Minimum Wheelbase, Tire Size, Raising Links, Gearing and Chain Length

[Mythos]

So you know where I'm going with this, what I have in mind is a Gen2 busa that is set up for twisties and sport riding that can be converted to LSR without needing to remove the chain to accommodate the lower ride height and tall gearing. Wheelbase, tire size, ride height, gearing and chain length all are interelated so lets take this one step at a time.

First, minimum wheelbase for sport riding. Has anyone ever tried threading the adjuster bolts in all the way so the locknuts and head of the bolts are all that’s visible? What is the largest tire you can fit without rubbing the front of the swingarm with the axle pulled all the way forward?

 

[michael parris heuberger]

So you know where I'm going with this, what I have in mind is a Gen2 busa that is set up for twisties and sport riding that can be converted to LSR without needing to remove the chain to accommodate the lower ride height and tall gearing. Wheelbase, tire size, ride height, gearing and chain length all are interelated so lets take this one step at a time.

First, minimum wheelbase for sport riding. Has anyone ever tried threading the adjuster bolts in all the way so the locknuts and head of the bolts are all that’s visible? What is the largest tire you can fit without rubbing the front of the swingarm with the axle pulled all the way forward?

HI. I know I will need 2 chains one for 18-44 and 6 inch over and one for 20-38. and 12 inch over. Do you plan to up the HP? You need more HP than stock to go over 200 MPH.

 

[c10]

Stock arm has limitations to gearing but your stock motor Busa wont pull the gearing that the stock arm wont allow 19/41 the axle almost touches the back of the arm adjustment .
I imagine to shorten it 19 / 45 would put you in the very front of a stock arm , but nearly equal OEM gearing of 18/43 . The 190 / 55 tire might touch the front of the arm with 19/45 .
While shortening the wheel base helps the .25 to .5 " will not help as much as a set of lighter wheels would at stock wheel base .
If you were ride to RJ in the Ozarks you would feel no need to alter wheel base to shorter

 

[fallenarch]

So you know where I'm going with this, what I have in mind is a Gen2 busa that is set up for twisties and sport riding that can be converted to LSR without needing to remove the chain to accommodate the lower ride height and tall gearing. Wheelbase, tire size, ride height, gearing and chain length all are interelated so lets take this one step at a time.

First, minimum wheelbase for sport riding. Has anyone ever tried threading the adjuster bolts in all the way so the locknuts and head of the bolts are all that’s visible? What is the largest tire you can fit without rubbing the front of the swingarm with the axle pulled all the way forward?

I don't get this. If the axle is against the front of the adjustment area how are you going to get it on. Also how would you then move it back for LSR? Truthfully its not the wheelbase. The geometry of the busa is set up to be stable, rake, trail, etc. My buddies Ducati 1198 was only maybe 3/4" shorter. Best handling tricks for the Busa are 1" riser in the rear and light wheels with wide bars. The bike has too much torque for a short wheel base. No matter what you do it won't be a sportbike, its best to learn to use the stability to your advantage. Just my opion though.

 

[Mythos]

HI. I know I will need 2 chains one for 18-44 and 6 inch over and one for 20-38. and 12 inch over. Do you plan to up the HP? You need more HP than stock to go over 200 MPH.

Yes I imagine with that 6 inch lengthening of your wheelbase, the sprocket sizes don't matter nearly as much as how far your extension is. I'm not planning to stretch. I'm just planning to use the stock swingarm for now.

Someday I would like to turbo the busa because I do want to hit 200 but that will be years from now if I ever do it. It's always been a dream. Nitrous is always an option too. I won't need the extended swingarm for LSR, will I? Hit the spray only in 6th gear and it's not going to wheelie.

The 190 / 55 tire might touch the front of the arm with 19/45 .
While shortening the wheel base helps the .25 to .5 " will not help as much as a set of lighter wheels would at stock wheel base .

