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  1. #1
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    switching out 27x1.25 wheels for 700c

    so i have a conversion fixed, panasonic frame 63cm. so far so good, replaced everything on it but the rims. as a result of that, today my back hub came apart while riding (super fun). my chain fell off and my wheel started wobbling around. luckily i didnt fall, but i had to walk my bike home about a mile. anyway, after toying with the back hub and being unsuccessful in trying to repair it (i have never worked on a hub before), i took it to the bike shop and they said i was missing a cone for my wheel. the guy at the shop replaced the piece, but it was just a quick fix, apparently he didnt have the real piece i needed. he said it would hold up for a short time, but i do need to replace my back wheel (at least) in the very near future. the shop i was at didnt sell my size wheels (27"), they only had the newer 700c size. he said i would be able to use the 700c on my bike. i told him i would ponder it and come back. so I go home and put my roomates 700c wheel on my frame. fits, i would probably need a new brake but that would be it. heres the problem... since i am riding a road conversion, the crank is a bit closer to the ground, resulting in pedal scraping when i make wide turns. I have mostly taken care of this problem by getting 170mm crank arms (original were 175) and new pedals that are about an inch shorter. so far, no problems. so annnnyway, my question is, if i were to put the 700c wheels on my frame, would i have a large problem with pedal scraping since the wheels are a bit smaller? has anyone on here done this? any input is appreaciated.

  2. #2
    Veteran Racer TejanoTrackie's Avatar
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    The difference in radius between a 27" rim and a 700c rim is about 4mm, so assuming you run the same size tires (27 x 1 1/4 is same width and height as 700 x 32c), then the effect is about the same as going back to 175mm cranks. Since you are already having problems with pedal strike, this will only make things worse. I think maybe you might try finding a complete new axle with cones to keep your 27" rear wheel if possible.
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  3. #3
    Senior Member seau grateau's Avatar
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    27" wheels are 8mm wider than 700c. Switching will but your bottom bracket 4mm closer to the ground (not considering tire change [you will need new tires]) which is pretty negligible. I'd say it's a good switch.
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  4. #4
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    would i be able to use 23c instead of 32c if i want thinner tires? do they fit universally on all road frames?

  5. #5
    Constant tinkerer FastJake's Avatar
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    You can always put a narrower tire in a frame (provided it will mount on your wheel.) You shouldn't have a problem putting a 23 on any 700c rim unless you found some super wide rims.

    I couldn't quite understand what went wrong with your wheel, but it sounds repairable. Definitely easier/cheaper than buying a whole new wheelset.

  6. #6
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    8cm difference in rim diameter means the rear of the bike will be lowered 4cm all else equal. That doesn't equate to a full 4cm at the crank because the front is still at the same height. ~2cm BB height change is pretty negligible.

    You shouldn't be dealing with the possibility of pedal strike via rear wheel size in any case- if this really is a problem, swap cranks down to 165 (spins better anyway) or get even narrower pedals. You can order a new 27 without any trouble, and this would be the path of least resistance. If you get a rear 700: a) your wheelset will be mismatched, which is weird but has no functional drawback, and b) your brake will need to be dealt with. If it's an old centerpull it might reach, otherwise you're going to have a hard time since a 700 on a 27" frame tends to require extremely long reach calipers which are hard to find, and then of course your brakes will be mismatched. I bought some sidepulls and ground the slot the pad clamps to all the way out through the end, which works fine but isn't necessarily your best option.

    If it's a fixed, you don't really need the rear brake anyway. There's a range of tire sizes that will work on a given width rim- narrow tires fit relatively narrow rims. I don't know how narrow your rim is now. 23s are overrated- on a track bike great, on a commuter not worth it. You'll be more prone to getting flats and you're going to really get hurt if you fail to post over a bump. As an aside, going to the narrower tire is going to lower the bike also- again, though you don't deal with pedal strike through wheel and tire choice.

    I think you should buy a 27" wheelset of your desired width and call it a day. SunRingle makes some nice ones for cheap- CR18 is nice.

    I don't understand how a wheel could function even for a minute without a cone, nor do I understand how one could possibly fall off. Are we talking about steel wheels here? You could presumably find a cone, repack the hub with new bearings and roll on, but the hub shell might have been damaged and your wheels might not be worth any effort other than the effort required to remove them from your bike and throw them as far as possible.
    Last edited by ismellfish2; 09-15-10 at 09:58 AM.

  7. #7
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    so I have decided that I am probably going to switch out my back wheel for another 27". my rear hub is too damaged to repair. the local bike shop was going to charge me 130 for the wheel and to swap it for me quick, since i dont have the proper tools to remove my cog and freewheel. i thought this sounded a bit expensive... is this an average price to pay? 100 for the wheel +tax+service. does anyone know where I can get a 27" with flip flop hub online for cheaper? i am not too familiar with online bike part retailers. i was also looking at the eightinch ameilia wheelset... comes with two 700c wheels, tubes, tires, flip flop hub, fixed cog and lockring for 100. are these reputable? seems like the better deal to switch to 700c and get TWO wheels for 30 cheaper...

  8. #8
    Veteran Racer TejanoTrackie's Avatar
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    You can get a pair of 27" track wheels for $125 at Velomine, and they'll space the rear to fit your dropout spacing >>> http://www.velomine.com/index.php?ma...roducts_id=395
    What, Me Worry? - Alfred E. Neuman

    Quote Originally Posted by Dcv View Post
    I'd like to think i have as much money as brains.

  9. #9
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    Looks like Harris has a 27" fixed gear rear wheel for $80 + shipping.

    http://www.sheldonbrown.com/harris/wheels1.html#630

    Considering you're also going to have to buy brakes if you switch to 700c (and the fact that $100 track wheelsets tend to be bottom of the barrel with little quality control), it seems like much less of a bargain.

    I would definitely trust the Harris wheel.
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