Single Chain Ring Considerations

A Canadian Peugeot with single chain ring and spider mounted chain guard.

Most of my bikes have multiple chainrings – double or triple.  I’ve gotten so used to the shifting patterns on my bikes, that I don’t think much about the double rear shifts that might be required to maintain cadence when shifting the front ring, nor do I worry that I might have to trim out the front derailleur from time to time (I use friction shifting for the most part).  But, that is not normal.  I am a geek, and the vast majority of cyclists are not (no offense to the wonderfully geeky readers of this blog).  Non-geeky cyclists are probably drawn to the seeming simplicity of a single chain ring up front.  Less shifting equals better riding, right?

The only bike in my constellation of daily riders with a single chain ring up front is my 1987 Panasonic MC 7500 – a bike I acquired as a frame and fork and then built into a city commuter.  Even though it’s the heaviest bike I ride, it’s the one that gets the most daily use.  One of the reasons for its appeal as a commuter bike is the simplicity of its equipment.  It has a rear freewheel with 6 speeds and plenty of range, plus a single chainring up front.  I installed a $7 ratcheting no name friction shifter on the handlebar to move the rear derailleur, and the shifter works intuitively with the lower end but perfectly decent Shimano Acera long cage rear derailleur.  At first, I didn’t use a chainkeeper, but experienced the chain jumping off on a few occasions, so decided to install Paul’s chainkeeper.  Chainkeepers are designed to keep the chain from falling off either side of the front ring of a single chainring bicycle when shifting vigorously or oddly, as can happen when unexpected events occur while cycling, and especially while commuting.

After a few mishaps with Paul’s chainkeeper, the most recent of which caused me to re-locate this device, as shown above (it is now a “fender keeper”), I have been thinking about the way returning cyclists, as well as those not mechanically inclined might have dealt with my recent near disaster.

I was cycling home after a day at work, heading downhill when suddenly my cranks would not turn.  Since I was still freewheeling I knew that the problem was at the front of the drive train and I immediately suspected that the chainkeeper had become dislodged and contacted the chain.  I pulled over immediately, and after confirming this was true, disengaged the chainkeeper, as shown above.  I rode home with no further issues, but shifted very gently, hoping my chain would not jump off the front ring, and all went well.  It is unlikely that the average cyclist would have been able to diagnose this problem, much less solve it.  Nor should they really need to.  Instead, the marketplace needs some much better solutions to the single chain ring challenge.

1947 Camille Daudon with single chainring

Vintage bicycles with single chain rings don’t need chain keepers.  Why?  The rear freewheel will have only 3 to 5 speeds for the chain to navigate, causing the chain movement to be very manageable as compared to modern drive trains with 8 – 11 speeds at the rear.  For commuters, it’s not necessary to have tons of gears, but instead to have enough gear range to accommodate the hills you encounter on your commute.  So, 3 to 5 speeds might be all you need, if the gear range is appropriate.

Paul’s Chain Keeper

The problem with many chainkeepers, such as Paul’s, is that they work TOO well. Since they are designed to prevent chain movement, there isn’t enough clearance to provide for even the slightest change in chain angle, and they require extremely precise adjustment that can go out of whack with even a small mishap.

One solution is to put a spider mounted chain guard on the crank, and then use a seat tube mounted chain watcher on the other side.  Or, you can put two spider mounted chain guards on the crank – on either side of the chain ring.  Sheldon Brown published an article for Adventure Touring Magazine in 1999 which deals with chainring issues for touring bicycles, but he also includes some good advice on anti-derailment devices that can help prevent the chain from dropping off a single chain ring.

If you are going to convert your bike to a single ring up front, here are some points to consider:

Shorten the Chain – you will want to remove links from your chain in order to accommodate the switch to a single ring up front.  This will help to prevent chain slap and chain jump.

Decide about a chainkeeper vs. chainwatcher vs. chainguard(s):  Depending on the width of your rear cassette or freewheel, you’ll need to think about the demands you are placing on the front ring.  If you are trying to go with an 11 or 10 speed system at the rear, then you’ll need something to help deal with the extreme angles that the chain will experience at the front ring.

Make sure the rear derailleur can handle the range: when switching to a single ring up front, you often need to increase the range of your rear cassette or freewheel.  If you do so, make sure that your rear derailleur can handle the the bigger cogs.  You may need to adjust your b-screw, or invert it (a la Sheldon Brown) to get the clearance you’ll need for the larger cogs.

Or – shift carefully and don’t worry about any of this.  Occasionally your chain may fall off, and then, you’ll put it back on again.

Shake, Rattle and Roll

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My 1990’s Terry Symmetry is a great commuting bicycle.  It handles well and can keep up with the faster bikes on my regular commute.  But recently I had been hearing an annoying rattle on the front end of the bike.

