Dear ETRTO 520,
This matter of drum brakes being fitted to Dahon folding bikes has had extensive discussion on the Dahon Community Forum earlier this year - to which both Brakemeister and I have contributed several posts - though with rather different opinions about the usefulness of drum brakes.
Like you, I have experienced the limitations of rim brakes in the very wet and muddy conditions that we often have on the canal towpaths and cycle trails in the Glasgow area, and also on the hilly terrain and steep slopes that we have locally. After trying various models of V-brakes on my Phillips Boardwalk Lite (an older model of the Dahon Helios) and experiencing no real improvement, I also opted for sealed drum brakes.
So I had two new wheels equipped with drum brakes built by our local bike shop (Kinetics). The front wheel has a SRAM Spectro drum brake. The back wheel is fitted with a Shimano Nexave roller drum brake. Both brakes are operated using the existing brake levers that were already fitted on the bike. They give excellent stopping power - as good as the V-brakes were in the dry and much better than the V-brakes in the wet.
You then asked the question - "Are you aware of Bike Forum members or others who have spread Dahon forks to 100mm". Well the answer is that this is exactly what Ben Cooper at Kinetics did in order to fit the new front wheel with its hub brake to my Boardwalk Lite. When I asked him about this particular matter, he told me he does this spreading from 75mm to 100mm using a special tool that is built for the purpose. Apparently he has performed this task on quite a number of occasions. He also told me that, as long as it is a steel fork with TIG welding that is being spread (as is the case with the Boardwalk Lite), there is no difficulty in carrying out the operation successfully. The steel is sufficiently ductile to allow the spreading to be done relatively easily. However he told me that he would not attempt to do this spreading operation with an aluminium fork or with any fork having braised fork tubes.
Since it wasn't me who carried out the actual work, if you do wish to get more detailed information about the spreading of the forks, I suggest that you send an e-mail message to Ben Cooper at the following address -
mail@kinetics-online.co.uk
Details of the SRAM Spectro drum brake are given on the hubs and headsets pages of the Kinetics Web site with the following URLs:-
http://www.kinetics.org.uk/html/hubs___headsets.shtml
http://www.kinetics.org.uk/html/hub_brakes.shtml
I hope that this information is useful to you.
Gordon Petrie