Skip to content

[Bicycle] Retrofit Post Mount Disc Brake Calipers to IS Mount Fork and Frame

This article is kind’a out of place, but as a tinker/gear head/wrench I also fix 20~40 year old bicycles for neighbors who can’t afford a brand new $3000 war rig. I just wanted to make a quick note about IS mounting points for brake calipers – but it became a full page article.

Last week, we found a Porsche Bike FS covered in dust in a warehouse. Sold in 1998 and originally priced at $4500MSRP (valued at $270 currently on Bike BB), this bike has a Votec frame, Votec GS front fork and Riesse rear suspension, Formula hydraulic disk brakes, SACHS grip shifters, and SACHS top/high-normal derailleurs. There was virtually no rust but everything with grease or oil in it was seized. Rather than take apart the mechanics and replace all the O-rings, I decided to bring everything to 21st century standards for easier future maintenance.

The BIGGEST HEADACHE was MOUNTING THE BRAKE CALIPERS. During the 90s when hydraulic disc brakes were becoming popular, bike manufacturers came together and agreed on a sizing standard they called “International Standard” or “IS”. Mind you, it is not an ISO standard, so traditionally ISO countries like Japan (read Shimano) wouldn’t stick to this standard for too long.

The measurement standard for IS mount calipers were simple but impractical. The caliper mount holes were situated perpendicular to the rotation of the wheel. It was a standard decided on a table rather than the road. You see, wheels and discs rotate, flex, and bend. The IS mounts did not allow for on-the-go adjustments for lateral shifts in bike structure.

In comes the Post Mount standard. The caliper mount holes were set parallel to the rotation of the wheel AND the caliper base had oblong holes for lateral adjustment. This way, if the wheel or rotor deforms on the road, the rider can simply recalibrate the caliper position with one allen wrench. No adding or subtracting of washers needed.

So how do we put a Post Mount caliper onto a IS frame? Use a 90 degree adapter of some kind? YES. Shimano, SRAM, etc. makes (made) all kinds of caliper adapters for all kinds of mounts… BUT, as less and less older bikes remain on the road, they are making less or even stopped making some of these parts. So I had to go hunting for these adapters and their spec sheets.

The important thing to remember when using an IS to Post adapter is that: At its lowest setting (i.e. no adapter, no washers) IS was made for 160mm front rotors and 140mm rear rotors.

The Porsche Bike FS came with 185mm front and 160mm rear rotors. The old Formula calipers were already mounted on custom machined aluminum IS mounts and had no other IS standard mounting holes on the fork/frame. That meant short of making custom aluminum parts, I had to stick with 185/160 or go bigger. I decided to stick with the rotor sizes.

An easy mistake to make here would be to get the mounting adapters for 185 front and 160 rear – but remember, the IS standard is 160/140. This bike ALREADY HAS +25/+20 mounting holes. So the correct part to get is a ±0 IS to Post adapter. I decided to go with Shimano calipers so I got the SM-MA-F160-P/S adapter for both front and rear (SM-MA-R140-P/S does not exist and would be exactly the same as F160). By the way, SRAM is a little more scientific about this and labels their adapters by the height it adds.

A caveat to this article is that 185mm is an old rotor standard and is hard to find. New rotors are 180mm. I have yet to see anybody sell a -5mm or any minus mounting adapter. So if this bike needed a new brake rotor in the future, then it might be time to buy a new bike… or shave the adapter down a little?

Posted in English, Sidetracked.

What to do before selling or giving away your iPhone, iPad, or iPod touch

Found this helpful Apple KB

Posted in Apple, English.

A Little Hint When Updating AVIC Firmware

To update the firmware on the Pioneer AVIC series GPS navigation systems, you need to utilize an SD card formatted in MS-DOS FAT16. If you’re using a Mac, this might be difficult for you to come by because Disk Utility only formats MS-DOS discs in FAT32.

Of course, the solution is to use the Terminal. BUT FIRST YOU MUST USE Disk Utility TO PARTITION THE SD CARD. The whole reason behind FAT32 was that the FAT16 file system for MS-DOS/Windows had this memory issue where it couldn’t handle any primary or secondary memory (HDD or RAM) larger than 2 Gigabytes. So if you look at machines from the mid to late 90s, you’ll see that they were maxed out at 2GB of RAM and 2GB partitions even if the hard disk had a larger capacity. Well, for whatever reason, the same goes for the firmware upgrade program that is riding on Pioneer’s AVIC series GPS systems.

If you’re using an SD card larger than 2GB (who isn’t), you’ll first need to make 2GB partitions using Disk Utility. Then use the Terminal to format ONLY THE FIRST PARTITION on the SD card – Essentially making the SD card into a 2GB card.

The Terminal command you’ll be using is newfs_msdos. You may look at the man pages if you want to learn more, but for now, the command you want is:

sudo newfs_msdos -F 16 /dev/partition_location

*partition_location probably being disk1s1 if the SD card is the only storage device other than your main HDD.

Go ahead and mount this partition using Disk Utility again. Drop the un-zipped AVIC110 folder onto the SD card, and use CleanEject* to eject the SD card without the Mac writing un-necessary invisible files to the volume. Pull the SD card out of the reader, lock it, and you’re ready to put it in your car nav.

*CleanEject is donation-ware made by JaVaWa. Check them out!

Posted in Apple, Cars, English.

Batch Resize Images in Mac OS X [Terminal]

You can batch resize images in Mac OS X using the terminal command sips, the Scriptable Image Processing System.

For making quick 300px previews of the images, you can use this command:

sips -Z 300 *.jpg –out destination/directory/

*Read man sips for more info.

If you’d also like to batch rename the files and you’re using bash, then you can use regular expressions:

cd destination/directory

for f in *.jpg; do echo mv “$f” “${f/.jpg/_thumbs.jpg}”; done

The {f/.jpg/_thums.jpg} looks for the string “.jpg” and replaces it with “_thumbs.jpg”.

Posted in Apple, English.

SEO Providers –

Today, I received the e-mail below from a SEO provider that ultimately has something to do with “”. ( is registered through the private domain service “”).

To: webmaster


***SPAM*** FWD: Quick question regarding link removal… [] (FROM:


I am contacting you from a third party agency who is contracted by “” to monitor and improve the organic ranking of their website in various search engines. As part of a recent update to search engine algorithms, Google’s tools have detected that there are some links from various pages of your website which have now been considered “spam” by Google and are having a harmful effect on  rankings. This is due to the way in which these links were created.

Organic rankings and traffic to the site are vital to our client’s business, and so it is important for us to bring our site into compliance so that we do not continue to be penalized by what Google thinks are links we acquired purposefully against their Webmaster Guidelines. Since this was not the case, we are formally requesting that you remove all the links to the site from your website.  In addition, I will be forwarding this email to Google to verify that we are taking the proper measures.

The link to my client’s site is on the following page:

Thanks again

As you see, they don’t give me their name or any contact info other than the e-mail address. It’s up to me to go search for it. But I don’t need to. The probability is very very high that this is a SEO staff.

These SEO services have really bad rapport, and I was going to ignore this mundane request, as I was not doing anything wrong or illegal. If you actually look at my pages they refer to, it is somewhat of a negative review of the book “212 Degrees” that they (still) sell on their website. It’s not really a review of the book – but of people who gift such books without much thought.

There’s nothing I need to do – BUT being the nice person I am. I decided to make this a win-win situation. I will go edit that old article and make the “simple text” anchor link into a “relevant text” anchor link.

Also, notice… there are no anchored hyperlinks within this article. :)


Posted in Uncategorized.