Cycling UK Forum

pwa wrote:https://forum.cyclinguk.org/download/file.php?mode=view&id=64963
The JTech seatpost is new and you will see a wrap of insulation tape 1mm from where it disappears at the clamp so I can see if it slips down. It is well greased but with a lot of torque I think I have got it immobile. At least, a one mile test ride didn't budge it.

Have you thought of using the gritty grease used in carbon fibre seat tubes? It might be a better compromise than regular grease and lots of torque and/or multiple clamps.

pwa wrote:If you look at Spa's current description of their steel Tourer (which will have the same steel fork) all that is said about the paint is that the steel is ED coated, by which I assumed they mean that is the complete paint job, just ED coated (in a bath) and job done.

I don't think that's the case, maybe someone who's purchased a Spa frame other than black will let us know what colour the steerer is.

(I think Thorn may have moved away from powder coating)

My Thorn is DuPont Imron over an ED coating, it's the nicest and toughest finish of any frame I've owned. Still looks like new after two years (Very unusual for my bikes and wasn't the case with my powder coated Thorn), the one scrape from a fall has exposed a tiny amount of the black ED coating, where I would have expected it to go down to bare metal.
Whatever - frame paint isn't something you have to worry about with your new one

fausto99 wrote:

pwa wrote:https://forum.cyclinguk.org/download/file.php?mode=view&id=64963
The JTech seatpost is new and you will see a wrap of insulation tape 1mm from where it disappears at the clamp so I can see if it slips down. It is well greased but with a lot of torque I think I have got it immobile. At least, a one mile test ride didn't budge it.

Have you thought of using the gritty grease used in carbon fibre seat tubes? It might be a better compromise than regular grease and lots of torque and/or multiple clamps.

So far it looks like it is staying put, so there may be no problem at all. I have another bike with a carbon post and of course I did use the gritty paste stuff on that, and I would entertain the idea of using it on an alloy post if I had a problem. But would it prevent the alloy post getting stuck in a titanium tube? At the moment the post is smeared with anti-seize grease to stop that happening.

The seatpost itself is this one:

https://www.sjscycles.co.uk/seat-posts/ ... -x-272-mm/

It is far nicer than a post of that price has a right to be. The clamp is I suppose a variant of the "hockey stick" but the top surface of the curve is wide and flatish with a large contact area. It is shiny so you might suspect it could slip but the grip comes from the underside, which has the two bolts going through a curved spacer that presses against the non-shiny curved underside of the hockey stick in an arc concealed in a recess. So you are not relying on the clamp holding onto a shiny surface. And the finish has a classic look. Only in 27.2 though. It is easily the nicest looking seatpost I've had for that sort of money.

30mm layback is a little more than average.

Spot the difference?......https://www.planetx.co.uk/i/q/SPHOGS/holdsworth-gran-sport-seatpost
The PX / Holdsworth post has featured on here before....

reohn2 wrote:I find these Tektro levers very comfortable:- https://www.sjscycles.co.uk/brake-lever ... rs-silver/

I have those on my singlespeed. I find them comfortable too

I agree it's definitely the same post*. Maybe I'm imagining it or it's down to the variation in how photographs appear on computer screens, but to my eye the photographed seatpost on SJS's website looks to have a better polished/shinier finish than the PX version, something which I imagine JTek could readily do in house at the same time as applying their screenprinted logo on the post.

* Edit to add - I've just noticed however that the SJS post is 350mm, whereas the PX (and I think VO) versions are only 300mm. Neverthless, I'm still convinced that otherwise they are the same product.

531colin wrote:Spot the difference?......https://www.planetx.co.uk/i/q/SPHOGS/holdsworth-gran-sport-seatpost
The PX / Holdsworth post has featured on here before....

It does look the same (at a lower price) but fails to mention the oval void in the shaft, thicker in one plane, thinner in the other. Maybe the JTech is a different version of the same basic design.

pwa wrote:It does look the same (at a lower price) but fails to mention the oval void in the shaft, thicker in one plane, thinner in the other.

