Brompton Modification Questions
I am looking at seriously modding a Brompton in the style of LittlePixel's fixie conversion, I have learnt a lot from reading over the posts here but still have a couple of things that aren't clear in my mind:
1. Does anyone know a place I can source an aluminium alloy chain tensioner as available on the Merc / Flamingo bike? I've looked for the eBay ID '123maddy' mentioned in LittlePixel's post and cannot find anything for sale
2. Can Birdy size (ETRTO 355) wheels be made to fit the Brompton rear triangle & fork if slicks such as Schwalbe Stelvios are used?
3. If I did make the above modification would I mess up the handling of the bike or the fold? Am I limiting the tyre choice I have available to me in comparison to 349? The benefit I can see is that I can use shorter drop brake callipers resulting in better braking.
Many thanks for your time
Raleigh20 PugFixie, Merc
Thanks for the advice on the tensioner, I'm converting a single-speed Brompton that should come with the plastic derailleur you mention. Yes - I'm planning to ride fixed.
After a bit more reading on these forums I can see that the ETRTO 369 Moulton might be so large that it interferes with the seatpost when the bike is folded, does anyone know for sure?
355 might be a more sensible option, what rims are available in that size? The Alex DA-16 is fitted to some Birdy's, is that any good in comparison to the Velocity Aerohead's that I can get in 349?
The most concerning thing before I take the plunge is will a certain tyre size continue to be available for some time. I don't want to be stuck with some size that I have to eBay from the US.
Currently there are 369 Stelvio's available from SJS cycles, and there seems to be no issue getting the 355 or 349 size from many sources on the web.
But Schwalbe seem to have discontinued the Stelvio, it's not in the 2009 catalogue from memory (but it still seems to be available from Brompton's distributors). The replacement is the Kojak, which is a little wide for my liking.
I do not know for certain that the 369 tires will fit on a Brompton, but you may want to refer to the following site that gives diameters of various size tires:
Based on the information on that site, the 32-369 (Moulton) and 40-355 (Birdy) tires have an outer diameter very close to the 37-349 Brompton tires.
Check Brompton Talk for a table that discusses different wheel/tire combinations that fit the Brompton. Although I don't think that the mod is worth it.
Originally Posted by Lewis Butler
Thank you everyone for their input on wheel size, I'm sticking with the real 16" (349) in the shape of 28 hole Velocity Aerohead rims. Seems to be more sensible as I at least know the tyre choices from almost 7 years of owning a Brompton.
Pixel/Huw - one more question, do you happen to have the official wheel building dimensions for the 74mm Pantour Delite Suspension Hub? It looks to be symmetrical and I've measured the width from center to flange to be 23.5mm & the diameter of the flange to be 52.2mm, spoke holes seem to be 2.8mm. Just want to know I'm on the right track with those measurements before calculating spoke length.
Raleigh20 PugFixie, Merc
lewis - don't have them sorry - Pantour manual leaves a lot to be desired. I built mine using a vernier caliper to measure the sizes; front hubs are always symetrical as far as I can tell.
Thanks anyway Pixel, just thought I'd ask.
I've eventually got Pantour to answer my e-mail, so hopefully I'll be able to cross-reference *my* vernier calliper measurements with their take on reality.