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Story with Bowman?

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Comments

  • Registered Users, Registered Users 2 Posts: 5,929 ✭✭✭fat bloke


    One thing I can't understand is how the bikes were so damn nice to ride. I still miss riding mine. You'd have thought a hastily bodged together misaligned series of tubes would ride like a dog.

    What does he think of mainstream alooominum bikes from the major manufacturers? I've never heard any reviewers gushing about Giant Contends and the likes.

    There's the CAAD range of course but is Hambini similarly defacatory on them? :)



  • Registered Users Posts: 607 ✭✭✭ARX


    Giant Contends aren't artisanal.

    Apropos welding, I remember reading that Ferrari had a reputation for sloppy welding. I found these pictures taken at the Ferrari museum. As I said, I know nothing about welding, but these look a bit crappy: https://imgur.com/a/5e61w



  • Registered Users, Registered Users 2 Posts: 2,986 ✭✭✭Plastik


    I think he has undoubtedly shat all over Cannondale's (at least at one point in time) notoriously bad QC on BB30 shells. Wouldn't keep track of all his stuff, got tired of watching them after a while, but don't recall him ever taking an alu bike apart like that.



  • Registered Users, Registered Users 2 Posts: 8,050 ✭✭✭cletus


    I watched a couple of his videos, they popped up in my feed before I knew anything about him.

    I found them hard work, to be honest, even if he knows his stuff from a technical standpoint. As a result, I don't bother with his videos anymore, but when I saw the Bowman video, I wanted to see what the story was, especially in light of the company going bust, and our own fat bloke's ongoing saga.


    Those Ferrari welds aren't great, either...



  • Registered Users, Registered Users 2 Posts: 1,905 ✭✭✭Mefistofelino


    TBH, its not that difficult in many cases. Pick an Asian firm already bulk fabricating frames in the material of your choice. If you want to "indiviualise" the design, pick angles based on the more-highly rated similar frames already on the market. Choose features based on what t'internet regards as the must-haves for that type of bike - headset bearing size, through axles, tyre clearance, BB standard, mudguard eyes etc. Then leave it to the engineers at the subcontractor to sort out the design and fabrication details. No different to personally speccing a one-off titanium frame from one of the Chinese suppliers.

    There's more than Bowman taking this approach, and not just for frames either.

    (One British firm did take a little more "hands-on" approach with the design where I suspect that they may have overruled the reservations of the fabricator engineers. The end result was their occasional "special offers" of cheap sample frames where it transpired they'd made some giant balls-up of a design detail)



  • Registered Users, Registered Users 2 Posts: 21,721 ✭✭✭✭Squidgy Black


    They probably had the geometry well planned out and aligned in the jig but just blasted through the welds. Or else all the pinholes were giving you enough flex to make it a lovely ride!



  • Registered Users, Registered Users 2 Posts: 1,905 ✭✭✭Mefistofelino


    Flow straightener (I think) from one of the display engines at the Ferrari museum..




  • Moderators, Sports Moderators Posts: 25,160 Mod ✭✭✭✭CramCycle


    He hates Cannondale (from memory)and sh1t on them as a point when I first heard of him, giving out about their QC tolerance limits. The truth is though, they work, are well regarded and despite his reservations, you don't hear that many people giving out about them. Most modern BBs are designed with the ability to take those slightly wider QC tolerances, I imagine part of his issue is that his machined ones probably have little to no give in them so rather than accept that bikes aren't going to have as tight tolerances as maybe they should (which would lead to higher costs), he then has a product that isn't fit for purpose for a wide variety of frames.

    As for asll the welding talk, my Dad done alot of welding (I can do a bit but not good at it) and liked it to look neat but the key component to a good weld wasn't its appearance, it is whether or not it would hold up in working conditions for what the item was designed to do. Everything else is just niceties, and such things are usually a sign the worker is good/diligent and therefore most likely the rest of the job was good but also, just because it looks nasty, doesn't mean it is.



  • Registered Users Posts: 607 ✭✭✭ARX


    So basically he picked a bunch of options from a menu? 'Design' makes it sound like he sat down with a CAD program and y'know, designed it. From scratch like.



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  • Registered Users, Registered Users 2 Posts: 1,905 ✭✭✭Mefistofelino


    Not saying that was specifically the case with Bowman, but "design" can have a lot of meanings. Even the person driving the CAD program isn't necessarily the "designer" in the sense that you mean it - they may just be a draftsperson, working to instructions from an engineer. And to close the loop, the initial designer, who doesn't do the actual mechanical engineering design but instructs the engineer, may bring a lot of valid experience in the specification of the item. Picking a bunch of options from a menu only works if you know what those options bring to the product.



