I remember that Biopace chainrings were controversial when Shimano introduced them in the early ‘80s — and not very successful. Unless they really bug you, I recommend using them until they’re worn out, then replacing them with new round rings.
A few months ago, I tried to sell a couple of used Biopace rings on eBay. There was absolutely no interest. That tells me that they’re not fondly remembered by bikies. I wound up giving them to a friend for his old bike.
Smaller Chainrings for an Ultegra Triple
DEAR JIM: I just picked up my new LeMond Victoire with an Ultegra triple crankset. The 117-inch top gear is way too big for me. I prefer to spin at 90-100 rpm and could easily be happy with the 100-inch top gear that a 48-tooth chainring would provide. What recommendations do you have for smaller chainrings? — Leon W.
JIM LANGLEY REPLIES: The Ultegra crankset uses chainrings with the 74/130 bolt pattern, which means you can swap your large rings for any made for a 130. This measurement is the bolt-circle diameter, the distance in millimeters from the center of any chainring bolt hole straight across the chainring to the arc of an imaginary circle drawn to bisect all chainring bolt holes.
You will have to go with something other than Shimano chainrings, though. Shimano doesn’t offer 130s in other than “conventional” sizes. However, companies such as Sugino and TruVativ have 48-tooth rings if that’s what you want. Sugino offers a 50, too, and has middle rings of 38, 39, 40, 43, 44 and 46 teeth.
So, as long as you don’t mind changing brands, which might slightly decrease shifting performance, you can change the rings to suit your needs.
How to Check Chain Line
DEAR JIM: Do short chainstays necessarily mean shifting problems? I have a ’99 Litespeed Ultimate, which I believe has chainstays on the order of 39.3cm. The bike has a 9-speed Ultegra kit (double crank) and a 12-27 cassette. I get chain jump when I combine the big chainring with the 24 or 27 cog. Is this normal? — Darrell G.
JIM LANGLEY REPLIES: Triple cranksets definitely work best on bikes with long chainstays. However, after I answered a question about another Ultimate with a triple, two readers commented that while their Ultimate triples were a bit finicky to keep adjusted, while in tune they shifted flawlessly.
So, I believe something is amiss with your bike. It should shift nicely and run smoothly unless something’s worn, defective or misadjusted.
It’s not unusual for drivetrains to run poorly on the large chainring and extreme large cogs, though usually it’s just rough and noisy, not so bad that the chain jumps.
First check the chain line to ensure that you have the correct relationship between the crankset and the cassette (called the “chain line”). This is easy with a straightedgethat can fit between the chainrings. Just slide it in place and let it rest on the cassette. It should fall exactly on the middle of the cassette if the chain line is correct. If it lines up toward the smaller cogs, the angle from the big ring to the bigger cogs is worse than it should be and that’s likely the reason the chain won’t stay put.
I should point out that it’s best not to use the big/big combination. But you still need to have an accurate chain line because sometimes you make this shift without realizing it and you don’t want problems. Also, if the chain line is off it can affect shifting throughout the range.
Now, if the chain line is right, the problem could be a bent rear derailleur, which can happen if it hits something or the bike falls over. To check for this, stand behind the bike and sight to see if an imaginary line passing parallel through the cassette cogs will continue through both derailleur pulleys. If not, that’s a sign that the derailleur has been bent. (Or it might be the frame’s derailleur hanger, which is something a shop should be able to fix for you.)
Chain line can be corrected, but because parts are usually required, you’ll probably want a shop to handle that, too. If the shop that built the bike is available, it ought to be willing to fix chain line for free if they got it wrong initially.
Chain Wear and Drivetrain Groans
DEAR JIM: I own an Italian bike with full Campy Chorus 10-speed gearing. I’ve maintained the chain and the rest of the bike religiously since new. I have two questions.
First, I’ve put 4,500 miles on the bike and original chain. I believe campy recommends changing the chain at 2,500 miles or sooner. But my Park CC-3 chain checker says it’s in almost new condition. Should I replace it anyway?
Second, there is a groaning sound somewhere in the drivetrain under load. It seems to be coming from the bottom bracket area. I’ve done various experiments to isolate the source but can’t find it. I read somewhere that the sound may indicate that the BB shell may need to be faced. The bottom bracket cartridge is a Campy Record that came new in the bike, so I wonder if facing it would matter. What do you think? — Don O.
JIM LANGLEY REPLIES: Chain wear depends a lot on how and where you ride, and how you maintain your chain. If your CC-3 tool shows that your chain is still in like-new condition after 4,500 miles, I would expect that you don’t ride hills all the time, don’t accelerate/sprint/hammer a lot, don’t ride in the rain much, and you shift with finesse. It certainly helps that you maintain your bicycle so well.
If I were you, I’d keep riding the chain until the tool tells you it’s time for a new one. As long as the chain’s in good shape, it can’t accelerate cog wear. Campy 10-speed chains are expensive, so get your money’s worth.
As for the noise, it’s hard to diagnose through e-mail. Usually the bottom bracket is faced at the factory or by the shop mechanic who builds up the bike. You can sometimes tell by looking carefully at the edge of the bottom bracket shell. If it’s been faced, there’ll be a sharp edge without paint.
The bottom bracket might simply have loosened, which is easy to check if you have the tool to snug the cups in the frame. With it, you can also remove the bottom bracket, check everything and reinstall it.
What’s tricky about noises that seem to come from the bottom bracket is that they can be caused by many things, including pedals, chainring bolts, shoes/cleats, crankarms, the seat (!) and so on. If you haven’t done so already, enlist some help. Ask a friend to kneel next to your bike while you stand in place, squeeze the brakes and apply pressure on the crankarms. Sometimes two sets of ears are better than one.
Most shops will be happy to test ride your bike to diagnose the noise. Of course, a shop can handle the repair, too.
SRAM’s Versatile Chains
DEAR JIM: What are the pros and cons of setting tandem cranks 90 degrees out of phase? — Bill K
JIM LANGLEY REPLIES Proponents of out-of-phase cranks believe that it creates more efficient pedal power because it eliminates both riders simultaneously having their cranks at the “dead spots” where no force is applied — the top and bottom of the pedal stroke.
In other words, one rider is always powering the pedals, whereas with in-phase cranks, both crankarms simultaneously pass through the point with the least power available.
Depending on how you prefer to mount and start, offset cranks might help here, too. For example, one crankset can be ready to deliver power while the other can be set with the pedal down for mounting (if that’s how you get on).
The reason most tandems use in-phase cranks is because when they’re out of phase, the possibility of striking a pedal in a corner is increased. It takes experience to remember where all four pedals are in relationship to the ground.
Plus, if you like to stand when climbing, in-phase is the way to go because it’s the only way two riders can efficiently do it.
It’s simple to change the phase. If you mainly ride seated and don’t corner aggressively (or if you have a hybrid tandem with high pedal clearance) you might give it a try.
Jim Langley is RBR’s Technical Editor. He has been a pro mechanic and cycling writer for more than 40 years. He’s the author of Your Home Bicycle Workshop in the RBR eBookstore. Check out his “cycling aficionado” website at http://www.jimlangley.net, his Q&A blog and updates at Twitter. Jim’s streak of consecutive cycling days has reached more than 8,000. Click to read Jim’s full bio.