaned his bikes after a trip in the rain while living in Seattle–now THAT will make you feel like you NEVER clean your bike!!) :-))

  • tdp says:

    Just discovered the DropStop today and would love to try it out or see a review of it. I wonder if the long version would work for a single ring as well as the Chain Keeper?

    Jtek DropStop:

  • Tim D. says:

    Paul definitely makes beautiful stuff, but like David, I can’t imagine throwing down that much cash for this. On my commuter, I don’t use anything on the front, and I don’t get derailments. On my commute, there is about a 2 mile stretch on a very rough gravel road (and I mean exploded mine field rough) and I have traversed it fine. On my 1×9 MTB, however, I definitely needed something to hold the chain on. I did as David did with an old front derailleur, but I hacked it down with an angle grinder so that it doesn’t hang down to the chainstay. It’s not the prettiest solution, but this is the old bike I thrash around on single track with, so who cares?

  • David says:

    I find even on my 1×9 MTB that i haven’t had problems with derailments. It is a converted Single Speed 29er so it has a tall tooth profile on the chainring, no pins or ramps etc. Price wise the chain keeper is not cheap but better than a new crankset and probably on par with a new chainring. Lovely stuff he designs, i would spend hundreds on Paul stuff, if i had it…

  • EcoVelo » Blog Archive » Back in Black says:

    […] related, but I swapped the triple for a 1×9 drivetrain (read about it here). I also added a Paul Chain Keeper and replaced a damaged Pletscher center stand (that’s a story for another day). I ordered […]

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