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By stinkwheel
#91126
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On the basis I need every bit of help I can get, I'm looking at places where I can achieve some meaningful weight loss on the trials bike. I'm aware weight-loss on a motorcycle is an exercise in diminishing returns so some things are simply not worthwhile, others may be?

Already got alloy bars. I'm also ditching the rear subframe in favour of a plastic mudguard with a single loop bracket and one of those rubber taillights (or maybe make up something from alloy plate to hold the existing light).

I'd like to do a classic long distance trial at some point so it has to retain lights. I do have a thunderbird top-yoke somewhere but I'm not sure how much weight that will save over the casquette by the time I've fitted a steel yoke, headlamp, headlamp stays and a bracket for the speedo? i don't remember the casquette being all that heavy?

The front mudguard stays are steel. I suppose I could make them from alloy bar but again, not certain they'd be much lighter than the fairly thin guage steel tube I'm using now?

The bash plate is fairly meaty, 2mm steel frame with alloy chequer-plate. From the damage it took last time, I'm not sure if making this less meaty would be a great plan?
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Fuel tank is a major weight source. I'm keeping my eye out for a dinky used tank that'll fit. I don't think I can justify the cost of a new alloy trials tank and I'd be terrified of throwing it about and damaging it. My understanding is that the tank on enfileds is a partly structural member? So it needs the bolts front and rear. I did have an idea that I could possibly make up a couple of alloy braces that run between the frame mounts and attach a more universal, possibly plastic/fibreglass tank to those. Or just keep my eyes open for a slightly battered trials tank coming up on ebay.

Alloy rims? Are they THAT much lighter? I've fitted a half-width front hub. I do have a half-width rear too but will it save much weight? Also compromises the ability to do a "field" tyre change, the QR wheel setup is handy!

I'm keeping the two lifting handles! Or maybe I should replace them with a webbing strap/bit of rope?

I could probably thin down the toolkit.

Make an alloy chainguard? Anyone got a picture of how to do one?

Looking at it with the mudguard removed, I think there is *just* enough room for a 4.00 tyre if I made a lower-profile chainguard. I'm wondering if dropping to a 18" rim would be a sensible idea? It would massively increase the range of tyres available and help gear the bike lower overall. That said, it would further compromise ground clearance which is already an issue.

Already got a very dinky battery, all the electrics are hidden in a tea-caddy air filter housing mounted on the left side of the bike.

Already has an alloy barrel.

Anything I've missed?
User avatar
By Adrian
#91127
The alloy trials top yoke 92591 would be lighter than the (malleable iron?) Thunderbird lump, though they cost a fairly whopping £264 (inc VAT). Or hosts' accessories can be excellent for lightening our bank accounts if not our bikes.

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I have also seen street tracker customs with a small, lightweight LED headlamp built into the front competition -type front number plate fitted across the top and bottom yokes, though one thing I haven't seen is a kit for pumping the frame tubes full of helium.

I'll get me coat.

A.
User avatar
By stinkwheel
#91128
Aye, I suppose that's the main thing, the Indian frame is one big lump of steel. Probably weighs more than a modern trials bike by itself.

I suppose the ultimate solution would be to use almost anything other than an indian bullet as a trials bike.
By PeteF
#91129
Is that an alloy barrel? Or just painted?
Quite a few pounds to be lost there (in both meanings of the word)
User avatar
By stinkwheel
#91130
PeteF wrote:
Mon Jun 29, 2020 9:40 am
Is that an alloy barrel? Or just painted?
Quite a few pounds to be lost there (in both meanings of the word)
Yes, alloy barrel. Got it after I cracked the bottom ring off the iron one trying to remove a seized-on head with the "indian rope trick".

It was looking tatty so I painted it with simonize VHT paint while I had it off. Must say, I'm very impressed with the result. Very easy stuff to work with.
By mauri
#91132
of you go for a aluminium fuel tank!
or any other aluminium tank that hold flammable liquids.

never ever bolt it straight to the frame, always put rubber(isolator) in between it and the frame .
By mauri
#91133
stinkwheel wrote:
Mon Jun 29, 2020 9:32 am
Aye, I suppose that's the main thing, the Indian frame is one big lump of steel. Probably weighs more than a modern trials bike by itself.

I suppose the ultimate solution would be to use almost anything other than an indian bullet as a trials bike.
if you take all the un needed brackets of its actually lighther than you might think.

for example the brackets that hold the standard rear frame and rear foot pegs, and the plug at top of the top frame are heavy items.
the rear drum brake/sprocket is also heavy.
i have made this in two parts, one is the parts that sits in de rubbers of the hub and is in aluminum the ofther the brake drum its self and made in cast iron.

as with any wieght savings the last grams cost the most
User avatar
By stinkwheel
#91135
Wheaters wrote:
Mon Jun 29, 2020 1:18 pm
So the bike is on a diet. How about the rider? :lol:
I can drag myself out of a bog, the bike takes a bit more doing. Although for the first time in about 15 years I am now merely overweight rather than obese.

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