Modern Vespa

What started as a discussion over in Charlieman's "Vintage Vespa With Sidecar" thread led to me ordering new tires & rims to replace my worn and rub-damaged tires with some big ol' 11" 120x70-11 Heidenau K61's on SIP Tubeless rims. The tires arrived, even though the new SIP site still says the order is awaiting fulfillment, and so I installed them on the Sprint yesterday, which would up being more work than I was expecting, with more to come.

First off, these tires are not only big, but WIDE, and that's what makes this interesting. The front tire went on almost just fine. first I had the unpleasant surprise of discovering that the lower shock buffer had twisted and was about to pop out of the mount, so first things first, I had to fix that.

Then, even with that fixed, I discovered that the wheel was rubbing just a tiny bit on the front spring, so I pull the tire off (again) and put a washer under each wheel. Not the best, but it fixed the rubbing. It doesn't seem like a lot of work, but doing all that was a lot of work.

Then on to the rear wheel. I knew that I'd have to drop the motor out of the rear shock mount, plus remove the PM Tuning pipe to get the tires swapped. But then I found that I was rubbing on the clutch cover just a tiny amount. No biggie. More washers under the wheels, and I'm good to go. Again, and this was partly due to working out of boxes right now, this was a lot more work than it needed to be because I didn't have some basics like jack stands which would have made it all much easier.

so with my 1mm spacers (aka washers) in place, rear wheel back on, shock bolt re-installed, re-attach the pipe. Which rubs. A lot. To figure out how much, I started stacking washers on the attachment bolt from the bracket to the pipe itself. eventually, I determined that I needed a good 10mm of spacers, which is a lot of washers. Then, I remembered that I had some 8mm ID aluminum tubing which I'd actually seen recently. Dig through boxes until I find it, cut two lengths and install those as spacers. This gave me decent clearance from the tire to the pipe and it's FINALLY time for a test ride, which I know is the part you've all been waiting for.

Oh, and the center stand is now too short, so I have to stick a board under it to park it. I guess it's center stand time, which will go better with the tuned pipe anyway.

The extra diameter is noticeable when you're on the bike and took a tiny bit of getting used to. In terms of ride quality, I didn't notice it being any rougher than I'm used to, but they definitely feel better cornering. That could be because I was used to my old, crappy tires, but I don't know if they ever cornered like these do, and the old tires were also K61's, so I guess I'll never really know.

On on the highway is where I noticed the biggest difference. In the past, 65 was about as fast as I'd want to ride before it started feeling dangerous. This time, I was up to 75 and it still felt good. The increased mass and diameter really helped steady the wheels at speed. About that same time, I had a minor panic attack that I was doing 75 on wheels and tires that I just installed, and started worrying that something was going to come unstuck. So I jumped off at the next exit, gave everything a quick once-over, which all looked good, then turned around and headed home.

All in all, a PITA to install, but a big difference. If you're going to switch over to bigger, wider tires like this, be ready to do some custom fitment (at least on pre-PX bikes), especially if you're running a leftie tuned pipe. If you have a box, expect to need to drop the motor out of the rear shock, but it'll be a piece of cake after that.


That's not good.

Josie approves of the new wheels

bigger

wider

center stand is the new side stand

fat tire

Well that was less modification than i expected. Sounds like they were well worth it.

I like the positive comments for feeling more planted, that's the second good review of the larger diameter tires.

Are you going to put extensions on the center stand? How much do you actually need?

Could you put a flat piece of steel or aluminum under the mounting bolts as a spacer to lower the stand?

Is there a smaller OD pipe that could slide inside of the current stand, expand the part sticking out to size? Then the boot could cover up the extension.

Slide a smaller diameter pipe inside then a piece from an old stand over the outside if you have one?

Pull out the welder and put extensions on?

Last edited by Christopher_55934 on Sun, 29 Nov 2020 15:31:40 +0000; edited 1 time

The 120mm width on a 2.5" rim is supposed to fit but may need a little caressing to fit, depending on your scooter.

Wide tire aka tyre kits and taller tires.

From my research,

The 130mm is technically 5mm wider in both directions, that's where moving the engine 4 mm to the right, using an offset 3" wheel made for the application, 130mm can be made to fit and clear the clutch cover and shock spring.

