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Old 03-02-2015, 05:46 AM   #1
Dakar83 OP
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Triple Clamp Offset

I would like to hear from anyone who has installed HPMGuys 38mm offset triple clamps on their airhead. Ideally one with the 100mm extended monolever and either 50mm Marzocchi Magnums or 50mm WP forks.

I have an 80G/S with the 100mm monolever extension and 50mm Marzocchi Magnums. The forks were off a KTM, I think a 450EXC, and I used the stock KTM triple clamp with 14mm offset. While this gives great straight line stability off road and on, it comes at the expense of turning circle. Unfortunately the lower triple clamp bolts are set to the rear of the triple and hit the frame limiting the turning lock. This is a real PIA in the garage or parking lot but does not bother me when riding unless I get into some tight tracks. Then it can be a wrestling match to turn around.

I have the opportunity to install a set of HPMGuy triples but the jump in offset from 14mm to 38mm seems like a huge step, so I would really like to hear how others have found them on and off road. Like many folk my knowledge of steering setup, geometry etc is limited, I think the change from 14-38mm offset will reduce trail and therefore may reduce stability, is that right?

Would really appreciate any help from those who have gone down this path, thanks.
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Old 03-02-2015, 08:49 AM   #2
bgoodsoil
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I don't have the exact set-up you have but I can weigh in a bit on the offset.

I had DR650 forks with 22mm of offset on my stock-swingarmed G/S for years. I put on a wp4860 with HPMGuy's 38mm triples a few months ago. I haven't gotten to take it down any trails yet I can tell you that it feels twitchier on the road and at least 'feels' like it deflects more if I ram in to a curve wrong.

It feels hinged in the middle--like the bike is two lines with a pivot in between them instead of before where it felt like one line that I was bending as I turned. If that makes any sense.

The difference in the turning radius is HUGE. This thing turns on a dime with the HPMGuy clamps. I'm not running a steering stop at all. The steering tubes bottom out on the HPN tank perfectly. I glued a long strip of foam on the tank right in line with where it touches. I've kicked the bike over several times to see what happens when the bars lock out in a crash. I'm not worried that I'll do damage to anything with this set-up at all. I'm doing locked-out low-speed donuts that almost fit in a single lane.

I think you can get the best of both worlds--stability and turning--using a steering damper. I haven't got my damper installed yet but I've ridden GSes with dampers. I'm sure I can dial out the twitchiness by dialing in the damper to kick in at the right angle.

I think a lot of people start building their airhead and they look to emulate the best--HPN. However, HPN built desert racers and unless you're racing in a desert I don't think copying their high-speed, straight-line build is a good idea. HPN has a lower offset on most of their bikes but I don't think that means I should do that for my woods riding. Something to think about.
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Old 03-02-2015, 05:28 PM   #3
Dakar83 OP
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Triple Clamp Offset

Thanks bgoodsoil, your comments line up with what I was thinking would happen with the greater offset. I've read that KTM now tend to stick with 20-22mm offset and I read somewhere else on the forum that Pruster uses 28mm? Which sound like a better step up from 14mm than jumping to 38mm

Where I ride we tend to get a lot of loose gravel and sand, more so than tight track. Hence I'm wary about changing the setup and loosing some of the current stability. But then I'm a complete newbie to suspension geometry and setup so don't know if I've figured this right. There were a lot of the HPMGuy triples sold so I'm hoping there should be plenty of experience out there that I can learn from. Also expect a lot of thinking must have gone into the design and selection of 38mm offset and this would have been done by folk with a lot more experience and knowledge on the subject than me.

Your comments about the steering damper make sense though it becomes an expensive exercise if the only end gain is better steering angle for low speed manoeuvres.

This picture helps me get my head around the effect on trail of increasing offset. That and the example of a shopping trolley wheel where greater straight line stability is achieved by having the point of contact of wheel and ground a greater distance behind the steering pivot point. Ie greater trail.


Dakar83 screwed with this post 03-02-2015 at 05:36 PM
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Old Yesterday, 12:56 PM   #4
djc
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hi,just getting in to these bikes & have absolutely no experience,that said I have read a shit load about this & the bike im building has Husqvarna triples with 25mm offset,paul rooney gave me this advise for this bike,setting it up adv touring,hope this helps,also paul is very easy to talk to for his advice iv,e found
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Old Yesterday, 12:59 PM   #5
djc
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hi again,have followed your builds,the bike with the hydraulic clutch is this mod succesfull ? thanks djc
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Old Yesterday, 06:26 PM   #6
Dakar83 OP
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Triple Clamp Offset

Quote:
Originally Posted by djc View Post
hi again,have followed your builds,the bike with the hydraulic clutch is this mod succesfull ? thanks djc

Hi djc yes the hydraulic clutch worked out really well. That said the manual clutch with Siebenrock oil resistant plate works fine to and is not too heavy.

Thanks also for the info on Paul and the Husqvarna triples. I have on loan a set of HPMGuy triples with 38mm offset and would really like feedback from those who have installed a set. There is lots on Advrider about the design of these clamps and even installation, but I am yet to find reports on how the users find the handling post change over.

It would also be really good to get feedback from riders who have used other triple clamps such as the Husky ones you mention, how do they ride with the longer swing arm/bigger forks combo?
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Old Yesterday, 09:01 PM   #7
Solo Lobo
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Originally Posted by Dakar83 View Post
It would also be really good to get feedback from riders who have used other triple clamps such as the Husky ones you mention, how do they ride with the longer swing arm/bigger forks combo?
I really like mine, but the change to the KTM forks is so radically different its hard to think the whole bike has been transformed....

Marcus Best rode around the world with a set... RDubb may have done some miles as well. Check into the Holy Union Threads
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