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I've always questioned how they maintain an exact measurement. If a rider likes the axle in a certain position but you can't get the proper slack in the chain, what do they do? You're not going to change gearing or run a chain too tight or too loose. Do you then find the compromise?
They make adjustments on the front and rear sprockets to maintain the correct wheelbase and chain slack, and then make trans ratio/primary gear changes to get back to where they want it. I want to say one of ML’s Testing Talk podcasts went over that when talking about Roczen’s factory trans and ML talked about trying to acquire some primary gears from the remnants of Geico Honda for his team to do exactly that
keep in mind the yamaha guys have been running an older longer swingarm for this reason
a few things Ive run into...
Keefer tells me the Triumph guys like the axle farther back
Also said he has run a half link at times to get axle where he wants
MXA says the Triumph is the shortest wheel base of all of them
I have both bikes and yes the Triumph is a whole inch sorter. I was suprised
Im told by an insider that there are very few changing internal gearing these days track to track
with chassis setup everything effects everything and simple answers to things like this thred can be confounded bike to bike
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It’s all a give and take. Also need to consider the adjustments around moving rear wheel back. You need to adjust sag because now there’s more leverage on shock. Maybe need to stiffen fork because it’s moving the weight bias forwards. Might even feel like slight loss in rear traction depending on the bikes anti-squat. Gear change to get the right length. If you change counter shaft sprocket it will then change the bikes anti-squat(could be better or worse).
Personally I like the longer rear wheel in swingarm for So Cal on 23 Yamaha, but should see middle working well on other bikes. I’m also on 14t front which really frees up the suspension feel.
How does more leverage on the rear shock move the weight bias forward? Increasing leverage on the shock would shift the weight bias to the rear, right?
I wonder why the manufacturers don't make longer slots/swingarms on the stock bikes, and then use larger axle blocks to limit the range for stock riders, if they know that at pro levels, nearly every guy is running a really long setup?
It wouldn't cost anything significant to manufacture, and they already know that it is needed for riders who won't be using stock chaingear, blocks, and shock setup anyway.
no, moving the axle back is moving, not literally, the engine closer to the forks, thus more weight on the front as the rear is getting farther away. I know it sounds odd but that is the case.
Do the pros need longer swingarms because of the Scoop tires?
Was Dunlop selling their spec tires because all of the pro riders wanted a scoop instead?
I've been running my bikes this way since 2019, started at the dunes to protect my splash guard and the bike felt good in the whoops.
It’s like a cantilever effect. My brain thinks about it as the farther the rear is away like grabbing the end of a broom stick or breaker bar, more leverage and it’s forcing the front tire into the ground, which creates more grip
Soooo....
This same thred has been run at Thumptalk. Similar ideas passed around as here BUT one post had a simple but I suspect spot on reason. Sure all the normal reasons could be true (stability, gearing) BUT the overwhelming number of them doing it made me think theres more to this one.
right or wrong Heres where Ive landed........
what does every single pro have in common? stiffer forks and lower sag numbers than stock
that taller chassis has a higher center of gravity. A taller structure needs a wider base to balance itself under changing loads
thus the need for nearly every pro to lengthen the bikes wheel base
Seems many bikes are comming stock with softer forks and 105mm or so sag
Yet many pros are in the 100-102 mm range with sag, some even less
To balance that out ya need a stiffer /taller fork wich means ya end up with taller bike overall
AND to balance that out ya need a longer wheel base. (less pitchy)
sure the "other" reasons can apply BUT the overwhelming number of bikes I see with the axle far back seemed to me to suggest there might more to this .
A couple link longer chain must have been worth it because a lot of factory bikes had the set up once upon a time. As the one poster said most of us wouldn't be able to notice the difference. Just like thinner or thicker motor mounts and things like that. I had a 2011 YZ450 that I threw the kitchen sink at and one of the things I did were the motor mounts that rotated the engine forward a skosh. Between that, careful suspension tuning, and radiators dropped an inch I got the thing where it didn't twitch the front end anymore, but it still was a bit of a dump truck lol.
Should be the opposite, no? Longer the lever (moving the wheel back) puts more weight on the front wheel, not less?
I think adding rider weight is an important variable, and the rate of wheel base change matters as well.
In my experience moving only the axle back, the bike will ride lower in the shock stroke and loses front end feel, especially when accelerating.
Some comments above mentioned gaining front end feel because the weight bias is dispersed more towards the front. I think this is true until you add the rider's weight. Sag is used to reset the weight bias to rider preference.
On the extreme end you have drag and hill climb bikes, where the extended swingarm does bias weight to the front, but the amount of wheelbase change is so big that the weight bias could not be balanced with sag adjustment on a normal length shock.
How do you add half a chain link?
If it was an advantage then I wonder why no factory teams are doing it now?
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If the rider doesn’t reset sag after wheel adjustment and the rear is now sitting low it could give the feeling of less traction?
But the trade off is traction.
moving the rear wheel back changes the front/ rear weight bias
in effect moving the rear wheel back puts a bit more weight on the front wheel and a bit less weight on the rear wheel. Some claim a bit more confidence in front tire feel ( I believe some refer to this as a " more planted" feel)
I noticed a small change in corner entrance on the Triumph 450 moving rear wheel back about 15mm. Not sure the front feels any more "planted"? But the chassis feel overall was a tad different. I did do carful sag adjustments during these tests AND manipulated that sag up and down a bit to make sure the feel wasnt just a sag thats out a mm or two eather way.
With the longer wheel base it started to feel a bit more like the CRF. Hard to explaine. At present I am in a compare between the 2025 CRF450 and the 2025 Triumph 450. The CRF chassis feels more like a "sit into it" chassis and the Triumph feels more like your " on top of it " chassis. What the hell does that mean right? ha. With the honda I feel like im sitting down into the seat more and can manipulate the turn entrance more with the seat of my pants and my bodys core area. With the axle moved back on the Triumph it too feels a bit more like the crf at turn entrance. Not the same exactly but just a tad more. Not a game changer, just a small change. BTW ergos play a part here and I have raised handlebars on the Triumph to simulate the ergos of the honda wich imo is better. I tryed 10mm raise but ended up needing about 15mm to get the feel right.
I havent noticed any big change in stability. Not sayint there isnt a difference, there may be, but so far I havent had a stability issue in eather stock or moved back positions BUT this is at 105mm sag. I suspect if I went to a lower sag numbers (taller rear) and taller forks to balance it all out, then the 15mm axle move may start to show itself in the stability dept more?
On my 2024 KX450 I run the stock gearing but added a link to the chain. I felt like this both A: put more weight on the front tire making cornering more predictable, and B: increased stability. It might have cost me quicker handling, but I prefer a more stable bike to a quicker handling one.
Yes - look at it in the extreme - how would the center of gravity change if a longer swingarm was installed that moved the rear wheel back by a foot or more.
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