Quantcast

IH 7Point with Sunday rear triangle to lower BB?

E

extremecarver

Chimp
Sep 12, 2010
10
0
Anyone knows if it is possible to lower the BB on a Ironhorse 7point by using the rear triangle & the rocker arm from an Sunday? (I'ld still use a 222x70mm shock).

I would really like to lower the bottom bracket from 15" to around 14" by about 2-3cm on my 7point. Stock BB drop is +37mm (or 33mm with -2° angleset which I'm getting soon).

Maybe the rocker arm alone would help by 1cm (and increase travel to around 187mm)??
 
Jason4

Jason4

Monkey
Aug 27, 2008
338
0
Bellingham
It sounds like you're putting a lot of effort into your 7point to make it something that it isn't. It would be easier and probably not much more expensive to sell your frame and buy a Sunday frame and get what you want.
 
D

dw

Wiffle Ball ninja
Sep 10, 2001
2,943
0
MV
extremecarver said:
Anyone knows if it is possible to lower the BB on a Ironhorse 7point by using the rear triangle & the rocker arm from an Sunday? (I'ld still use a 222x70mm shock).

I would really like to lower the bottom bracket from 15" to around 14" by about 2-3cm on my 7point. Stock BB drop is +37mm (or 33mm with -2° angleset which I'm getting soon).

Maybe the rocker arm alone would help by 1cm (and increase travel to around 187mm)??
Click to expand...
Sorry man, I'd love to give you better news but this is not going to work. Both the upper and lower links are completely incompatible between the Sunday and 7POINT. Stock BB rise is +30 btw, so at least you are gaining something over what you thought you had!

Dave
 
D

dw

Wiffle Ball ninja
Sep 10, 2001
2,943
0
MV
Nagaredama said:
I know guys riding the old 7POINT with 8.5" x 2.5" shock to make it lower and slacker. Cuts the travel down to 6" but they seem to like it a lot better.
Click to expand...
Basically a 6POINT, although the 6POINT frame had a lower BB rise and different front end geometry.
 
E

extremecarver

Chimp
Sep 12, 2010
10
0
Thanks a lot for all answers - especially Dave (great that you still stand behind your designs!!! - that support will mean DW-Link forever when I can scrape together the money for a new bike/frame)

okay, bad luck. I really love the 7point and have not yet ridden a bike that I like nearly as much for an alround trail to freeride bike.

Okay stock rise 30mm. Well if I measure it with zero stack headset and 565mm fork, I still arrive at 32.5mm (but most single crown forks won't clear the bottomtube then - at least on a medium frame). For arriving at a BB height of 30 would be like using a zero stack headset and 560mm fork. But that would explain also why my wheelbase calculations/measurements are longer than indicated.

Well I'll get a -2° headset with 11mm stack height and thereby arrive at a head angle of pretty exact 65° and wheelbase of 117cm. That should already improve performance a lot (I like slack head angles, still remember some great runs on a Summun Pro with 61°)


Going for a 8.5x2.5 shock would of course drop the BB by about 1.5cm, but then I love to have 180mm available for bikepark visits - even though most of my riding is trailriding. If I ever find a good condition not too expensive 2008 large 6point frame / front triangle I'll probably get it, and put the parts from my 7point onto it. Probably the 6 Point with -1.5° angleset (I don't think -2° will be possible due to 44mm headtube) and 222x70 shock would be the bike I want the 7point to be.... (and on top 600-700g lighter frame compared to the 2007 7Point).

I already went for really thin pedals, and think about getting the new 5.10 Baron shoes as they are about 1.2cm lower than the 5.10 impact (according to info I got from 5.10 at ISPO)...
Or instead of 6 point I'll try to find someone to build me a custom rocker arm that lowers the BB by around 2cm...
 
S

Slater

Monkey
Oct 10, 2007
378
0
extremecarver said:
Or instead of 6 point I'll try to find someone to build me a custom rocker arm that lowers the BB by around 2cm...
Click to expand...
You would need to obviously model this first. I dunno how much extra room there is between the tire and front triangle at bottom out, but I'd hazard a guess that there may not be enough to lower the BB 2cm and still have 7" of travel.
 
