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700c conversion with 90+mm ish front fork?

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700c conversion with 90+mm ish front fork?

Old 09-15-21, 03:11 PM
  #1  
The Trashman
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700c conversion with 90+mm ish front fork?

Hello, I have a old 27 inch 10 speed road bike that really has no right for the amount of effort I've put into it, but sunk cost, pure stubbornness and it's cheaper than the alternatives.
I've been wanting to convert it to 700c given me finding a cheap enough donor to strip them off of given the cost and rarity of 27 inch more offload oriented tires. I've tried several wheels from other bikes just to test fit, the rear spacing is 126, which lead me to try and make it a 12 speed with a spare set of 27" aluminum wheels, but I never really got it to work right, with the stock derailleur it''d rub spokes and the shimano off the donor didn't agree with it. Didn't really want to bother more since it was a shimano type freewheel that is obsolete.

Long irrelevant preamble aside, I found some donor wheels for free (just happen to have a full bike attached) the hub spacing on the front wheel is 100mm, the standard from what I have read. The spacing on my fork is 93ish with the rim unbolted, but I assume it is 91 when tightened as I've read that it was common for lower end hubs. The cone nuts as well as the lock washers do look to be quite a bit thicker than other ones I have worked on, would it be possible to buy a shorter axle and thinner nuts to get a few mm's off each side and get away without having to mess with doing something like cold setting the fork?
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Old 09-15-21, 10:09 PM
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Leisesturm
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"93ish" is not a valid measurement. Sorry. You need to be a real geek about these things and get it right. Use calipers or measure 3x and average the results. If you really did end up with something significantly less than 100mm, honestly I think it would be easier to find a new (or used) 100mm OLD (over locknut dimension) fork that is the same length as the old, than a shorter axle. That being said, have you simply tried putting the new wheel in the fork and seeing what happens when you torque down the axle bolts? I would.
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Old 09-16-21, 06:15 AM
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hokiefyd 
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To the question of thinner axle cone nuts...sure -- if the existing ones look to be pretty thick and you think you could gain a few millimeters on each side with different nuts, I don't see why that would not be worth trying. Unless the front hub uses a quick release mechanism, you wouldn't necessarily have to shorten the axle -- at least not initially for your proof of concept. If it looks like it's going to work, you could find a shorter axle or you could also consider just cutting your existing one. You'd just need to make one cut, to get it to the overall length that you want. If you leave one side of the axle assembled (with cone and lock nut, etc.), be sure to leave one of the other side's nuts inside of the cut, so you can thread that nut OFF the axle and straighten out the threads after the cut.
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Old 09-16-21, 06:59 AM
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Front hub OLD has commonly been 100mm forever, but there were a lot of bikes with 96mm made in the '60's, IIRC. My advice to you would be to:

1. check your frame for straightness.
2. Spread/cold-set/align your fork and rear dropouts to the widths that will fit your chosen set of wheels.
3. align your front and rear dropouts.
4. align your derailleur hanger.

If you don't know how, there are lots of YT videos on how to do this, many of them show you how to do it without using expensive proprietary tools.

This can be done, easily with a little work and attention to detail. Here is an old Dunelt that I "hot-rodded" a few years ago.





Some guy bought this and rode the entire Pan-Mass Challenge on it. Here's the build-link: https://www.bikeforums.net/classic-v...urrection.html
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Old 09-16-21, 02:58 PM
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Originally Posted by J.Higgins
Front hub OLD has commonly been 100mm forever, but there were a lot of bikes with 96mm made in the '60's, IIRC.
It is a 91mm hub, I have seen it referenced as either low end hubs (Sheldon) or as Japanese, which is likely accurate because the bike certainly falls into both categories.
I cannot get my calipers on either the hub due to the spokes, or the dropouts when they are tightened. The 93 came from me measuring the inside of the dropouts with the wheel out, but when the stock wheel is bolted on, the few mm gap closes up.
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