But there's the whole cascading effect, moving rear shock top right to align properly. Shock not clearing body so you have to massage the body to clear shock spring. Motor hitting the right engine cowl possibly.

Then you haven't even mounted the front tire, I've seen suggestions of using the same 3" wheel with a narrower tire such as a 110 or 120. The tracking is supposed to not be that far off and noticeable.

Putting a 2.5" wheel on the front to clear with the same issues of tracking as above.

The center stand needs at least 1.5" extension, and I may go that route once I have a chance to examine it further. By the time I got the wheels on and not rubbing yesterday, I was pretty much done.

I think that I coudl sand the clutch cover a tiny bit and not need the washers on the rear hub, but would still need to sort out the rubbing on the front spring.

Time will tell

How close are you to the shock spring in the back?

Also out of curiosity, can you get a picture of what exactly is rubbing? Without getting into a lecture on safety, is it a peak on the edge of the tire, that could be a wear surface when cornering? Could you help the wear process along safely and create some clearance? Just thinking I've never been down to the wear bars on the edge always down the center.

CM
Wow. Well, I'm a bit surprised by three things:
1. Front spring rub. Mine didn't - but I forgot I had done all sorts of yoga and have a disk set up.
Likely means I have an extra few mm of offset from the factory vs drum.
2. Rear scrubbing clutch cover. This really confuses me. I have a 5mmish DRT spacer on my cover so it pokes way out. But it's no where close to my rim which is too tall to have any impact on that cover.
3. Funny how wildly different your 3.5-10 Heidenau are vs my 3.5-10 Continentals!

Miffed how there could be clutch cover interference. That ones got me curious.

Glad you found hwy speeds more stable.

Now I'm wondering what is rubbing? I thought it was the wider 120 tire, didn't you put on a 110 tire?

Be careful shaving the clutch cover, I once took off about 1mm (guesstimate!) for it to crack along there in under 50 miles.

AHHHH.
Christopher - right.
I have 110/70 11.
Chandlerman has 120/70 11

So he has taller, fatter tires than I do.
Thus:
softer ride
wider interference issues - tho only very slight.

Now all the differences make sense.

So I'll go with Plan B: Don't shave the clutch cover!

I've attached various pictures of clearance, old damage, and the spacers on the exhaust bracket.

I want to get a few more miles on them before I reserve final judgement, but thus far, other than the installation adventures, they're all good. I have a new front shock coming, so I'll probably get that installed next weekend and try to put a few miles on them after that.

I didn't have any interference issues with the rear shock/spring, just the clutch cover. I'd like to have a 110 to compare, because it sounds like a much easier fit for those few millimeters.


This was the old rub damage on the rear wheel.

not a lot of clearance, even with the spacers

how close in front? Real Close!

The sprues are touching the spring.

spacers. The final frontier.

Chandlerman, did you put a 120/70-11 on the front too? I'm sure I read that 100 or maybe 110 is about the max for the front (and with a 2.50" SIP rim). The back can go wider with the swing arm cut and the bigger offset rim (3.00" wide).

Yup. 12/70-11's front and back. It's tight, but it fits.

I decided that I didn't want to stick with the old shock after the lower buffer came loose, so I got myself a little early Christmas present.

My 2c on wide tire conversions:

Rear: 130/70-11 is the widest (standard) conversion - using the SIP tubeless 2.0 rims. Requires 10mm cut off the motor swing arm to shift it right. JB make mounts specifically for this conversion. Results in a 4mm left-of-centre offset. Some leftie pipes are designed to accomodate this conversion (and listed as such). The frame will need modification for the rear shock to fit. In theory the upper shock mount should be shifted 10mm rightward to keep the shock travel vertical (I haven't done this). This will require even more extreme frame beating for the shock to clear at the top. Removing the rear wheel with a 130 is a drama: remove pipe, airbox cover off, undo rear shock and drop motor as far as it will go - only then can the wheel be coaxed off the hub and out of the well. Some people cut a section from the left side of the frame to make this easier. SIP rims scratch if you look at them funny.

Front: 110/70-11 is the widest (standard) conversion - again using the SIP tubeless 2.0 rims. They will also result in a 4mm left-of-centre offset. PK disc conversion forks with PX disc hubs also add leftward offset of ~3mm - so the combination leads to about 7mm left-of-centre offset.

