"SamB76" <
[email protected]> wrote:
> I just bought a 16" wheel moulton mark3.
> Can I fit 17" wheels without modification?
There were two models of Mk3 front fork. The early model had fat, round-section blades (in common
with the later Series 2 bikes) and measured 3 3/4" (95mm) across the dropouts, while the later
model had oval blades and measured only 3 1/2" (89mm). Either can be carefully spread to the 100mm
width of a modern hub, and you'll need to enlarge the dropouts very slightly with a file to take a
modern 9mm axle - unless you intend to keep the old hub. In terms of blade length, a 17" AM rim and
tyre will fit, and the brake reach will be about on the limit for a 57mm-reach calliper. Mudguard
clearance is minimal using the Wolber or Bridgestone 17" tyres, so you may want to consider filing
the crown very slighty if using mudguards. A Series 1 fork will also fit the Mk3 frame, and has the
same essential dimensions as the Series 2 save for its slimmer (and therefore easier to spread)
fork blades.
At the rear you've plenty of room, but fitting a brake will be an issue if the bike has the original
Sturmey drum and you opt to replace the hub. If you leave the 'seatstay' bridge where it is, you'll
need to reinforce it and use a longer-reach brake than at the front - or re-position it downward
towards the rim.
Whether or not the conversion is desirable is a common point of debate among Moultoneers. The
popularity of the 16" format means that tyres and rims are more widely available at better prices.
My stolen Mk3 used 17" wheels because I happened to find a pair at a very good price, but I'm not
sure what my next Mk3 will use.
> Also can I spread the rear forks to admit a standard hub without cracking them?
When you say 'a standard hub' ... ? The Mk3 used a 4 1/2" (114mm) rear end, which was a standard of
sorts for Sturmey 3- and 5-speed hubs. I've seen Mk3 rear triangles spread as wide as 135mm, but
it's a bigger job than I'd be happy to advise on. The stay bridges will need to be removed and re-
brazed at very least. A Sturmey S5/2 or Sprinter 5 makes a happy match with the Mk3 if you want to
increase the gear range.
I'm no longer a regular here, and I don't know if other Moultoneers are about, but your best source
of further information is the Moulton list at Yahoo Groups:
http://groups.yahoo.com/group/moultonbicycle/
There's also a searchable archive of the old Moulton list at:
http://www.topica.com/lists/moulton/read
Enjoy your Mk3. With the right upgrades they make wonderful city bikes - agile and comfortable,
with great carrying capacity. Mine was stolen about a year ago in Paris. If you happen to see it
around ...
http://photos.yahoo.com/ph/yosnappyj/detail?.dir=/Mk3
James Thomson
