Motorcycle wheel alignment

[fixer]

Hi all,

This is technical question, though it is not strictly-speaking a bucket question. But I know there are a lot of smart and experienced motorcyclists on this forum, so I thought I'd throw this question out there.

First confession ... I've recently bought a 2014 Triumph Scrambler. Yeah, yeah, feel free to take a pot shot or two. Anyway, the front and back wheels are not rotating in the same plane and Triumph NZ are telling me (and apparently Triumph UK agree) that this is correct and not unusual. However, in 33 years of riding motorbikes, i don't recall coming across this before. The longitudinal vertical centrelines of the front and rear wheels on my new bike are parallel and offset by about 15mm. The front tyre is 100mm wide and the rear is 130mm wide and the right hand side of both tyres line up precisely. The left hand side of the front tyre is offset to the right of the same side of the rear tyre by 30mm. It doesn't seem to affect normal handling though the bike does pull noticeably to the right if I take my hands off the handlebars. Though it might be a factor that the entire, heavy exhaust system of the Scrambler is on the right.

So basically, my question is, does anyone know what the effect is on the handling of a motorcycle of having the wheel centrelines offset (by say 15mm) and are there motorcycle that are constructed this way intentionally?

Thanks guys.

Tim

[nodrog]

Bmw are the same

[Blackbird]

It does affect the handling but by how much is open to debate. It also depends what you use your bike for and how hard you push it. I know that top race teams are very fussy but I guess that's the ultimate test. The alignment marks on a swingarm are only an approximation and even small differences of how each fork is clamped can lead to an offset. If that all sounds to hard and depressing, it's not hard to measure accurately and correct it.

Back in 2003, I built a simple laser alignment rig for my Blackbird because I was fed up with tyre fitters not realigning my wheels properly. You can see the principle here: http://geoffjames.blogspot.co.nz/2010/03/wheel-alignment-improve-your-handling.html . I've simplified it a bit since then and it still works perfectly. I've also attached a write-up I did for a fellow Street Triple owner as he wanted a starting point to check and correct his own alignment. In the photos, you can see that I've substituted a tape measure for the front rig shown in the blog.

I mainly did it because I'm an anal mechanical engineer :facepalm: . I don't know whether it's of much interest to you but hope it might answer a few questions. 15mm offset is bigger than I'd want to put up with.

Cheers,

Geoff

[fixer]

Thanks for the feedback. In this case, the wheeltrack offset is so substantial that it's patently obvious even if you just lie on the ground behind the bike and eyeball it. I'm sure that even the fanciest of frame alignment machinery would show something similar. I've tried both a straightedge and the string method with the same result - at the front the gap between the rh side of the tyre and the string is 0mm and on the lh side, the gap is 30mm.

I suspect it might be harder with a shaft-drive BMW, but in principle, with a bit of spacer reshuffling and some machining of the rear wheel, i think it would be possible to get the wheels of the Scrambler to line up properly and for the sprockets to line up correctly at the same time.

However, moving the rear wheel over by 15mm, is not something I would do lightly. Presumably Triumph built it that way for a reason. Though I am almost completely stumped as to what that reason might be. I had a quick glance at a Triumph Thruxton in the bike shop and the wheels did not appear to be anything like as offset as mine, if they were offset at all. I can only assume that the offset of the rear wheel in some way helps to move the centre of gravity of the bike to counteract the weight of the HUGE but very pretty exhaust system on the right hand side of the bike.

To be honest, other than when I take my hands of the bars, I can't detect any strangeness in the way the bike turns in. Though it does seem to be a little harder than I would expect to ride in a straight line at a slow walking pace. And, lets face it, this is not a GSX-R. It has Trailwing tyres and makes 59hp. It's never going near a track and probably won't even be pushed that hard on the road.

But I would love it if someone could explain to me the reason(s) why a manufacturer might build a bike this way. And there must come a point where the offset is so great that an imbalance in the steering of the bike would become obvious to the rider. I would have thought?