E

extremecarver

Chimp
Sep 12, 2010
10
0
Slater said:
You would need to obviously model this first. I dunno how much extra room there is between the tire and front triangle at bottom out, but I'd hazard a guess that there may not be enough to lower the BB 2cm and still have 7" of travel.
Click to expand...
No, that's no problem at all. Even running fat tires I could lower by about 4cm before hitting the seat tube. Maybe for more than 2-3cm one would have to shave a tiny bit of from the DW-Link.
Else running a 8.5x2.5 shock wouldn't work either (it'll be lower on bottom out than a 9x2.75 stroke shock).
 
D

dw

Wiffle Ball ninja
Sep 10, 2001
2,943
0
MV
extremecarver said:
Thanks a lot for all answers - especially Dave (great that you still stand behind your designs!!! - that support will mean DW-Link forever when I can scrape together the money for a new bike/frame)

okay, bad luck. I really love the 7point and have not yet ridden a bike that I like nearly as much for an alround trail to freeride bike.

Okay stock rise 30mm. Well if I measure it with zero stack headset and 565mm fork, I still arrive at 32.5mm (but most single crown forks won't clear the bottomtube then - at least on a medium frame). For arriving at a BB height of 30 would be like using a zero stack headset and 560mm fork. But that would explain also why my wheelbase calculations/measurements are longer than indicated.

Well I'll get a -2° headset with 11mm stack height and thereby arrive at a head angle of pretty exact 65° and wheelbase of 117cm. That should already improve performance a lot (I like slack head angles, still remember some great runs on a Summun Pro with 61°)


Going for a 8.5x2.5 shock would of course drop the BB by about 1.5cm, but then I love to have 180mm available for bikepark visits - even though most of my riding is trailriding. If I ever find a good condition not too expensive 2008 large 6point frame / front triangle I'll probably get it, and put the parts from my 7point onto it. Probably the 6 Point with -1.5° angleset (I don't think -2° will be possible due to 44mm headtube) and 222x70 shock would be the bike I want the 7point to be.... (and on top 600-700g lighter frame compared to the 2007 7Point).

I already went for really thin pedals, and think about getting the new 5.10 Baron shoes as they are about 1.2cm lower than the 5.10 impact (according to info I got from 5.10 at ISPO)...
Or instead of 6 point I'll try to find someone to build me a custom rocker arm that lowers the BB by around 2cm...
Click to expand...
Thanks for the kind words, I appreciate it. Keep in mind that 2degrees angle change at the steering axis will be closer to 3 degrees at the ground (steering angles are measured in relation to the ground, not each other).

A custom rocker arm will equal major bottom out. The 7POINT tire almost touches the seat tube at full compression. That's why there's no crossbrace on the seatstay, there's no room! Only way to lower the BB with a link is through travel reduction.
 
Last edited:
D

dw

Wiffle Ball ninja
Sep 10, 2001
2,943
0
MV
extremecarver said:
Well I once used a Summun Pro with 61° and that wasn't too bad....
Click to expand...
Sure, we've tested bikes with all kinds of extreme angles. 61-62 degree test bikes in 2002 with 7" travel forks, heck we were running angle changing headset cups and 63.5 degree head angles in 2006, back when many riders considered 66 to be slack. Whatever works for you is good!

My point was that seeing as you are looking for a slacker head tube angle, even though the angle changing headset says 2 degrees change on the steering axis, you will be closer to 3 degrees at the ground, getting you closer to your goal than you may have realized.

have fun!

Dave
 
Bikael Molton

Bikael Molton

goofy for life
Jun 9, 2003
4,022
1,154
El Lay
The 7 point with -2 headset cups will do you up pretty well. It won't turn it into a 2012 model $3000 DH race frame, but you will notice the difference, and it WILL feel more stable in the steeps and at high speed.

I had mine like that for 1/2 a season before going to a new frame.
 
S

Sov

Chimp
Jan 1, 2008
73
19
Adelaide, Australia
dw said:
My point was that seeing as you are looking for a slacker head tube angle, even though the angle changing headset says 2 degrees change on the steering axis, you will be closer to 3 degrees at the ground, getting you closer to your goal than you may have realized.
Click to expand...
I have just woken up so I might have this backwards, but I always figured the opposite was true - ie a 2 degree slacker change at the steering axis ends up being slightly less in practice for a given length of fork.

Eg. if you sit a stock bike on the ground and fix the frame at the rear axle and BB, putting on slacker cups will push the front wheel forward but also up off the ground. Once you drop the front wheel back down to the ground, the BB and bar heights drop, and the steering angle steepens a touch.
 
