I was thinking about the old frame approach, but I'm not sure how I'd attach it.
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Xyz spaceframe reumbent trike
(82 posts)- Started 3 years ago by steveo
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Posted 3 years ago #
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Can't help thinking the whole of the rear half of this bicycle should be made of a old bike, with the square ally tubing to make a new front-end...
Posted 3 years ago # -
+1 to neddie's approach. Frankencargobike! Or if you like a reverse Xtracycle...
Remove forks from an old step-through 26" frame, e.g. an MTB or hybrid. If it has an intact drivetrain, even better. Bodge a connection to the cargo carrying front end, e.g. using stainless steel adjustable hose clamps/duct clamps. Adapt the steering mechanism accordingly.
Posted 3 years ago # -
Thinking about it, you could even keep the forks on, use them to connect to the steering rods for the front wheel at the front of the cargo platform.
Posted 3 years ago # -
I've seen bikes based on this approach I think the safest approach is to weld them together. Put a 90° post from the head tube to join to the cargo bucket and use the headset for the steering somehow.
Posted 3 years ago # -
"use the headset for the steering somehow." Could just use the forks. Connect rods via the wheel dropouts maybe. Would need some kind of articulated connection, but could be a simple vertical eyelet/rod joint.
Agree that maybe using head tube to connect to cargo platform seems sensible. Could just run two parallel square section tubes horizontally, then a retaining section perpendicular to these goes behind head tube, between top tube and down tube, or if a single spar step through, just snug up against back of head tube. Bolt securely with long bolts through the square of the retaining section for extra strength? Could double all these square tubes up if extra strength required. To stop cargo section rotating laterally you might need to brace against down tube somehow, maybe some extra square tubes running from platform and clamped there.
Posted 3 years ago # -
Got all the easy stuff finished today, cargo bin is a bit on the small side I think. First mod will be building it up a bit more especially after seeing an urban arrow up close. (cargo bike envy)
Looks like it's going to rain all week so that's probably as much as I'm going to get done for a bit though I'm out of bolts, big washers and aluminium tube so I'll have time for bits to arrive.
https://photos.app.goo.gl/d2aLHJpeR4WVrVKW7
Made the headset out of hmwpe, a fancy, slippy and tough plastic. I think it'll hold and saves the question of how to seal the various bearing surfaces.
https://photos.app.goo.gl/xJv5yDqRJdvycbSC9
Need to have a think about front brakes. I'm thinking roller brakes since they're more self contained than discs.
Going with a conventional drive train, cassette and mech plus a disk on the rear. If this rides I'm going to electrify it so need to keep that pretty vanilla.
Posted 2 years ago # -
Drum brakes are good - 90mm Sturmey Archer. @chdot cargo bike has these I think. Roller brakes can overheat - first UA we sold had that as Dutch spec and not really suitable for laden bike on long downhill. All been Shimano disc since then. Traditional Bakfiets sold here use Magura hydraulic disc or rim (although not keen on hot and worn rims).
Sounds like you are making good progress.Posted 2 years ago # -
Cheers laidback I'll keep an eye out for sa drum brakes instead.
Decent progress yeah. I suspect the rest will be small victories taking a lot of time to complete. 80/20 rules strikes again.
Posted 2 years ago # -
+1 for SA drum brakes.
These are on my Pashley Pronto and they are very solid. Hardly any maintenance required. Front hub also has a dynamo integrated so that takes care of the front light too. Worth considering.
Posted 2 years ago # -
If you want plain Sturmey drums, either 70mm or 90mm – I'd go for 90mm if you can — you may have to import them. SJS Cycles is out of stock, although they do have the hub dyno versions, for a price.
Ginkgo is, I understand, now shipping to the UK again, at least for anything about 20" rim sized and smaller. 70mm is €55; 90mm is €65, no doubt now excluding duty and VAT, though they should knock off their own equivalent of VAT first.
I thought Really Useful Bikes might have something but their website is becoming rather useless. Practical Cycles seems to have minimal stock advertised (on eBay) but may be worth phoning.
Posted 2 years ago # -
Cheers allercat, the sa seems to be out of stock through out the UK.
@crowriver I'm hoping to add a motor and battery so don't really want a dynamo. Running leds of a battery able to propel me should run forever!
Posted 2 years ago # -
@steveo worth checking fleaBay as I'm pretty sure there will be drum brakes available on there. Indeed I see a few Pashley Mailstar/Pronto front wheels being sold complete with drum brake. A couple appear to be new. Can find the levers etc. there too.
EDIT - These may be 70mm rather than 90mm. As Arelicat mentions, Practical Cycles have a couple of left or right side mount 90mm hubs in the fleaBay store. Don't you need the more conventional one though? Here's one: https://www.ebay.co.uk/itm/123794958168?epid=1665703970
No sign of the rear cassette hubs though you're using a disc brake there right?
Posted 2 years ago # -
Cheers crowriver, I'll keep an eye on ebay. I've got a decent 26" with a disk for the time being.
Posted 2 years ago # -
About as cheap as you'll probably find:
Posted 2 years ago # -
Cool thanks. These things seem easy enough to service.
Posted 2 years ago # -
That wheel arrived, hit another snag.
The axle needs to go through 50mm of aluminium section, 25mm at each side. The axel is only 135mm wide minus the hub at 100mm Its a bit of a problem. One solution is to use a m9 bolt as the axle with lock rings to hold it but this hub has sealed bearings so can't just move the races to where they're needed.
Another thought I had was to make a dropout out of some 6mm plate aluminum for the wheel to sit in and bolt this to the rest of the fork assembly. This would mean moving the pivot point back from where it is on other xyzs and i'm not sure how much of a difference that would make to the steering.
Unless there is some way of setting the bearing positions I'm not aware off, this picture would suggest he has over come this exact issue with a bolt.
Posted 2 years ago # -
I would suggest making the dropout from plate steel rather than aluminium. A square or rectangular piece. Drill holes away from the dropout end to bolt through your box section aluminium.
Posted 2 years ago # -
Yeah, I would probably replace it with a couple of lengths of stainless steel after I got everything built.
Posted 2 years ago # -
Sooooooo...
Finally made some progress, fabricated the bottom bracket assembly. Ended up having to buy a pillar drill and inverter for the shed to get the accuracy. Plan is to epoxy the bb into this and screw it to the frame.
Not sure if there is any way to make sure it's aligned or how much wiggle room I have before it gets irritating/fails.
Posted 2 years ago # -
Ended up having to buy a pillar drill
I'm failing to see any problem with this situation. :) I've only had mine a month and it's been amazingly useful. Only took a couple of hours to make a replacement pulley cover cutout switch adjustable prong thing, then it was good to go.
Posted 2 years ago # -
:)
It is actually a very useful tool to have available, just pretty bulky in my wee shed!
Posted 2 years ago #
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