Stem Clamping Issue
 

I have a 2013 Giant Defy 1. Stem is a Giant Connect 110mm, 8 degree. Steerer fork is Giant original equipment, aluminum steerer tube.

I'm having trouble with the stem loosening on the steerer every 100 miles or so as evidenced by the slightest feeling of the headset shifting and a "clunk" that develops after a couple of rides (100ish miles). The shifting is difficult to describe: I feel a shift in the bars/headset when first taking off for a ride (yes, the bars are tight in the stem.) It's subtle, but after having disassembled, degreased, adjusted and properly torqued the headset, I will start to feel the shift a couple of rides after adjustment and the clunk is guaranteed to appear on the ride when I first start to feel the shift. I am not talking about the headset being flopping around loose, but it seems that the stem slips on the steerer after some miles and the shift is just barely discernable. Having made this adjustment a gazillion times, I am loosening the stem clamp bolts before tightening the top cap and then tightening the stem clamp bolts using a calibrated metric torque wrench. Stem clamping bolts have a touch of grease on them. I have been pushing the limits of the torque spec on the stem bolts a bit in an effort to finally lock the assembly down once and for all - with no luck. This issue has existed pretty much since day one and the bike now has about 10,000 miles on it. I may very well have posted about it here before.

I could easily ignore it because, as noted above, its not like the headset is flopping around loose. But don't really want the bearings knocking around in the head tube and wallowing out the head tube (no way to fix that).

Any suggestions? I am considering trying different stems. Other options: new headset bearings, new fork, new fork and steerer? I have kind of decided that the issue is a slight shifting of the stem on the steerer but I could be wrong. I've been looking for different stems trying to find one that has a longer (as measured along the steerer) clamping surface but this measurement is not a spec that is published.

As always - thanks in advance for any advice.

Hi,
A couple of things. Proper headset preload reduces stress on the bolts retaining the stem clamp to the steerer. So you need to make sure the top vertical screw is nice and snug which also preserves the bearings due to road assault.
Other than that, use a torque wrench. Most are torqued to 55 inch pounds or there abouts. You could try Loctite 242 on the screws if you ride a lot over rough road surfaces to keep the small 4mm allen bolts from backing out.


A last thing is....very few bike manufacturers make a decent stem. Companies have expertise and specialities. Stem manufacturing isn't a long suit of most large bike mfr's. My favorite value stem is the Ritchey WCS 4 axis which comes in a different rises and lengths. Retail they are about $90 but you can find them on ebay for less.


You will probably save a few grams if you ditch the Giant stem as well. Btw, I have never experienced your issue and I have been at this a long time. Your stem design maybe less than robust if your installation technique is sound...adequate preload and correct stem steerer clamp bolt torque.


Good luck

I've never seen or heard of this either. I would agree that proper preload is paramount. You could try carbon assembly paste on the steerer under the stem inner surface. That might keep things snug. Also make sure you have all the required small parts of the headset in the stack and in the right order. You may have botched the assembly of the parts.

I'm x2 on the try a replacement stem first...and also endorse Ritchey.

I would never use carbon paste between a stem steerer clamp and steerer...for one...the paste could wick down into the top bearing past the top dust cover.


Yes, OP...check your bearing order...make sure you don't have one bearing upside down...angular contact bearings don't like that and will spoil the headset performance.

Have you tried putting a 2mm spacer above the stem to see if that helps things? What does the rest of the spacer stack look like?

I'm wondering if the top cap doesn't have enough space to properly snug things down, but it's really close until things settle.

Get a new stem- after re-tightening it 12 times-

that was 8,800 miles & 88 adjustments ago.

Thanks. I'm considering a stem change and Ritchey is one I was looking at. I'd like to think I'm doing things right. I also had the LBS adjust it and the result was the same.

I considered carbon paste, but everything I have ever read has indicated that the steerer/stem surfaces should be completely degreased. I might give it a go with the paste, but am a bit concerned about the grease that is the "carrier" for the grit that gives carbon paste its bite.

Thanks, bearings, dust caps and spacers are all in the proper order. I have only had the headset completely apart two or three times. I added a very light coating of lube to the bearing outer surfaces to facilitate their proper seating in the head tube on the thought that one of them might be not seating properly. This did not help.

There are several spacers above the dust cap, but probably an 1/8 to a 1/4" inch of stem above the steerer so I dont think the top cap is bottoming out and preventing proper loading of the assembly.

Ha, Ha! Seeing this in print has me questioning why I have tolerated this for so long. I think a new stem is in order and the Ritchey products have been recommended here and are on my short list.

Looks like this will be my next fix attempt. I was looking at the Ritchy Pro series at Performance. Any thoughts on those vs the WCS 4 axis that CAmpag4life suggested?

Ritchey Pro series is fine...but the WCS 4axis is their best and lightest all Al stem. FWIW Ritchey carbon matrix stems aren't as good...I have owned several of each...carbon delaminated around stem clamp bolts on one carbon Matrix stem...and Ritchey did warranty it but honestly, their carbon stems are more for aesthetics...not discernibly lighter or stiffer than their WCS 4 axis all Al stems.


A more value oriented stem and better than their Pro series is their Comp 4 axis....basic same design as their WCS 4 axis but a bit heavier.


Reading all you have written and done, I would say you have a good handle on your installation. Probably best to swap stems at this point.
Good luck

It isn't grease. It is a gel.

Above the steerer or just above the stem? You can have spacers above the stem and still have the steerer too close to the top of the stack to allow the top cap to work properly.

Is the expansion plug sitting firmly in the steertube?

I had this same issue, and my problem was actually that the expansion plug would slide up, allowing for some movement. I ended up having to use carbon paste on the expansion plug and torque the hell out of it to get it to stay in place.

I've had an expansion plug do that as well. But it was my fault and the fix was easier.

Sorry - What i typed was wrong. The stem is higher than the top of the steerer and the top cap is not bottoming out on the end of the steerer.