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Diagnosing bicycle noises while riding brings to mind Dante’s Inferno.  As one’s thoughts spiral through endless ideas and related solutions, the bicycle itself seems drawn further toward complete annihilation, into the concentric circles of hell.  After decades of riding, I have hopefully learned to pay more attention to the occasional odd and unexpected sounds coming from the bike I am riding.  It’s almost always a good idea NOT to ignore them.  Like most cyclists, I love and expect a certain silence from my bike.  Encountering dry, squeaky chains, rattling fenders, and loose fitting luggage on other cyclists’ bikes weighs on my conscience:  should I point out that their rear wheel is out of true or that a little bit of chain lube is in order?  But that’s a question for another day.

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Front end rattles can be as difficult to nail down as noises coming from the center or back of the bike.  In my case, because I had used an unusual mounting system for my fenders, my first thought was that the cantilevered portion of the front fender was bouncing around more than usual.  After holding my hand over the front portion of the fender and hearing no change to the rattling noise, I realized that this wasn’t the problem.  So, I continued my diagnosis while riding by holding my hand over different parts of the front end, to no avail.  Nothing stopped the strange rattling noise.

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As it turned out, the culprit was a broken fender nut on the Bluemels “over the top” fenders that I had mounted on this bike.  I had used all the original hardware on the stays, and paid no attention to how rusted the eyebolts looked.  Finally, one of those rusted eyebolt nuts cracked, and that caused all the rattling.  I didn’t really figure this out until I had:  checked the fork for lack of play (there was none), checked the brake mount for a loose bolt (none), and checked the torque settings on the stem’s handlebar bolt and on the stem itself.  All were in order.  A process of elimination led me to the fenders.  I removed them and discovered the problem right away when one of the nuts fell apart in my hand.  I replaced all the hardware, and then decided to re-mount the fenders using these Velo Orange fender brackets, which are designed for bikes which lack fender eyelets (a sad truth of my 1990’s Terry).  I had been using P-clamps to mount the fenders to the fork.

The Velo Orange brackets, shown above, really clean up the front of the bike, but make front wheel removal more time consuming and finicky.  Fortunately, the rear drop outs of this bike have fender eyelets, so no brackets are needed on the back end of the bike.  I’m glad I took the time to resolve this issue.  A loose fender could have caused a crash.

Paul’s Thumbies

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I pretty much love all the Paul’s components in my collection.  I have used Paul’s chainkeeper, Paul’s cantilever brakes, and now Paul’s Thumbies.  These products were developed here in the US, and the company is home-grown, hailing from Chico, California and founded by Paul himself back in 1989.

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Paul’s components have a distinctly industrial look – similar to that of Mafac brakes.  While some people may be turned off by this lack of “beauty”, I find it charming.

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Nitto Rando bar with downtube Shimano shifters

As I have been recovering from my broken leg last Fall, I noticed that I really wanted to ride in a more upright position on my 1980’s Guerciotti.  I had previously set it up with a Nitto Rando bar and stem, but when I originally purchased the frame, I had set it up as a city bike with upright bars, as shown below.  The only reason I changed this configuration was that my Nitto city bars were recalled and no replacement ever materialized.

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Guerciotti with Nitto city bars which were recalled

So, it was time for a new bar, stem and shifter set up for the Guerciotti.  Since I was going to be using flat bars with this new configuration, I wanted to bring the shifters up onto the handlebar.

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To use Paul’s Thumbies, you need some shifters which don’t have a curved mount to the square boss on the downtube.  That means that all Shimano bar end shifters will work, but that many downtube shifters will not.  The above Shimano downtube shifters which were on my Guerciotti will not work with Paul’s Thumbies for this reason.

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“Pointy” Shimano shifter pods

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Right side shifter mount

So that meant I was going to replace the shifters with some bar-end shifters.  Shimano 8 speed bar end shifters are very versatile, due to their friction mode, which is how I shift with this bike’s drive train.  Once you’ve figured out which shifters you are going to use, you will need to add some shifter pods to the downtube bosses if you weren’t already using bar end shifters.  I found these 1980’s Shimano pods in my parts bin – they are very pointy compared to their modern counterparts, and look fun to me.

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The set up is very simple, once you have chosen the appropriate shifters.  Paul makes Thumbies for both Shimano shifters and Microshift shifters, and for MTB and Road bar sizes.  So, when you order, pay attention to the fine print.

Once the Thumbies are mounted to the handlebar, it’s just a matter of placing the shifters in the correct position, and screwing in the supplied bolt and washer.  You can control the feel of the shifter by tightening or loosening the supplied bolt, in the same way you would do with the Shimano bolt for any bar end or downtube shifter.

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I was concerned that the bar end shifters I mounted to Paul’s Thumbies might be “ergonomically incorrect”, in that they weren’t designed to be used on the top of the handlebar.  Fortunately, they were very easy to use and felt at the ready with a simple touch of my thumb.  They needed no fine tuning after an initial rainy commute.  While some people may balk at spending an extra $50 bucks or so to move your shifters to the handlebar, in my view that is better than throwing out your shifters and buying new ones.  And, if you ever want to go back to your downtube or bar end shifters, you can easily do so.

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