I did a visual and the well worn 200/55 I have on there now is about a half inch from the front of the swingarm. The adjuster bolts have about a half inch of thread showing. I didn't measure yet but it looks like if I'm lucky, I might be able to stick with a 200/55 and minimum WB or else get a 200/55 on after the chain has worn in. I think the wheelbase lengthens about an eighth inch from adjusting the chain pretty quick after installing a new chain and sprockets.

Oh don't you worry, those BST wheels are fully expected to be a part of this but I didn't bother to mention them since they won't effect ride height, tire size, chain length, gearing or chain length. My ZX-14 with minimum wheelbase matters very little for handling, I agree. I'll take the -1/2" for wheelies though, especially since I like a taller rear tire and plan to use raising links both of which are going to inhibit wheelies.

I don't get this. If the axle is against the front of the adjustment area how are you going to get it on. Also how would you then move it back for LSR? Truthfully its not the wheelbase. The geometry of the busa is set up to be stable, rake, trail, etc. My buddies Ducati 1198 was only maybe 3/4" shorter. Best handling tricks for the Busa are 1" riser in the rear and light wheels with wide bars. The bike has too much torque for a short wheel base. No matter what you do it won't be a sportbike, its best to learn to use the stability to your advantage. Just my opion though

My ZX-14 has the axle pulled all the way forward with new chain and sprockets and I got the chain on the sprocket without much problem. The chain has some slack in it without me sitting on it. With the bike on a spool stand, I believe I had to roll the chain onto the last 5 or six teeth like I did when my bicycle chain fell off back in the day. After the chain and sprockets wear in, it's no longer a problem. It probably would be easier to get the chain on with minimum WB if the bike is lifted on a swingarm pivot stand. The swingarm would hang all the way open and the chain will be looser. There wouldl be enough slack in the chain to get the chain over the sprocket without needing to roll it much if at all.

Moving the wheel back for LSR would be automatic because I would change back to stock dogbones but we didn't quite get to that part yet. We didn't get to the 1" rise of the raising links yet either but that will come. You're thinking ahead. As mentioned to c10, the BST Rapid TEKs will also come into play for sport riding and LSR but maybe they will be retired if I go with a monster turbo someday. Back to stock wheels then perhaps. As for wide bars I don't think I can do that because I thonk the bars look about as wide as I like them now. I would remove the control pods and try shorter bars. That to me would look very cool and be better for LSR aeros. Yes, lower tire pressure makes the steering even more heavy so long bars work better for cornering, I'm sure.

Far as too much torque for short gearing, I like +4 on my Gen1 ZX-14. A couple less ft lb of torque with that engine though. Still, I find the tightest corners are best done at quite high rpm with the throttle just cracked as I enter. Throttle response feels a lot more precise to me when the engine is turning fast. Short gearing is perfect for that. The way my busa is now, I must shift down to 1 to get that effect on the technical corners and the high rpm also avoids that timing retard which is a small annoyance in a corner.

 

[c10]

why stock wheels with a Turbo if you have CF wheels ?? Keep the wheels , and add the TURBO Your not going to have wheelie problems with LSR gearing with stock motor or even spray . their track is not prepared like a drag strip thats ultra sticky especially the first 300 feet . The guys that wheelie in anything over 4th gear are the built grudge bikes turning 200 plus in the 1320 ' making 500 plus hp with wheels on a 370ish pound busa

 

[Mythos]

@c10 After spending 4k on a set of CF wheels I'd love nothing better than to keep them on with a turbo. If that wheel will take 300 hp, it would stay. And it is true that LSR gearing is going to be very gentle even with turbo. Maybe michael paris heuberger needs an extended swingarm but I doubt very much I will ever have a busa like his.

@fallenarch I was mistaken about the raising links. If I use the raising links, the axle will need to pull forward when I switch to stock links, won't it. I think it will still be ok though.

I'm estimating I will be able to use a stock length chain for both LSR and sport riding gearing. The LSR sprockets have a total of 9 less teeth which will set the axle way back. Switching in the stock links will cause the axle to be pulled forward about one inch. I think the LSR WB will be a little over stock which sounds good to me.

