The BB92 Grind: Make Way for the 1-Piece Bottom Bracket

The BB92 Grind: Make Way for the 1-Piece Bottom Bracket

December 28, 2022

 

This procedure is super easy and requires only a little skill and some basic DIY equipment. We didn't cut the video throughout the operation to show the technique in real-time so you can see how quickly the material comes off. Some precautions: If you don't have a vacuum to collect the carbon dust you should wear a mask. Do not breath the carbon particles. If you are uncomfortable with this procedure for any reason, don't do it. For the rest of you this will merely be an additional technique for your DIY arsenal as you handle whatever half-baked situation the bike industry throws at you with aplomb. Huge thanks to legendary local Little Rock shop Angry Dave's Bicycles for lending us Dave's very own brand-new Marin Wolf Ridge for this epic install.

 

Big old full suspension Marin is BB92 and it's one of these kind if you want to come in here you can see that it's a solid tube all the way through as you can see right there rather than having like carbon on either side and being kind of a void inside there's a lot of them like this the ibis a lot of the Ibis bikes are like this you name it all the yetis all the SB's are like that there's one danger with a bottom bracket structure like this and that is once you get past these outsides right here they're not real careful about this dimension here sometimes it can be bigger great sometimes it can be smaller and the way that I find that out is I go ahead and I measure with an inside mic and I go ahead and I take a measurement and then I go in here and I take another measurement and then I go in a little bit deeper and take another measurement and I did all that and what did I find I find that there is a considerable reduction in diameter on the inside of this bottom bracket now I'm not recommending that you do what I'm about to do because it's not for everybody and if you see what I'm about to do because I'm going to use this right here Dremel tool to open this up inside obviously I'm not going to be touching these outer edges the outer like half millim - excuse me, 10 millimeters or half inch of this bottom bracket shell because that's what's necessary for the press fit interface now so and in order to not do not mess those areas up I went ahead and I've put some tape mark on here so I know if I went too deep see that it's stopping me before I go there and then I know when to stop here now some people are gonna be like oh I'm afraid that's gonna violate my warranty then don't do it it's really that simple or if you say "well that looks crazy" - don't do it this video is not for you but there's plenty of you out there who've had a lot of problems with these systems and you want a real solution so you want to use the one piece bottom bracket system and this is the only way you're going to get it done because if there's a reduction of diameter on the inside the bottom market will never pass through there you can't just squeeze it through there it's not just going to like expand like a Chinese finger trap it's not going to work that way it's just going to get lodged in there and you're going to be you're going to be dead in the water and you're going to have to do this anyway all right one more thing this right here this piece this structure is solid there is no way I'm going to be able to like sand through it okay now the carbon is going to come off very rapidly so I do want to check on the diameter as I go so I'm going to go ahead and fire up the vacuum because I don't want to breathe I'm gonna go ahead and check this out you guys probably noticed that I wasn't just sawing back and forth you know what I mean I wasn't using this like back and forth plunging action I was just rotating I was just orbiting it on the inside of here and I was just taking it off a little bit by a little bit as you can see right there all right it's not going to come off like super even it's going to come off pretty darn even but don't forget this this really doesn't matter in here as long as the diameter is larger all the way through except on the edges where it needs to be you know 40.97 everything's going to be gravy so this is how I'm going to check it I'm going to put the inside mic in here to all the way over to this side and I'm going to open it up until it is in the measurement position and all I'm going to do is grab it and drag it back and you see how just it got loose right away and then when it gets to the other side all of a sudden it's tight like so tight that I actually have to loosen it up to get it out so there you go that is done it is really that easy



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