Current Projects chat and miscellany

What issues could crop up?

You might get more help over at the tandems thread

Is it a sensible idea to replace these wheels with modern 26” size?

Probably not. 26×1⅜ is 590, so the best way to modernise would probably be 650B, i.e. 584. Common 26" (i.e. MTB) rims are 559, which is a much bigger change and will probably make it almost impossible to find brakes given that you already have a pretty long drop with the 590 rims.

you can force it to shift out of place if you hold the wheel still

If you apply that much force in normal service, you have already crashed.

I’d lose the drum brake of course

Not necessarily, you can still get drum brakes and the hubs to mount them on.

thanks for the response Tester. Mentioned losing the drum brake only because I would probably have to get a wheel built (to be 559 size) + a drum brake rather than just picking up a cheap 26” wheelset 2nd hand.

Seeing as those won’t fit I wouldn’t be averse to picking up a rear wheel in 26 1 3/8 with a working drum brake. Or could replace the existing drum brake.

A 650b rim brake wheelset could be nice, I’ll check on cost and availability. Annoyingly the brakes are at nearly their max. drop wise so a smaller diameter rim might need a new brake set which is another cost I’d like to avoid

a smaller diameter rim might need a new brake set

It would be worth trying a 700C, would probably fit with fairly skinny tyres.

picking up a cheap 26” wheelset 2nd hand

That's probably not going to work whatever you do, rear spacing on tandems can be almost any size, but very unlikely to be 135mm on an old one. That's the first thing you need to check, because all bets are off until you know what size hole your rear hub has to fill.

Ok I’ll have a crack with a 700c wheelset and see how’s much space is left. would like to keep the guards and have wide-ish tyres if possible so may keep the current size if 700c means I have to sacrifice both..

Will also measure the space between dropouts as well. If it was say 120mm or more would it be ill advised to push it out to 130mm if thats what I have available?

If it was say 120mm or more would it be ill advised to push it out to 130mm if thats what I have available?

Won't do any harm for the purposes of test fitting a 700C wheel. I'd be surprised if something with a drum brake thread was that narrow anyway, 140mm seems more likely.

Made my stock B'twin folder a bit nicer and lighter

Cranks are a little ott maybe but as I don't have any track bikes to put it on...

@Carabo best Btwin so far, well done mate

Always wanted one of those. Looks ace

wow! looks great!

excellent work!

They're pretty cheap! Not a lot wrong with the stock bike either except for the gearing and I would defintely add a double kickstand. Much easier to fold it that way and makes it stable enough to keep it from falling over in public transport.

First glance I thought they were wee Shamals. Great build!

Awesome Carabo !!!

too good...

I’ve now got a btwin folder need/want inverse proportionality problem.

Also has an old clip type headset, the quill stem that is currently installed seems a lot more modern and is very hard / impossible to do up tightly, as in you can force it to shift out of place if you hold the wheel still. Are there different internal steerer diameters but still ‘1inch’ (particularly for old bikes)?

Clip type stems on single bikes are ~22mm diameter quill, not 22.2mm like usual. The pinch bolt in the clip holds it in afaik and there’s no wedge or expander. I’ve got a 70s French Atax stem in my Parkes which fits in because it’s 22mm. It’s secured by the expander but I haven’t tried pulling it around while done up.

I -think- there is a slightly bigger diameter clip for tandems and I wonder if yours might be. Could well be that a 22.2 is loose in there and the wedge doesn’t really pull it up. Could also be worn quill or the steerer reamed to fit a normal quill but done a bit too much. Wonder if it’s worth putting a spare set of bars in another quill and seeing if it makes a difference. If you’re anywhere near Staines you’re welcome to borrow some of mine.

wow that looks great, how does it ride? out of interest whats the rear spacing?

This the the first Btwin I've actually wanted

Thanks! Ride is nice enough although my frame of reference is limited. It rides a lot better than a 16" folder I owned a decade ago. I am going to adjust the saddle angle to point upward slightly, with this riding position you're sitting further back on the saddle than I'm used to.

Rear spacing is 130mm. Rear triangle is stiff as F so will be hard to cold set.

Clip type stems on single bikes are ~22mm diameter quill, not 22.2mm like usual. The pinch bolt in the clip holds it in afaik and there’s no wedge or expander.

Ah, I didn’t know that. The stem is actually too narrow in diameter for the clip to hold it at all- it sits in there with a sizeable gap, and secures (somewhat) with the expander further down.

staines

Thanks v much but its quite a distance!

I’ll experiment with some alternative quills for now

This is too cool.