Here's my thought process on that:

From experience with the ZX-14, the chain needs to be two pins longer than stock length to admit a +4 sprocket and the axle needs to be pulled almost all the way forward. With 1" raising links on instead of stock links, that should allow me to take that one extra link out of the chain. So with +4 sprocket and raising links, we're at stock chain length and minimum wheelbase.

Switching from sport sprockets to LSR sprockets is going to be a net reduction of 9 sprocket teeth. That would have the same effect as adding more than two links to the chain. So, if the bike is at minimum WB with raising links and +4 sprocket, switch in 20/38 gearing for LSR. Now the axle is back as far as it will go and maybe the chain is still too loose. Take off the raising links and swap in the stock links, this pulls the wheel forward about an inch.

@michael parris heuberger do you know if 20/38 gearing works with a stock length chain and stock dog bones?



?

 

[ZeePopo]

@Mythos What ya running on your rear shock? If you go with a hydraulic preload and the right spring you can raise and lower the rear as needed by quite a bit. Add to that the 10mm shock length increase on the eyelet that many aftermarket shocks have that's a considerable ride height increase. 200/60 Pirelli V3 on the rear with a matching front will raise you up as well. At that point your front forks will be your limiting issues. You gonna need a serious springs, valve and shim stack to handle the Busas weight while cornering and braking in the twisties. For that I go Racetech. The shim valve combo I got from them has been amazing. Make sure to get the high frequency rebound valve. Also make sure to get one size stiffer spring than whatever they recommend. When I was there last year they realized their program was wrong for the Busa. They had me on 1.0 spring and we couldn't get sag right. Had to bump up to 1.1. On the website they still haven't updated it. Guess not many Canyon Busas get done by them lol. Advanced canyon Rider is the setting for the valve stack. On the canyon or on the track this shim stack with speeds in the triple digits it has not let me down.

Wheelbase is a whole other beast. I would leave it at stock and work on increasing your turn in rate rather than count on the wheelbase to help you. Low speed u turns in a parking lot will train ya well. I can do a U turn within 2.5 parking spots, sometimes 2 when I get it just right. And thats with stock wheelbase.

Tire pressure on twisties I run 39 hot. Otherwise the weight of the Busa will overpower the front tire. I tried every other pressure. 39 is the sweet spot.

 

[rubbersidedown]

Mythos you start out talking about moving the adjuster blocks all the way forward as close to the swingarm pivot as possible to shorten the wheelbase.OK,you gained a few MM's. If you are lucky,and I doubt it,your chain will be tensioned correctly. This would be a fluke. The chain will have slack in it. You could then cut out 1 link say,hope for the best again. Maybe pull the blocks back a bit for the perfect adjustment. Fine yer set for the twisties. OK, now its LSR day and you want stability for your high speed run by pulling the blocks back. How are you going to do this with the same length chain,and still have it adjusted perfectly?
Sometimes,and I believe in this case,you just can't have it both ways.
As the smarter boyz have pointed out above...the 2 goals require major changes in set-up to be as successful as your 2 goals.
I personally don't see the huge accomplishment in taking a near stock Busa out for LSR...its been done. Now the twisties is different.If you want to ride faster there,cool...follow the advice of ZeePopo etc and have yourself a great time. This stock length arm that rocks both worlds is a waste of effort if you ask me. Also the cost of LSR is extreme.
IDK...
Rubb.

 

[fallenarch]

@Mythos What ya running on your rear shock? If you go with a hydraulic preload and the right spring you can raise and lower the rear as needed by quite a bit. Add to that the 10mm shock length increase on the eyelet that many aftermarket shocks have that's a considerable ride height increase. 200/60 Pirelli V3 on the rear with a matching front will raise you up as well. At that point your front forks will be your limiting issues. You gonna need a serious springs, valve and shim stack to handle the Busas weight while cornering and braking in the twisties. For that I go Racetech. The shim valve combo I got from them has been amazing. Make sure to get the high frequency rebound valve. Also make sure to get one size stiffer spring than whatever they recommend. When I was there last year they realized their program was wrong for the Busa. They had me on 1.0 spring and we couldn't get sag right. Had to bump up to 1.1. On the website they still haven't updated it. Guess not many Canyon Busas get done by them lol. Advanced canyon Rider is the setting for the valve stack. On the canyon or on the track this shim stack with speeds in the triple digits it has not let me down.

