honitonhobbit Posted April 20, 2006 Share Posted April 20, 2006 If the welding is poor, then the whole thing is rubbish. A safety device can then become a death trap. Not insulting Dirtydiesels qualifications as a welder, but spotting poor welds isn't rocket science, if the weld looks like it's sitting on the metal, rather than a part of it, then it's not going to be strong enough for it's intended purpose. I'm sure there are plenty of people out there that don't realise that their safety device could so easily be a killing projectile because some idiot can't weld properly. carp welding is my pet hate. (assuming you aren't going into x-rays/crack testing) But it's obvious that with poor welding it's more likely. Les. Couldn't agree more... Quote Link to comment Share on other sites More sharing options...
honitonhobbit Posted April 20, 2006 Share Posted April 20, 2006 It is difficult to give the kind of discounts traders want (Need?) without making a loss yourself once you factor in your overheads.I actually rather like some of the Scorpion kit - bumpers in particular. I'd sooner stick needles in my eyes than buy them - but they do look nice! Si To right, especially when the end user is always looking for a 'bargain' and driving the price down, thus giving birth to the need for high overhead companies to 'reduce manufacturing/buying costs'. I thought long and hard before buying from Scorpion and I searched the market for the right product. My decision was made by certain circumstances that forced the choice somewhat. And oddly enough, I felt guilty with my choice of supplier, not just becuase of your treatment but because I know most of the other suppiers who have recieved similar rewards or worse Hey ho - such is life Quote Link to comment Share on other sites More sharing options...
MudAllOverIt Posted April 20, 2006 Share Posted April 20, 2006 Speaking of front radius arms, I was browsing the web site of the folk that sell Equipe stuff in the UK and noticed that the Equipe front radius arms sell at £950 Does anyone know why they cost so much more than the QT or ScrapIron ones? Quote Link to comment Share on other sites More sharing options...
honitonhobbit Posted April 20, 2006 Share Posted April 20, 2006 Mark 90 told me they are made from platinum, inlaid with gold wire and encrusted with emeralds Quote Link to comment Share on other sites More sharing options...
MudAllOverIt Posted April 20, 2006 Share Posted April 20, 2006 encrusted with emeralds Emeralds? No diamonds then? Explains why they're under a grand I suppose Quote Link to comment Share on other sites More sharing options...
dirtydiesel Posted April 21, 2006 Author Share Posted April 21, 2006 If the welding is poor, then the whole thing is rubbish. A safety device can then become a death trap. Not insulting Dirtydiesels qualifications as a welder, but spotting poor welds isn't rocket science, if the weld looks like it's sitting on the metal, rather than a part of it, then it's not going to be strong enough for it's intended purpose. I'm sure there are plenty of people out there that don't realise that their safety device could so easily be a killing projectile because some idiot can't weld properly. carp welding is my pet hate. (assuming you aren't going into x-rays/crack testing) Les. I never said there was a lack of penetration, because I can't prove it. But i did suspect that the welds had very little penetration, I did fancy cutting one up and dye penning it. Anyone want to volunteer their arms for a bit of destructive testing? Quote Link to comment Share on other sites More sharing options...
simonr Posted April 21, 2006 Share Posted April 21, 2006 Equippe said their hockey sticks are cnc machined out of big blocks of dural - they said it was the only way of achieving the weight saving with the strength. They look good too! Si Quote Link to comment Share on other sites More sharing options...
MudAllOverIt Posted April 21, 2006 Share Posted April 21, 2006 Equippe said their hockey sticks are cnc machined out of big blocks of dural - they said it was the only way of achieving the weight saving with the strength. Thanks for the info -- if that's what they do then it figures. Quote Link to comment Share on other sites More sharing options...
Mark90 Posted April 21, 2006 Share Posted April 21, 2006 The Rakeway arms are "Precision machined from quality aluminium alloy", shame they only seem to do DiscoII arms at the moment, I guess cos they are catering for the race/Bowler market. Quote Link to comment Share on other sites More sharing options...
isuzurover Posted April 21, 2006 Share Posted April 21, 2006 The Rakeway arms are "Precision machined from quality aluminium alloy", shame they only seem to do DiscoII arms at the moment, I guess cos they are catering for the race/Bowler market. You wouldn't want an aluminium bolt on the end of an older style arm!!! Surely you can make a steel arm that is as light without the inherent fatigue problem that aluminium has. Quote Link to comment Share on other sites More sharing options...
simonr Posted April 21, 2006 Share Posted April 21, 2006 You wouldn't want an aluminium bolt on the end of an older style arm!!! Surely you can make a steel arm that is as light without the inherent fatigue problem that aluminium has. Possibly! Aluminium has better performance in compression than steel - and the arms need better compressive strength (on braking - or hitting a curb, fast) than tensile. The grade of Aluminium used is nowhere near as prone to fatigue or work harnening as most of the stuff you come across (coke cans and the like). Reckon they could be very good if they have done their homework. I suspect the compressive strength issue is why Land Rovers use cast steel as standard. Ones made from welded plate are probably plenty up to the job for 99% of use - Land Rover and Equippe just cover the extra 1% as well. Si Quote Link to comment Share on other sites More sharing options...
