Originally Posted by
Jipe
But it seems more difficult for the Birdy because to fold the bike the chain must be on the smallest sprocket and belt drive sprockets are bigger than chain sprocket what could cause problems to fold the bike.
This is not an issue, I think. The fold works well enough on middle sprockets, and I don't think it's about sprocket size, really. It's more about sprocket position, the outermost sprocket gives least trouble when folding.
Originally Posted by
Jipe
Another issue is folding the belt on the opposite side of the teeth what for many belts isn't allowed by the manufacturer.
Yes, but apparently it's fine for Gates CDX, which the Delite uses. You can see it bends the belt backwards over a quite small tensioner wheel.
I had a look at the sprockets now. The smallest Shimano IHG compatible Gates sprocket is 22t, that means 52t up front for my gearing. The closest Gates offers is 50 and 55t which is close enough. Belt pitch is 11 mm, vs. 12.7 mm for chains, so the sprockets are a bit smaller for the same tooth count, though they are wider. If there are no chainstay problems or belt length issues, the main challenge is making a suitable belt tensioner, which gives enough tension while not blocking the fold, and ideally keeping tension during the fold.
Originally Posted by
Jipe
For the Birdy suspension I have Multi-S suspensions (front and rear) the front Multi-S is real shock with a spring + an oil damper and adjustable spring pre-load.
Interesting. That probably costs quite a bit too, but you're happy with it? For now I've ordered a green elastomer for the rear, and then I'll see if that is enough.