“This builds upon our previous work in which we kept cells alive for weeks at room temperature within a similar hydrogel.
“However, it is important to note that this is still years away from potentially being available to patients and it is still vitally important that people continue to donate corneal tissue for transplant as there is a shortage within the UK.
Traditional rear hubs came with a standardized set of threads to which a standard freewheel/sprocket cluster could be screwed on.
Some newer Freehubs have the right-side bearing farther inboard, but these use oversize axles.
The Freehub incorporates the ratchet mechanism into the hub body (although the ratchet mechanism is still replaceable).
To remove the lockring, you need to turn it counterclockwise, but then the cassette will freewheel, so you need a chain whip to hold the cassette.
A special tool is available to remove and retighten the lockring on the road, using the bicycle's frame and chain to provide leverage.
“Many teams across the world have been chasing the ideal bio-ink to make this process feasible," said Che Connon, professor of tissue engineering at Newcastle University, who led the study.
“Our unique gel - a combination of alginate and collagen - keeps the stem cells alive whilst producing a material which is stiff enough to hold its shape but soft enough to be squeezed out the nozzle of a 3D printer.
By scanning a volunteer’s eye, they were able to use the data to print off one with exactly the same dimensions.
Professor Connon said: “Our 3D printed corneas will now have to undergo further testing and it will be several years before we could be in the position where we are using them for transplants.
Beginning around 1980, the Shimano "Freehub" largely replaced the conventional threaded rear hub.