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Chainsets and heel clearance

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  • August 28, 2012 at 3:27 pm #16687
    notfastenough

    Hi everyone,
    I currently use SRAM Rival crank/chainset, with no problems. I have a heel-in pedalling style (confirmed with a sports therapist) to alleviate knee pain. This means that my right shoe is not far from touching the rear mech cable alongside the chainstay when pedalling through the upstroke.

    I had in mind to go for Ultegra on my next bike. However, I’ve been reading reviews of a bunch of compact crank/chainsets in Cycling Plus this month. There is a mention of the ‘heel clearance’ provided by each product, but can anyone tell me how this is defined? Presumably the measurement is agnostic of different sized feet etc? The SRAM offerings seem to offer considerably more clearance than Shimano or indeed any of the other manufacturers (19mm for one of the SRAM components, versus a measly 4mm for Ultegra), which makes me think I might have to stick with SRAM, or be very cautious about a third-party offering.

    I’d hate to splash out on, for example, Di2, only to find that my knee problems return. Any thoughts from anyone with similar issues?

    Cheers for any help.

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  • August 29, 2012 at 12:20 pm #697329
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    step-hent

    i think Q factor and heel
    i think Q factor and heel clearance are seperate:

    – Q factor measure how far out the crank is from the centre of the bike at the point at which the pedals attach;

    – heel clearance is about how far out the crank is from the centre of the bike at the point where your foot passes the crank arm in the rotation (i.e towards the middle of the crank, where you would get scuff marks on the crank from your heels).

    Heel clearance in relation to the rear stays is, as Jimmy says, a product of the frame design (how the stays curve and how large they are) and Q factor. So I’m not sure the ‘heel clearance’ which C+ describe will make any difference to you at the back – it might, however, make a difference to whether your feet scuff the cranks.

    It’s worth knowing that some pedals will allow you to adjust Q factor by fitting a different axle (Speedplay, for starters), but the ideal Q factor should really be dictated by alignment of your knees, hips and ankles, not by needing more clearance.

    August 29, 2012 at 8:51 am #697327
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    notfastenough

    Hi Jimmy, thanks for the
    Hi Jimmy, thanks for the reply. I was thinking about Q factor, but including it in my original post made it a bit too long-winded. I haven’t measured the Q factor – is only influenced by the BB and the cranks, or the frame as well? I use Speedplay pedals, for which spindle extenders can be obtained if necessary.

    My hips are externally rotated, not by much, but enough that when I stand/sit/walk etc I have my heels in relative to the forefoot. If I stand with my forefeet directly ahead of the heel, I feel like the toes are pointing inwards.

    Full disclosure time: I got back into cycling knowing that the old knee pains that kept me off the bike previously would have to be sorted. Specialized Body Geometry insoles and wedges, a knee-friendly pedal system, a bike fitting focusing on cleat positioning etc, a session with a sports therapist, and a list of regular stretching exercises prescribed by them, all conspire to keep me comfortable.

    The cranks have scuff marks where my shoes are evidently rubbing very slightly – not all the time, but there sure isn’t much clearance.

    Any/all comments welcome!

    Perhaps I should ask Cycling Plus how they measured heel clearance in the review.

    August 28, 2012 at 7:18 pm #697325
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    Jimmy Ray Will

    Hi there. Sadly there is
    Hi there. Sadly there is nothing that scientific or official out there, heel clearance is defined by your perception and experience as much as anything. Shimano aren’t too had heel clearance wise actually, but DRAM does provide more on some cranks as do Campagnolo.

    However the bigger point is frame clearance for your heels as you mention that you are not rubbing your crank with your heels. Now frame design is most of this, however the starting point is how far apart your pedals are in the first place. Most manufacturers list this measurement as q factor. For you wider is probably better.

    Referece you heels in pedal stance, what is causing this? Is it muscle tightness or just bio mechanics or both.

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