A fiver's worth of Ruption SRI

Don't know much about this, but I wanted a BMX to ride while I'm out with my son and relive my own youth so I picked this up for a fiver. Yes it needs a damn good clean and definitely a new seatpost. I think the chrome on the frame will clean up well enough, although we're not talking show standard. I think I'll strip the remains of the chrome from the cranks. New grips, new tyres, new chain, etc. etc. and I'll hopefully have a nice bike for just riding.



Can anybody tell me anything about the history of this model?

I had a Ruption Hacker back in '95 and it looks like it's from the same era.

Bin the cranks....one piece can be pretty dangerous when they let go.

I was guessing mid nineties, but there's very little history of ruption bikes available.

As for the cranks, I've been riding bikes for the best part of forty years and I haven't broken my cranks once in that time. No matter how many pieces they started they stayed in that many pieces.

Stripped it down tonight ready for the big clean and rebuild, the steerer is stamped 96 01 and since the serial number starts CHI96 I think that confirms it's a 96.

GarethPJ":38eiq5ha said:

I was guessing mid nineties, but there's very little history of ruption bikes available.

As for the cranks, I've been riding bikes for the best part of forty years and I haven't broken my cranks once in that time. No matter how many pieces they started they stayed in that many pieces.

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If your going to ride BMX seriously one piece cranks are a no no. Friend of mine got a a snapped section of crank in his calf when they decided to snap. Has a set on my Ruption and they bent pretty quickly and that wasn't even riding street, just trails.

Looks like a good bike though and sure the chrome will come up pretty clean.

Neil G":1j286xms said:

GarethPJ":1j286xms said:

I was guessing mid nineties, but there's very little history of ruption bikes available.

As for the cranks, I've been riding bikes for the best part of forty years and I haven't broken my cranks once in that time. No matter how many pieces they started they stayed in that many pieces.

Click to expand...

If your going to ride BMX seriously one piece cranks are a no no. Friend of mine got a a snapped section of crank in his calf when they decided to snap. Has a set on my Ruption and they bent pretty quickly and that wasn't even riding street, just trails.

Looks like a good bike though and sure the chrome will come up pretty clean.

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I'm just going to use it for riding round with my five year old son while he learns to ride, so it's not going to get any stress. And while 4130 might bend it's very unlikely to snap, at least under the sort of forces you'd find in normal riding. The one thing I always do with cast or forged components, however, is stress relieve them. Look for the casting/forging lines and any stamped or raised digits on your cranks and linish them away and you've just made them a whole lot stronger. Lines like that concentrate stress. Likewise drilling components. Weight weenies who drill things full of holes to make them lighter scare me. Every hole will concentrate stress and is a potential breaking point, machine away material evenly to lighten components and they are much less likely to break. Take a tip from the engine builders, they know about stress in ways cyclists can only dream of and you'll never see con rod or a crank shaft drilled full of holes to save weight.

Sorry, but I'm always wary of advice on metal snapping. I was often told by MIG afficionados that I shouldn't braze a car spaceframe because the joints would snap, even though race car frames have been brazed since almost before time began. I was always told not to ride jumps on an aluminium frame because it would snap. My almuminium jump frame is hung up in the garage with plenty of scrapes, but it never snapped and it was always a lot lighter than my friends' snap proof cromo frames.

Doesn't matter if they snap or not , they are opiece , they will already be bent

Not sure I would want a brazed spaceframe chassis , the extra weight would outweigh any benefits over a monocoque and if a welded frame fails it'll likely be down to poor geometry . Not saying you can't , it's just moved on a bit .

From memory the sri wasn't the lowest model , but Ruption wasn't a top company .

I see what you mean but a forged one piece isn't strictly bent, it's made that shape. The cranks on mine are forged BTW. The "grain" structure follows the curves and it's strong.

Yes things have moved on, but how many people do you know who could build their own monocoque? I certainly don't have the kit to do it, but I can cut, fishmouth, fit and braze a spaceframe. Brazed framea still work very well and are pretty damned light, ever heard of Caterham? Ever see how fast the R500 got round the top gear test track. Pretty impressive for heavy, outdated technology.

A welded spaceframe wouldn't be any stronger than a properly brazed frame, indeed a brazed joint will have a higher tensile strength than the steel that makes up either side of the joint. I've seen brazed frames that have gone head on into armco at speed and the joints haven't failed even when the tubing has. It's good stuff, but doing it properly takes more skill than fusion welding. Fusion welding can bridge a badly fitted joint with brazing your joints need to be perfectly fitted and that's the main reason you don't see it too much. In top level racing carbon composite tubs are where it's at. At lower level fusion welding, TIG and (please no!) MIG rule. But where you need a spaceframe and manhours aren't a problem, bronze welding is still where it's at. In bicycle frames you hear a lot of talk about fillet brazing, but trust me it isn't any stronger than ordinary brazing. It's just a fashion thing.

Fair enough, if it's not going to be used for street/jumping they'll most likely be okay.

Plenty of BMX racers used aluminum frames i.e Brian foster but people like that were smoooth unlike average joe so could probably get away with it.