[ZenkiGarage]

Im getting ready to build my DH bike for this season. After Cutting and mitering all my tubes I realized I have enough steel left over to build another frame, so Im thinking of building a DH oriented hardtail. What do you guys think I should be shooting for geometry wise?

 

[mattmatt86]

Evil Imperial. Best hardtail I've ever ridden, I'll probably always regret selling it.

 

[Lumagent Morple]

I'll agree. The Imperial's geometry is spot on. DW spent a long time fine-tuning the numbers and it definitely payed off.

 

[HardtailHack]

I am just about to get one of these bad boys built up.
These are the specs-

585mm (23") top tube, dropped 30mm from top of seat tube

350mm (14") seat tube 72 deg seat angle

405-430mm (15.95-16.93") adjustable chain stays with clearance for 2.5" tire with some mud on it, hopefully using Evil D.O.C. dropouts if they reply to my email.

115mm (4.53") 1.5" headtube (so I can drop the front a bit as I will have the forks running up to 7")

66 deg headangle

73mm BB with ISCG mounts

325mm (13") BB height.

That's about it I guess, I rode my On-One 456 on DH tracks and adjusted geo to what I thought would work better. It was pretty good but the BB is too high and the HA is slightly too slack for a crazy fork.

 

[ZenkiGarage]

I always thought the Imp was really goofy looking and a little short in the rear. No doubt it was burly though. What was the geo on it? I always thought the free radical was cool.
Im thinking for my frame 65-66* head angle, 13in BB height, 16.75in(slammed) chainstay w/ horizontal drops.

 

[Santa Maria]

SC Chameleons can do it all

 

[ZenkiGarage]

Maybe, I should of rephrased my question. Im not looking for a production frame, Im looking for geometry numbers. Obvisuosly a HT is a rough way down a mountain, but Id still like to have good geo. This will only be used for pointing downhill. The chameloen is a bit more xc than anything else.

 

[mattmatt86]

I guess what I was getting at suggesting the Imp was saying just copy it's Geometry and you'll be set.

These would obviously change with different fork lengths, I with I had my old laptop, I had all of the files saved for different setup options, and differing geometry numbers for the imperial with different forks.

Stockish setup

Headtube angle 69.2 with 4" fork
Headtube length 5"
Headtube size 1.5"
BB height 26" 12.75"
BB shell 73mm
Chainstay length 15.5 - 17"
Toptube length 20 - 24"
Seat Post size 31.6mm
Seat tube length 13.5"

 

[SLOPE]

Find a used Imperial, you will not regret it

 

[ZenkiGarage]

I guess what I was getting at suggesting the Imp was saying just copy it's Geometry and you'll be set.

These would obviously change with different fork lengths, I with I had my old laptop, I had all of the files saved for different setup options, and differing geometry numbers for the imperial with different forks.

Stockish setup

Headtube angle 69.2 with 4" fork
Headtube length 5"
Headtube size 1.5"
BB height 26" 12.75"
BB shell 73mm
Chainstay length 15.5 - 17"
Toptube length 20 - 24"
Seat Post size 31.6mm
Seat tube length 13.5"

Those seem to be decent numbers. think a little slacker headtube and it would be mint. Thanks for the numbers.

 

[LMC]

Im getting ready to build my DH bike for this season. After Cutting and mitering all my tubes I realized I have enough steel left over to build another frame, so Im thinking of building a DH oriented hardtail. What do you guys think I should be shooting for geometry wise?

have u pics of any other frames you have built?

 

[ZenkiGarage]

have u pics of any other frames you have built?

Ive only built one other frame prior and didnt take any pics because it wasnt anything special, just a basic xc hardtail. My brother rides it now. These 2 frames will get documented the whole way through. I recently took a frame building class to add to my fabrication repertoire.

 

[monkeyfcuker]

Personally think the geo of my charge blender is perfect for pretty much everything as long as your going fast!

geo can be found here http://www.chargebikes.com/products/bikes/detail.php?id=1

I make the BB height 12.5 inch and the head angle 68deg with Maxxis Bling blings on and Pikes at 100mm

 

[ZenkiGarage]

that charger looks good.

