Ask a Mechanic | Fixing Foot Problems and More Bottom Bracket Answers

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.

Specialized OSBB cups without bearings installed

In this post Daniel discusses how to reduce foot pain on long rides and what the difference is between OSBB and the other bottom bracket standards on the market.

Question

I have a quick question about toes cramping and feeling a burning sensation. I have tried everything from moving the seat post up and down and same with the cleats. Everytime I go riding within two hours I get like a burning sensation and cramp like feeling on my right toes. I have two pairs of shoes, one is a tight fit, and the other is a good loose fit. Any ideas of how to get rid of this sensation?  – Omar

Answer

Oftentimes our love of cycling is paid for by the foot. This is a problem that lots of cyclists struggle with, but is solvable; it just requires a bit of experimentation.

For some guys, riding with full carbon soled shoes causes problems because the pressure on the foot remains essentially the same throughout the ride rather than changing slightly as the foot goes through the pedal stroke and the sole flexes. That is the expensive potential solution if you currently have two pairs of carbon shoes.

The more cost effective solution is to get new footbeds. I recommend either getting some heat moldable offerings like those from Fizik that will provide you with a custom fit, or a stock offering that is adjustable such as Giro’s Supernatural Fit Kit.

An option representative of the latter that I personally use is the Specialized BG footbeds. In my case they have been the cheapest speed I have ever purchased. Just switching to these insoles and experimenting a bit with the included shims, I found I was able to go 1 gear harder on all of my regular climbs without any perception of increased difficulty (sorry I don’t have power meter data to confirm this anecdotal evidence). These took care of some hot spots I was experiencing too, but I must admit that I do get numbness in my left foot from time to time (as I said, it is a process). The fact that you are having a problem on one foot only would imply that there is an imbalance. This imbalance can be adjusted out somewhat with the BG shims.

You might also try pedaling out of the saddle more frequently as this tends to change where the pressure is exerted on the foot and gives the affected area a break.

Recently I took up walking barefoot along our local dunes and I feel that the sand has done wonders for my feet. Walking on the sand feels like a deep foot massage and it strengthens the muscles in the foot, which is always a good thing. Since doing this, my bad left foot has improved quite a bit. Your mileage may vary. If all else fails, see a podiatrist.

May you soon be footloose and fancy free my friend.

 

Question

Hi, was reading your blog post on demystifying BB’s but it didn’t mention Specialized’s OSBB. I have done a bit of searching on the internet and have not found a site that tells you anything other than the official blurb from Specialized. Is it just a standard BB that they have dressed up and called something fancy? I would like to get my bike up and running as soon as possible but am having problems figuring out a crank/BB solution and would like to see what options I have as I have no desire to use Specialized’s own in house crank. –  Angus

Answer

The story behind Specialized’s OSBB bottom bracket is an interesting one. The open BB30 standard used by the entire industry was conceived and named by Cannondale. Specialized was one of the first adopters of the standard (to be fair it wasn’t much of a standard at this time, as is was so rare) but Specialized was loathe to advertise a Cannondale-designed system used on their bikes; hence the name, OSBB.

So the short answer to your question is that any BB30 road crank will work with your Specialized OSBB road frame. The same is true of mountain BB30 cranks working with Specialized OSBB mountain frames. There are many versions of OSBB with respect to frames with some being exactly the same as BB30, and others that are similar or identical to PF30 (PressFit 30).

Currently, on Specialized’s aluminum road bikes OSBB=BB30. On their full carbon road bikes, with carbon bottom bracket shells, OSBB is comprised of a pair of plastic bearing cups (see photo) that press into the frame and accept standard BB30 bearings without the use of the steel snap-rings typically included in replacement BB30 bearing kits. PF30 bottom bracket cups and bearings will not work if installed in one of these bikes, as the spacing of the cups is different, even though the spacing of the bearings is identical (I know it is confusing, but trust me). On current Specialized mountain bikes OSBB=PF30 so you can simply use a standard PF30 bottom bracket and any BB30 mountain crank.

Some earlier S-Works mountain bike models and many of the carbon road bikes with alloy bottom bracket shells used the BB30/OSBB standard, so please don’t apply these remarks to anything prior to 2012 as they differed from year to year as OSBB evolved.

I hope this clears up any confusion without raising too many more questions. I am really looking forward to the industry settling on a true standard. What I think will likely happen however, is that mid to low-end bikes will settle on a couple of standards and the high-end bikes will continue to use proprietary, or nearly proprietary, standards in order to optimize the bikes as the engineers, designers, and marketing departments see fit.

While these don’t apply directly to your case, I will pass on these bottom bracket dimension drawings so readers can take measurements of their frames in order to better determine which “standard” they use.

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 University. When he is not riding, wrenching, or writing he enjoys spending time with his wife and two children.

2015-03-20T14:07:26-08:00