Grippy Front Tire?

You might check out sidecar block tires. They're only available in 18" and 19".
The Metzeler tires are great for wet work but otherwise the deep tread is not a long mileage front tire for sidehack use. A Dunlop lasts much longer though they don't have as deep a thread but use a harder rubber compound.
Heavy loading and hard braking willcause the sidecar to "outrun" the bike unless there is a sidecar brake and the sidecar tire has a good grip on the road. Often with a sidecar brake there will be a sharp lurch to the right under these conditions.
Racing rubber compounds are formulated for the specific road conditions expected, whether dry, wet, or offroad. Street tires must compromise. Sidehack front motorcycle type tires usually long outlast the rear tires unless auto tires are used on the rear.

Do you have telescopic fork?

thats what happens with no sidecar brake - its all good till a panic and then it will lurch left right when the front starts to lose traction

no good answers

i run a sidecar brake - but stopping straight in a panic is still a bit of a art and its easy to overcorrect.

three wheel abs would solve the issue entirely

Yes, I have a telescopic fork.

Would a block front tire provide more grip on pavement? I'd think a standard motorcycle tire would work better.

I am considering a sidecar brake. Seems to me the best setup would be a wimpy sidecar brake -- not enough to provoke a right-hand swerve, but enough to keep the front tire from skidding left.

Would an electric brake be a solution? They make such for trailers. Would be simple enough to wire a relay up to the brake lights that dumps power to a solenoid, yes? It would be on-off, but that might be good enough for this application.

Hmmm -- maybe an eddy current brake would work. You need a steel rotor and a beefy electromagnet. Or a really strong permanent magnet you can swing towards/away from the rotor. The good thing about an eddy current brake is the magnet and the rotor don't have to touch -- no wear! The braking force is entirely electromagnetic.

Crazier yet would be an electric reverse for the sidecar wheel. Engage the motor for dynamic braking -- that could be modulated through a variable resistance. Only dump power to the motor when you want reverse drive.

(Dynamic braking is an old slotcar technology. Simple and cheap once you have a DC permanent-magnet motor on board. A DC/PM motor can be used as a motor or as a generator. Put power across the leads -- it's a motor. Backdrive it without electric power -- it's a generator. Short the leads together and backdrive it, and the motor acts as a brake. Really! More wear in this setup, but it IS dual-purpose.)

The problem with eddy current and dynamic braking is the braking force should vary with speed. At high speeds the braking force might be much more powerful than at low speeds. Provoking a right-hand swerve at high speed sounds dangerous! A conventional friction brake wouldn't be speed-sensitive.

Sorry to be thinking through my fingers. I do that...

Ed Bianchi

I've had similar thoughts Ed. I'm hoping the folks here with real world experiance can shed some light on how these theories fall down in practice.

The sidecar block tires are flat tread design like auto tires resulting in a much larger footprint than the rounded tires.
A lot larger footprint= more stopping traction.

Was the front wheel locked up when you braked hard? If so you would not be able to steer. Yes, you can ad a sidecar rbake but it WILL NOT be a cure all in panic situations! You need to practicce hard braking under various conditions. It is also advisable to not just rely on braking but learn to try and develope some evasive maneuvors. P R A C T I C E in a safe place and try to do so above your comfort zone. THAT will do you worlds of good.

I'm not looking for a cure-all, but I am looking for more grip.

FYI -- more rubber on the ground does NOT necessarily mean more grip. Tire compound makes a big difference, which is why I asked about racing rubber.

And yes, I can practice, but I want to practice with excellent rubber and, possibly, a sidecar brake.

Ed Bianchi

This may not apply,but I noticed the front tire sliding and losing steering on left hand turns on icy roads. I found that weight transfer to the front would restore steering by goosing the throttle and breaking traction on the rear.

Ed Bianchi - 3/31/2011 2:32 PM

I'm not looking for a cure-all, but I am looking for more grip.

FYI -- more rubber on the ground does NOT necessarily mean more grip. Tire compound makes a big difference, which is why I asked about racing rubber.

And yes, I can practice, but I want to practice with excellent rubber and, possibly, a sidecar brake.

