Sunday, February 22, 2009

Q&A: Torque Wrenches, tires sizes and sources

Q: Jim,
Just got a new Giant racing bicycle (love it) and have been out on a maiden voyage. The frameset and many of the components are made of carbon and I am concerned about getting the torques right as I make adjustments and repairs. Do you recommend a bike-specific torque wrench (Park has one in the $40 range), or can I just go pick one up at Sears and get the same thing?


A: Good question, Chris. Yes, I definitely recommend a torque wrench for caring for carbon bicycles and carbon components. These bikes and parts have a different feel than steel and aluminum ones and the only way to get the tightness right is by reading the instructions or looking on the components to find the recommended torque (often written on the parts), and using a torque wrench to get the bolts just tight enough.

Also, in my experience with these super bikes, things tend to loosen more and need regular checking. Anytime you're installing a new part or making adjustments, getting the torque right will ensure you never break or damage anything, which can save you a lot of money when you consider how expensive most carbon bikes and parts are.

I have 2 Park torque wrenches, like them and recommend them. The ones I have are bar-type wrenches that have an indicator needle that points at a little scale on the tool as you torque the bolt (photo). Park also shows a new click-type tool on their site that they say will be available in April. Click-type wrenches are set to the torque you require and when you're tightening the bolt, the wrench makes a click you can hear and feel when the bolt is tightened right so you can't overtighten it.

While you can get torque wrenches from places like Sears and The Home Depot and Harbor Freight, etc., I recommend bike-specific ones because most general torque wrenches are made for car work so they often provide a ton of leverage with long handles. That's not ideal for bike use where you often have to reach into small places and where you don't ever want to overtighten or break things with too much power. So, I would look for one that's not too big and that measures in inch pounds and Newton meters since bike parts are usually marked that way. The Park models do this and work fine.
Another wrench you might like is the Giustaforza, a $150 Italian bicycle-specific model that I reviewed a while bike and now keep in my toolbox because it's so handy. Here's a link where you can order it. Another one that's very low tech but does work for most stem/bars with basic 4mm bolts is Ritchey's Torque Key. It's preset and only does 5 Newton meters but that's right for most bolts and most Ritchey stuff. It only has the 4mm Allen bit, though, so it's not that versatile, but if you have only, or mostly 4mm Allen bolts it could work. It's $20 and is a click-type tool small enough to take anywhere.

If you're interested in reading many more tips about caring for carbon bicycles and components, visit this link,

To proper torquing,
Q: Hi Jim,
I need to change the tyre of my bike and I'd like to order it online. I'll be able to fit it myself but I'm not sure which size is the right one. If I read the number on the old front tyre it says 700 x 38c. This is a normal tyre, while at the back I have an anti-puncture Schwalbe tyre, and the size on it is 700 x 32c. So now I'm confused. Which size should I get: 700 x 38c or 700 x 32c? And, where can I buy it online?

Hope you can help,

A: Hi Antonell,
Your tire sizes of 700 x 38c and 700 x 32c mean that they are both the same diameter (700c) but that one is 38mm wide and the other is 32mm wide. In other words, you have one tire wider than the other tire.

It's actually up to you how wide you want your tires to be. You can choose whatever width you want as long as it's a 700c tire and as long as it's not so wide that it rubs against your frame. Common 700c tire widths (different brands and models of tires come in different widths) include 23mm, 25mm, 28mm, 32mm, and sometimes 38mm and wider.

Typically, you would use a wider tire to get a softer, more comfortable ride and some additional flat tire protection, and you would use a narrower tire to get more performance and to save some weight. It's really just up to how you want your bicycle to ride. If you ride off road the wider tires are good for more traction, too.

Now, for a good source for bike tires you can try BikeTiresDirect. They often have good specials.

Have fun!

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