Tuesday, March 24, 2009

Q&A: Carbon touch-up, triple upgrade, how much chain lube

Q: Hi Jim, You can use the techniques described to remove bar logos too
I have a Bontrager X-Lite carbon handlebar that I want to sell, and I don’t know what I can use to polish it up. The bar’s scratched where the grips were, and I need to make it look shiny and pretty as much as I can! How would I go about that?


A: Good question, Staci. Since the handlebar is actually scratched, you're probably going to need to refresh the clear coat that was originally on there in the area that was scratched. (I'm not positive your bars had a clear coat, but most do.) An easy shortcut that might work is to just get some clear fingernail polish and take the brush and try painting the scratches just like you were doing your nails (if you do), and see if the scratches disappear. That sometimes works. It depends on the scratches but maybe you'll get lucky. If so you'll be done with your "repair" in a few minutes, plus drying time. This works as a way to touch up a paint chip on carbon frames or parts too. Just get the right color of fingernail polish for a paint finish (fingernail polish comes in an amazing assortment of colors and is often easier to find than regular touch-up paint... FYI, I even know someone who painted an entire frame with fingernail polish).

If this doesn't do the trick, it might be that the bars are scratched more. In general you want to be very careful with any carbon part that has scratches on it because carbon as a material is highly notch sensitive. This means that if you scratch it deep enough you create a weak point in the piece (a notch) that will usually result in the part breaking right at the scratch/notch.

The tricky part is figuring out what's a minor scratch and what's a real notch you need to be concerned about. You can usually do this with a good magnifying glass. A notch to be worried about looks like a break, or if you have a strong magnifying glass, it looks like a small Grand Canyon in your part where you can see down into the granular structure of your part (your handlebar). A scratch won't look like this. It will be a shallow indentation. Here are lots more tips on caring for carbon bicyles and components.

In most cases what you are describing from the grips on your bar will be scratches in the clear coat on your handlebars, not a real notch. But, I just wanted to make this real clear since you wouldn't want to sell anyone a handlebar and then have it break when they are riding. An example of a notch issue is when you overtighten levers on the bars, or if the levers are slightly loose and they move around on the bars and actually cut into the carbon fibers of the bar. That wouldn't be good.

For simple surface scratches in the clear coat the fix is relatively easy:
1. Get some fine wet-sanding emery cloth at a place like The Home Depot. 600 or 400 grit will work fine. You only need a few pieces.
2. Put the emery cloth in a pan of water to wet it.
3. Gently sand the bars until the scratches are removed. As you sand you will roughen the clear coat on there and you won't be able to see the scratch you're working to remove. To check how it's coming along, wipe the bar with a damp rag. This will show how you are doing removing the scratches. Stop sanding when the bar is nice and smooth and the scratches are gone. Keep in mind that I am assuming these are only surface scratches. It will take too much sanding to remove deep scratches and probably not worth the trouble since they will be covered with grips/levers anyway. I would just cover deeper scratches with the clear nail polish I mentions, but again, be sure they are only scratches, not structural damage.
4. Once the bars are nice and scratch-free, clean the sanded areas completely with something like rubbing alcohol that leaves them clean and residue free.
5. To finish the job, you next spray the bars with a clear coat of enamel. You can get this at Home Depot when you pick up the 400/600 wet/dry emery cloth. Get clear coat enamel. It can be a little hard to find. You don't want what's used on wood. You want an auto body clear coat enamel paint. It's best sprayed when it's warm out, about 70 degrees. One light coat will usually do it. It dries quick.

If you do all this right the bars will look brand new when you're done. One more thing: you want wet sandpaper and to sand when wet because you need to prevent any carbon dust from being created. You don't want to breathe carbon dust. Sanding with wet paper will prevent any issues.

Hope this helps! The photo with this show carbon dropped handlebars as an example, because I use the procedure outlined above to remove even large logos on bars like these and it works perfectly (sometimes the logos don't look right with a certain frame color or if you use a stem that's not that same brand).

PS: A reader named Bill offered these great suggestions, "A better way for the carbon scratches is to go to a motorcycle shop. Buy a tube of Scratch X. It is designed for helmet faceshields and windshields. It will polish out a surface scratch quickly and leave it as new. Also in auto paint stores, 3M makes a clear-coat polish that does the same thing." Thanks Mike!

Q: Hey Jim,
I have a blast reading and learning from your site. Thanks so much for all the great info! My wife has a Raleigh Venture 7-speed comfort bike. She wants more gears, but doesn't want to buy a new bike. I think she should, but she loves her red color that is no longer offered by Raleigh on the 2009's. I have been wondering if I can modify the bike to make it a 21 speed?. Is it as easy as adding a 3-speed shifter on the left handle, a front derailleur, triple crankset, and new chain? Or is there much more involved?

I'd like to do the job myself, but don't know what it will require beyond these components. I can run the shifter cable and install the shifter myself, but don't know how hard or easy it would be for the front derailleur or crankset. Thanks for any advice you have.


