Chainset or freehub? Chain slipping

W3LSH
W3LSH Posts: 17
edited October 2014 in Workshop
Hi all

I picked up a Trek Madone 5.2 recently to use as a winter bike.

The bike has a new chain and cassette. On my first outing all seemed fine until I got out of the saddle and tried to power up a short hill - as I went to power down my foot at the top of the pedal stroke dropped to the bottom of the stoke, with a metal/grinding sort of noise... I looked down and the chain was still on, took a few more pedal strokes that were fine, got out the saddle and again and only when I really tried to power down the same thing happened.

I've since done about 100miles including a couple of good hills (which are ok as long as I don't try the above).

From the searches I've done my guess would be the front chainset (which isn't new like the chain and cassette) or the freewheel hub? Any ideas?

Thanks

Comments

  • beetle1
    beetle1 Posts: 189
    Hello there, does this only happen when you apply more pressure ie out of the saddle? It sounds to me like it could be the pawls inside the freehub body. I had a recent problem with my Fulcrum wheels but the freehub and cassette would not engage at all as the spring inside the freehub body had broke. This can sometimes be as simple as the freehub body needs removing and lubricating with very very light oil. So, depending on which wheels you use I would start there, always good to check it anyway before a long arduous winter ahead. Hop this helps
  • W3LSH
    W3LSH Posts: 17
    Hi - thanks for the reply

    yes only happens max pressure when out of the saddle and 'going for it'. I'll look into how to remove the freehub :-)
  • keef66
    keef66 Posts: 13,123
    Normally I'd say that's a symptom of a new chain on a worn cassette, but you say both are new...

    Stick a different rear wheel on and see what happens. If it still jumps you can suspect the chainrings.

    Ditto with the suspect wheel in a different bike; still jumping and it's likely the freehub.

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