[Paul in NZ]

My suggestion is to stop looking at the wheels... You cant see them from the seat anyway BUT if you are worried look at another scrambler...

[Blackbird]

All good questions but I suspect that you're not going to get uniform definitive answers from different manufacturers. I suspect that one of the larger contributors to misalignment on a new bike is a combination of manufacturing tolerances and assembly. From memory, my Street Triple had an offset of closer to 10mm when I first got it. Judicious uneven movement of the rear adjusters and moving one fork fractionally in the clamps brought it much closer. This might well be your best course of action if it really bothers you. However, if you're not generally a hard charger in the twisties, you probably won't notice anyway so doing nothing might be your best option.

I rode a pre-unit construction Tiger 100 when I was a student. The frame used to flex horribly and I never checked wheel alignment either. Rode like a complete twat everywhere and when I fell off, it was inevitably because I was riding like a dick. What I'm trying to say is that the impact of misalignment for normal road riding is pretty small in the scheme of things you can do to keep yourself safe :yes:

[HenryDorsetCase]

why would anyone give you a hard time about buying a Scrambler. I really liked mine. I even kept the Ohlins shocks I got for it in case I got another one. Or a Bonnie.

I never noticed any misalignment in mine but I never looked for it either. I did clean a lot of shit out from the cover over the front sprocket. It is a real trap for grit and chain lube and shit - FYI

[Yow Ling]

before lasers came out people used string, i suppose you could use red string for the laser beam look

[HenryDorsetCase]

or bolt something to the front sprocket (which I thought was genius) and measure the offsets that way:

http://www.kiwibiker.co.nz/forums/showthread.php/158121-RG-Extensive-clean

[Grumph]

This thing has wire spoke wheels. yes ?

If so, first check the front is central in the forks. This is more important than the rear...

The out of line problem could be as simple as a badly built wheel. If you're dead sure you want it moved over - and there's room tyre/chain line - take the bare wheel to a good wheel builder and ask for the rim to be moved over the appropriate distance.
It won't be cheap as some spokes will probably have to be replaced - but it's easier than making up spacers and machining the hub.

[mossy1200]

They used to make k100 brick race bikes with larger back wheels and offset of up to 20mm due to the shaft drive.
Apparently was successful.

[AllanB]

Read some of the big block Hogs are offset significanlly due to the primarly drive/belt alignment.


Weird shit.


Appears the main alignment issue on a m-cycle is not so much the plane parellel to each other although offset but a twist within the factory set plane.

[nodrog]

ffs its how its built.

[koba]

We had a local bucket with about a 20mm offset, this was corrected and then it went faster on the track.
Not saying it was certain cause and effect but the owner at the time was well experienced and he seemed to like it a lot better when it was in line.

[fixer]

Thanks guys.

This conversation, while not overly revealing, has at least made me relax a little. It looks like "don't worry, be happy" is the general consensus, and no one can really explain why a bike would be built that way.

An email from Triumph read as follows: "Several of our models have an offset between the wheels, this is not unusual. Running the wheels with an amount of offset improves the overall stability of the bike without any noticeable effect on handling."

Not exactly enlightening, but it is at least authoritative. Though how an amount of offset would improve the overall stability is a bit of a mystery to me.

So basically, from what Triumph tells me, you can't use the good old string method to check the wheel alignment on my bike unless you know that the wheel centres are offset (I have asked them to confirm that 15mm is the correct offset). The user manual tells me to rely on the marks on the chain adjusters. Of course, the unreliability of marks on chain adjusters is one of the few things that I thought pretty much everyone agreed on. Check with Mr Google.

Thanks for all your contributions ... even "ffs its how its built".

And I can't subtract ... I've been riding for 43 years, not 33 years. :)

[Blackbird]

Call me cynical, but whilst Triumph's statement about stability, or at least slightly slowing down the reaction of the bike to put it another way is probably correct; I still think assembly can easily account for your offset. From memory, I moved one fork stanchion through the clamp less than half a mm to bring mine as close as dammit. You could try that if it still bothers you.

