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I bought this new Kalloy quill stem, with Sakae 25.4mm handlebars as pictured below. The handlebars were purchased at an eBay auction.

enter image description here

Here's the setup from the side

I've tightened the handlebar clamping bolt (m8 size, 10mm thread engagement) to the maximum torque of 10 N m as printed on the stem, photo here, which does fine when riding on flat surfaces, but as soon as i hit a bump when on the hoods, the handlebars rotate forward. Adding fibre grip doesn't solve this problem.

When looking up the torque values of typical quill stems they range between 14 - 30 N m, Park tool's recommended torque ranges reflect this.

Would it be okay for me to torque higher than 10 N m despite what it says on the stem? As far as I know, Kalloy is a fairly reputable company when it comes to components, so I'm surprised the torque is so much lower, and that this slippage problem is occurring.

My current strategy is to incrementally up the torque until it's at an acceptable level. If that still doesn't work, I'm considering using a shim.

Please let me know if there's anything I should consider!

EDIT:

I've heard back from the store I bought it from and this was their reply:

Good morning, The first thing I would check is the handlebar diameter just to make sure it is within spec. We see a lot of bars that are on the low side of the specification, 25.2mm is probably ok, anything below could be an issue. If it is within spec you should be able to safely exceed the recommended torque, just make sure the bolt threads are greased. I would have sold over a thousand of these stems over the past 10 years or so and more than likely the majority of customers wouldn't bother with a torque wrench, no doubt they have taken them well past 10 N m I would go up in 0.5 N m increments

I rechecked the diameter of the handlebar, and they are within spec. Bolts are also greased. I've tested it up to 15 N m (as far as my torque wrench allows), and will try shimming it with a beer can before borrowing a torque wrench with higher torque setting. So far seems promising!

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    Try a narrow (5-10mm) beer can shim the width of the clamping eye. Over-torquing is the path to destruction. – Carel Dec 27 '20 at 15:35
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    The handlebars are not new right? So there's a chance they're compressed, or their "grippy lines" are worn down? Another idea is to mark the bolthead and the stem with a pen, and check if it is backing out a little over time. Make two marks together, then after a ride see if they are still together. – Criggie Dec 27 '20 at 21:31
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    Because eBay links are not persistent, I'm editing the post to include a photo of the bars. You can revert the edit if you object. However, in general, we do prefer persistent image or web links where possible. We do recognize that permanence can't absolutely be assured, of course. – Weiwen Ng Dec 27 '20 at 23:39
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    The correct way to typeset the torque unit Newton-metre is 10 N·m or 10 N m or 10 N×m. Also (borderline) ok is 10Nm, but please not 10nm or 10N. – leftaroundabout Dec 27 '20 at 23:53
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    Stupid question: Is the handlebar slipping in the stem clamp, or is the sleeve on the handlebar slipping relative to the bar itself? – Daniel R Hicks Dec 28 '20 at 0:32
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You are correct that 10N is a low number for this kind of stem. It's hard to recommend carte blanche to go past a manufacturer recommended torque, but it seems likely that's what you'll have to do if it's ever going to work.

The other thing to check in a situation like this is the actual physical dimensions of the parts.

Most stems of any type are going to have something short of perfect contact area with the bar if you examine the scuff pattern left by them on the bar, but single-bolt ones like this can be pretty bad if the bore of the stem is too large for the bar due to tolerance issues. Beer can shims can solve that problem.

Make sure the bolt is thoroughly lubricated, including the shoulder and washer.

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  • Thanks for the suggestion. I've measured the handlebars with a caliper, so the dimensions should line up. I'll definitely take that into consideration the contact area when tightening, and maybe go with a shim instead. Thanks again! – andoofthewoods Dec 27 '20 at 18:07
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    @andoofthewoods another is to paint the area with permanent marker, fit, and then remove carefully. The areas of contact will be mushed and the gaps will still be coloured. This might show you something useful. – Criggie Dec 27 '20 at 21:27
  • another marker suggestion! That sounds like a good idea. – andoofthewoods Dec 27 '20 at 21:56
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A few things to think about:

  1. Are you using grease or threadlocker on the bolt threads? This will minimize corrosion and galling problems, and means that the same final torque value is actually clamping tighter than if the threads are not lubricated. Personally, I would use grease on this bolt, but others may differ. Ask Kalloy whether their torque spec is using lube or not.
  2. Does the handlebar looseness change over time? Is it the same "looseness" from the start, or does it get looser the longer you ride? (Is the bolt loosening during the ride?)
  3. Does the handlebar indeed measure 25.4mm in diameter at the clamping point (measure using calipers)?
  4. Are the threads on the bolt and in the stem's clamping region in good shape?
  5. Is the bolt used and might have been stretched from being overtorqued in the past?
  6. How do you know your torque wrench is correctly calibrated? You might try a different one, or a visually-calibrated one like a beam-type if that's not what you're using.

fwiw, found this Kalloy/Uno stem online and by zooming in on the photo for the 80mm model it reads "15Nm" next to its clamp bolt. Not sure if it is the same model as yours but it looks very similar: https://www.performancebike.com/kalloy-road-quill-stem-black-25.4mm-80mm-13-kl-80-bk/p863539

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  • 1. I greased the bolt prior to tightening. I did it once again after experiencing problems to be thorough. Unfortunately Kalloy is difficult to reach being a Taiwanese company, and a barely functioning website. 2. The handlebar only moves when I hit a bump in the road 3. I measured the handlebar with calipers before buying it second hand, so it is indeed 25.4mm – andoofthewoods Dec 27 '20 at 17:57
  • 4.The stem itself is new, the handlebar is used. So the bolt is in good condition. The clamping region didn't show any imperfections that I could observe. 5. As per 4, bolt is new, so wouldn't be stretched 6.I have a newer torque wrench from GIANT, but i actually borrowed someone elses torque wrench to make sure after I realised something was wrong. – andoofthewoods Dec 27 '20 at 18:00
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    The comments don't do formatting as easily but there is some info by clicking "help". Sounds like we all are grudgingly converging on "tighten it more or shim it" after you're finished with the various marker tests. The Kalloy site was surprisingly low-functional for a major company, but it did include an email so you may be able to get an answer, probably after you've solved the issue one way or another :) – Armand Dec 27 '20 at 23:12
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    @Armand I think that Kalloy is mainly an OEM supplier, i.e. they don't really care about selling to retail consumers, they sell more to bike manufacturers who spec their parts. In that sense, they may not need a well-developed site so long as the manufacturers know who they are. This is similar to their fellow Taiwanese brands Bitex and Novatec, who supply a lot of OEM hubs. You can contrast to DT Swiss, which does sell its own hubs, wheels, and hub internals OEM, but which has long sold to consumers also. – Weiwen Ng Dec 27 '20 at 23:43
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    @Armand yeah, i've shot them an email, but I've also got a reply back from the local distributor. I've added their reply to the OP as an edit. regarding the 15 Nm stem, that's an interesting find, and indeed the exact same stem. It seems the manufacturer was playing it arbitrarily safe for my model when it came to max torque. Thanks for the help! – andoofthewoods Dec 28 '20 at 2:37

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