Inspect your bikes

[dookie]

+100

I'm a former pro wrench (pre-Thomson) and always use a calibrated torque wrench. Gave up on Thomson many years ago after my 3rd cracked stem (Elite and X2 faceplates, X4 steerer clamp).

They were always good about warranty and claimed design changes to address, but I immediately sold off the replacement.

Do your face a favor and avoid their stems. For real.

[soulspinner]

Have one on my Strong and was just thinking of retiring it after many years. This confirms its time. Yikes that's all the way through. I always quick check my bikes pre ride after once ending up under the front of a suburban.

[Clancy]

Originally Posted by Velocipede

Unfortunately it's a really common issue. Usually you see the stem crack on the back near the bolt hole. When I was at Thomson we switched to the small 3mm hex head due to people not using torque wrenches and over tightening them. We found it difficult to get a ton of torque on the 3mm keys vs the 4. The Allen wrench would twist or flex before it was critical overtorquing. We also found that torque on the bolts increased an average of 15% if grease or anti seize was used.

Two questions

I was always taught that manufacturers torque values included grease on he fittings. Not true?

And, I have stripped out or rounded over the inside of the 3 mm bolts more than once. It’s as though the hex tool is slightly undersized regardless of the brand of hex tool. Seems like the bolts are very soft. And yes, I am using a torque wrench. Anyone else experience this?

[ahsere]

Wow, I have Thomson seatposts on most of my bikes and I like them, but I always found their stems too bulky looking, I thought if anything they were overbuilt for road applications, looked more like mountain bike stems. Boy was I wrong.

[zap]

Originally Posted by Clancy

And, I have stripped out or rounded over the inside of the 3 mm bolts more than once. It’s as though the hex tool is slightly undersized regardless of the brand of hex tool. Seems like the bolts are very soft. And yes, I am using a torque wrench. Anyone else experience this?

I found this useful.

https://www.bikeradar.com/features/a...-need-to-know/

Allen keys are wear items so either carefully cut off the worn rounded end or purchase new.

[Velocipede]

Originally Posted by Clancy

Two questions

I was always taught that manufacturers torque values included grease on he fittings. Not true?

And, I have stripped out or rounded over the inside of the 3 mm bolts more than once. It’s as though the hex tool is slightly undersized regardless of the brand of hex tool. Seems like the bolts are very soft. And yes, I am using a torque wrench. Anyone else experience this?

1st question: no. Traditionally the torque setting are based on dry threads. Unless the manufacturer recommends grease and say so, they are based on dry threads. Thomson specifically states no grease on their threads which in turn means the torque settings are based on dry. Now, for companies like Shimano who has grease already on the Hollowtech 2 crankarm bolts(the non-drive ones), the 12-14nm they recommend is clearly based on that bolt fit that way, so with grease. Their instructions specify grease and no grease very clearly. They have really great detailed instructions.


2nd question: it's really common for hex/Allen keys to be slightly undersized. if you measure the bolt head, it is usually on spec or slightly over- say 6.05mm/6.10mm for a 6mm head. But it's really the Allen keys that's the issue. Even ones as nice as the Wiha or Silca are slightly under. They can't make them to spec. Too many variables- the head is dead on and the Allen key is too tight and such.

There is a very shallow socket on those 3mm heads. I am not a fan of that part of the bolt. But in the hopes of a cleaner looking and less prone to over-torquing bolt, that's what they came up with. A good 90% of the stems and posts that came back were due to over-torquing or self inflicted. I will post a picture of a post I kept. Macon saw it and were speechless. I'm still trying to figure out how they killed it. I remember the shop it came from, Iron Cycles in Chicago. I replaced it on the spot but it was wild.

Most people as the Allen keys wear down they just grind them shorter and flat. But the issue really is the Allen keys.

I personally have used Thomson stems, posts and seat collars for decades and have never had one break. And I'm not a light guy(240 pounds.).

[duff_duffy]

Only stem I ever had break was Thomson. Love their seatposts but stems don’t inspire confidence in me.

[joshatsilca]

Originally Posted by Velocipede

1st question: no. Traditionally the torque setting are based on dry threads. Unless the manufacturer recommends grease and say so, they are based on dry threads. Thomson specifically states no grease on their threads which in turn means the torque settings are based on dry. Now, for companies like Shimano who has grease already on the Hollowtech 2 crankarm bolts(the non-drive ones), the 12-14nm they recommend is clearly based on that bolt fit that way, so with grease. Their instructions specify grease and no grease very clearly. They have really great detailed instructions.


2nd question: it's really common for hex/Allen keys to be slightly undersized. if you measure the bolt head, it is usually on spec or slightly over- say 6.05mm/6.10mm for a 6mm head. But it's really the Allen keys that's the issue. Even ones as nice as the Wiha or Silca are slightly under. They can't make them to spec. Too many variables- the head is dead on and the Allen key is too tight and such.

