I have my idea of a custom bike but not sure if it’s possible or even how it’ll ride

23.6″ virtual TT
19″ seat tube
66deg head tube angle with a 120mm fork
74 ish deg seat tube angle
44mm ID head tube
Short chain stays
ISCG 05 tabs
Gusset on head tube for strength
Low BB
Top tube brace, low stand over. Similar in looks to my 2011 turner 5spot.
Oversized tubing
30.9 seat tube
No guides for front mech

Thinking titanium, do the Chinese and Russian builders need much more info?
Im wanting a nice HT for smoother trails and just prefer slack HT angles (I just do)
Any help appreciated.

Anything is possible, I was having a discussion about this with someone today,the sticking point is more how much people will pay to obtain a custom frame and the quality level,

I think they’d need more info than “low bb” and “74ish”.

Thanks thepodge.
Seat angle (unsagged) should probably be nearer 72deg?
12.6″ BB height sound about right?

Comp pro, Ive been trying to get hold of you for ages, I want to bring our prototype over to discuss manufacture

Ed

Sancho/Ed,

Drop it around mine, I’ll pass it on (honest) 🙂

You need to specify a precise fork length to go with all that, 120mm RS or Fox etc, and that can make all the difference to teh actual angles.

Tube diameters may be as important as all the geometry details so think about stiffness – slack angles and big forks may need a fairly stiff frame to support it all

And your top tube length is very precise considering the seat angle is not : )

66 head tube!!!!!!!!!!!

Cheers James O.
I based the TT length on my spot, but the seat tube angle is subject to front and rear sag, which is not the case on a HT so I’m a bit stumped.
Any recommendations on chain stay length? I’d like short stays but still capable of taking conti RQ 2.2’s.
woodsman, it’ll be more like 67-67.5deg sagged I think.

Top tube length on an MTB doesn’t need to be as precise as most think, imo. Stem and seat position can account for a lot of variation in teh frame. Balance / weight dist is the important bit. If interested, have a play on bikeCAD (searh bikecad and bikeforest) and the sag / fork / variables thing will become clearer.

Or, measure the BB axle to bar or headtube, or use reach and stack to make comparisons. It doesn’t need to be exact tho since one bike will ride / feel different to another.

CS – 420 is short, 425 is normal. Not much variation on 26″ HTs really. HTH. Or, save some money and risk and just buy something like a Piglet?

66° headangle?? FFS it’s Orange County Choppers you should be calling!

Look at Ragley unsagged HT angles. I just want the long travel Ht angles without the long travel!
I probably would buy a piglet (despite the name) if it was alu.
If I wanted a steel bike, it would probably be a Stanton slackline, Chromag Aperture or Transition Trams Am. All of which would realistically require a 140mm fork.

I like the idea of long travel geo without the long travel.

I’ve often wondered what a 6 or 7 inch dh bike would be like if it only had 4 inch. everything would be nice and low but you’d still get the stability and in a lot of places you wouldn’t need the extra travel

4X bikes are quite good for slack short travel. Dialled Holeshot has great angles for 100mm travel – tiny though and probably overbuilt for your needs, but it might give you some ideas.

yeah been looking at 4x stuff but as you say its all tiny and heavy

Funnily enough, my initial idea was a bastard child of a 4X/Trail bike. A pure 4X would be too small for me though.
Single ring, dropper post. Used for smaller rides (2-3 hours) on tight twisty stuff.

Draw it up!

Thats got to be your starting point, doesn’t have to be bob on first revision but you can’t really think your way around any design or get others to offer feedback without have actually layed it out it in some way…

But I’m a muppet. 😀
Computery stuff is not my strong point. CAD scares me to death.
Perhaps we should see an On-One Wrecker?!?!
Do you hear me Brant? Make me one in aluminium, I DEMAND IT!

CAD is a Piece of Piss Honest! I’m sat of a CAD station right now (Clearly Not doing any work though) it’s the supporting calcs that scare me more…

If you really can’t face CAD, Draw it on paper, people used to do that all the time…

Why are you designing based on unsagged numbers? So it handles well while you’re looking at it? 😉

Mainly because a lot of manufacturers quote their geo in unsagged numbers (some do, some state metric, some imperial). As you can read above, allowance has been made for fork sag.

there is no need for cad at all, the builder will do that for you.

what you do need to do is check their drawing thoroughly

earlier you were on about ti, now its aluminium. what are you after?

custom aluminium builders are rare as rocking horse poo

I would be happy with alu as it’s cheaper and ideally would want a stiffer frame but will probably have to shell out for Ti as I don’t know of any custom alu builders.

What diameter wheels?
How tall are you?
What fork?
What gearing?
What’s your xc saddle height from centre of bb?
I have a long flight coming up. I’ll have a play about.

Nothing is impossible,if you dream it,sometimes you can do it.

What diameter wheels?
How tall are you?
What fork?
What gearing?
What’s your xc saddle height from centre of bb?
I have a long flight coming up. I’ll have a play about.

Yay brants here. I’m 6ft.
26″ wheels
Probable something like a reba or f120. Maybe even a rev reduced to 120 (if possible)
1×10 gearing. 32 or 34 tooth chainring with chain device
Saddle height is roughly 700mm from centre of BB.
Thanks!

You can use a 16.5in frame with a 400mm post. Why you want a 19in seat tube?
(in hong kong airport)

Only because that’s what my 5 spot is.
As I mentioned earlier; I’m pretty clueless.
(in the toilet)

Oh ok. What’s your email address. I will make you one as a sample with my new ti factory for £500.
(in bed in Taipei)

Top tube length on an MTB doesn’t need to be as precise as most think, imo. Stem and seat position can account for a lot of variation in teh frame. Balance / weight dist is the important bit.

Talk about contradiction

ThegeneralwreckerATyahooDOTcoDOTuk
I may be joining the brant worship crowd!

Brant, make 2 to keep costs down, I’ll give you £250 for the 2nd one.

Three, I will have one for £166.6666666666666666666666

Oh braaaaant!
No email yet mate. Still keen.