 

[mandown]

I am just about to get one of these bad boys built up.
These are the specs-

585mm (23") top tube, dropped 30mm from top of seat tube

350mm (14") seat tube 72 deg seat angle

405-430mm (15.95-16.93") adjustable chain stays with clearance for 2.5" tire with some mud on it, hopefully using Evil D.O.C. dropouts if they reply to my email.

115mm (4.53") 1.5" headtube (so I can drop the front a bit as I will have the forks running up to 7")

66 deg headangle

73mm BB with ISCG mounts

325mm (13") BB height.

That's about it I guess, I rode my On-One 456 on DH tracks and adjusted geo to what I thought would work better. It was pretty good but the BB is too high and the HA is slightly too slack for a crazy fork.

I've got the 456 Summer Season and it sticks to the ground like mad. That thing is stable and would probably be a good starting geo (see this link ). I'd use the base numbers from that and add some HT length to bring the bar height up. I'm running mine with a Pike at 140mm and I feel a bit forward on it when things get steep, even with some spacers and a riser bar.

Your fork choice will make a bit of a difference. What are you leaning toward?

 

[ZenkiGarage]

The 456 is about dead on with what I wanna build i think, but around a 160mm fork. How is it riding a HT that slack? I know that i prefer a long, low, slack fully for DH but havent really had a HT thats low, long, and slack.

 

[mattmatt86]

The 456 is about dead on with what I wanna build i think, but around a 160mm fork. How is it riding a HT that slack? I know that i prefer a long, low, slack fully for DH but havent really had a HT thats low, long, and slack.

I rode an Imperial for a while with a 170mm 66 and I absolutely loved it. I think the head angle was 67ish and I rode it with the chainstays at 16.5". I rode it twice at Diablo and twice at Snowshoe and got crazy looks from people but it rode incredibly well for being a hardtail. Only trail that ever gave me a hardtime was Waterfall at SS, but we were practically riding through a creek bed and even my friend on a V10 was having a little trouble. (though he'll probably eventually chime in and say he didn't have any trouble)

 

[HardtailHack]

[/URL]

I've got the 456 Summer Season and it sticks to the ground like mad. That thing is stable and would probably be a good starting geo (see this link ). I'd use the base numbers from that and add some HT length to bring the bar height up. I'm running mine with a Pike at 140mm and I feel a bit forward on it when things get steep, even with some spacers and a riser bar.

Your fork choice will make a bit of a difference. What are you leaning toward?

Wow your Summer season would be crazy slack at 140mm, my 456 with 2.5" tyres and Kowa 160SS forks at 160 mm has a 14" BB height. This crazy height is the main reason I am getting I'm getting the custom frame, the On-One is great but it's too tall for tight berms. The slack seat angle is great and I have only added 15mm to the top tube because it will be running a 35mm stem to try and keep some sort of snappieness up front.

Oh yeah I will be running Kowa 200SI forks up front on the new frame.

Also something to think about is the length of the rear stays the longer they are the smoother the ride. Didn't really think about it til I read about the old Planet-X Compo (456 with a Easton frame) but the further the BB is forward the more weight you put on your forks which makes for a smoother ride. I wouldn't go any longer than a 456 back end as it would get hard to manual.

 

[mandown]

The 456 is about dead on with what I wanna build i think, but around a 160mm fork. How is it riding a HT that slack? I know that i prefer a long, low, slack fully for DH but havent really had a HT thats low, long, and slack.

I've only got a few rides in on it, and unless I'm going slow, I don't notice the HA being slack at all, but then again, I like slack bikes. I haven't had a problem climbing with it either. It just feels natural. I'm thinking that the extra 20mm to get a 160mm fork would probably help a bunch. I've got at least that in the headset/stem spacers right now. Be aware, this rig does not like to "pop" and the front won't come up without some effort. I think the taller front, combined with a slightly shorter CS length would help quite a bit, if that is what you are looking for. For comparison I was on an IH Bakuto before this and claimed geo's look like this
IH / On-one
TTT - 23.8 / 23.5
ST - 17 / 18
HA - 69.5 / 66.6
SA - 71 / 73
CS - 16.6 / 16.75
BB - 12.65 / 12.5

The Bakuto was fairly stable but a bit more "playful" and you can see the geo isn't that much different, so subtle changes make a big difference. I think the shorter TTT on the On-one is more about the SA than anything else. I didn't compare the WB on each bike, but I'd bet the On-one was longer given the CS and the HA numbers.