Yes, you can still use the string line or laser. It's just that you'll have to factor in your offset when taking the measurement. Even if you don't try and alter the offset, it's worth checking periodically to make sure nothing's changed, particularly after you've had a tyre changed or chain adjusted.

[koba]

I checked the cain adjusters on a few bikes, on my bucket (NSR frame) they are perfect so I use them.
On most other bikes they have been out by quite a bit.

[TALLIS]

I checked the cain adjusters on a few bikes, on my bucket (NSR frame) they are perfect so I use them.
On most other bikes they have been out by quite a bit.

So what your really saying is, sell the triumph, get a Honda, problem solved!
And as always "you meet the nicest people on a Honda"

[Yow Ling]

The chain adjusters are not going to cause an offset, all they are going to do is point the wheel in a different direction.
Adjusting a fork stauntion 1/2mm isn't going to do fuck all either

[F5 Dave]

I was going to say Greg or Paul will be along in a while but they have both given input which I thought would be sager than mine on the matters of ye old bikes. Norton I believe built wheels offset probably due to a silly heavy cranked big twin doing its thing. I've read about it but promptly lost the whys & whereforalls due t lack of interest in the subject mater. I do recall that wheel builders that corrected the obvious mistake resulted in queer handling bikes.

Sheesh, who'd buy a British bike?:crazy:

[Grumph]

I was going to say Greg or Paul will be along in a while but they have both given input which I thought would be sager than mine on the matters of ye old bikes. Norton I believe built wheels offset probably due to a silly heavy cranked big twin doing its thing. I've read about it but promptly lost the whys & whereforalls due t lack of interest in the subject mater. I do recall that wheel builders that corrected the obvious mistake resulted in queer handling bikes.

Sheesh, who'd buy a British bike?:crazy:

British ? where ? thought they were built in Asia like nearly everything else...

It was Syd lawton who sorted out Nortons and Triumphs back in the day. from memory, the factory jig for Norton wheels was out...
And when in line, the handling was miles better.....The old test is try riding it hands off - if it goes straight, fine. If you've got to grab it to stop going in the gutter, fix the bloody thing.
Given the wheels are probably spoked by girls in Thailand, I'd still pick a spoking/jigging error. If it can be done by unskilled labour, it can and will be fucked up.

[F5 Dave]

Not sure where my Triumph was built as an 07, but the are pretty much all Thailand now.

Moving a spoked wheel at least a little sideways used to be easy. Take off tyre (so you can see if spokes protrude through nipple & risk puncture) then loosen every 2nd spoke/tighten alternate spoke which will move rim quite a bit. With more modern tubeless spoked rims I cannot comment, I've only seen my Trials bike one -which was just some mastic over the nipples.

[jellywrestler]

i suppose you could use red string for the laser beam look I can send you some if you like, my girlfriend has a supply of it, every twenty eight days.

[AllanB]

I don’t agree with Triumph statement as a generalisation - bike specific probably. Your bike for example presumable is offset so the front and rear sprockets align - to correct the offset imagine cutting off the headset and rewelding it Xmm left or right (depending on the existing offset) so the wheels align perfectly. The engine and bulk weight will now be bias one side - If a pillion sits side saddle you can feel the bike naturally pulling to the side their legs hang off (don’t ask how I know this, miss spent youth). Take your hands off the bars while travelling straight and the bike will pull that way too.

But really they should have designed that bloody engine so it sat sweetly in the frame with wheels aligned!!!!!

[Blackbird]

But really they should have designed that bloody engine so it sat sweetly in the frame with wheels aligned!!!!!