A: Thanks for the kind words, Michael. I appreciate it. Adding gears is usually possible, but it depends on a few things. I checked out the Venture online and from what I can tell, I believe you could install a triple crank, front derailleur and shifter and be good to go. You might or might not need a new chain. It will depend on how large a chainring is on the bike now compared to the size of the large one on the triple.

It's not a difficult job to make this upgrade but you need to figure out what to buy to make sure it all works properly. There are some dimensions to get right. So, the easiest thing might be to have your local friendly bike shop figure this out and buy the parts from them to ensure you get stuff that will work right. One issue you need to check is the cable path. I know you mentioned that you can do this, but you need a way to run the cable/housing from the new shifter to the front derailleur.

I can't tell from the photo online if the Venture is setup for that or if you'll have to come up with your own solution (clamps, zip ties, etc.) Sometimes the manufacturers include this, sometimes not. It's details like this that the shop could tell you about just by looking, and then get you what you need. Front derailleur clamp size and cable pull are other details, plus you'll want the correct bottom bracket for your frame and the triple crank you choose.

Something to think about is what you really gain by upgrading to a triple crankset. Right now the bike probably has 7 gears, some pretty easy ones, some pretty hard ones. Typically if you go to a triple you will end up with several easier and harder gears. If you knew that all your wife wanted was to make the bike easier to pedal, you could probably provide that by simply installing a larger cassette on the rear wheel. That would be a lot cheaper and easier than converting to a triple chainring setup and it would give her the gears she needed if all she really wants is easier pedaling gears.

Hope this helps and have fun dialing in the bike,

Q: Jim:
I wonder if you can help me. I have an old Mavic sew-up rim (probably 25 to 30 years old) that I would like to change over to a clincher. I don't know whether to buy a 700c rim or a 27 inch rim. It has 36 spokes if that makes any difference. Any thoughts?


A: Hi Bruce,
Sure! You should get a 700c rim. That is the same size as your sew-up rim. A 27-inch rim is actually larger diameter so your brake pads won't line up the same - they might not even brake anymore. As long as you go with a 700c, the "new" wheel will fit almost exactly the same as the old one. Also, it will be the same size as the other wheel on your bike - even more important probably ;-)

Hope this helps!

Q: Hello,
I have a question about my bicycle chain. I use my bike to ride to the train station and then I have to leave it there all day until I get back from work. This make it hard to keep clean. I initially had a big problem with black greasy buildup on my chain. I was told that my problem could be fixed by using silicon based lubricant, and only use one or two drops. I cleaned my chain and switched to this lubricant, and the greasy buildup problem went away. Unfortunately, now my chain is prone to rust.

I was told that the way to keep rust off the chain was to keep it “well lubricated.” I think this would then put me back in the first situation again with the greasy buildup. Is there some way out of this catch 22?


A: It sounds to me like you were using too much lube and then you switched to too little lube, Larry, hence the rust problem. You want to keep your chain fully lubed but not too lubed. The key is to clean it once so there's no grimy buildup and then lube each link (every link, all around the chain) with one drop each, of good quality bicycle chain lube suited to the conditions you ride in. Your local bike shop should be able to recommend a lube that's perfect for you or ask riding friends in your area what they use and check out their chains to see how they look too.

To apply, drip the lube on the links on the lower run of chain (beneath the chainstay) and do it while pedaling slowly backwards so the rear wheel is not spinning, or else the rear wheel will throw any lube that mistakenly gets on it across the room. After you lube the chain let it sit overnight so it soaks in and dries. Then wipe off the excess in the morning before riding.

Most people who ride every day for commuting or fun can ride for about 2 weeks before having to repeat the lubing process. But, you never want the chain squeaking or rusting. Those are signs of not enough lube and you'll want to relube. Greasy buildups are signs of overlubing so clean again and lube less. There's a learning curve to figuring this out and you have to find a lube that works. I use ProGold ProLink Chain lube, which is expensive but works nicely in our rather dry conditions here in Santa Cruz, California. I use it on my road bike that sees heavy use. And, I relube about every 2 weeks. I also take care to wipe the chain down before and after lubing to get any buildup off. That works well. You have to keep after it, lubing, cleaning, lubing some more, and so on, but it's pretty routine after awhile and your chain won't squeak or rust.

To a clean, smooth, quiet drivetrain,


Jase said...

do you have an email address? i would like to ask you a bike question privately.

Unknown said...

I managed to crash my road bike at the weekend and amazingly did little damage appart from frustratingly scratching my deep section carbon tubular FFWD rims. The scratches are deep enough to be felt when braking on the wheels, as they are on the braking surface, but not so deep (I hope) to be serious in structural terms. I was planning to fill them (epoxy?) and then sand/polish them back down so they are flush with the braking surface. Can you give me any advice about how to approach this and what to use. It would be much appreciated.

Jim Langley said...

You could try basic 5-minute epoxy, but it's messy to work with and thick enough that if it's only small scratches it might leave too thick a layer to easily stand down. It's important to make sure the scratches aren't structural. You could tap on the rim with a quarter to see if it sounds different than a non-scratched part of the rim. If not, the rim's probably okay. I bet the scratches won't effect the braking much and if not, you might just not worry about them.
Hope this helps,