[/URL]

Wow your Summer season would be crazy slack at 140mm, my 456 with 2.5" tyres and Kowa 160SS forks at 160 mm has a 14" BB height. This crazy height is the main reason I am getting I'm getting the custom frame, the On-One is great but it's too tall for tight berms. The slack seat angle is great and I have only added 15mm to the top tube because it will be running a 35mm stem to try and keep some sort of snappieness up front.

Oh yeah I will be running Kowa 200SI forks up front on the new frame.

Also something to think about is the length of the rear stays the longer they are the smoother the ride. Didn't really think about it til I read about the old Planet-X Compo (456 with a Easton frame) but the further the BB is forward the more weight you put on your forks which makes for a smoother ride. I wouldn't go any longer than a 456 back end as it would get hard to manual.

This is an old pic it's a SS now with lots of other bits-
http://i426.photobucket.com/albums/pp350/fairy1_02/IMG_13331.jpg

The Kowa is a fork I've considered upgrading to. Thanks for a pic.

I agree that with the 456 geo, any longer would make it much more difficult to manual, again, if that is your thing.

 

[ZenkiGarage]

Here is what Ive drawn up:

Main Tubes and seat tube are 1.375 .035 wall
Stays are .75 .035 that have been ovalized toward the front.
Im debating on a gusset for the head tube.

 

[mandown]

BB seems a touch tall, and the CS to TTT measurement makes me think it should pop up a bit easier than the on-one 456SS but not so much that is is unstable for the DH-ish trails, touch certainly no park bike feel to it.

i don't see a HA on that.

 

[ZenkiGarage]

the head angle is 65*, Its at the bottom of the front wheel.
Also droped the BB to 12.5

 

[rigidhack]

Go with the geo of a 2004 Sinister Ridge. Super sweet handling bike!

 

[P.T.W]

Hey Zenki i raced dh in our hardtail class here in nz for a few years an was planning on building a custom dh race hardtail frame.my geo numbers where(off the top of my head tho)
23" toptube,66 headangle,70?seattube angle,17 chainstays an a 12.5 bottombracket height....this was with a 160mm fork

Heres my old whip....great lil bike.....just wanted somthing a lil longer wheelbase wise an a lil slacker for chasing down those big bikes

 

[ZenkiGarage]

Hey Zenki i raced dh in our hardtail class here in nz for a few years an was planning on building a custom dh race hardtail frame.my geo numbers where(off the top of my head tho)
23" toptube,66 headangle,70?seattube angle,17 chainstays an a 12.5 bottombracket height....this was with a 160mm fork

My geo will be around a 160mm SC(or 180 dc) fork also, But for the BikeCad drawing I was limited to 140mm.

 

[P.T.W]

My geo will be around a 160mm SC(or 180 dc) fork also, But for the BikeCad drawing I was limited to 140mm.

Looks like you an me are both thinking along the same lines geo wise...i went for longer stays for high speed stability as thats where a ht really begins to loose out..and to move more of my weight forward and off the back wheel,but with a steepish seat tube to help if an when i needed to get my weight back

 

[ZenkiGarage]

Looks like you an me are both thinking along the same lines geo wise...i went for longer stays for high speed stability as thats where a ht really begins to loose out..and to move more of my weight forward and off the back wheel,but with a steepish seat tube to help if an when i needed to get my weight back

Yeah, our geo's are pretty close. My CS length will actually be closer to 17 too since Im using horizontal drops, so after the chain is tensioned it should be right near or at 17.

 

[JohnnyC]

Black market Mob with a 5" fork

 

[cntstpthestnk06]

Here is my DH hardtail it rides awesome!! trust me

 

[ZenkiGarage]

Black market Mob with a 5" fork

had one, great street/dj frame, too steep and short for what i want now.

 

[ZenkiGarage]

Here is my DH hardtail it rides awesome!! trust me

Super Monster
maybe a little excessive? How high is your BB with that sucker?

 

[cntstpthestnk06]

Super Monster
maybe a little excessive? How high is your BB with that sucker?

i dont usually run that fork on that bike, but when i did i was able to rol like 3 to 4 foot drops. it was stupid, but the front was waayyyy yo heavy and it made freeriding really hard but as far as just descending steep trails it killed it because that fork eats everything.