Syncros "slanted" stem cap variants

[RockiMtn]

Let's discuss the dreaded Syncros "slanted" stem cap we love to hate. Why hate? Because no other company used/made them, and if lost or broken… good luck finding a replacement/substitute. :facepalm: And before anyone chimes in, yes i know someone has made some reproductions ones now.

So I've seen and have owned three variants of these. The typical and most prone to over-tightening and cracking are the plastic ones. Second and less common are the cast metal ones. I like the fact that they are metal, but I like the look/design of the plastic ones better.

Lastly there is a CNC version. I've only seen a few of these. I had two at one point but sold one along with a stem. I found these quite odd and I've always thought this was DIY job, and not an original/official Syncros cap. Profile is flat compared to the other two and it requires the use of an odd tapered head/countersunk bolt. It's less elegant than the other two and I find it looks clunky in comparision to the other two. Another reason why I think this was a DIY job is that the the round edge of the cap and the portion inserted into the stem isn't angled like the cast metal version, but is squared with the flat top surface. So basically a flat cap design with only the bolt hole bored at the appropriate angle.

Feel free to chime in regarding the origin of the CNC version. Also would love to hear peoples thoughts on the availability of the caps in relationship to production dates of the stems.

 

[hamster]

People seem to forget that the top cap is only used to tension the bearings. After the stem is tightened you can loosen the bolt a quarter turn and then the cap lives forever.

 

[FluffyChicken]

Re:

I prefer the middle one, metal deep profile and designed for their job. They are also the original ones used until 1997

I've seen them cracked though, proberby over tightening.

I other metal is round and flat with just the recess drilled on an angle.
If these where made oval, to actually properly fit, then they would be nice. My bodged ahead plastic can work better. Assume these are post 00's or some CRC specials.

I have one of each, but most seem to go 'somewhere' never to be seen.

The plastic ones ( nylon glass composite) came out in GT used from 1998, I think to stop people over tightening them, problem is the smoothness against the steerer affects the force needed, so I lube mine up to make it easier and smooth off anything that should be rough.

None of the caps seem to feel strong like some of the flats you get nowadays (the ritchey ones are nicely made)

 

[ishaw]

I have a black metal one in my stash, I think it is the middle one of the three. Doesn't seem to fit as nicely as the silver version I have which I assumed was the same.

 

[xerxes]

Re:

People seem to forget that the top cap is only used to tension the bearings. After the stem is tightened you can loosen the bolt a quarter turn and then the cap lives forever.

These are for quill stems with threaded headsets, so they have nothing to do with the bearings.

 

[FluffyChicken]

Re: Re:

People seem to forget that the top cap is only used to tension the bearings. After the stem is tightened you can loosen the bolt a quarter turn and then the cap lives forever.

These are for quill stems with threaded headsets, so they have nothing to do with the bearings.

No, they are for the cattlehead, a ahead/thread less stem.

 

[xerxes]

Re:

No, they are for the cattlehead, a ahead/thread less stem.

As the man in the orthopaedic shoes said, I stand corrected.

 

[Fatboy1974]

I'm trying to get quotation for reproducing the plastic one. Maybe I can get for 6-7 € if I order 20 in a batch. Do you think that somebody would be interested? At the moment in 1-1/8" because I think it's the more common. I need one for myself.

 

[Prodigal Son]

Syncros took the shape of the cattle prod and made that cap. Not only it breaks but makes you cut the steerer instead of letting some out for future change. The cattle head stem has other problems. The way it tightens on the steerer is not as good as the common two allen bolt fit which distributes the force along the full wrap. I heard of syncros stem breakage (on testing machines) and it´s the last place you want to break on a bicycle while riding. It may look pretty but that stem is a no go for me.

 

[Fatboy1974]

Hi@Prodigal Son. I'm Mechanical engineer, with experience in machinery but also in bike and components design ( what I'm doing since 2005 for differetn companies).
I agree with you that it is not the best clamping system. It concentrates the tension in a different way, but I don't think it's unsafe. And it's by large the cleanest. Clamping pieces are well designed, and the piece on HT is a single CNC piece incuding clamping area. Then main tube is welded, and it has an enlarged section compared to other stems. It's widder and higher than 90% of the industry.
The angled cut yes, it is a "bad idea" but it's there and the ones we want to use this stem, we need tod eal with it. particulary me, I'm not cutting the steerer in angl. The clamping area in a Syncros is long enough to allow an straight cut, and still have plenty of space for tension distribution. The area that receives higher tension, are the sides of the stem clamping ara with steerer tube. And Syncros stem, IMO are thick enough and well machined to ensure a long life. For XC I think it's safe ( not for DH or Enduro).