Well i've been struggling with my Mini V's on the Roadrat for a couple of months now.
The brakes are fine when set-up right, but tend to be a pain if removing a wheel and stop the mudguards lifting far enough away from the 32c Small Block 8's I am running.
Well plenty of tinternet googling and sorting and I have found the answer in the form of a set of extra long reach Tektro R556 or 559 calipers.
Thes fit perfectly though the mudguard mounting holes on the frmae and fork. The only mod was the purchase of a additional long bolt (70mm) and they work a treat.
They open up with a neat quick release and open with plenty of room to clear the tyre.
here are some piccies, I thought if anybody else is in a similar position they could use these.
[url= http://farm7.static.flickr.com/6158/6235521356_fab205d005_b.jp g" target="_blank">http://farm7.static.flickr.com/6158/6235521356_fab205d005_b.jp g"/> [/img][/url]
[url= http://www.flickr.com/photos/17059060@N00/6235521356/ ]P1040047[/url] by [url= http://www.flickr.com/people/17059060@N00/ ]eastham_david[/url], on Flickr
[url= http://farm7.static.flickr.com/6233/6235518136_9da090093e_b.jp g" target="_blank">http://farm7.static.flickr.com/6233/6235518136_9da090093e_b.jp g"/> [/img][/url]
[url= http://www.flickr.com/photos/17059060@N00/6235518136/ ]P1040048[/url] by [url= http://www.flickr.com/people/17059060@N00/ ]eastham_david[/url], on Flickr
[url= http://farm7.static.flickr.com/6222/6234992345_f9e9470281_b.jp g" target="_blank">http://farm7.static.flickr.com/6222/6234992345_f9e9470281_b.jp g"/> [/img][/url]
[url= http://www.flickr.com/photos/17059060@N00/6234992345/ ]P1040046[/url] by [url= http://www.flickr.com/people/17059060@N00/ ]eastham_david[/url], on Flickr
[url= http://farm7.static.flickr.com/6222/6234984857_3602cff088_b.jp g" target="_blank">http://farm7.static.flickr.com/6222/6234984857_3602cff088_b.jp g"/> [/img][/url]
[url= http://www.flickr.com/photos/17059060@N00/6234984857/ ]P1040049[/url] by [url= http://www.flickr.com/people/17059060@N00/ ]eastham_david[/url], on Flickr
[url= http://farm7.static.flickr.com/6031/6235504466_6d271c1c24_b.jp g" target="_blank">http://farm7.static.flickr.com/6031/6235504466_6d271c1c24_b.jp g"/> [/img][/url]
[url= http://www.flickr.com/photos/17059060@N00/6235504466/ ]P1040050[/url] by [url= http://www.flickr.com/people/17059060@N00/ ]eastham_david[/url], on Flickr
[url= http://farm7.static.flickr.com/6158/6234989155_9b3cd7a1dd_b.jp g" target="_blank">http://farm7.static.flickr.com/6158/6234989155_9b3cd7a1dd_b.jp g"/> [/img][/url]
[url= http://www.flickr.com/photos/17059060@N00/6234989155/ ]P1040051[/url] by [url= http://www.flickr.com/people/17059060@N00/ ]eastham_david[/url], on Flickr
cheers
Chucky.