Wheelbase is a whole other beast. I would leave it at stock and work on increasing your turn in rate rather than count on the wheelbase to help you. Low speed u turns in a parking lot will train ya well. I can do a U turn within 2.5 parking spots, sometimes 2 when I get it just right. And thats with stock wheelbase.

Tire pressure on twisties I run 39 hot. Otherwise the weight of the Busa will overpower the front tire. I tried every other pressure. 39 is the sweet spot.

Good advice all my friend. I like the Dunlop Q3's because they seem to have stiffer side walls so they will allow lower pressures than the Michelins. My setup is right between stiff enough to run hard and smooth to be tolerable when slabbing with little squat or dive in braking/accelerating. BTW: I really like the RaceTech boys, they know their stuff and are super helpful.

 

[michael parris heuberger]

@c10 After spending 4k on a set of CF wheels I'd love nothing better than to keep them on with a turbo. If that wheel will take 300 hp, it would stay. And it is true that LSR gearing is going to be very gentle even with turbo. Maybe michael paris heuberger needs an extended swingarm but I doubt very much I will ever have a busa like his.

@fallenarch I was mistaken about the raising links. If I use the raising links, the axle will need to pull forward when I switch to stock links, won't it. I think it will still be ok though.

I'm estimating I will be able to use a stock length chain for both LSR and sport riding gearing. The LSR sprockets have a total of 9 less teeth which will set the axle way back. Switching in the stock links will cause the axle to be pulled forward about one inch. I think the LSR WB will be a little over stock which sounds good to me.

Here's my thought process on that:

From experience with the ZX-14, the chain needs to be two pins longer than stock length to admit a +4 sprocket and the axle needs to be pulled almost all the way forward. With 1" raising links on instead of stock links, that should allow me to take that one extra link out of the chain. So with +4 sprocket and raising links, we're at stock chain length and minimum wheelbase.

Switching from sport sprockets to LSR sprockets is going to be a net reduction of 9 sprocket teeth. That would have the same effect as adding more than two links to the chain. So, if the bike is at minimum WB with raising links and +4 sprocket, switch in 20/38 gearing for LSR. Now the axle is back as far as it will go and maybe the chain is still too loose. Take off the raising links and swap in the stock links, this pulls the wheel forward about an inch.

@michael parris heuberger do you know if 20/38 gearing works with a stock length chain and stock dog bones?



?

Hi. I do not know yet I bought a roll of Titanium chain. The C/F wheels will work for LSR, But for bikes running 6.30- 6.40 in the 1/4 the front will brake. DME uses Marvic Magnesium wheels. You want to be as low as you can go for LSR. The longer the wheel base the more stable the bike will be at high speed. That is why I went with the 6 to 12 inch over and the 1 inch positive raked custom triple trees. To lower the bike I lowered the front 3+ inches. For the rear I went with a Penske 1 inch shorter shock with a Titanium spring. What I should have done is extened the frame after the neck 8 inches. Keep the front of
the bike long and the back of the bike short for better traction at high speed above 250 MPH.[ But to do that I would have to have made custom carbon fiber body work made, maybe $8,000.00 to $10,000.00 + $3.000.00 to $4.000.00. At first I only wanted to go 200 MPH. So in hind sight that is what it should have done. Eric at DAS went 266 MPH and his rear wheel speed was 310 MPH. So I say decide what you really want to do first and build for that, and do not change your mind!

 

[Mythos]

@ZeePopo said


“If you go with a hydraulic preload and the right spring you can raise and lower the rear as needed by quite a bit. Add to that the 10mm shock length increase on the eyelet that many aftermarket shocks have that's a considerable ride height increase.”

