Grime TIME
Your questions answered
carbon care
I took a big stack on my carbon fibre Scott Spark – totally my fault – and I think I’ve broken it. There are some cracks in the paint on the chainstay, and I’m not sure I trust it any more. Is there anything I can do? I’ve only had the Spark for 18 months and it cost a packet.
Jay, Warwick
You’re right to be cautious, Jay. While the damage may just be cosmetic, it could be structural, so it’s not worth taking any risks. Fortunately, carbon fibre is repairable, so all may not be lost. Several UK companies offer a full carbon frame repair service, from assessment to repainting. To find out the cost you’d have to get in touch with them (just do a quick Google search), but it may well be economical to get it sorted. From an environmental point of view, repairing a carbon frame is definitely preferable to throwing it away. Good luck!
Shit creak
A quick one (hopefully!) – my 12-speed Shimano cassette creaks like mad and I can’t seem to get it to be quiet. It’s pretty new, on a greased Micro
Spline freehub, and the lockring is done up tight. It’s driving me mad! Rhiannon, via email
There are few things more annoying than a mystery creak! The first step is to check all the bolts in the drivetrain – including the mech hanger, main mech bolt, jockey wheels, etc. However, Shimano’s XTR cassette is known to be prone to this problem, and it’s potentially really easy to fix. There should be a very thin, see-through spacer located behind the cassette. It’s easy to miss out if you fitted it yourself, and we’ve had bikes arrive without it in place, too.
If it’s not there, hopefully this will solve
the problem. Head to your local bike shop to purchase one, or find it online. It’s called the Shimano CS-M9100 cassette spacer and the part number is Y1X401500. It should only cost a pound or two.
viscy business
I’ve got a set of Fox knee pads with a D3O insert in them. Riddle me this – how does D3O actually work? It’s soft and flexible most of the time and then hardens when it’s hit. Is it magic?
Tom, via email
It isn’t magic, just science! D3O, and other similar compounds, are constructed from materials known as non-Newtonian fluids. The viscosity (ease of flow) of Newtonian fluids such as water or oil only changes when their temperature changes. However, non-Newtonian fluids’ viscosity can alter due to other changes in their environment, such as agitation or pressure, known as ‘shear stresses’. Some non-Newtonian fluids get less viscous when they experience shear stresses, whereas others get more viscous. D3O is in the former category – if you get a bit of raw D3O putty, you’ll find that it flows very slowly. When you gently push the D3O (a low shear stress) the polymers that it’s made up of can move out of the way, allowing it to be flexible. But when you apply a quick force (a high shear stress) the polymers can’t flow quickly, and thus it gets more viscous and ‘hardens’, offering you protection. Hopefully that explanation demystifies things a bit!