Yep, but then you run into another problem in that the weight of the motor isn't evenly distributed about the centre of the bike. I suppose there comes a point when the designers say "fuck it, most people won't notice a bit of misalignment" or words to that effect :rolleyes:

I experienced that problem in the early 70's shoehorning a Triumph twin into a Ducati 200 Elite chassis - bloody nightmare in aligning sprockets, making spacers and so on!

[fixer]

I've recently exchanged an email with Steve Bridge at F1E Motorcycle Works on this subject. I hope he doesn't mind me quoting him here: "The only bikes I have known to have offset wheel alignment from the factory are some harleys due that have the wide back rims and the clearance from the drive belt to the tyre becomes an issue, not saying there aren`t any others but I can certainly say it is not a good scenario and I can`t imagine why Triumph of all company would make a bike with such a poor design and compromise the handling. I have owned and repaired a few of the 865 hinkley twins of the same period as your scrambler and none of them have an offset wheel alignment certainly not when they leave here. Also they would not pass the 308 chassis certification if they did."

I think that if I knew for certain that the wheel offset was there for a good reason, then I would be able to relax. But I can't help being reluctant to push the bike in corners when there is even a suspicion that the bike is not assembled correctly.

If Honda made a Scrambler, I probably would have bought one. But I really like my Triumph and I will pursue this issue until I am satisfied or too tired to care any more.

[HenryDorsetCase]

mastic over the nipples.

wait, whut?

is that what we're calling it now?

[HenryDorsetCase]

I can send you some if you like, my girlfriend has a supply of it, every twenty eight days.

she might have some of that nipple-mastic as well.

I really have nothing to add to this thread.

[AllanB]

Have you checked the chain is fulling nice and parallel with the sprockets? Just in case some knob switched over axle spacers from left to right on the rear (presuming they'd fit if one did so.

[BASS-TREBLE]

Not sure I'm reading this right but are you sure your rear wheel is aligned properly as far as how the adjusters are set?

When you move an adjuster on one side of the wheel it will point into a slightly different direction so I don't see why you can't move it until the centerline of it has moved 15mm at the front wheel so it is now spaced 15mm on one side and 15mm on the other of the front wheel?

[Grumph]

Not sure I'm reading this right but are you sure your rear wheel is aligned properly as far as how the adjusters are set?

When you move an adjuster on one side of the wheel it will point into a slightly different direction so I don't see why you can't move it until the centerline of it has moved 15mm at the front wheel so it is now spaced 15mm on one side and 15mm on the other of the front wheel?

True, grasshopper...but the chain line must remain parallel to the wheel centerline...

And no, I wouldn't like to pay your chain and sprocket replacement bills....

[BASS-TREBLE]

True, grasshopper...but the chain line must remain parallel to the wheel centerline...

And no, I wouldn't like to pay your chain and sprocket replacement bills....

Fully agree but I see no mention of being certain that the wheel centerline is parallel to the chain line.

[fixer]

The marks on the chain adjusters approximately match now, with the wheels offset by 15mm. This chain adjustment was done by the dealer at the bike's first service. And it is the dealer who is telling me that it's adjusted correctly as it is right now.

I have a small pointer that clips on the rear sprocket that I have used for checking the chain and sprocket alignment. From what I can see, the sprockets do not quite line up at the moment. However, when I set the chain adjusters so that the front and back wheel are rotating in the same plane (chain adjuster marks differ by about 3mm), the rear sprocket has turned too far the other way and the sprockets again do not appear to line up.

Tomorrow, if I have time, I'm going to try and get reasonably accurate measurements between the swingarm pivot and the rear axle on both sides. I've done this before but not since the dealer adjusted the chain. If the measurements on both sides are not equal, I will have something else to ask Triumph about.

[koba]

If Honda made a Scrambler, I probably would have bought one.

Make one!
I did.