I've got a black version of the PX post. It's got the same variation in thickness at the SJS post. Incidentally, although in their description SJS say "Internal oval cross-section to improve strength/weight ratio", I think that is not quite accurate. The thicker sections are fore and aft and the sides are thinner, and I think that the manufacturer has copied this aspect of the design from Thomson, who refer to it as a 'bending fuse':

The Thomson seatpost design incorporates a bending fuse to prevent catastrophic failure. All competitive seatposts we tested failed catastrophically with the seat and clamp components, and sometimes pieces of the tube and head flew off in all directions.

The Thomson seatpost has a clamp, head, and upper tube strong enough to withstand 350 foot-lbs of torque. The tube will start to yield and bend at the seat tube clamp at about 250 foot-lbs of torque. Under severe impact the Thomson seatpost will bend slightly and allow the rider to come to a safe stop or finish the ride.

mcshroom wrote:

reohn2 wrote:I find these Tektro levers very comfortable:- https://www.sjscycles.co.uk/brake-lever ... rs-silver/

I have those on my singlespeed. I find them comfortable too

Good levers I've been using them on my Vaya for about 8years without fault,very pleased with them

slowster wrote:

pwa wrote:It does look the same (at a lower price) but fails to mention the oval void in the shaft, thicker in one plane, thinner in the other.

I've got a black version of the PX post. It's got the same variation in thickness at the SJS post. Incidentally, although in their description SJS say "Internal oval cross-section to improve strength/weight ratio", I think that is not quite accurate. The thicker sections are fore and aft and the sides are thinner, and I think that the manufacturer has copied this aspect of the design from Thomson, who refer to it as a 'bending fuse':

The Thomson seatpost design incorporates a bending fuse to prevent catastrophic failure. All competitive seatposts we tested failed catastrophically with the seat and clamp components, and sometimes pieces of the tube and head flew off in all directions.

The Thomson seatpost has a clamp, head, and upper tube strong enough to withstand 350 foot-lbs of torque. The tube will start to yield and bend at the seat tube clamp at about 250 foot-lbs of torque. Under severe impact the Thomson seatpost will bend slightly and allow the rider to come to a safe stop or finish the ride.

As the Planet X post does have the oval void it must be the same basic post, except perhaps for finishing. So a good buy. That is a lot of post for not much dosh.

I have an Easton post at least 20 years old with the thick/thin wall feature. (and it was old stock when I bought it)
Thompson have thick/thin walls and also a "bending fuse"....but I can't see where they say those 2 features are one and the same thing.

'Tis a nice machine.

pwa wrote:I think I'll live with the bottle cages because doing so fits with the self-image I like to foster: as someone who doesn't bother about things like that...

By signalling that you don't care about things like that, you are in fact caring about things like that :p

If it was my bike, I would go the other way to what most people here think, and turn the bottle cages into part of a theme by getting some other matching blue parts - maybe skewers and seatpost clamp.

pwa wrote:...But would it prevent the alloy post getting stuck in a titanium tube?..

Carbon paste functions like normal grease in that regard - good enough, but it's still wise to remove the post every so often.

531colin wrote:I have an Easton post at least 20 years old with the thick/thin wall feature. (and it was old stock when I bought it)
Thompson have thick/thin walls and also a "bending fuse"....but I can't see where they say those 2 features are one and the same thing.

You're right. I've always just assumed the thin/thick walls were the feature that constituted the bending fuse, but having done a bit of digging I think the fuse essentially is the combination of various design features of the clamp section which are supposed to increase the strength of that part, such that the lower part of the seatpost will fail before the clamp, and will do so by bending backwards (or forwards) (so the thick/thin walls do play a role in influencing the direction in which the post bends). Details here.

Mr Evil wrote:'Tis a nice machine.

pwa wrote:I think I'll live with the bottle cages because doing so fits with the self-image I like to foster: as someone who doesn't bother about things like that...

By signalling that you don't care about things like that, you are in fact caring about things like that :p

If it was my bike, I would go the other way to what most people here think, and turn the bottle cages into part of a theme by getting some other matching blue parts - maybe skewers and seatpost clamp.

pwa wrote:...But would it prevent the alloy post getting stuck in a titanium tube?..

Carbon paste functions like normal grease in that regard - good enough, but it's still wise to remove the post every so often.

One slight concern I have with the JTech seatpost is that it is polished alloy, which looks very nice but lacks any barrier coating to prevent naked aluminium corroding within the seat tube. It really does rely on the grease. Or paste if that does the same job.