There are many other ways to perform wide tire conversions. Brother E has found a Kymco rim that will take a 140/70-12 - required some serious grinding of the swing arm to fit. (I have heard a local scooter shop in Jakarta caught wind of his idea and is now producing replica rims!) Mixing halves of rims and adding spacers is another tried and true option (but not tubeless).

I needed to have both the front and rear wheel balanced (take in a PX hub so they can fit them on the machine).

There is a lot of debate about whether or not wider = more traction/stability/anything.

There is a lot of debate about whether tires need to be aligned/centred.

I have no point of reference apart from riding an ET2. Supposedly that is meant to be a stable well tracking bike. My custom bike/wide tire conversion feels way more stable and leans so much better on corners. It has been ridden by someone with expert level experience and they gave it the thumbs up.

Nice write up PP. The difficulty in changing the wheel would put me off.
Wonder what the biggest non-pita tyre is?

CM1 has new toys.
Pheas's rat scoot is lookin good!

The JL pipe would likely mean that anything short of a bike tire would require the pipe to come off for wheel removal?

That's correct, and was the case even with 3.5x10's. The spacers I put on the pipe *might* be enough to squeeze the tire by without removing the pipe.

I realize that I took a bit of a Poor Man's approach on the wide tire install, but I didn't notice any difference in terms of offset when I did it or balance while riding it.

I'll head out this morning once the sun comes up and take a closer look.

You can definitely see the offset if you look closely and think about it.

I'm going to just run these puppies for now, because I don't feel like doing the work to address it and it feels so much better than the other tires, even with the offset.

Also, I don't necessarily want the wider tires, I just wanted the taller tires for stability at speed and arguably didn't do enough homework before I pulled the trigger.

That offset at the front looks like the 4mm the rims are meant to create so that the tire clears the clutch cover or front shock/fork. Wide tire conversions have to offset to clear stuff on the right.

Typically a 110 would be used on the front to ensure it doesn't rub the shock or fork. So a 120 adds 5mm more on both sides - you've added 1mm spacer and got clearance. Which seems about right - I recall checking and there is about 4mm clearance on my 110 (K61).

So 5mm offset in total. I reckon mine is more like 7mm at the front (PK fork with PX hub = 3mm plus rim).

One thing I played with - the fatter the tire the less that offset is noticeable (to the eye).

Another thing - the centre of mass (equilibrium point) on these bikes is somewhere way to the right because of the motor. Alignment that would actually balance these would be way over to the right. So what's a few more mm?

You could say that all Vespa riders are compensating... but wide tire conversions are compensating a little more ;P

This pretty well sums up my thinking on the matter. Even being hyper-attuned to any change in balance or performance, when I headed out today to pick up some lunch, if there was any noticeable change in the balance, I didn't notice it. I did, however, notice that the bike just feels so damn stable, especially at higher speeds, compared to what I'm used to. LOLOL!

What do you mean by stability? Wanders less? What did it feel like before compared to now?

Obvs I can't answer for CM1... but something I notice is that I feel so much more confident leaning into corners (c.f. the ET2 on City Grips). Don't feel that puckering feeling like I'm about to slide out and low side. Which is an interesting thing to feel - like what sense is it that you use to feel the difference in traction on corners? It's not like the ET2 is actually sliding out in any way - it's some weird perception that just makes me think the G force limit on my custom setup is higher. Not something I'm willing to actually test to completion obviously!

And also completely different everything: tires, shocks, wheels, forks, frame, centre of mass....

With UK roads in such a poor state, the bigger the better. My VBC feels very planted at speed, and whenever the wheels hit a divot, tram line, small pothole or manhole cover, I don't feel at all unnerved (ok, maybe at 70 mph). This with a 100/90-10 on 2.50" front rim and 120/70-11 on 3.00" rear. On a PX with Piaggio 2.10" rims and decent 3.50-10 tyres, I never feel as brave going into sweeping bends at speed and have a tendency to edge towards the centre line and oncoming vehicles. Not so on the VBC. The extra contact area and leanability makes all the difference.