[cotswold]

I had a 2007 and I would not worry too much as the pegs will be on the deck well before you lean it very far.
ps I liked mine too apart from ground clearance. ( if you pull out the baffle they sound nice too )

[fixer]

I'm actually quite impressed by the ground clearance on the 2014 Scrambler. It's substantially taller than both the Bonnie and the T100 that I've ridden recently and the suspension, both front and rear is decently firm. The Bonnie scraped the side stand on the ground if you even thought about turning left. On the Scrambler I haven't scraped anything, even in bumpy corners.

So I measured the distance between the swingarm pivot and the rear axle (quite tricky to do accurately) and came to the conclusion that the left hand end of the axle was about 2.5mm further away from the swingarm pivot than the right hand end of the axle. Armed with this info, I decided that the workshop at Holeshot had simply put blind faith in the chain adjustment marks when they adjusted the chain, which IMHO was completely unjustified. I.e. they messed up.

I moved the left hand end of the rear axle forward 2.5mm and carefully checked the wheel alignment (pretty good), the sprocket alignment (very good) and the vertical alignment of the wheels (not bad either). This time I also loosened the front axle and re-tightened it carefully.

So I'm largely back where I was before I took the bike in for its first service. At that time, everything looked largely okay, except for the chain adjustment marks being about 2 or 3mm out, and the bike pulling to the right when I took my hands off the bars. I haven't taken it for another test ride yet, but I suspect that it will still pull to the right. If it does, I think I might take it to Gill Tuffin, the frame certification guy in Hamilton, and get him to check it in his fancy laser machine.

Whilst I don't believe that any of this is causing a noticeable handling problem, I do think that I'm getting to the point where an expert opinion is justified. Partly because my opinion of correct wheel alignment and Holeshot's opinion seem to differ so substantially. And partly because the bike pulls to the right either way!

At some point I will give up and just enjoy my bike. I have not yet reached that point.

[fixer]

Make one!
I did.

Out of what?

[Ocean1]

So I measured the distance between the swingarm pivot and the rear axle (quite tricky to do accurately) and came to the conclusion that the left hand end of the axle was about 2.5mm further away from the swingarm pivot than the right hand end of the axle. Armed with this info, I decided that the workshop at Holeshot had simply put blind faith in the chain adjustment marks when they adjusted the chain, which IMHO was completely unjustified. I.e. they messed up.

I moved the left hand end of the rear axle forward 2.5mm and carefully checked the wheel alignment (pretty good), the sprocket alignment (very good) and the vertical alignment of the wheels (not bad either). This time I also loosened the front axle and re-tightened it carefully.

So I'm largely back where I was before I took the bike in for its first service. At that time, everything looked largely okay, except for the chain adjustment marks being about 2 or 3mm out, and the bike pulling to the right when I took my hands off the bars. I haven't taken it for another test ride yet, but I suspect that it will still pull to the right. If it does, I think I might take it to Gill Tuffin, the frame certification guy in Hamilton, and get him to check it in his fancy laser machine.

Whilst I don't believe that any of this is causing a noticeable handling problem, I do think that I'm getting to the point where an expert opinion is justified. Partly because my opinion of correct wheel alignment and Holeshot's opinion seem to differ so substantially. And partly because the bike pulls to the right either way!

At some point I will give up and just enjoy my bike. I have not yet reached that point.

I like your opinion. And I think you're already there.

Find a flat, non-cambered surface long enough for a decent play and then see if the bike still wants to pull right.

All of my bikes have tended to drift on a normally cambered road if you let the bars go, to the point of having to shift my weight sideways a couple of inches to keep it straight.

'Course, you could always see what happens if you ride on the right hand side...

[F5 Dave]

If rear isn't aligned you often notice it at very low town speeds it will wander and be a pain to keep in a straight line. Kobas Honda is a joy to behold. Surprising they didn't make a production version really.

[fixer]

If rear isn't aligned you often notice it at very low town speeds it will wander and be a pain to keep in a straight line. Kobas Honda is a joy to behold. Surprising they didn't make a production version really.

Are there any photos of the Honda floating around?