There is a very shallow socket on those 3mm heads. I am not a fan of that part of the bolt. But in the hopes of a cleaner looking and less prone to over-torquing bolt, that's what they came up with. A good 90% of the stems and posts that came back were due to over-torquing or self inflicted. I will post a picture of a post I kept. Macon saw it and were speechless. I'm still trying to figure out how they killed it. I remember the shop it came from, Iron Cycles in Chicago. I replaced it on the spot but it was wild.

Most people as the Allen keys wear down they just grind them shorter and flat. But the issue really is the Allen keys.

I personally have used Thomson stems, posts and seat collars for decades and have never had one break. And I'm not a light guy(240 pounds.).

Velocipede- do you have any documentation from Thomson showing dry threads? I googled and everything from them currently available shows lube points on all threads. Not saying you're wrong, just seems crazy any company would ever recommend dry torque?

I'll say that in my 25 years spanning aerospace engineering, top level motorsports and cycling I've never seen a component specified as dry torqued unless the fastener or female thread was already pre-coated with a known lubricant/coating. Even when using CarbonFiber/PEEK fasteners into Vespel threads in aerospace (both of which are naturally lubricious) we had to use a specified loctite and torque within specified time period.. my experience is that if the threads aren't lubed, no engineer will trust the bolt tension as the torque is more or less rubbish.

As for hex keys, you are correct, by ISO rule, the hex in the bolt head has to be slightly oversized and the hex key has to be slightly undersized. What you are buying with high quality hex keys typically is a harder base material or special coatings to help the tools last longer and with some brands (like ours) you might also be getting closer to the upper end of the tolerance, so for instance we recycle tools that measure in the lower 1/4 of the tolerance band.

Honestly, the biggest problem with hex is in the way the keys wear. You can see this in some microscope photos from our test lab. The softer keys are reduced in size over time as the material deforms and sort of extrudes off the end of the key.. making the corners less sharp and the tool effectively undersized in the lower mm or two of the hex. This leads to fastener damage, which in turn leads to more tool damage. Inexpensive hex keys should be replaced regularly for this reason:

[Toeclips]

Rounding the edges, I had boss who would go crazy if you rounded a tool.

[Velocipede]

Originally Posted by joshatsilca

Velocipede- do you have any documentation from Thomson showing dry threads? I googled and everything from them currently available shows lube points on all threads. Not saying you're wrong, just seems crazy any company would ever recommend dry torque?

I'll say that in my 25 years spanning aerospace engineering, top level motorsports and cycling I've never seen a component specified as dry torqued unless the fastener or female thread was already pre-coated with a known lubricant/coating. Even when using CarbonFiber/PEEK fasteners into Vespel threads in aerospace (both of which are naturally lubricious) we had to use a specified loctite and torque within specified time period.. my experience is that if the threads aren't lubed, no engineer will trust the bolt tension as the torque is more or less rubbish.

I am not in the office today but I'll find the paperwork showing it. God knows I have tons of it still. I wouldn't be surprised if they've changed it though given everyone greases bolts. I even do it on Thomson parts. I just change the torque values.

Tying into the second bolded comment, we found an average of 15% increase in torque value on a lubed bolt VS non-lubed bolt. Is that similar in your findings?

[ThasFACE]

Adding to the pile-on, only bike part I've ever had fail was a X2 stem. Happened as I was getting on the bike and first putting some weight on the bars; they just rolled forward. Crack at the top bolt in the face plate. Super lucky it didn't happen on the road/at speed. Everything was torqued to spec, and the stem had fairly little use, so it was unsettling.

[zzy]

I've seen more Thomson stems fail than all other stems COMBINED. Thomson CNC's from raw billet aluminium. Everyone else forges the aluminium. At least Thomson used to be generous with warranty, and you could just drop a cracked faceplate in the mail to Macon. No longer. And the 3mm bolts were such a stupid bandaid solution to an engineering fault.

[unterhausen]

Originally Posted by Velocipede

Tying into the second bolded comment, we found an average of 15% increase in torque value on a lubed bolt VS non-lubed bolt.

I assume you mean 15% increase in clamping force at a given torque

[Velocipede]

Originally Posted by unterhausen

I assume you mean 15% increase in clamping force at a given torque

Correct. A bolt with no grease at 5nm registered 5nm. One with grease registered great. On average 15%.

[tylercheung]

I am trying out their seatpost collar mostly as I like the sculptural shaped look of the thing! But that whole "2.8 N-M or else you will crush the seatpost" warning on the instructions is driving me nuts. 1st ride out I was overly gentle with the bolt so the post slipped...I just made it "hand tight and firm-ish" on w/ the allen key this time so we'll see...