Help Needed to figure out how to remove wheels on unusual German (Draisin) Trike

[iangreenhalgh]

Hi folks

Got some broken spokes on the rear wheels of one of my trikes so need to get the wheels off. However, they aren't held on by a nut or in any way I can figure out, never seen anything like this before. The hole in the side of the hub doesn't have a grub screw in it, it seems to be a helical spring. Anyone seen anything like this before and got any idea how to take the wheel off?

 

[amberwolf]

It's a split tube or "spring" pin, seen them called dowel pins and roll pins too.

Does the hole go all the way thru to the other side? If so, you just tap (sometimes with a very big hammer ) the pin out from whichever side it is farthest from.

split tube pin - Google Search

Once you have the pin out, the axle may be pressed into the hub tightly enough to require a 3-jaw puller to remove the wheel, but first I'd just try a bit of lube into the joing and turning the one now-loose wheel while standing on or holding the other.


I had two of these fail at the same point (at the same time) on my SB Cruiser trike on the pedal-only drivetrain, on the sprocket that receives the pedal chain, that's on the transfer axle to the left side wheel. After I knocked out the broken halves, I temporarily used a crappy 5mm (?) allen wrench I have a bajillion of from assembling things that come with them...it still hasn't broken that in the many months (year+?) since then, because I keep forgetting to look up and order the right size pin.


BTW, if you are relacingg the wheels yourself, they don't have to be removed to do this. (might be easier to remove them iff taking them to a shop, though)

 

[iangreenhalgh]

Aha, cheers, that is very useful. I also have a ton of those allen keys for the same reason.

I was hoping to replace the wheels with some different ones so I can add disk brakes - this trike has just one brake, a Shimano rim type on the front, and as I'm going to put an electric motor on it, it needs a brake upgrade.

However, I'm not sure if I'll be able to change the wheels now, certainly not with the ones I have, which are Skyway Tuffs with moped tyres and 203mm brake rotors.

I guess I'm stuck with using the wheels that came with the trike because I've never seen any like this before.

 

[amberwolf]

What does the outboard side of the plastic wheels look like? (the discs will ahve to go on the inboard side anyway to have somehwere for the calipers to mount).

FWIW, if the center of the hub with the keyway in it is a steel tube all the way thru the hub (should be), you can drill a hole thru it (and the plastic hub) that lines up with the existing hole in the axle, and install the same type of pin in it. Might need a much longer pin so you can guide it in place thru the plastic part and set it.


If the axle holes are the same diameter, you can change the whole axle out to one that is just a bit longer and has threaded ends for nuts if you like, and then all your bearings can stay as-is. This hsouldn't be too difficult; it's likley that anythingg mounted on the axle is secrued the same way as the hubs, but I can't clearly see all of that--the part that goes into the difff on the left side looks like it narrows down; it might be a splined piece, that you could emulate on the new axle by having it machined or even hand-filing / dremeling if you have the patience.

If theyr'e different diameters you'd have to change the bearings too, for ones that have the right size ID.

 

[iangreenhalgh]

They are double sided plastic wheels - same both sides, a screw thread for mounting a freewheel on both sides.

The axle is a solid bar, 18mm in diameter, the plastic wheels have a much smaller diameter hole, they had standard BMX axles in them, which are 8mm diameter if memory serves me correctly.

I'll study the trike in more detail tomorrow and try to get the wheels off, I'll take more pics so you can see what I'm dealing with.

Much appreciate the advice, cheers.

 

[amberwolf]

The axle is a solid bar, 18mm in diameter, the plastic wheels have a much smaller diameter hole, they had standard BMX axles in them, which are 8mm diameter if memory serves me correctly.

In that case, did they use bearings in the wheels, with the wheels spinning on the axle, or were they fixed on the axle like what you ahve now? (they look like they have keyslots, which would imply fixed, but maybe that's shadows from whatever the stuffing is in the axle holes).

If they have bearings, you would have to remove the bearings in those wheels, and install a fixed (keyed) tube with an ID to fit the a larger axle. The tube must be affixed to the wheel such that it can take the entire torque load on the wheel of both accelerating and any braking done via the axle itself.

If they don't have bearings, you would probably still have to remove the original tube and put a larger one in there--the 8mm size may not support single-ended use (bend under load, leaving you with wobbly wheels, or bend back and forth while rotating and snap off during a ride).

To get a large enough ID you might have to use a tube with a larger OD that may not fit the existing metal part of the hub, so that might have to come out, too--if it's cast into the plastic instead of press-fit, it would probably destroy the wheel to do it.



It might be easier to just install a disc brake rotor on the axle itself, and mount hte caliper on the frame. Then you keep your existing wheels and don't have to futz with that stuff, just do the relacing with new spokes. (like 14/15 butted Sapim Strong...13/14 at most if you have to go any larger for whatever reason)

 

[amberwolf]

If you decide to put the rotor on the axle, the diff may already have a place to bolt it right on, like the stuff on Main Street Pedicabs:

Disc Brake Rotor

Pedal vehicle parts & tools. Pedicabs, Delivery Trikes, Pedal Trucks by Main Street. Resources and repairs.

shop.pedicab.com

If not, a collar can be found to fit the axle diameter that you can drill or have drilled for a rotor plate like that one, and a caliper mount can be made to bolt to your frame in the right spot. I'd check first with the various pedicab companies to see what they have, because it's likely already being made and just has to be adapted to your specific frame and axle.



You would have to get at least half of the axle far enough out of the fframe on the side you're mounting the rotor on to slip the rotor over it, but this is almost certainly done with grub screws or roll pins (like the wheel hubs) at the entrance to the diff itself. If not, then at (one or more of) the pillow-block bearing collars.

 

[iangreenhalgh]

I've not made any progress to update you on, I managed to borrow some pin punches but I haven't managed to get the pin out yet. The battery I bought for this thing has arrived, it's a 60v 20Ah thing intended for an electric scooter, I got it very cheap NOS.