landrover598 Posted April 21, 2006 Share Posted April 21, 2006 Gong off topic a bit here, but why is there big concern about the weight of these arms ? Quote Link to comment Share on other sites More sharing options...
minivin Posted April 21, 2006 Share Posted April 21, 2006 Possibly! Aluminium has better performance in compression than steel - and the arms need better compressive strength (on braking - or hitting a curb, fast) than tensile. The grade of Aluminium used is nowhere near as prone to fatigue or work harnening as most of the stuff you come across (coke cans and the like).Reckon they could be very good if they have done their homework. I suspect the compressive strength issue is why Land Rovers use cast steel as standard. Ones made from welded plate are probably plenty up to the job for 99% of use - Land Rover and Equippe just cover the extra 1% as well. Si From what I've seen 7075 is a possible grade they may have used, IIRC it's also the grade they use for making main wing spars for commercial jet aircraft Quote Link to comment Share on other sites More sharing options...
isuzurover Posted April 21, 2006 Share Posted April 21, 2006 From what I've seen 7075 is a possible grade they may have used, IIRC it's also the grade they use for making main wing spars for commercial jet aircraft The difference with aircraft parts is they are usually inspected regularly and replaced periodically whether they need it or not. I have seen plenty of failed 7005 and 7075 mountain bike frames. I agree that the arms, if designed correctly, are a good idea, but I would never fit them to a road-going vehicle. Quote Link to comment Share on other sites More sharing options...
MudAllOverIt Posted April 21, 2006 Share Posted April 21, 2006 Gong off topic a bit here, but why is there big concern about the weight of these arms ? As I understand it lighter arms reduce the unsprung weight of the suspension which can improve the handling of fast road and race cars. Can't imagine it matters that much if you're prepping an off-roader? I suppose anything that reduces the overall weight of whole vehicle helps -- but in the overall scheme of things I would have thought that the weight savings of lighter arms are pretty insignificant? Quote Link to comment Share on other sites More sharing options...
freeagent Posted April 21, 2006 Share Posted April 21, 2006 in certain situations, ally would be a superior material from which to make the arms, as it does have a slightly better strength-to-weight ratio than steel... however i don't think its worth the agro, on a 2 tonne+ off roader or challenge truck does a couple of kilos make any difference... 'of course it doesn't.. it might on a racer.. but not for mucking about in quarries. ally is easier to damage than steel (in some situations) and does suffer from fatigue problems, but as already said, if its the right grade, and its been heat treated/ manufactured properly then it would be fine.... i'd love to hear one of the numpties at scorpion explain the steel v ally arguement... might ask them at Billing.... Quote Link to comment Share on other sites More sharing options...
02GF74 Posted April 21, 2006 Share Posted April 21, 2006 I have seen plenty of failed 7005 and 7075 mountain bike frames. going off off topic. how come you get to see these frames, any pics? where in the frame do they normally fail? what usually is the cause (lardy blokes doing 6 ft jumps ) Quote Link to comment Share on other sites More sharing options...
Bull Bar Cowboy Posted April 21, 2006 Share Posted April 21, 2006 going off off topic. how come you get to see these frames, any pics? where in the frame do they normally fail? what usually is the cause (lardy blokes doing 6 ft jumps ) All those that I have seen have failed at the downtube to headstock joint ……. It usually starts off as a small crack just behind the weld, then just gives out with no warning. I have always assumed that this area must be highly stressed when jumping etc ………… my son has broken two….. Kona & Cannondale ………. He has now gone back to some fancy moly Cr steel frame (‘kin expensive). ……. So far so good …… but it maybe that now he is nearing his thirties perhaps he is not quite so stupid daring . Ian Quote Link to comment Share on other sites More sharing options...
dollythelw Posted April 21, 2006 Share Posted April 21, 2006 (lardy blokes doing 6 ft jumps ) oi - easy fella having said that I've snapped a few motorbike frames, Quote Link to comment Share on other sites More sharing options...
freeagent Posted April 21, 2006 Share Posted April 21, 2006 All those that I have seen have failed at the downtube to headstock joint ……. It usually starts off as a small crack just behind the weld, then just gives out with no warning. classic fatigue failure. Quote Link to comment Share on other sites More sharing options...
Ex Member Posted April 21, 2006 Share Posted April 21, 2006 Apples and oranges. Mountain bike frame are purposely made as light as possible without them failing too often. Racer do NOT EVER run a frame more than half a season because they will ALL break when used hard. For us, weight is not a big concern unless you are racing. Having the radius arm not collapse when emergency braking on the highway is a bit of a concern though. Quote Link to comment Share on other sites More sharing options...
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