Gearing

[af1-windy]

Hello all..

Just about to join the clan, picking up a Red 2017 next Tuesday. 

I've read loads about this bike, nothing really scary to worry about, I spent 12 years with aprilia so I know all about gremlins in the works. 

Anyway, I have seen mentioned, more than a few times, that the engine is in the high (ish) rev range at 85mph in top. Is this the case? has anyone tinkered with the gearing, front/rear sprocket.

I'm assuming that the engine has sufficient grunt to sacrifice a bit to give slightly lower revs when cruising..? 

  windy

[Antares]

Originally Posted by af1-windy

Hello all..

Just about to join the clan, picking up a Red 2017 next Tuesday. 

I've read loads about this bike, nothing really scary to worry about, I spent 12 years with aprilia so I know all about gremlins in the works. 

Anyway, I have seen mentioned, more than a few times, that the engine is in the high (ish) rev range at 85mph in top. Is this the case? has anyone tinkered with the gearing, front/rear sprocket.

I'm assuming that the engine has sufficient grunt to sacrifice a bit to give slightly lower revs when cruising..? 

  windy

42 T rear is a common conversion (stock is 45) I personally run a 44T cos that's the smallest size JT makes in steel for the bike. It's a minor improvement, mainly for controlling the bike as it doesn't wheelie absolutely everywhere even in 3rd gear but it's not noticeable for acceleration or top speed at all. XR is Aero limited for top speed anyway not gearing. Imo it depends on your bike and how much buzz you got. Most have a slight buzz right about 6400-6500 rpm which is bang on where you're cruising at 85 with stock gearing. 42T shifts your cruise RPM down by about 500 rpm, so you're just below 6k. Imo it's absolutely not an issue either way, there are plenty of ways to effectively dampen the buzz and I've never found it to be an issue, if you're cruising on a motorway simply just set the cruise control at 83 or 87 mph or something like that, when you're riding it about you're going through the revs so quickly you'll never notice. 42T sprockets do help, and the bike still pulls great, but number 1 issue is that there almost only Ally sprockets that come in that size, the only ally hub steel outer sprocket in that size I've seen is made by supersprox and even those are completely out of stock with 1-2 month waiting time AND they cost about 80 quid to your door. I'd go with a steel 44T JT or equivalent if i'm honest, it even makes the speedo a little more accurate

[af1-windy]

Originally Posted by Antares

42 T rear is a common conversion (stock is 45) I personally run a 44T cos that's the smallest size JT makes in steel for the bike. It's a minor improvement, mainly for controlling the bike as it doesn't wheelie absolutely everywhere even in 3rd gear but it's not noticeable for acceleration or top speed at all. XR is Aero limited for top speed anyway not gearing. Imo it depends on your bike and how much buzz you got. Most have a slight buzz right about 6400-6500 rpm which is bang on where you're cruising at 85 with stock gearing. 42T shifts your cruise RPM down by about 500 rpm, so you're just below 6k. Imo it's absolutely not an issue either way, there are plenty of ways to effectively dampen the buzz and I've never found it to be an issue, if you're cruising on a motorway simply just set the cruise control at 83 or 87 mph or something like that, when you're riding it about you're going through the revs so quickly you'll never notice. 42T sprockets do help, and the bike still pulls great, but number 1 issue is that there almost only Ally sprockets that come in that size, the only ally hub steel outer sprocket in that size I've seen is made by supersprox and even those are completely out of stock with 1-2 month waiting time AND they cost about 80 quid to your door. I'd go with a steel 44T JT or equivalent if i'm honest, it even makes the speedo a little more accurate

That's some good feed back, cheers.

I'll ride for a while, get some miles under my belt and see how I go. If I need to tinker at least I can refer back to this post. 

  windy

[Antares]

Originally Posted by af1-windy

That's some good feed back, cheers.

I'll ride for a while, get some miles under my belt and see how I go. If I need to tinker at least I can refer back to this post. 

  windy

Also forgot to mention if u go 42T You need to remove links from the chain, and then you can't change your mind. With 44T it's easy enough to buy another 45 or even 46T sprocket for 20 quid, whatever floats your boat.

[Winger]

Originally Posted by af1-windy

That's some good feed back, cheers.

