A £100 bike would only realistically appeal to occasional or low requirement cyclists from a volume sales point of view, which may mean the equipment could be tailored to suit (and therefor the cost minimised to suit)
15 gears ? is it really neccessary for most occasional cyclists. My son, although he commutes daily albeit short distance, rarely ever gets out of the middle chainring. Is a triple really neccessary for most low mileage cyclists.
No fancy looking (supposedly) oversize (and therefor heavy) frame. Simple and as light as realistically possible.
In my book, a 5 speed with single, maybe double chainrings, simple but half decent V brakes, simple but light frame, perhaps 26 x 1.5 tryes, that will make the bike a bit faster and more useable than having heavy oversized tyres that no-one really wants, no accessories.
The biggest problem then is...whenever i talk to anyone who wants a first 'cheap' bike, i tell them try to buy the best quality you can, and as simple as you can, you don't want suspension, you don't really want 100 gears because you wont use them, don't get a stupid oversized cheap frame because they're heavy.....and what do they do ?, buy a cheap bike with all those flaws. Why ?...perhaps its the flock mentality, perhaps its because all those things actually DO appeal to buyers, even though we all know theyre just a gimmick.
And 6 months later...they're not using that stupid gimmicky, overwieght bike because its cream crackered because of poor quality components, or because its just a plain shoddy bike.
I think the idea's fantastic BTW and i think it could be done.