Featured Speedmaster Something For Growler Part One

Over the festive period I've been prototyping a pillion seat because Triumphs 'comfort' seat is far from that due to it's narrowness. We went for a test ride Friday and things are looking promising, after a 1h10m my wife reported that she could go a bit further without a break. With old seat she was looking to take a short brake after about 45 mins.

My fab skills aren't up to Dilli's standard, but I don't own a proper vice and never even been in the same room as any welding kit before, so think I should be given some leeway I'm also not the master of suspense that he is . The plan is for a plywood seat pan and get that professionally upholstered. The mounting system is following the original seat method so I don't need to modify bike and can easily swap seats if required. I pinched the rubber feet and black mount bracket from the stock seat, but made other brackets from 3mm aluminium

Next step it to redo those brackets with keyholes because backrest gets in way for mounting with slots that way around.

 

I had, but I thought it looked too weird and the curve of the base was all wrong to fit. Though I see from your picture that if I removed the backrest the curve may actually work better.

 

I decided to go for a second prototype to get seat shape and contours right, so Nudger isn't the only Speedmaster with a helicopter landing pad, though this one seems to have attracted a flying mouse!



For seat contours I made some shapes from the layers of foam I had bought when I was trying to make a cushion for the original seat...



I even got my sewing machine from the loft to bodge together a vaguely correct shape cover from an old damaged roll bag...



New seat on the bike, ready for a test tomorrow...



Main problem with the design is how high it sits on bike...



That's most dictated by using flat wood and having to clear the ridge in the centre of the mud guard. May have to rethink design. Though final seat will need some beading around the bottom edge of the seat, so water drips off rather than running along bottom, that will bring the edge down to cover where you can see the wood showing. Profession upholstery will also not be as 'baggy' and perhaps can get away with less foam (though wife wasn't keen on just the two layers).

 

Not yet, spent the weekend riding with a couple of mates

Latest prototype was really comfy according to my wife. But I've decided to go for another prototype where I lower the seat height by ditching the extra bit of wood and cut a slot straight into the seat base. Also ordered samples of a denser foam, so may be able to get away with less height there too, and some closed cell foam for top layer which is waterproof, because as my mate pointed out, with a vinyl cover, water will get in through stitching so I'll need a waterproof layer under it. Oh, and I've decided to get some vinyl and try and make my own cover, with the idea that I don't need to find a professional upholsterer. Got to keep busy in my retirement

 

Final prototype, complete with a vinyl cover (sans piping)...



Changes since last time is to make recesses in base to mount brackets direct to seat (reducing gap above mudguard by about a centimetre) and a ledge around base to hide a bit more of the gap, and to allow water to drip off rather than going under seat...



To help counter weakness caused by cut-outs I added a piece on top...



Upholstery is some layers of foam, a layer of closed cell foam over the top to keep water out, and a vinyl cover.



As I had to shop online, I ended up buying a load of useless foam whist trying to find some decent stuff, so let me pass on this advise: any upholstery foam is about as firm as so much fresh air. For the top soft layer in my seat, I used 'high density very firm' foam. The rest is '6lb' reconstituted foam, which at least offers support because it doesn't squish down so much. I did try some heavier recon foam and slicing up the foam from original seat but including layers of those don't help comfort.

 

Thanks all. Considering my only sewing project before this seat making business was to turn up a pair of trousers, I was surprised how neat the seat looked too, through the photo doesn't show the details of some quite bad mistakes. For the final seat I'm going to 'cheat' and use impact adhesive to hold the pieces in place so I don't have to hold and stretch the vinyl around curves as I sew. That way I can concentrate of the neatness.