E

extremecarver

Chimp
Sep 12, 2010
10
0
Well, just to follow up here. I did install the -2° headset reducers about 1 month ago. They really made the 7point one class better. The first day trails and uphill felt a bit lame, but now I don't notice it anymore. For going down really steep stuff the 64.95° headangle and longer WB made it muuuuccch better.

Well good enough for a few weeks. Got a deal on a 6point 2009 large frame, and will change over. The 2009 large frame with -2° headset reducers (yeah, works compoments got them in stock since around a week) with 8.75x2.75 shock, and 180mm fork will end up nicely slack at 64.3° HA, while still having a much nicer 72.9° SA (so up 1.4°). Bottom bracket dropp will end up at around 17mm instead of 30m so I think it'll kick ass.

Also I'll loose around 1.5lbs (getting Saint cranks for the Moto-X at the same time, maybe mounting the cranks even with the lighter SLX bash) getting a 180/180 freerider with 2ply tires at around 16kg (with saint brakes and steel suspension front/back). Yeah, sound awesome.

Only bike intriguing me right now is the Durham R - but then 180mm and +10 BB drop and 61° HA (with the reducers that come with the frame) sound too crazy to be true.
 
sundaydoug

sundaydoug

Monkey
Jun 8, 2009
611
275
extremecarver said:
Well good enough for a few weeks. Got a deal on a 6point 2009 large frame, and will change over. The 2009 large frame with -2° headset reducers (yeah, works compoments got them in stock since around a week) with 8.75x2.75 shock, and 180mm fork will end up nicely slack at 64.3° HA, while still having a much nicer 72.9° SA (so up 1.4°). Bottom bracket dropp will end up at around 17mm instead of 30m so I think it'll kick ass.
Click to expand...
I could be wrong, but I don't think that those reducer cups will work with a 6point headtube. It's not 1.5".
 
R

rideitall

Chimp
Feb 2, 2006
35
0
Vancouver, BC
I previously had a 6 point (med) and never could get it to ride the way I wanted. I felt the HA was too steep for my liking. I did try a headset externalizer from Real World Cycles (http://www.enduroforkseals.com/id183.html), it did help but still never felt right.

Sold the frame and transferred most of the build to a 2008 7 Point. So now the build is setup with a 8.75 x 2.75 ISX-6 on the back, 180mm 66 RC2X. The key to the build was a Cane Creek Angleset. I used the 1.5 degree set of cups that resulted in a HA of just over 65 degrees (hard to accurately measure with my cheap measuring device).

The bike feels way better heading downhill, especially on the steeps, still climbs (requires effort on the steeper climbs to keep the front down), and has a nice playful feel (does not feel like driving a tractor).

I am seriously considering a Talas 180 now. The weight reduction would be good, but the ability to drop the front to 140 for climbs is the main reason.
 
E

extremecarver

Chimp
Sep 12, 2010
10
0
Well, I just went the other way. I am right now buidling up a 6 Point. Just not sure what angleset to get. I think for convenience I'll take a -1.5 with 9mm lower cup (my fork shaft is too short, so I can't go external twice -- possible would be -2.5° on the 6 point ZS44, and -3.5° on the 7Point with external bearings...).

Together with a 8.75x2.75 shock, and 180mm fork (RC2 ETA, droppable to about 60mm) and 64.5° HA, 36cm BB (the HA reducer does not make good as much as the 180mm fork makes the BB to lift up) and the 2° steeper seat angle vs the 7Point, plus about 1cm lower BB, should in my eyes be superior.

I went from a 2007 7Point Medium which was maybe a tiny bit on the small side, to a 19" 2009 6Point which will be a bit longer. I cut down the setpost by 1cm, so actually it's now an 18.5" and not 29" frame. Cause 19" seattube is a bit too much for me for really really steep stuff.

I am even thinking if I should go all the way to 63.8° with a custom head angle reducer from HAS. But maybe that's a bit too much for a 6point??

Works Components and HAS both have anglesets for ZS44 right now. (up to -2 or -2.5°).

HAS: http://www.ofanaim.net/has.html
Works Coponents: www.workscomponents.co.uk
 
Last edited:
miuan

miuan

Monkey
Jan 12, 2007
395
0
Bratislava, Slovakia
I never liked how my 7point rode, and gave up on it. Killer up the hill for sure, but my cheap Stinky rides better and has a good geometry as is, no need for expensive headset. It's kinda same as a downhiller being given a new gen Giant Faith. Just too steep.
 
You must log in or register to reply here.
Top Bottom