  • Registered Users, Registered Users 2 Posts: 8,050 ✭✭✭cletus


    I'd agree broadly about the welding, but these welds were not good. I've done plenty of ugly but structurally sound welds. In this frame there was oxidisation holes (pinholes or blowouts), there were many points where there was no penetration on the weld, so that the bead was sitting on top of the joint, so very prone to cracking or shearing, and there were a number of places where it looked like they hadn't welded at all.

    I understand your dislike for Hambini, but in this case he's not wrong



  • Registered Users, Registered Users 2 Posts: 897 ✭✭✭gn3dr


    The dimple on the weld behind the seat tube was described as a blowout but it looked to me like the classic instant stop in an aluminium weld which always leads to a crater in the weld. It then becomes a stress riser / failure point. It's the classic "do not do this" from aluminium welding 101. You are supposed to back off the current slowly at the end of the weld.



  • Registered Users, Registered Users 2 Posts: 8,050 ✭✭✭cletus


    You're very probably right. I've never chanced welding aluminium 😁



  • Registered Users, Registered Users 2 Posts: 1,516 ✭✭✭hesker


    So you reckon most modern BBs have give in them. Interested where you got that from as I haven’t heard that before.



  • Registered Users, Registered Users 2 Posts: 8,050 ✭✭✭cletus


    It's not so much that they have 'give' in them, more that they can operate properly with a relatively large tolerance.


    Tolerances, in machining terms, are tiny. 10'000ths of an inch is a measurement commonly used in machining. It equates to about 0.025mm. Building things to these levels of tolerance increase the cost.

    Having components that can operate even when the tolerances are (relatively) big is important in mass production



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  • Registered Users, Registered Users 2 Posts: 1,516 ✭✭✭hesker


    What characteristics do they have that allow them to operate properly in this situation.



  • Registered Users, Registered Users 2 Posts: 8,050 ✭✭✭cletus


    I couldn't say for sure, I'm not an engineer, but one of the ways tolerances are allowed for would be in thread formation, whether the 'peak' of the thread has been flattened or not.

    Another way might be shell wall thickness, so that ovality in the bottom bracket hole doesn't bind the bearing.


    I'm sure there are other things, but I'm only a PE teacher.

    There are a variety of levels of tolerance accepted in all areas of manufacturing. If a hole is specified at 10mm diameter, there is a range of sizes that might actually suit, depending on the requirements of the piece.

    If I drill a hole in order to tap it, there are a couple of different sizes of hole that will suit, depending on the amount of thread engagement I might need, for any nominal hole size.



  • Registered Users, Registered Users 2 Posts: 1,516 ✭✭✭hesker


    I think I understand what tolerances are well enough. I was just probing a line of reasoning proposed by some in this thread that to me seems really out of whack with reality.



  • Registered Users, Registered Users 2 Posts: 8,050 ✭✭✭cletus


    Well, if you understand tolerances, what was the line of questioning? That plug and play parts are built with those tolerances in mind? I'm not sure I understand



  • Moderators, Sports Moderators Posts: 25,160 Mod ✭✭✭✭CramCycle


    Apologies, tolerance would be more appropriate, I was using more layman's terms. In work we would have other terms but not used in laymans terms. Basically, there is an acceptable margin of not being in line that the BB (that you buy) can tolerate, alot of modern BBs, can tolerate these micrometers, they tolerate it through the threading on the bike and the BB not being completely flush (damn near impossible), or the pressfit taking the almost unnoticeable compression somewhere. So imperceptable that once faced off, no person on their own could tell. Some companies when QCing, allow wider criteria than they should but realistically, the bigger companies have assessed that if they apply certain criteria with a suitable level of sub sampling, that even though there will be outliers that may fail, the majority of frames are more than acceptable. There are some smaller companies that may be more stringent, which may potentially increase cost, or less stringent (if they bother at all), which will reduce cost.

    To make it more simple, wheel manufacturing might be a simpler one to visualise. I know there was a video on here on how to make money quick rebadging cheap chineses wheels. Well imagine that the cost difference between HUNT or similar and the direct from factory, isn't solely the rebrand, but it is the local team QCing on this end, they may need to send X% back to the factory or scrap, depending on their business model but the mark up they charge means they can tolerate those returns and also tolerate the lower than you would get from direct sales returns, as they QC'd them locally, possibly every set of wheels.



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