After doing a short season 4-5 k miles on my CSM/1150gsa auto rear wheel rig it became apparent to me the front 19" where going to be chewed off pretty fast and when turning or braking vigorously I didn't have enough tire on the road. I did the Dedone style trail mod, when starting this project, it retains stock wheelbase and fork angle and seems to not require a monster front spring even though the bike has more weight on front spring (2 spring numbers over Ohlins GS recommendation.per PPS loaded gs suggestion ) One of Strokers 15 " fronts has made it a completely different rig again, it dropped the front a little reduced trail a little more and gave me a decent tire contact patch, easier steering and great pavement handling and braking.It turns in a little quicker but no real bump steer head shake, I may add a damper to slow up steering slightly. So why hasn't all the GS heavy sidecar rig crowd gone to an auto front (they ain't inexpensive) ? Is anyone else building an auto wheel anyone considered attempting to get Woody's to lace a un-drilled 15" rim to a motorcycle hub ? DB A little more has anyone contacted http://www.buchananspokes.net/ ? That's a 135/80/15 Nankang oddly enough it was round and balanced easily, they're a copy of one of Bridgestone tire.There's room for a 145/80/15 and even tire rack has 145/65/15 winter tires Blizzaks and a Firestone Graspic that looks doable. EML,EZS and Armec have embraced auto rubber years ago.Another plus for Strokers effort he adds a double row ball bearing on the right front and brake disks with allot more float than our GS's ever had.Onward and forward.DB Tire size calculator http://www.tacomaworld.com/forum/tirecalc.php
Very nice. I'm gonna have to talk to Stroker and see if he makes one for the R12GSA. Keep us updated on how it's working out. Cheers.
Dave, we actually use a double row bearing on both sides of the front wheels. This type of bearing will handle the angular loading that a sidecar rig wheel gets. The left side bearing on the 1100/1150 wheels and both bearings on the 1200 model is the same special item that BWM uses for the upper fork bearing on Oilheads. To recalibrate the speedometer while using these front wheels, a R1100RT speedo drive must be used. This is a direct replacement on both 1100 and 1150 models. Obviously the speedo drive is not an issue on the 1200 model as the drive is not on the front wheel.
These smaller tires are actually becoming more common as the vintage VW and hot-rod guys are using them as well.The "smart-car'' also uses another size that will work for us. I use a 135R15 on my R1100GSA rig but a 145R15 will fit on the 1150 because of the different lower fork design. A search on the internet or ebay will give you some options for these tires. I see that 125R15's are even available again. I had not seen this size tire for several years, and was popular for use on some older Airhead sidecar rigs using 15" auto rims.
OK, all this is kinda confusing for a dimwit like me. But . . . The OEM rear moto wheel and tire for a 1150GSA is 150/70-17 with a diameter of about 25.5". Right now, I have a 155/80-15 Vredestein Snow+ car tire on the rear with a diameter of about 25". So I've lost about 1/4" in rear axle height because axle height depends on radius, not diameter. If I was to mount a 165/65-15 Vredestein Snowtrac 3 with a diameter of about 23.5" that would drop my rear axle height about 1". That means then to balance out the front and rear, I'd need to drop the front axle by about 1" too. The OEM front tire is around 26". A 145/65-15 (like the Blizzak) according to that TacomaWorld calculator should run around 22.4" which sounds a little too short. With a 145/80-15 (Michelin, Firestone and Nankang make 'em) I get a diameter of about 24.2 which is just about right (.9" drop in axle height.) But to complicate matters, I have a DMC trail reducer on the forks which is going to lower the front ride height, and a big spring (a 15-62) on my front Ohlins that heightens the front. I'm thinking that maybe I should simply park the loaded rig on a flat piece of asphalt and get a buddy to take some pics from the side with me and Kirby on board. If it "looks" OK, then it's OK. If it "looks" too tall up front then it is, and if it "looks" too short, then it's too short. I wonder how everybody else does this? Like when a builder is making custom leading-link forks for an outfit, how do they figure out how tall to make them? After all this blather, I do have a question for DaveBig. I know that you've got the Dedone-style lower fork mount (so it doesn't change your ride height) and you have the OEM front shock with a 13-56 spring. With the Nankang 135/80-15 on the Stroker wheel, what is the height of your front axle from your garage floor? Is it, in fact, 11 3/4"? BTW, here's another tire size calculator-- http://ejelta.com/tiresize/index.html
It can be done, the front is a 125 15" but the rim is 3.5 so a larger tire could be used... The rear and sidecar have 4" rims on BMW hubs
Yeah I've got the same setup on my rig as Drone does.I've just put a 16580r15 Nagkang all season on the rear.Around here it was all I could find.. Got that from Mid America VW..The stock wheel does keep the height good,but I do like the ideal of a car tire on the front its juat avabilty when traveling if you destroy a tire like I did this year on my way to the nationals.Had a hell of a time finding a 165hr15 took a day&half to find one... That would mean caring 3 spares...Its a nice looking setup....
