I am currently having my R100GS frame strengthened/modified with TAG in Italy. Their strengthening is basically along HPN lines, their mods are more interesting. Their basic package includes changing the rake by 2 degrees, through alteration of the headstock that will require a longer t-clamp stem. They also move the engine position forward within a bandwidth of approx 5-10mm, depending on fork length and rear swing arm used. The way this has been explained to me is that in most "unholy union" mods the front gets jacked up disproportionately to the rear, with the effect that the center of gravity gets moved backwards. The engine relocation is done to mitigate this effect. I will be going for the rake change, but am still considering the engine move. Initially the move felt counter-intuitive for a dirt bike, but I get the argument about rebalancing mass. At this stage I am also put off by the practicalities of the engine relocation on things like exhaust and swing arm. I would assume that there is enough overlap on the exhaust pipe junctures that you can reclaim 10mm overall, the swing arm is a bigger problem. TAG's make their swing arms specifically to deal with this issue, I assume by being +105-110mm. My issue is that I have a shiny new +100mm mono from Moorespeed that I got before focusing on the frame. So my first question is whether there is an obvious way to use my +100mm swing arm for a repositioned engine while keeping shock mounting points where they were intended to be. The two ways I could think of are either at the front or back of the drive shaft: - on the front you could simply put a (10mm) spacer onto the front flange of the drive shaft. This seems easy enough in theory, but problems could arise given extent of movement on this juncture. Also the rotating section behind the flange would be sitting further inside the swing arm and I dont know if this is ok. - alternatively on the rear you could just live with a less deep overlap on the rear coupling. There seems to be approx 5cm of depth there, so would 4cm be sufficient? I would be grateful for any input on this. if its all too much brain damage can live with OEM engine location, but its worth thinking through before ditching idea.
I know this may be the easy way out, but why not just sell your extended SA and use the one that is engineered to work by the company that has engineered the product. I'm sure you could recoop your purchase price on the swing arm. You are already dropping some serious cash on the bike, so what's a little more?? It might end up saving you money and frustration going with what TAG has developed. They have worked out the fitment issues.
Do both mods(more speed and TAG) end up with the same wheel travel ? Could it be that the TAG mod with the U-joint further from the swing arm gives room for more swing arm movement ?
Goodies: they make 3 types of tanks, two are variants of the stock g/s tanks, the third is a monster 56l made to work with their fairing kit. All are made of kevlar and have internal baffles to limit petrol slosh. You will also see the front scoops so as to allow for USD forks. I bought the 35l G/S PD variant, as this has the side steps brought forward by approx 40mm from the stock version, to allow for longer legs.
Trust the Italians to get the styling right, check out the angle of the muffler to the rear shroud, perfect. Would the tank on that have two filler caps?
Yes two (BA) caps, and obviously two separate compartments in addition to the baffles. I have to admit tanks of this size do it for me- the issue on this one is that it is really designed to go with their fairing, so the front portion is too 'cut-off' to look right naked. Am trying to persuade them to do a version for un-faired bikes....
yes all available EUR 550 for the 19l, EUR 750 for the 35l and approx EUR 950 for the 56l (all pre tax) my sense is that the 19l OEM is available at reasonable prices, but the 35l OEM is approx EUR 1,050 new and difficult to get secondhand- so cost is relative
RT. Very interested in what you are posting re TAG. I never could get much out of them and gave up a few years ago. 5-10 mm is not a lot; a spacer on the gearbox output flange will cope OK. Finding suitable bolts and bolt insertion clearance is a minor issue. The pictured bike with parlever rear seems to have more than a 10mm forward move. More like 20mm judging by the position of the exhaust nut in relation to the frame tube. Photos can be deceptive . Longer swingarms have the effect of moving the CoG forward as the back wheel moves away from the engine mass Making the rake steeper doubles up as the front wheel moves towards the engine. Given the same length fork tubes it also jacks up the front end in comparison to the rear which seems to be the original problem that you want to overcome Surely it is easier to engineer the forks for the corrrect ride hight for the amount of swing arm extension than it is to re position every thing else. Some reduction in total wheel travel will result. My experience is that anything over 250mm becomes a handfull with weight transfer. Moving the CoG forward certainly helps make the front end feel more planted. How much is enough? Since you are in country do they have a demo bike you can ride? .
Did you get any other pics while you were there ? The pic of the bike with the 19l tank looks interesting, around the steering head area and the bar clamps and I would love a pic of the rear shock mount, (if that one has the 1100 rear end ) They do some very nice stuff, your bike will be awesome when done !!
You guys are getting this real-time, so not everything is understood/figured out. Rucksta, I think your comments are basically right. One of the primary drivers behind the engine move and consequent rebalancing of the CoG is to lighten the rear so as to allow for a free-er rear suspension travel. The genesis of the TAG mods were primarily for rally preps, rather than overland tourism- hence the focus on max suspension travel. Given that I will be putting an extended monolever on the bike, they have advised against the engine move. Effectively stating that the subtlety of the effect on the rear suspension will be lost due to the stiffening effect of the shaft jacking. This is why their preps are largely done with R1100 paralevers, which they modify significantly (pics to come). I am now questioning my logic for having chosen monolever in the first place, at the time rear wheel offset of the R1100 paralever put me off and the hope that the extension on the mono would almost cancel out the jacking effect. I agree that changes in rake will marginally add to the chopper effect, but am assuming that the effect on handling materially outweighs this. I also agree that playing with fork slide is still something you want to do at the end of the day, but am not at that stage yet. Cant comment on the ideal suspension travel, again because I am not there yet. I would have thought that much of this is ultimately subjective, depending on rider height and typical riding terrain.
What are/were the prices of the two swingarms? Have you a link to the TAG Moto website please..... Timpo.