A shock that adjusts the ride hight by a full inch would be awesome but that would do the same thing to the chain and wheelbase as the 1” raising links. Raise the shock 1”, the chain goes loose, swap in sport riding gearing, now the chain won’t even fit, move axle all the way forward, the chain is just right. —-and the opposite routine when you go back to LSR gearing. A fancy new front and rear suspension isn’t in the budget for next year so the raising links will have to do for now. I’ll keep all that in mind for the future though, Thanks. Got it bookmarked.

“200/60 Pirelli V3 on the rear with a matching front will raise you up as well.”

I’m using a 200/55 tire right now and I like it so 200/60 will be the next step if it will fit with the wheelbase range I’m dealing with switching between sport and LSR gearing.

“Wheelbase is a whole other beast. I would leave it at stock and work on increasing your turn in rate rather than count on the wheelbase to help you.”

A literbike has a wheelbase about 3 inches shorter than a busa. I agree, reducing the busa’s wheelbase about one inch isn’t going to make a lot of difference. However, since it appears that the wheelbase will have to shorten an inch to accommodate my sport gearing, might as well take advantage of whatever it has to offer. The same is true for the LSR gearing, a little longer wheelbase would seem to help maintain straightline stability a bit more.


“Tire pressure on twisties I run 39 hot. Otherwise the weight of the Busa will overpower the front tire. I tried every other pressure. 39 is the sweet spot."

I use 25/25 psi tire pressure cold. The steering does feel heavy at low speed at first but that pressure must increase quite a bit when the tires warm up. I don’t notice any heaviness when I get into the twisties. Racing tires like Super Corsas tolerate low pressure really well. I’ve tried as low as 15/15 and it felt about the same as 25/25. 15 psi cold is awful low for the street though…and not necessary for me. I used 18 psi for the track and it was a dramatic change from the 35 psi I started out with! LOL 35 psi had the rear end squirming all over the place!! It is amazing to read about the scientific explanation of traction v surface area. The math formula doesn’t really work in the real world, larger contact patch does in fact = better traction….although that may be mainly due to higher tire temps from increased tire flexion and a couple other variables. Interesting.

 

[Mythos]

@rubbersidedown


“Mythos you start out talking about moving the adjuster blocks all the way forward as close to the swingarm pivot as possible to shorten the wheelbase.OK,you gained a few MM's. If you are lucky,and I doubt it,your chain will be tensioned correctly. This would be a fluke. The chain will have slack in it. You could then cut out 1 link say,hope for the best again. Maybe pull the blocks back a bit for the perfect adjustment. Fine yer set for the twisties. OK, now its LSR day and you want stability for your high speed run by pulling the blocks back. How are you going to do this with the same length chain,and still have it adjusted perfectly?”

The way the I hope this will work using the same length of chain is that the links on the shock also get swapped with the gearing. The sport gearing goes with long tie rods to raise the tail. The raising links will create a lot of slack in the chain because the swingarm opens. The axle getting pulled forward creates even more chain slack. Put in the sprocket gearing with larger total diameter and now the slack is taken up. You have short gearing and short WB for sport riding fun! The opposite effect happens when you swap in the short tie rods and smaller diameter LSR sprockets. I know, we are taking a trip through Theoretical Land here but I’m pretty good with these kinds of guesstimates. It might end up that I need to go with a tooth more or less or a chain link more or less. Only test fitting parts will tell that tale. Also, just going out and measuring the parts I now have on the bike with various axle adjustments will be necessary to make a real good estimate of how this all might work. Haven't done that yet, thus we are in Theoretical Land.

“I personally don't see the huge accomplishment in taking a near stock Busa out for LSR...its been done. Now the twisties is different.If you want to ride faster there,cool...follow the advice of ZeePopo etc and have yourself a great time. This stock length arm that rocks both worlds is a waste of effort if you ask me. Also the cost of LSR is extreme.”