Not sure if it's the case but a VBC seems smaller and more nimble than a typical 10" wheeled largeframe, even when it's no longer on 8s. Anyone else find the same?

One of the reasons I tried the larger tires - was traveling and knew I might be on roads that were less "Californiaesque".
Potholes and irregularities are less daunting.
Like being in an SUV vs a Miata.
Probably give a little something up in parking lot conditions - but more meat in contact with street in corners - at least that is my perception.
Stability at speed on HWY - don't feel like the wind is going to just blow me over.
Also - due to my rig - the extra 15MM of clearance to ground at tail doesn't seem to have diminished the cornering - but it is much more robust for not scraping when coming out of steep drives or parking lot exits - now I dont have to baby it.
Those are my perceptions anyway.

This sums it up nicely for me.

Additionally, one of the most stressful maneuvers at 55+ on the old wheels was just a plain, boring lane change. Now, a lane change at 65 or 70 doesn't feel risky at all, and that's a huge difference.

What terrifies me is a curve over crosswalk lines in the rain. Few times I've slid a bit on those. Hopefully the fat tires help with that.

Ok thanks. In that case I'm not sure I need the 11's just yet. Mine feels pretty good as they are. Although trying out new Heidenau K58's and it feels less planted than the K47's from before. But will be doing 1000km's this coming week, we'll see after that.

The reason SIP made 11's is that they are meant to be easier to fit the tires on. My tire guy assures me they are not. The 70 vs 90 profile looks sportier and I'm sure that was a reason too. But it seriously limits your tire choices.

The K58's are an all weather all terrain tire and get great reviews. Let us know how they go. Looking forward to the story and pics! Stay upright and try not to break down

First big ride last week - was meant to be 2 x 400km rides around Bathurst NSW and I had serious ignition issues...had to get a 150km ride back to the van and come back to pick up the scooter. This was on the 177 which had the stock ignition. So the ride was cut short by a day and and a bit. I fitted the Vape from the 200 when I got home. Much more betterer!

EDIT: posted this in wrong thread. Mildly related to this topic.. so including the moved post location here:
http://modernvespa.com/forum/post2441987#2441987

Posting here since its kinda part of the discussion but if you want me to move it let me know and I'll get rid of it.

While I was messing with balancing front hub and rim, I got around to test mounting to the front fork my 2.5x10" tubeless rims with 130/70 10" tires on them just to see if they would fit. Straight mounted and the tire rubs against the fork. With 1 washer on each stud to space the rim out a bit the tire just barely clears the fork. I'm sure that is not safe as sitting on the bike or hitting bumps/etc would cause the tire to deform and rub against the fork still. With 2 washers on each stud to act as spacers it clears fine. Probably enough to avoid rubbing when tire deforms in usage, but I am not sure I would even want to bother with it having 2 washers behind the rim. Purely an experiment just to see if the 130/70 tires would fit. Haven't tested on rear yet... too damn cold out
and I don't want to get down on the ground and freeze while doing it just for knowledge sake.


130/70-10" no spacer washers

130/70-10" 1 spacer washers

130/70-10" 2 spacer washers

This is a perfect spot to add your measurements, Swiss

I have noticed that I get a tiny bit of rubbing sometimes, but not enough to make me do anything about it, so all good by me

it's going to be in the low 60's here today, so hopefully I'll be able to sneak out and and least run a few errands on the scoot today, because a cold front is coming through tonight, so rain and back to cold(er) for the holidays.

I still would like to know if you guys think you could take a bit off the side as if the tire tread was wearing down on the edge and get enough clearance. Those pictures make me think there is tread to make clearance.

I bet you could.. there is a few mm of tread on these new tires and it looks like it only needed 2-3mm to get ok clearance at least on the 130/70 tire up front. But the question then is do you really want to spend the time shaving a few mm off each tread on that side of the tire just to get the clearance?

Especially when you can do nothing and eventually have it done for you.

I was thinking a piece of 100 grit taped to the surface that is rubbing to clear out the rubber so it doesn't wear a groove in the metal. I was also thinking on a 120 tire not a 130.

Or just use a tire that fits

I rounded off some very soft Heidenau's that had been squared off. I used a surf form tool. It was really easy.

Do y'all celebrate April 1st at xmas time down under?