Forum menu
Custom bike;possibl...
 

[Closed] Custom bike;possible?

Posts: 0
Free Member
Topic starter
 
[#3384886]

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.


 
Posted : 23/11/2011 10:35 pm
Posts: 0
Free Member
 

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,


 
Posted : 24/11/2011 12:27 am
Posts: 7972
Free Member
 

I think they'd need more info than "low bb" and "74ish".


 
Posted : 24/11/2011 7:38 am
Posts: 0
Free Member
Topic starter
 

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


 
Posted : 24/11/2011 10:34 am
Posts: 0
Free Member
 

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

Ed


 
Posted : 24/11/2011 10:40 am
Posts: 0
Free Member
Topic starter
 

Sancho/Ed,

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


 
Posted : 24/11/2011 10:51 am
Posts: 9596
Free Member
 

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 : )


 
Posted : 24/11/2011 11:01 am
Posts: 0
Free Member
 

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


 
Posted : 24/11/2011 11:56 am
Posts: 0
Free Member
Topic starter
 

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.


 
Posted : 24/11/2011 11:59 am
Posts: 9596
Free Member
 

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?


 
Posted : 24/11/2011 12:55 pm
Posts: 0
Free Member
 

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


 
Posted : 24/11/2011 12:57 pm
Posts: 0
Free Member
Topic starter
 

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.


 
Posted : 24/11/2011 1:23 pm
Posts: 7972
Free Member
 

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


 
Posted : 24/11/2011 1:36 pm
Posts: 1680
Full Member
 

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.


 
Posted : 24/11/2011 1:47 pm
Posts: 7972
Free Member
 

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


 
Posted : 24/11/2011 1:53 pm
Posts: 0
Free Member
Topic starter
 

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.


 
Posted : 24/11/2011 1:57 pm
Posts: 15458
Full Member
 

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...


 
Posted : 24/11/2011 2:03 pm
Posts: 0
Free Member
Topic starter
 

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!


 
Posted : 24/11/2011 2:07 pm
Posts: 15458
Full Member
 

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...


 
Posted : 24/11/2011 2:16 pm
Posts: 0
Free Member
 

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


 
Posted : 24/11/2011 2:20 pm
Posts: 0
Free Member
Topic starter
 

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.


 
Posted : 24/11/2011 2:28 pm
Posts: 7972
Free Member
 

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


 
Posted : 24/11/2011 2:56 pm
Posts: 0
Free Member
Topic starter
 

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.


 
Posted : 24/11/2011 3:01 pm
Posts: 7563
Free Member
 

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.


 
Posted : 25/11/2011 3:36 am
Posts: 0
Free Member
 

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


 
Posted : 25/11/2011 8:17 am
Posts: 0
Free Member
Topic starter
 

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)
1x10 gearing. 32 or 34 tooth chainring with chain device
Saddle height is roughly 700mm from centre of BB.
Thanks!


 
Posted : 25/11/2011 2:10 pm
Posts: 7563
Free Member
 

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


 
Posted : 27/11/2011 10:55 am
Posts: 0
Free Member
Topic starter
 

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


 
Posted : 27/11/2011 12:40 pm
Posts: 7563
Free Member
 

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)


 
Posted : 27/11/2011 10:50 pm
 flow
Posts: 0
Free Member
 

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


 
Posted : 27/11/2011 10:54 pm
Posts: 0
Free Member
Topic starter
 

ThegeneralwreckerATyahooDOTcoDOTuk
I may be joining the brant worship crowd!


 
Posted : 27/11/2011 10:59 pm
Posts: 41395
Free Member
 

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


 
Posted : 27/11/2011 10:59 pm
 flow
Posts: 0
Free Member
 

Three, I will have one for £166.6666666666666666666666


 
Posted : 27/11/2011 11:07 pm
Posts: 0
Free Member
Topic starter
 

Oh braaaaant!
No email yet mate. Still keen.


 
Posted : 03/12/2011 6:48 pm