TAG frame mods

[Phreaky Phil]

Originally Posted by Ras Thurlo

From what I have understood so far:

- its a modified 1100 SA

- yes its strengthened post alterations, they also mentioned this was a necessary step

- Net offset (after wheel offset in compensation) 15-17mm, do not know what the gross offset of the SA alone is.

If this is correct I do not think that sub 2cm offset is that bad considering that I see this as the principal drawback of going for a 1100 para.

With my rear disc conversion I nwas able to get things back in line ( or very close) by a radical offset with the R1100 Hub and R100GS rim. With the 1100 swingarm it will put the final drive more to the right than with the R100 swingarm, therefore should require less offset. Using the pic that Anton posted of thge two swingarms I would say about 10mm or so less offset than I have.
I have not had the chance to compare an 1100 final drive alongside an R100 final drive to see if there is any offset difference between the two.
I'm not sure of the strengthening they do but the other two pics of similar setups I have seen have had a long web on the shock mount to spread the load.
like this one

[AliBaba]

The TAG-bikes looks nice. They have lots of smart details, like relocation of the pegs.

Personally I'm not a big fan of the side mounted shock, but it leaves a lot of free space that can be used for a watertank.

Originally Posted by Ras Thurlo

From what I have understood so far:
- its a modified 1100 SA
- yes its strengthened post alterations, they also mentioned this was a necessary step
- Net offset (after wheel offset in compensation) 15-17mm, do not know what the gross offset of the SA alone is.
If this is correct I do not think that sub 2cm offset is that bad considering that I see this as the principal drawback of going for a 1100 para.

I have 6mm offset with a HPN-swingarm, I think HPN has the same offset with the 1100 swingarm.

[AntonLargiader]

Originally Posted by Phreaky Phil

With the 1100 swingarm it will put the final drive more to the right than with the R100 swingarm, therefore should require less offset.

You have that backward. The 1100 swingarm normally sits to the right of center, so putting it in the center of the Airhead frame offsets to the left. I have had an 1100 swing arm/FD/wheel on a rolling chassis for a while and it's unusably (to me) offset.

I have not had the chance to compare an 1100 final drive alongside an R100 final drive to see if there is any offset difference between the two.

Pretty sure there is no difference. The geometry of the gearsets (pinion axis to bolting face) mostly eliminates the possibility of changing that. I'm pretty sure the housings are all pretty much the same in this dimension. In fact I have a chart of these components on my site now at the bottom of the gearing page (I was bored one afternoon): http://largiader.com/articles/gearing/

I recently bought a K11 FD just to get the housing because I wanted a shock-stud type Paralever housing with the larger cover bolts so I can run a later (11GS-type) disc cover. I'll probably run a 3.0 gearset in it and then try it on my R100R with some yet to be determined wheel.

[Ras Thurlo]

Since I dont get to test ride HPNs every weekend, a couple of questions to you guys:

what is the typical net offset on a 1100 para conversion and can you really feel it riding?

I had done my homework based on the thread below, from which I understood it as being a gross swing arm offset of approx 32mm. Is this right?

http://advrider.com/forums/showthrea...=204897&page=2

How much can you reclaim on the wheel offset, keeping in mind you will want clearance for a 140 rear tyre?

How much can you feel it after all that? I assume offroad not at all.

Since I am trying to understand relaltive merits of para vs mono, I assume that on a mono extension you are still going to do a rim offset to get the 140, so will probably have the same general issue anyway.


sweet bike btw

Originally Posted by Phreaky Phil

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[Airhead Wrangler]

I can't give you numbers, but here's a photo of an HPN Rallye Sport mid-build. To my eye, that looks pretty close to dead center. If not, it's still definitely less than 32mm. I know they give you different engine spacers to move the whole engine and trans over to the right a bit which reduces the offset. What further modifications they do, I'm not sure.



This what you get when you just bolt it all together (I think I stole this photo from Lornce):

[Ras Thurlo]

Originally Posted by Airhead Wrangler

I can't give you numbers, but here's a photo of an HPN Rallye Sport mid-build. To my eye, that looks pretty close to dead center. If not, it's still definitely less than 32mm. I know they give you different engine spacers to move the whole engine and trans over to the right a bit which reduces the offset. What further modifications they do, I'm not sure.

I have a Vespa Sprint with the engine hanging off on the right, after a while you get into it

this moves suggests that such small variance in wheel offset is worse than engine weight imbalance

...Im feeling a renewed glow of monoluv

[Airhead Wrangler]

Here's a shot of the frame modifications. Without a good photo of a stock frame I can't pick out all they do, but I'm sure there's a fair amount more than meets the eye.



and here's how it all goes together:

[Ras Thurlo]

Whats the consensus view of vertical vs diagonal suspension on these swing arms?

Originally Posted by Airhead Wrangler

[Airhead Wrangler]

I'd prefer HPN's design for a couple of reasons. The rear shock is better shielded from crap coming off the back wheel and would thereby probably last a bit longer between rebuilds. Second, HPN's design distributes the loads of the suspension more evenly into the main frame. Mono G/Ss occasionally break the right rear frame tube as it has to cope with ALL the loads of the suspension. Bottoming out hard, especially on a loaded bike, can be too much for it and can snap the rear right frame tube. HPN's design spreads those forces evenly on both sides of the frame as well as the spine tube. The other side to it is that in HPN's design the swingarm has more mechanical advantage on the shock and thus the suspension stresses are greater. Lastly, the unsprung weight of the shock would have a bit less detrimental effect on the suspension performance in HPN's design, but in the real world I bet the effect would be negligible. In short, I don't see any MAJOR advantage of one design over the other, but without knowing more about TAG's, I'd opt for HPN's.

[Ras Thurlo]

Originally Posted by Airhead Wrangler

The other side to it is that in HPN's design the swingarm has more mechanical advantage on the shock and thus the suspension stresses are greater

what do you mean by this?

everything else I get

[Airhead Wrangler]

Originally Posted by Ras Thurlo

what do you mean by this?

everything else I get

Yeah, I didn't word that very clearly. The swingarm has greater leverage to compress the shock (or so I'm assuming from photos without actually measuring it and doing calcs). This results in greater axial force in the shock which requires a heavier spring rate. That greater force has to be transmitted to the main frame somehow and would require much sturdier means of mounting the shock, hence HPN's shock "subframe" with three points of connection to the main frame.

[Ras Thurlo]

got it

by the sounds of things the difference between the HPN and the TAG approach is within the realms of subjectivity

[Airhead Wrangler]

Originally Posted by Ras Thurlo

got it

by the sounds of things the difference between the HPN and the TAG approach is within the realms of subjectivity

Probably. I'd just ask them how hard and for how long they've beat on them and if they've ever broken anything. It's not exactly scientific, but that's all that really matters in the end. The differences in their approach to reducing the wheel offset as well as frame stiffening remain to be seen though. Let us know what you find about about how they do it. More than one way to skin a cat, as they say.

[CrazyIvan]

Originally Posted by Airhead Wrangler

To my eye, that looks pretty close to dead center. If not, it's still definitely less than 32mm.

It's definitely not dead center. I'm building one a the moment, if you wan't to use a 140 rear tyre you will end up with about 15mm offset.

That is with the swingarm moved as far as possible to the right, and the engine moved to the right also.

The guy who has build my rear wheel used the HPN sport specs for offset.

If you go the monolever route, you will probably end up in the same ballpark, to use a 140 tyre the wheel needs to be spoked out of center 10mm or more.

[Airhead Wrangler]

Feel free to tell us more about that. Looking very nice.