[F5 Dave]

Probably spy photos, I heard there were some Japanese gentlemen enquiring of its whereabouts at the local TSS bike shop, but they were vague on why they wanted to know. They tried to throw them off by saying it was in upper hutt, but they only had to look a few blocks away.

Maybe it will show up in production yet?

I'd buy one, except of course I hate Hondas.

[koba]

Out of what?


Are there any photos of the Honda floating around?


Probably spy photos, I heard there were some Japanese gentlemen enquiring of its whereabouts at the local TSS bike shop, but they were vague on why they wanted to know. They tried to throw them off by saying it was in upper hutt, but they only had to look a few blocks away.

Maybe it will show up in production yet?

I'd buy one, except of course I hate Hondas.

Yeah, only a grainy spy shot at this stage...
Info is thin, it's rumoured to be a high performance two stroke.

Upload to come.

[F5 Dave]

More real ability than those stylised R100GS thingys Ewan & Charlie movie star holidayed around on, and well capable of a quasi continental jaunt of say Thailand or Bali.

[fixer]

More real ability than those stylised R100GS thingys Ewan & Charlie movie star holidayed around on, and well capable of a quasi continental jaunt of say Thailand or Bali.

I've heard a rumour that a small group of Auckland riders are gallivanting about the gravel roads of our fair countryside on GN250s with road tyres! As far as I'm concerned, if it gets you out and about on a bike and you're not ashamed to be seen on it, excellent! Ewan and Charlie might have had satellite phones, free Beemers and an entourage the Sultan of Brunei would have been proud of but, of all the things they could have done with money and fame, they chose to ride motorbikes on grubby backroads. Good for them I say. :-)

[AllanB]

I ordered a bloody great big measuring caliper from the USA some years back. I use this for checking center points between the swingarm axle and rear wheel axle. Works a charm.

Here it is - big mother - given the freight cost I should have ordered a few, flicked them off and reduced each share.

You could make a suitable tool for this from a length of rod and a suitable sset of pointers each end (one needs to be adjustable of course).


http://www.harborfreight.com/24-inch-jumbo-aluminum-caliper-96509.html

[koba]

I've managed to procure a covert photo of this crazy machine.

[fixer]

That "bloody great big measuring caliper" would have been quite handy. Though the measuring was complicated by the fact that the ends of the axle and swingarm pivot are not the same distance from the centreline of the bike. They're about 20mm offset on one side of the bike and about 10mm offset on the other. But I made a caliper out of a piece of 1/2in steel rod, a couple of Bark Buster handlebar brackets and some bits of threaded rod that I cut to different lengths. So I'm reasonably confident that the rear axle was incorrectly adjusted before and is now somewhere near right.

But while everything looks to approximately line up now, the bike still pulls distinctly to the right. As an experiment, I thought I would quantify this, so I slung a small pack 0.5m to the left of the centreline of my bike (using the aforementioned piece of 1/2in rod attached to my packframe) and weighted the pack with plastic bottles of water. 5 litres of water wasn't enough, but 6 litres of water was about right to balance the bike to the point where I could easily take my hands off the bars and the bike would maintain a straight line. If you've carried two 3-litre bottles of water in a supermarket bag lately, you'll know that that's a fair chunk of weight. Especially if you try holding it 0.5m away from your body.

I've done some rough calculations based on the weight of the standard exhaust system (about 11 or 12kg) and the distance of it's c-of-g from the centreline of the bike (about 150mm), and I reckon that it should take about 3.5kg to balance the exhaust, not 6.5kg. And this assumes that Triumph have done nothing to balance the exhaust themselves.

So the saga continues for the moment. For your amusement, I've attached a photo of my bike with a 6.5kg weight slung on the side of it.

305255

[fixer]

I've managed to procure a covert photo of this crazy machine.

Nice! And I suspect that dropping it would not be such a concern, for various reasons. :niceone:

[F5 Dave]

So you've fixed it sweet (I supposed goes with your screen name)

Just b careful filtering with that sticking out the side.