GT Jimmy Posted February 24, 2015 Posted February 24, 2015 HI Hubbers I have a problem with the expansion plug in my carbon steerer tube coming loose. It has been setup with the manufactures torque settings (with and without carbon assembly paste) as has the stem. All seems fine for about half an hour then there is an annoying creaking. Upon inspection the expansion plug had slipped up about 2mm. I chatted to some guys at various bike shops and they recommend I glue it in. Would epidermix or Pratley Quick Set be the best to bond the aluminium plug to the inside of the steerer?(There is a layer of fibre glass and resin on the inside of the steerer tube so I'm not concerned about setting up a galvanic cell)Basically I was really just wondering what the best epoxy/bonding agent would be for the applications bearing in mind the forces applied in that area of the bike. Maybe I should mention that its on my CX bike, so it does get a few bumps etc
NotSoBigBen Posted February 24, 2015 Posted February 24, 2015 Just thinking out loud but if the stem is tightened properly surely it is not possible for the expansion plug to come loose or am I just talking poofy?
Amberdrake Posted February 24, 2015 Posted February 24, 2015 I might be talking absolute crap here but.... The expansion plug/star-nut in a headset is to pull steerer tight, while you tighten the stem. After this process your expansion plug/star-nut becomes redundant. I have actually eased the tension on the star nut before without any issues. This taken into account your stem is the likely culprit here.
Trackmonster Posted February 24, 2015 Posted February 24, 2015 Running an expansion plug on a MTB is not ideal. Theyre better for road bikes. You need a fixed expansion plug inside the steerer. It must be installed with a special tool and hammered in. Or maybe you already have this. I have used some of the Duel bonding epoxy you buy in a all in one tube mixer. Looks like a syringe. ITs pretty strong if mixed properly.
NotSoBigBen Posted February 24, 2015 Posted February 24, 2015 Running an expansion plug on a MTB is not ideal. Theyre better for road bikes. You need a fixed expansion plug inside the steerer. It must be installed with a special tool and hammered in. Or maybe you already have this. I have used some of the Duel bonding epoxy you buy in a all in one tube mixer. Looks like a syringe. ITs pretty strong if mixed properly. I always thought the hammered in types were not to be installed in a carbon steerer tube *confused*
GT Jimmy Posted February 24, 2015 Author Posted February 24, 2015 Thanks guys I've definitely installed the plug correctly. I have had no problems on my road bikes and my MTB's have alloy steerer tubes with a star nut hammered in. This is the first bike I've had with a carbon steerer for off road applications so that causing a bit of a problem. The stem has no cut-outs , so wraps the steerer almost 360 degrees and the bolts have been torqued to the correct force. 3 mechanics from 2 different shops recommend that I glue a plug in there... What would be best?
NotSoBigBen Posted February 24, 2015 Posted February 24, 2015 Well I have a suspension fork with carbon steerer on my Epic and a rigid fork with carbon steerer on my single speed MTB and both have been fine without glue ..... hopefully the cleverer hubbers will start waking now (their mom's bringing them coffee in bed ) and give some real advice
GT Jimmy Posted February 24, 2015 Author Posted February 24, 2015 The knurled section of my current expansion plug is 35mm. Do you get ones with longer knurled sections? If so, where can I get such a thing in JHB?
MoreTrails Posted February 24, 2015 Posted February 24, 2015 The expansion plug could be the problem, try using another one before starting to glue things in place...that is a very permanent fixing or a very big oops if it goes tits up. The clamping force of the stem to steerer should take over fixing duties from the expansion plug winching the headset up. Maybe try another stem as well.....before the glue comes into play!
FC&P2C Posted February 24, 2015 Posted February 24, 2015 the plug is only to tighten the stem and headset untill you tighten the stem then the plug doesnt really work further and can be removed. Check on cyclesafrica website at the last of their bmx stock that they are almost giving away and buy a sinz stem lock.
stratus5 Posted February 24, 2015 Posted February 24, 2015 If after all advice fails, and you must glue, then without a doubt, use epidermix 372 only. Stay away from the pratleys and other quickset epoxies. They do have there uses, but pratleys in particular tends to be a little soft when set compared to a "real" epoxy.
GT Jimmy Posted February 24, 2015 Author Posted February 24, 2015 Thanks guys Will try another expansion plug and stem combo. Unfortunately the stem lock won't work as the steerer ends blind... otherwise that would be a great option. Does anyone know if there is such a thing as lock-on headset spacers? Cause that could be another option... Will get some epidermix 372 as a back-up option too. Thanks all for your help
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