About a month ago, I felt it was time to make a few upgrades to my trusty road race bike (see below). When I built it up a couple of years ago, I did so with a limited budget, and sourced some of the finishing kit (bars, stem, post and carbon cages) from Planet-X. Their kit is light, fairly stylish and very good value and, to be honest, has never given me any trouble. However, when I decided to build up a new commuter/ CX bike I thought I'd transfer a few of those parts and use it as an excuse for some upgrades to my race bike.
This brings me on to the Rotor S-1 Stem. I'd seen a few reviews of this product, and read its claims of being the lightest in the world. I liked the look of it, so I ordered one, a bargain at £86(!!). I didn't weigh it, but it felt staggeringly light and is very beautiful, with its wide open faceplate and scalloped machining. I had read that it was a bit tricky to fit, with its headless, twin-threaded bolts. The UK importer assured me if I read the instructions (i.e. unlike typical male) I would be fine.
I had chosen to upgrade the alloy Planet-X bars too, to Deda Spectrum carbon jobs, and mated these to the Rotor S-1 Stem. Now I have a low-range torque wrench, so followed the helpful etched torque figures when tightening the bolts. With a suggested torque of 2.5Nm, this was not much force. Immediately I sensed the bars were not secure. I re-read the instructions and remounted the faceplate after resetting the bolts. I did this a number of times. Still the bars did not feel secure, so I nervously upped the torque a bit. A little happier, I then set off on what was to be a 50km training ride. Half a mile down the rode I went over a bump in the road while riding on the hoods and the bars immediately tilted downwards by 20 degrees or so. Rather rattled by this, I peeled off home and went back to the workshop. Having secured a few hours off from the family to ride, I quickly swapped the stem out for a Thomson X-2, and I was off again. Safe and sound.
So what was the cause of all this? It is true that the instructions recommend the use of "assembly compound" when fitting the bars to the stem, and I didn't use this. They don't provide any with the stem, but my Deda bars had a strange sticky high friction surface on the clamping area anyway. So, did I fit them incorrectly? Were by bars undersized? These were all theories put forward by the UK importer, who graciously agreed to refund me. They also let slip that they thought that the bolt threads in the stem might be a little short, therefore 'blocking' the tightening of the faceplate a little, and also revealed that a 4 bolt version was on the way (for the MTB crowd, not for any other reason, honest). They also told me that I could safely double the recommended torque figures (which I think I probably did anyway). Whatever the reasons, when it comes down to it, a stem that you cannot trust will prevent you from enjoying your bike, and let's face it, could seriously damage your health. I couldn't stop thinking of what would have happened if my bars had slipped while descending a Pyrenean col at 50mph. All in all, this was a valuable lesson for me. A few grams saved in a critical area is just not worth the risk. It also reminded me how dependable Thomson components are. The Rotor S-1 is a beautiful stem, but is let down (in my view) very seriously by its fiddly bolts. Couldn't they have used regular Ti bolts? It would still be light and almost as pretty. Maybe there was an installation or compatibility issue, but I do all my own maintenance, have a fully equipped workshop, and reguarly build up bikes for myself and friends from scratch. I may not be a mechanical genius, but if I get this result, so can others. This is a safety-critical component, and for me, it's not worth the risk.
Verdict: 5/5 for form, 0/5 for function.
For the past few years I have made a point of attending this great event, and as I now have a track bike, it is of even more interest (see below). Although the event seemed to be lacking in big names this year (no Brad Wiggins, Sean Yates, Malcolm Elliot etc..), it is still a spectacle to behold and a good number of people braved the cold on a very windy day. I 'm not sure I'd have been too happy with a disc wheel on my bike in those winds!
