Viewing 23 posts - 1 through 23 (of 23 total)
  • Carbon BB shell wear – appropriate fear level?
  • GarethClay
    Free Member

    Happy bank holiday weekend everyone. I haven’t posted here before, so hello 🙂

    Since I’m stuck at home due to work commitments and my trusty Five doesn’t seem to need any tinkering, I’ve been investigating a sticky bearing in the bottom bracket of my Cube Reaction today. Pretty ashamed to notice a pretty sizeable chip / wear mark around the BB after I took the chainset out. I guess the flimsy stick-on frame protectors which came with the bike have dropped off and I’ve been carrying on riding regardless without due care and attention 😳

    Just wondering if anyone with a bit more carbon frame knowledge than me (not hard) has any advice on whether this is just cosmetic or whether it’s something I actually need to be concerned about? I’ll post a picture if I can…

    Thanks for any advice!

    parkesie
    Free Member

    Most frames seem to be built to take knocks in that area i say if it hasn’t fell off protect it a bit better and carry on.

    GarethClay
    Free Member

    Thanks – I’m hoping that’s the case here, but thought it worth asking about. Here’s the pic:

    It’s the deeper scrape to the right of the BB that’s caught my attention.

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    steve_b77
    Free Member

    That looks like your chain has been rubbing the bottom bracket area when in the small ring.

    Is there any lateral play in the cranks when they’re on the bike?

    parkesie
    Free Member

    :I wouldn’t worry to much my self, although you may want to try making a guard and reinforcing it with some epoxy and some cutlery 😆

    It could of course go horribly wrong and lead to messy death.

    GarethClay
    Free Member

    I’ve never noticed any play in the cranks, but I’ll check again when I refit them. I’m sure you’re right about the chain rub. There’s very little clearance between the frame and the granny ring on this bike. When I first got it (from CRC) I thought sure their ought to be a spacer on the drive side, but checked with both them and Cube and they both assured me this wasn’t the case. Maybe I need to send them these photos and restate my case…

    steve_b77
    Free Member

    Jaysus, that makes chainring clearance on an on-one lurcher look massive!!

    Certainly looks like the chain rubbing on the frame from that pick. A double may solve it with a larger granny ring moving it away from the frame

    aracer
    Free Member

    Though chain rub doesn’t really explain the marks to the left of the BB in the first pic – unless you’re also getting chain suck.

    Ming the Merciless
    Free Member

    Missing crank spacer?

    GarethClay
    Free Member

    I think the other marks are probably due to mud and grit wear from the frame-side face of the granny ring.

    The missing spacer thing is nagging at me again now. Both CRC and Cube seemed sure of themselves… maybe I should have stuck to my guns. Think I’ll email Cube UK the pics and see what they reckon.

    steve_b77
    Free Member

    If there was a missing spacer, surely the cranks would move side to side when installed?

    GarethClay
    Free Member

    I think the type with a crank bolt which tightens up to a stop (like my RaceFace ones) would have that issue, but these are the Shimano type where the non drive-side crank arm just gets nipped up along the axle splines until it’s flush with the BB and then tightened on with two small allen bolts. I think it could accommodate a spacer… although not really sure if that would mean the non drive-side arm then wouldn’t be fully seated on the splines.

    mtbtomo
    Free Member

    I wouldn’t worry about it. Looks as though you’ve only take the top layer of paint / lacquer off.

    I would think that area would be fairly well reinforced to ensure the bb junction is stiff.

    nowthen
    Free Member

    Why dont you just fit a spacer…. whatever anyone says, it certainly looks like it needs one…

    jimification
    Free Member

    As said, carbon frames are usually pretty thick in that area. Looks like just paint damage. I’d stick some heli tape there to prevent further wear. If there isn’t room for heli tape then you definitely need a spacer!

    wobbliscott
    Free Member

    If it has worn through the lacquer and paint and into the carbon then i’d be tempted to put some lacquer on there to cover up the exposed carbon. My experience of carbon parts in industry is if the carbon is exposed then moisture can get in an cause delimitation. Probably less of an issue on a bike, but belt and braces and all that.

    jimification
    Free Member

    If it has worn through the lacquer and paint and into the carbon then i’d be tempted to put some lacquer on there to cover up the exposed carbon. My experience of carbon parts in industry is if the carbon is exposed then moisture can get in an cause delimitation. Probably less of an issue on a bike, but belt and braces and all that.

    Nail varnish maybe?

    br
    Free Member

    When I first got it (from CRC) I thought sure their ought to be a spacer on the drive side, but checked with both them and Cube and they both assured me this wasn’t the case. Maybe I need to send them these photos and restate my case…

    I’ve never dealt with these new-fangled BB’s, but on a HT2 there are 3 spacers in total and on my bike I need to run 2 d/s and 1 non d/s. Can you just swap them across too?

    GarethClay
    Free Member

    It sounds like the consensus is not to worry too much then, which is good news 🙂 I’ll definitely take a look at covering up the damaged paint… might go raise some eyebrows in the nail varnish aisle tomorrow.

    As for the spacers, the bike doesn’t have any at the moment, but am sure I can find one either in my spares box or at the LBS. Seems worth a try – surely that amount of clearance can’t be right.

    Thanks all for your advice 🙂

    GarethClay
    Free Member

    Hmm… confusing response from Cube:

    It is correct that on pressfit BB spacers are not needed. There should be one between the BB outerside and the contact of crankset naturally, this is not visible on the picture however.

    andyl
    Free Member

    sounds like the one they are saying is not needed are the HTII external bearing spacers which are obviously not applicable to the pushfit BB (and you were not asking about those but they may have thought you were) but you do need a spacer on the axle to push the crank away from the BB.

    Which would stop that rubbing.

    Oh and doesnt look serious to me either. But needs sorting.

    dirtyrider
    Free Member

    3 rings 😆

    BrickMan
    Full Member

    That looks too close to me, the chain won’t actually be touching, but as soon as it picks up any dirt/ mud it will be grinding it against the paint? Amaright?

    Also with production frames there is a lot of carbon down that end of the frame, I’ve seen fairly high end road bikes with 4-5mm deep gouges missing out of them at base of the d/t and/or chainstay and been ridden on the local rough as you like roads by people who abuse them without problem.

Viewing 23 posts - 1 through 23 (of 23 total)

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