Only have one bike with disc brakes and that is the Tandem. Hope m4's with 200 mm discs F & R and they work. Might seem ridiculous to have such powerful brakes on an offroad bike -even if it is a Tandem- but that Tandem is fast and heavy. On the road bikes I have never even thought about needing extra braking but have to admit that disc brakes are very easy on the hands and to modulate the braking.
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How long was I in the army? Five foot seven.
Spike Milligan