DMR V8 pedals: replacement cones
The DMR V8 flat pedal, introduced some time before the Millenium, is apparently still a best-seller at MTB specialists Chain Reaction Cycles, along with the V12 and V12 Magnesium. I've used the V8 since 2008 and the lighter V12 Magnesium since 2009, but both on road bikes, not MTB. Next time I'm feeling extravagant I'll buy titanium axles for the V12s to make them even lighter. My V8s are supposed to be fully maintainable but actually they're not. The cone nut on the outer end of the axle is the one part you might need, and DMR don't supply them as replacements. I managed to get some though, from DMR.
Like saddles and handlebars, pedals are a contact point and tend to be a personal thing. I don't like being clipped in, and DMR pedals are a grippy alternative with projecting pins screwed into the aluminium pedal body. I removed some of the pins as they catch your shins; my right shin is permanently scarred. But I do like the simple design of the pedals and how they are easy to keep clean. Viewed end-on they have a parallelogram profile with the centre of pressure a little forward of the axle, which suits my style of pedalling.
Unlike some other designs of flat pedal the DMRs have two bearings spaced well apart and the V8 has a grease port in the body, near to the inboard bearing. They are supplied with a small grease syringe and an allen key for the pins. Supposedly, the pedals come pre-greased – so the grease port seems a strange feature. When grease is squirted in the port it goes through the inboard bearing only. I suppose the idea is that you can regrease the outboard bearing by removing the dust cap at the end of the axle.
Anyway, the bearings in my pedals had become rough, or 'gritty'. There was also a slight amount of play between the pedal bodies and the axles. A good way to check the bearings is to remove a pedal, hold the body in one hand and turn the axle between a finger and thumb of the other. Any 'grittyness' can easily be felt through the thumb. When I took the pedals apart it was evident that the outer cones were pitted – a roughened surface on the 'race' where the ball bearings run, squeezed up between cone and cup. This outer cone is simply a nut with a concave head, and the inner cone is part of the axle. The axles were fine, as were the cups inside the pedal bodies. So I just needed some new outer cones.
My local bike shop is an official DMR stockist and they weren't able to obtain any. When I phoned DMR they said these cones never need to be replaced. Mine do, I said. You must have let the pedals come loose and run them with no grease, he said. I didn't, but to be fair, they sent me a pair of new cones free of charge. I put in new ball bearings as well. Photos:
The only tricky part is setting the tightness of the cone against the ball bearings. There isn't enough space for a socket spanner inside the hole so you use a flat bladed screwdriver or tweezers to wind it down so it just rests lightly on the balls. Then a washer, followed by the lock nut. A socket spanner does fit over the lock nut. It's best to clamp the inboard end of the axle in a vice so you can tighten this nut hard against the cone again.
Now hold the pedal in one hand and turn the axle with the finger and thumb of the other, to feel if it's 'gritty'. A little trial and error may be required: there should be no play between the axle and the pedal body but it should spin smoothly with no roughness. Unscrew the lock nut and adjust the cone as required, then put on the dust cap. My V8s are now spinning sweetly.
This is the first time I've taken bicycle pedals to pieces. Like Hilary, I decided to give it a try. I assume the loose bearing types are pretty much the same principle and can easily be dismantled to replace ball bearings and grease. If the cones are damaged and replacements aren't available then I suppose it's new pedals, or refit the old cones and take a risk. What ultimately fails to destruction is probably the balls. Does a pedal still turn with broken ball bearings? I don't know.
Magnesium V12s, incidentally, have a plain bearing (with no rolling elements) inboard and a sealed, replaceable bearing on the outboard end.