Ask a Mechanic Rotor BBright to 24mm spindle adaptor bottom bracket

Published on June 6th, 2012 | by Daniel

Ask a Mechanic | Slick vs Textured Tires & More BB Questions




Welcome to our Ask a Mechanic column where our expert mechanic Daniel Slusser answers your bike maintenance questions. If you have a question for Daniel, please post it on our Facebook Wall or e-mail Daniel directly at daniel.slusser@artscyclery.com.

Question

Which road tires have more grip: slicks, or textured treads? I am having a debate with my friend over this and I wanted to get your opinion on it. From: Ellis

Answer

Crashing on a group ride doesn’t look too slick, but are slick tires to blame?  This is a very old debate and it has been settled for some time. Legendary Stanford educated engineer Jobst Brant did extensive research on this question when he developed the first road slick for Avocet back in the 1980’s. His conclusion was that slick tires offer improved traction in both dry and wet conditions while having less rolling resistance. Slicks grip so well because tarmac is rougher than any road tire tread, especially when you consider how small the contact patch of the tire is.

The size of the contact patch also explains why slicks work best in the wet as well. A road tire’s contact patch is so small, and the tires are so rounded, that hydroplaning is impossible. Even if hydroplaning was possible, the tread offered on some road tires has nowhere near the voids required to evacuate enough water within that tiny contact patch to make a significant difference. I think Jobst explains it best:

“A window-cleaning squeegee demonstrates this effect well. Even with a new sharp edge, it glides effortlessly over wet glass leaving a microscopic layer of water behind to evaporate. On a second swipe, the squeegee sticks to the dry glass. This example should make apparent that the lubricating water layer cannot be removed by tire tread, and that only the micro-grit of the road surface can penetrate this layer to give traction.”*

With that said however, the placebo effect is, albeit ironically, very real. Many pros insist on riding road tires with tread because they believe that they will offer greater security in the corners. A rider’s cornering prowess is usually a direct result of his or her confidence. So if you feel the need to ride tires with tread, then do it.

Now before you or your friend does a little victory dance over the answer to this question, remember that the difference in grip between slicks and textured tires is nearly insignificant. Less than ideal tire pressure has a far greater effect on grip and rolling resistance than tread does. So don’t sweat it, ride the tires you like and have fun for crying out loud!

*click here to link to the Jobst Brant article on this issue

Question

I want to fit a BB30 FSA crank onto my Cervelo. What will I need to make this possible? Would you recommend this combination? Are there any drawbacks?
Is this the correct adaptor for this change? From: Johnny

Answer

Rotor BBright to 24mm spindle adaptor bottom bracket

If you have the wrong bottom bracket it would not BBright (work with me here on the puns). Assuming you have a newer Cervelo with a BBright bottom bracket the answer is: No, it will not work. BB30 cranks use a 30mm spindle and the link to the adaptor you provided is for 24mm spindles. However, FSA does make a good selection of BBright specific cranks in their K-Force Light and SLK-Light lines and they are made to work with a standard PF30 bottom bracket as is used in any BBright standard frame. We don’t have any of these cranks in stock at the moment but give us a call (800-or an email and we would be happy to get one for you.

If you were considering a 24mm spindle FSA crank, the adaptor bottom bracket you asked about would be the right one and there are no real drawbacks other than increased weight and a little loss of stiffness. Some BB30 cranks will also work on BBright frames, but for the most part BB30 cranks do not work on BBright frames because the spindle is too short. Here is a link to the official BBright standard page and it contains a partial list of cranks that are compatible with the BBright standard.

img_3348-2-smDaniel Slusser is a professional bicycle mechanic with over ten years of experience. He holds a bachelor’s degree in business administration from HSU and a master’s degree in history from Cal Poly University. When he is not riding, wrenching, or writing he enjoys spending time with his wife and two children.


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About the Author

Daniel

Slusser is a professional bicycle mechanic with over ten years of experience. He holds a bachelor’s degree in business administration from HSU and a master’s degree in history from Cal Poly. When he is not riding, wrenching, or writing he enjoys spending time with his wife and two children.



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