I'll ride for a while, get some miles under my belt and see how I go. If I need to tinker at least I can refer back to this post. 

  windy

And the other gazillion posts that are on this site about the same, large cup of tea and hit the search but button.😀

[Salem]

Each one tooth drop will decrease the diameter. I don't have a bike to measure but assume standard 45teeth  is 200mm diameter rear sprocket, 100 mm radius. One teeth drop is then a 2.2 percent change. The chain sits 2.2% of 100mm lower on the top chain slider.  One tooth less might work, 3 less is almost 7mm less and will eat up that protector on the back end fast.  The gen2 got longer 4th, 5th, and 6th because of user complaints.

[Antares]

Originally Posted by Salem

Each one tooth drop will decrease the diameter. I don't have a bike to measure but assume standard 45teeth  is 200mm diameter rear sprocket, 100 mm radius. One teeth drop is then a 2.2 percent change. The chain sits 2.2% of 100mm lower on the top chain slider.  One tooth less might work, 3 less is almost 7mm less and will eat up that protector on the back end fast. If you want acceleration, dropping a gear is the easy answer. The gen2 got longer 4th, 5th, and 6th because of user complaints. You can ride  all day long in 2nd/3rd if you want, the "one gear no brake" method.  Right now I don't see the point in changing sprocket sizes to make every gear shorter.

Fair point too, with a bike like the XR dropping a gear is too easy, I sometimes sh#t just for the fun of it, not because it's necessarily needed, takes a slight flick of the foot.

[Salem]

Originally Posted by Antares

Fair point too, with a bike like the XR dropping a gear is too easy, I sometimes sh#t just for the fun of it, not because it's necessarily needed, takes a slight flick of the foot.

Yes but changed my post.. By decreasing the rear sprocket size you make the gearing actually longer. But the wear point is still valid. A lot of cost and potential problems for small fuel savings. While the engine does do more rev's, the load is lighter too. Hence fuel economy does not change only with rev's

[smithy]

Originally Posted by Salem

Each one tooth drop will decrease the diameter. I don't have a bike to measure but assume standard 45teeth  is 200mm diameter rear sprocket, 100 mm radius. One teeth drop is then a 2.2 percent change. The chain sits 2.2% of 100mm lower on the top chain slider.  One tooth less might work, 3 less is almost 7mm less and will eat up that protector on the back end fast. 

Not true I'm afraid....I've been running a 42t Aluminium rear sprocket on my Gen-1 for over 4 years and now have over 48k km on the bike...the rubber swingarm protector is no worse for wear than it was when new..There's no evidence to suggest it will wear the rubber protector any more than normal.

My fuel economy is also excellent, average of 4.8L/100km on my dailty work commute...admittedly I do have full Arrow headers and a Rapid Bike Evo and it's mostly 100kmh+ motorway. Frequently get up near 400km per tank...filled up this morning before work with 314km showing on the trip meter, still had 84km range showing. Playing in the twisty stuff on the weekends is a different story though.

Smithy.

[Antares]

Originally Posted by smithy

Not true I'm afraid....I've been running a 42t Aluminium rear sprocket on my Gen-1 for over 4 years and now have over 48k km on the bike...the rubber swingarm protector is no worse for wear than it was when new..There's no evidence to suggest it will wear the rubber protector any more than normal.

My fuel economy is also excellent, average of 4.8L/100km on my dailty work commute...admittedly I do have full Arrow headers and a Rapid Bike Evo and it's mostly 100kmh+ motorway. Frequently get up near 400km per tank...filled up this morning before work with 314km showing on the trip meter, still had 84km range showing. Playing in the twisty stuff on the weekends is a different story though.

Smithy.

250 miles from a tank????? I'm struggling to grasp that. Even if I get insanely good motorway mileage, (best I've ever gotten was about 53mpg (4.4L/100km)) That's a theoretical maximum of 233 miles. And there is just no possible way to realistically do that for a whole tank. There are definitely other gains apart from the sprockets because they really don't affect economy that much, it's a myth, you can't bypass the laws of conservation of energy. The only thing you can achieve is work the engine at an RPM/speed combo where it's more efficient, this efficiency is the same regardless of your sprocket but with a bigger sprocket it's simply at a lower speed.