Jim’s Tech Talk
Before we get to today’s topic, thanks are in order for all your potentially life-saving comments on our speed wobble columns last week and the week before. These stories will be an awesome resource going forward. Catch up here if you missed the articles and be sure to read the comments:
Wobble Tip for Tubeless Tire Riders
You might have missed this one because it came in late. But I think this tip from reader Gary Carollo, specifically for tubeless tires run with sealant is worth sharing here. He said, “I had a wobble that showed up on one of my first spring rides. Ended up I had a “wad” of congealed latex in my tubeless tire….. should’ve known better!”
Thanks, Gary, that’s a good one and it could happen to anyone with sealant in their tires. Because if a bike sits long enough with liquid sealant in the tires, it can pool at the bottom of the tire and dry up inside. That creates a heavy spot in the wheel and it’s easy to appreciate how it could unbalance a wheel and cause a wobble.
The solution is to not let your bike sit long enough for the sealant to dry up. So, over the winter if you cannot ride enough, you could have a routine for spinning the wheels to keep the sealant from standing in one spot too long. It’s possible, too, that there are some sealants that don’t dry up, but I haven’t been able to verify those claims.
Correctly Clamping Carbon
Fear of Failure
Carbon bicycles have gotten a bad wrap because some have broken in spectacular fashion. You’ve probably heard stories or seen videos. My worst experience was a carbon fork failure. The top of the fork (called the “steerer tube” or just “steerer”) fractured. Luckily I was only going 15mph. Still, when you lose the front end of your bike you go straight down.
It happened so quickly, there was no time to even try to react. My right pedal, which was at 6 o’clock, touched down first. My foot was still in the clipless pedal. Unfortunately, I fell away from the bike bending my ankle at what seemed an impossible angle. While I’ll never forget the pain, it turned out it was only a sprain – hey, that could be a song lyric.
Stories like mine and others paint the picture that carbon is a fragile, delicate material. So, it makes sense that you might be concerned about putting a carbon bike into a bicycle repair stand. Most repair stands hold bikes with clamps and the concern is that they’ll crush the carbon tubes.
So many people worry about this that there are even special holders for carbon bikes that you put in clamp-style repair stands, such as Hirobel’s.
Get a Carbon Capable Repair Stand
If you’re worried about putting your carbon beauty in a repair stand, my advice is to make sure you are using one that is gentile on frames and that you always use it carefully. I know good repair stands are expensive, but if you’re going to work on bikes, I really believe you can’t spend your money any more wisely. Plus, I think you’ll enjoy using it so much you’ll be happy you bought it.
How bike-safe a repair stand is comes down to the clamp on the stand. A while back I reviewed the one I like the most, Park’s Professional Micro Adjust Clamp. If you’re buying one to retrofit an older Park stand be sure to read the details on the different models to ensure it’s compatible.
This clamp opens wide enough to handle almost any size frame tube or seatpost you’ll run into. It has soft rubber jaws to clamp safely. And it has a screw adjustment to fine-tune the clamping pressure plus a cam lever to open the jaws with a flip of the lever. Another nice feature is the narrow jaws, because they let the clamp fit on seatposts a lot of the time even if there’s a light or seatbag in the way. And, it’ll fit in other close clearance areas on frames, too.
Another favorite of mine is Feedback Sports’ clamps.
I have two of their stands, both much older than the upgraded newer models and still going strong. My clamp works much like the new ones. The jaws are narrow for excellent access. They’re rubber coated to protect frames. And there’s a screw clamp and a quick release for safe clamping. If you need to clamp super wide aero tubes or seatposts, the Park clamp is more versatile.
Use it Right
Even with the best repair stand you have to use it correctly. And not just on carbon bikes. Steel, aluminum and yes, titanium, too can be damaged if you misuse the clamp.
Maybe the most important clamping step is paying close attention to what you’re about to do. If you’re not watching you might not see past the clamp and not realize that you’re about to close the clamp on a cable or bottle boss or housing guide! Clamping these you could definitely damage the bike so don’t let it happen.
Don’t Over Tighten
Also super important is to not overtighten the clamp. The purpose of screw type clamps is to be able to feel when the clamp is getting tight and stop, don’t tighten it any further. If the bike slips in the clamp as you start to let go, it’s fine to tighten it a little more. But, go little by little until it’s holding fast.
Hold By the Seatpost
Another good rule is to try to always clamp bicycles by the seatpost. Seatposts are designed to support your weight so they can easily take the bike’s weight.
If you’re working with a frame only, you might want to insert the seatpost to hold onto if you have it. But be sure to tighten the seatpost or else the frame might slide free and fall to the floor. No!
With adjustable seatposts (“droppers”), grip the part of the post that doesn’t move.
It’s Okay to Grip Frame Tubes But Use More Care
If you’re careful and again make certain you’re not over tightening the clamp when you close it, it’s okay to grip carbon frame tubes. Just keep in mind that frame tubes aren’t as beefy as seatposts.
Which means you don’t want to perform repairs that put huge forces on the frame, such as beating pressfit bottom bracket cups out or using a cheater bar to break free a frozen pedal, etc. If you have to do these types of repairs, put the bicycle on the floor so it’s supported by the wheels. You might even get a helper to hold the bike so it can’t fall over.
One last tip: Keep the jaws of your clamp nice and clean and in good shape, no tears of breaks. And be careful about putting anything in the clamp. For example, you might put a rag in thinking it will protect the paintjob. The problem is, if there’s a wrinkle in the rag or it’s folded just wrong, that can create a high spot that might damage the frame under the closing force of the clamp.
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 cycling streak ended in February 2022 with a total of 10,269 consecutive daily rides (28 years, 1 month and 11 days of never missing a ride). Click to read Jim’s full bio.