In today’s episode we reel back to a question we received about why alloy bottom brackets corrode in carbon frames. In short, it is for lots of reasons, one of them being the dissimilarity in materials.
Dan: 00:02 Welcome to the #carbonqueries podcast, the interactive show where we answer your carbon fiber related questions hosted by Ruckus Composites. You can submit a question using the Hashtag carbon queries on instagram, facebook, twitter, linkedin, or email
Shawn: 00:17 So we got a a good follow-up question from jeff on facebook asking he works in the aerospace industry. Can say that he does. And um, he was talking, he was in follow-up to our comments about why manufacturers don’t put aluminum threaded shells and bikes. And I said it’s a high risk of failure of dissimilar materials, aluminum carbon and he, you know, works in aerospace. And he’s like, why don’t they just put an insulator and that is a great question. And the reason is, I don’t know, it is. So when you have two different materials that you can definitely put an electrical insulator, it’s just fiberglass generally. Um, so like when we put an alloy shell into a bike, we lathe that, get the correct diameters that we need a machine to down to the perfect diameter, we surface treat it, bonding to aluminum is it’s own special beast because it creates an oxide layer nearly instantaneously.
Shawn: 01:09 So you need to treat it specifically. So they actually bonds to it. Anybody else blew into aluminum short lifespan. There’s another one. Aluminum is hard to glue to, you know, is that oxide layer that has. It’s easy to shear. Basically. It’s a very thin, shear-able layer which sucks. It breaks and then we wrap it in fiberglass and cure it. So now we have an easy surface to bond to. It’s insulated and then we just glue in the frame and it’s perfectly fine. On the manufacturing side. I think there are good again to prep aluminum correctly is hard. You know, there’s a lot of pre documented manuals about how to prep different metals for bonding with composites. You know, a simple a titanium is one of the simplest ones to do. You just really have to clean it with acetone. Think it was actually also hard to glue too.
Shawn: 02:03 But um, that’s a reason. But aluminum is incredibly hard to glue to and it’s used so much because aluminum is dirt cheap. It’s easy to machine, right? Nothing’s cheaper than aluminum. I’m getting a lot of things that aren’t. But like when it comes to easy machining, aluminum dropouts, pivot points, whatever it holds its tolerances, but you know, an aluminum is exposed to air like it is, it creates that aluminum oxide layer and you basically need to prevent that oxide layer from forming in the first place. So the aluminum technically after you machine it cannot be exposed to air if you want it to bond it correctly. So typically before you bond to aluminum, you need to do an acid etching and a certain way that prevents that oxide retards, that oxide layer from being created quickly. And then you can glue it right away. We have our own tricks, how we actually do that because we don’t like those acids because they’re nasty.
Shawn: 02:56 And so I learned a bunch of tricks from some guys in boat guys on how to treat a aluminum environmentally friendly way to get the same bond strength because yet again, if our bonds broke, I repair breaks and our business fails, right? To make that short. So we take that stuff seriously. And if you don’t, aluminum corrodes and that’s called galvanic corrosion.
Dan: 03:20 And maybe we will cover that in another #carbonqueries
Shawn: 03:25 That one needs to get covered a lot. It’s still a problem. We just had a one, a brand new Emonda 700 come in and I’m already like less than a year old and the cable stops are boy are they disintegrating miles who even now probably it’s got to be trainers indoors. Adequate 30 sweat capture method. Not enough fans.
Shawn: 03:53 I guess you have a lot of fans on twitter. Ah. Oh my God. Dan, what if we created zwift fans? Like real, now I’m confused on the actual fan or the fan or the English language great sometimes not to learn. Well there you’re just getting a bar. That’s what fans. You can cheer on somebody through VR just to make it more absurdrs. I’m not as lifter. That’s fine. If you are a good thing, we’ll see everybody next week.
Dan: 04:28 Thanks for tuning in to the carbon queries. If you have a pressing carbon fiber related questions, you can submit it to us using the Hashtag carbon queries on instagram, facebook, twitter, linkedin, or email. We’ve thoroughly enjoyed putting together this podcast where everybody so far, and I’ve gotten some great feedback, so if you have anything to say, comments, suggestions, please go on to Itunes, give us five stars or just an honest rating that works as well. Other than that, please like comment and share, facebook, instagram, Google, play, wherever you get your podcasts. It would really help us out a bunch. Thanks everybody. We’ll talk to y’all next week. Yeah.