Tapered head tube development

[18bikes]

I don't use the forum very much byut thought some people may be interest in this, if this isn't appropriate use of the forum, I appologise and ask the mods to remove this thread.

We have basically run out of current design of tapered headtube and have been looking into alternative methods of production to reduce the cost. In order to make it viable I need other people to order some to. Details (including prices) are over on the MTBR forum in this thread - Tapered head tube development - Mtbr Forums.

If anyone has any questions, either ask here, on MTBR or you can email me direct at matt@18bikes.co.uk

Thanks,
Matt

[Willie1]

I looked at your head tubes last spring. I want a 44/49 combo, not 34/44.

[18bikes]

Can I ask why you want 44/49 and why 34/44 is not suitable? All feedback is good feedback

Thanks,
Matt

[Willie1]

I like the look of a tapered head tube. It just looks better than a straight 49/49. The 44 uipper can use a zero stack, and the bottom can use any 49mm cup. I could use tapered or 1.5" steerers with it. With the 34 upper, it is external cup only, 1 1/8 only. It just seems to be missing the options. I can use a Paragon 44/44 and have the same options, but without the tapered look. I also have three CK 49 lower headsets I can use.

[18bikes]

Our logic for going with 34/44 was to give the tapered look but in the correct scale for steel tubes. I can't remember the last time I even saw a full 1.5 steerer so for me that isn't a concern and, like you've said, there are other options from paragon or Reynolds if you want a low stack height upper. Considering these are for custom frames the headtube length can be adjusted to account for internal versus external cups so again it's not an issue for us. I can fit either a straight or tapered steerer in our headtube and even get a neat look with an internal lower on a semi-intergrated road fork. Thanks for your feedback, hopefully I've explained our reasons adequately

Matt

[Willie1]

Makes sense but I think the newer generation tapered road forks and oversized tubesets may see some more 44/49 ot 44/56 products offered so the look remains clean (important to some, not to others- to each their own). For all mountain offroad frames, the 44/49 makes sense there as well.

[18bikes]

Sorry to drag up an old thread but I've been pushed slightly with this so am looking at numbers again. Some people who have expressed interest will have just recieved an email, if you haven't and would like to then email me (matt@18bikes.co.uk).

Here is the basic rundown though:

44mm ID lower with 20mm insertion
100mm taper
remainder of 200mm tube at 34mm ID
1mm wall thickness
Reynolds 631

Price is looking similar to a 150/170mm paragon 44mm headtube depending on how many you want.

Matt

[Too Tall]

Thanks Matt. I'm sending you a PM.

[zank]

I've always wondered what the best way would be to miter a tube to a tapered tube. This is intriguing to me because I don't really like the looks of a 28.6 mm steerer poking out from a 44 mm ID headtube. Care to share your fit-up process?

[Mike Mcdermid]

i turned a tapered bobbin for the belt to run on and abrasively mitre them
but now we are using tapered head tubes for production i have been talking with a company who make shaped abrasives

[18bikes]

You aren't the only one who wonders about that, lots of people thought it would be really hard when I did the machined tubes. It's actually incredibly easy, here's what I do:

• Mitre the dt to bb
• Calculate the length from tip of mitre at bb to mitre at headtube along the top of the dt
• Mitre at this length +1mm or so at the dt/ht angle as it is on the drawing using a holesaw approximately the size of the headtube where the downtube will meet it. If nothing is close, go slightly smaller.

The above points are just how I do it, it doesn't really matter how you get there but you need an undersize mitre at roughly the right length but at exactly the right angle. The next bit is the bit people can't get their head round but is actually a hell of a lot easier than it sounds.

• Position the dt in the vice so the mitre is level and you are filing from the bottom of the mitre (fork side)
• Ignore everything you've ever learnt about hand mitring
• To start with only file the edge of the mitre closest to you, allowing your back hand to swing low and wide compared to the front. You are aiming to make this side wider and deeper than the far side. On a normal mitre you want everything to be parralel, here you need to forget that in both directions
• Gradually allow this wider/deeper profile to creep accross the mitre
• keep checking against the headtube by placing into the jig, you can really creep up on it as the tube will slowly drop into place and you can see exactly where you need to remove material.

That sounds much harder than it really is, it is much more intuetive when you have the metal infront of you. It usually only takes me about 5 minutes to go from the holesaw cut to a fitted tube. Our machined tubes go from 38-50mm over 70mm (off the top of my head), a 12mm difference, 6mm on radius. If you had a tube that joined at the very top of the taper and reached all the way down you would use a 38mm holsaw to start and be removing 6mm from the bottom. In reality your downtube will hit much lower (42/44mm maybe?) and will probably line up with the transition at the bottom, this means you will likely be removing around 3mm. I'm sure some of you guys could remove 3mm from a tube in 5 file strokes so it's really not going to take long. The new tubes aren't such an extreme taper (36-46 over 80mm) so it's going to be even less of an issue.

The other (cheating) option is to draw the tapered tube in bikeCAD and print out the mitre template, file to that and you're done. I'm not sure if cross posting is frowned upon but I did a post about it on another well known forum, a search for 'mitring to a tapered tube' should find it. Here is the old tube drawn in bikeCAD
Tapered headtube in Bike CAD.PNG

If I could show you how to do it instead of trying to explain it you would understand in about 5 seconds, hopefully this is adequate

Matt

[18bikes]

Forgot to say, although it should be fairly obvious, I do all of that without the seat tube in the jig and before the compount mitre

Matt