Ed Bianchi

On many outfits acheiving consistancy with a sidecar brake a concern under panic conditions. Effectiveness over there can vary with thhe static weight of sidecar, loading in sidecar, size of contact patch at sidecar tire (which can vary with loads directly related to many factors), etc. Some feel that consistancy if more important that PERCEIVED braking ability of a sidecar wheel. Remember panic situations are where it counts. Rolling up to a stop light with no steering correction seems good but we all need to know what happens when that emergency situation arises.

After a lot of reading and research I finally decided to order a Dunlop D404 100/90-18 front tire. I purchased it from 'Motorcycle Superstore' from their listing on Amazon.com. Cost me US$65.98 delivered!

This isn't a racing tire, but I decided I really wanted a tire with good wet traction, and to me that means lots of sipes in the tread. I also liked the fact the tread pattern jogs left-to-right, which should reduce any tendency to track grooved pavement or open-grate bridges.

I'm hopeful the tire's traction lives up to Dunlop's hype. I guess I'm okay with giving up a little bit of dry traction to get good wet traction. I try to avoid riding in the wet, but when I'm out on a weekend trip I have to deal with the weather I am dealt. And weekend trips are when I am most likely to have the wife aboard, so safety is absolutely top of the list.

I'll give Dunlop points for having a very good online fitment guide, which specifically calls out tires for a BMW K75C. I seriously considered buying the alternative tire they offered -- the GT501. But the difference in tread coverage made me decide on the D404. The fact I was able to pick it up so cheap was nice, but not a decider.

My next job is to get the tire mounted and give it some serious testing. If I live I'll report back here.

Best,
Ed Bianchi
Delaware USA
'87 K75C/Dauntless "Lady Carol"

Dunlop D404 is good tire, but it nothing "Grippy" about it.

Hi, It sounds like you already have a square block Metzler "Now my front tire is a Metzler -- a great brand of tire -- but it has an automobile-like tread." I run the same on the front of my 1977 BMW/Sputnik rig with no issues. However have the same problem with my 2005 Kawasaki Nomad/Motorvation rig using motorcycle tires, I found that by easing up on the front brake and using more rear brake it is better. That said I have to be ready in an emergency stop and thinking ahead.

Okay, update on the saga of my front tire...

I have just mounted a Dunlop D404F tire in place of the Metzeler Block K that the previous owner had mounted, and gave the Dunlop a rude introduction to the world. No 100-mile break-in. I HAD to find out if the tire change would make a difference. The new tire had maybe a good two miles on it before I took it up to about 50 miles per hour and jammed on the front brake.

It howled, but it did not let the rig pull sharply to the left like the Metzeler had. The rig stayed straight and I had control.

I tried a few more sharp braking maneuvers (all straight line), and the rig behaved itself. It wasn't until I absolutely seized the brake lever that I got it to pull a bit to the left -- primarily because the front wheel was locked and skidding. (At that point the front can no longer provide any steering, so I can't say it was a surprise.) Even so, the pull was nothing like the WTF?!? sudden change of lanes that I had experienced with the Metzeler.

Full disclosure here. I have only 28 pounds of air in the front. I wanted to plant a good amount of rubber on the pavement. From the side it looks like I have a good, but not excessive footprint. (I had reduced the air pressure on the Metzeler too, since that was the only way I could think of to increase its grip before I replaced it.) I might increase the air pressure somewhere down the road, but for now, as long as the front acts stable, I'll accept more tire wear and worse gas mileage.

Here's something else I have noticed -- the front-end wobble I had been getting at modest speeds is gone. I think that is mostly due to the round cross-section of the Dunlop versus the squared cross-section of the Metzeler. Steering the Metzeler left and right should shift the contact point from one edge of the tread to the other, which I think is what instigated the wobble. With the round cross-section of the Dunlop that sudden shift isn't present, so the wobble has nothing to drive it. The low air pressure in the tire should also increase the side-to-side damping.

Finally, the Dunlop has a smaller diameter than the Metzeler, overall, because it does not have that big, auto-like tread wrapped around it. The Metzeler rubbed against the lip of the front fender. The Dunlop has clearance. I never felt the rubbing was a real issue with the Metzeler, but I'm still happy to have that fixed.

On total I am very pleased with the tire swap. 'Course that is first impressions only. I might be suffering from the placebo effect. We'll see. Once I have a few hundred miles on the new tire, and especially some serious miles with a passenger, I'll report back.

Best,
Ed Bianchi
Delaware USA
'87 K75C/Dauntless "Lady Carol"