I've found tires not that hard to find,they are old VW beetle sizes I think I got the front here http://www.selecttire.com/Nankang-CX668-Passenger-Radials-C56.aspx http://www.tirerack.com/tires/TireSearchResults.jsp?skipOver=true&width=175%2F&ratio=65&diameter=15 175/65/15 I a 185 would go in there also. http://www.cokertire.com/15-inch-tire-sizes.html?adjclear=true Coker tire has a bunch 135 or 145 http://www.walmart.com/ip/Nexen-11766NXC/19473481 Even Walmart has a 165/80/15 Cheap ! Tire Rack has 3 different 145/65/15 2 winters and a Conti summer tire. We're always going to have diameter issues (as if any BMW speedo was even close) so I guess one gets as close as one can and soldiers on. hopscotching who laced up your wheels ? I just reattached my chair to the bike, I have a reasonably flat garage,I laid a level on the chair frame it was slightly nose high unloaded,putting the small auto wheel lowered it a bit, Drone my current axle height is 11 1/2 so your figures are pretty close.I put my bike back to as close to the way I got it before putting on the front wheel bike very close to straight up unloaded, loaded it has slight lean out and less than 1" of toe in. In case no ones figured it out sidecar alignment is all subjective and probably not many are identical. A sidecar installer who will remain unnamed at this point fixed my first rigs original owner up with gl1100/ural with 20" of wheel lead, I only asked the seller had the chair been professionally installed he said yes of course, I didn't know enough at that point, Claude and Brock of Side effects educated me and my welding buddy and I chopped her up and started over, so much pain so little time.It was from your neighborhood Drone but I'm not holding that against you. On the other hand I have a spare tire mount I will carry a bmw wheel with something mounted on it.DB 165/80/15 Nankang vs 175/65/15 Continental WInterContact
bmweuro (Chris) at boxermetal built up the wheels (and the whole rig) for me... He now stocks the 15" rims....
I think the rolling diameter of the 135 tires is about 2" less than the 165's.. If so this would give about a 1" drop with all other things considered staying the same.
I'm on that mission right now,going to a buddy's hidden VW bone yard with my hub adapter to look for a steel rim that fits and building a spare pusher tire setup to carry for trips a snow tire here would be nice...
Drone you old tracker of all interesting threads on Adv Hacks your a numbers cruncher ! I've been trying to figure out what your good at ! We've found it data and finding it LOL. But can we remember that sidecar setup and design may not be a hard science and everyone has an opinion we the consumers need to find our way. I've experimented quite a bit some by accident (setting tow in) the trick is to go slow and be prepared to change,take of test rides.People designing things probably start out with normal ride height and remember the wheel goes up and down.DB
Yes, on what you said there--both things--you've got it right! I'll tell you what I did for a living sometime--and I was very good at it--and I guess I'm still doing it. Anyway, you got me seriously, really seriously, thinking about calling Stroker. I might have to sell a couple of guns, but I really like that front wheel.
I ordered a Firestone Graspic from TireRack last night may have been bad decision or maybe not ! I hope for a neutral steer tire. Here's a review http://tires.about.com/od/buyers_guide/tp/Top-5-Dedicated-Studless-Snow-Tires.htm I'll post an image of it next to the 135/R15 Nankang I'm planning on running it till its warm again as here in the midwest our secondary roads are mushy till June and the pavement has sand in every corner unless Apiril showers are cooperative.DB Steer tire : sidecar rigs have way more in common with trucks than motorcycles !
The wide one on the right is a 17" 1150rt the left one which has same spacing as the GS front axle is from 1100rt if your changing wheels on one of the 11** series you need a the narrow one.DB
Great advice there Stroker .My brother riding my sidecar found out the hard way that the small bearing was not up to it .Not good when he was 2000km away from a workshop .He was lucky i had a spare bearing in the tool box . We are running a 180 80 15 rear motor bike tyre or a 165 80 15 car tyre on the front. Great in the sand with a wider front tyre . Cheers Ian
Howdy Pops, great photos of a serious rig. Is that the front wheel that you posted in process photos of awhile back? I was wondering how it would hold up when following your thread. The car tires probably put more load on the bearings than the stock wheel. How many miles did you brother have on the his front wheel when the bearing let go? I always had bearing failures with my car-wheeled hot-rod Harley rig years ago until switching to double row bearings on the front and Timkens on the rear. My BMW rig sees much more abuse than the Harley ever did, so I figured on using a heavy duty bearing from the start on the Beemer wheels.