Tell me you don’t want to hop on any bike and go as fast it can go!! I’d pay a thou to ride a stock busa on an LSR course for a weekend but I’d probably only be able to do that once or twice/year if I’m prudent with my $$. 190 mph would be ok with me. I don’t think I have the cojones to try that on the street. With the $$ I have to work with, I just have to go as far as I can go and that might be stock or nitrous.

 

[Mythos]

@michael parris heuberger


“The C/F wheels will work for LSR, But for bikes running 6.30- 6.40 in the 1/4 the front will brake.”

The front wheel will break on a 6 second busa? How is that? You mean the rear wheel, right?

“The longer the wheel base the more stable the bike will be at high speed. That is why I went with the 6 to 12 inch over and the 1 inch positive raked custom triple trees. To lower the bike I lowered the front 3+ inches. For the rear I went with a Penske 1 inch shorter shock with a Titanium spring. What I should have done is extened the frame after the neck 8 inches. Keep the front of the bike long and the back of the bike short for better traction at high speed above 250 MPH….So I say decide what you really want to do first and build for that, and do not change your mind!”

As I mentioned earlier, as much as I wish I could, I doubt I will ever have a busa like yours. A few inexpensive parts now that might get tossed aside later won’t hurt too much. When/If I go turbo, then I’ll have to start to narrow the application of this bike. Right away, turbo starts to detract from the road racing application. The $60 links will go in the old parts box or I’ll give them away.

 

[michael parris heuberger]

@michael parris heuberger


“The C/F wheels will work for LSR, But for bikes running 6.30- 6.40 in the 1/4 the front will brake.”

The front wheel will break on a 6 second busa? How is that? You mean the rear wheel, right?

“The longer the wheel base the more stable the bike will be at high speed. That is why I went with the 6 to 12 inch over and the 1 inch positive raked custom triple trees. To lower the bike I lowered the front 3+ inches. For the rear I went with a Penske 1 inch shorter shock with a Titanium spring. What I should have done is extened the frame after the neck 8 inches. Keep the front of the bike long and the back of the bike short for better traction at high speed above 250 MPH….So I say decide what you really want to do first and build for that, and do not change your mind!”

As I mentioned earlier, as much as I wish I could, I doubt I will ever have a busa like yours. A few inexpensive parts now that might get tossed aside later won’t hurt too much. When/If I go turbo, then I’ll have to start to narrow the application of this bike. Right away, turbo starts to detract from the road racing application. The $60 links will go in the old parts box or I’ll give them away.

Hi. The front wheel if they lift the front wheel they can come down very hard and do that a few times DME has broken them. That is why they went with the Marvic wheels, they have had to replace the front but they have never broken one. It is no fun to come down from a 160 MPH and have the front wheel fall to peices

 

[rubbersidedown]

Cool deal @Mythos I say go get 'em Bro.
You've put the thought in as usual.
Rubb.

 

[Mythos]

Hi. The front wheel if they lift the front wheel they can come down very hard and do that a few times DME has broken them. That is why they went with the Marvic wheels, they have had to replace the front but they have never broken one. It is no fun to come down from a 160 MPH and have the front wheel fall to peices

What do you think about normal 1st and second gear wheelies? I like to do them on occasion and I'd say I'm doing about 50~80 mph. They feel pretty soft to me. I do not think they are very high. Had one about 45° on the ZX-14 (on film so I'm pretty sure about the 45°) and even that touchdown didn't feel real hard. Since I learned how to wheelie I haven't had any rough landings. The last one on the busa was even held aloft for a few seconds and it came down soft backing off the throttle just a tad. I like my wheelies but I don't want to break a CF wheel doing them. I could get the reinforced BST wheels but it would suck to pay all that money for less than the lightest wheels.

 

[ptolemyx]

Only viable option would be two busas, one for twisties and one for lsr.

 

[Mythos]

and while I'm asking @michael parris heuberger , what about wheelies and ceramic bearings?

 

[michael parris heuberger]

and while I'm asking @michael parris heuberger , what about wheelies and ceramic bearings?

Hi They do not have any ceramic bearing problems. I run all ceramic bearings cams, trans and wheels.