Bicycle Mechanics - How to fix frame/axle incompatibility

OK, so, I'm building this bike. Among the parts are a Trek 7300 frame (a 700c hybrid) and a Shimano rear hub. I've built the hub into a wheel (second one I've done!) and *then* discovered that the hub I'd measured for this frame was, in fact, a different hub. That one had an OLD of 135mm. This one —*the one I spent an evening turning into a wheel, the one with the right number of holes for the rim — is 130.

This bike's destiny is to have 8 gears, no more or less. So I don't need all that room back there.

So, my question is this: it seems to me like I could carefully bend the stays 5mm closer to each other. That's 2.5mm each. Not a big deal, I figure. But this frame is aluminum. I don't *expect* trouble, but I figured I'd ask before grumbling around and rebuilding this wheel, of which I am already quite proud.

My plan is to tie a rope around the dropouts, stick a piece of wood between them, and twist until, when I release, the distance is 130mm. Does anyone anticipate an issue with this?

It's got the "fork" type of seat stays. Here, I'll show you.

http://joshuanewmandesign.com/xfer/rearFork.jpg

Edit: A secondary question is, how much of a hassle is it to change out the axle on a really normal Shimano hub? Maybe that's an easier thing to do.

Whatever you do, don't attempt to cold set (permanently bend) the rear triangle of an aluminum frame. That's for steel frames only.

Regarding your statement that you only need eight gears, and so you don't need "all that room back there" (i.e., the 135mm OLD hub), I'll point out that the freehub on modern Shimano-compatible 130mm or 135mm hubs will accept the same 8/9/10 speed cassettes, "road" or "mountain.". The wider 135mm hubs are "mountain" hubs, less dish makes for stronger wheels. Has nothing to do with which modern Shimano-compatible cassettes it will accept, though.

Joshua-

I would have to say +1 on not cold-setting an aluminum frame. Even if you were to space the dropouts correctly, you would then have to set the dropouts themselves to be parallel to each other. Dropouts that are not parallel have the propensity to bend or break axles.

I think your idea to change the axle is the better one. Get the proper length axle (I think it should be like 142mm, someone please correct if I am in error) , and a couple 2.5mm spacers for the axle and use the old cones and spacers. Be aware that doing this can sometimes involve fiddling with different spacers, wider cones, etc., POSSIBLY. Didn't say it would be easy, just a better choice than the respacing the frame.

Seriously? For 2.5mm?

Seriously? For 2.5mm?

You might be surprised how hard it is. But I am NOT a professional mechanic. Give it a few more responses here so you can let some professionals weigh in.

You might be surprised how hard it is. But I am NOT a professional mechanic. Give it a few more responses here so you can let some professionals weigh in.

I'm not a bike shop professional, but I fix people's bikes in my basement for beer. :p Seriously, that's a pretty rude remark.

I've cold set frames, I've also read the instructions on Sheldon's site. The first thing it says, in bold letters, is do not cold set unless your frame is steel. Is Sheldon considered professional enough for you?

Whether cold setting is really necessary in this case is another matter.

Btw, kenhill3, cold setting (a steel frame!) just 4 or 5mm won't affect dropout alignment enough to worry about. I'm not a professional (unless you count beer payments), but again I've done it and it works fine. I've also cold set greater distances, like from 126 to 135. For that, it's probably enough to matter, I re-aligned the dropouts for that. As pointed out in Sheldon's instructions (remember, he's a professioal, so this should carry a great amount of weight), if the dropouts were misaligned in the other direction than they are during cold setting, there would be a greater chance of broken axles.

I'm not a bike shop professional, but I fix people's bikes in my basement for beer. :p Seriously, that's a pretty rude remark.

I've cold set frames, I've also read the instructions on Sheldon's site. The first thing it says, in bold letters, is do not cold set unless your frame is steel. Is Sheldon considered professional enough for you?

Whether cold setting is necessary in this case is another issue.

Well biked-

Please accept my apologies for being rude to you, I did not mean to diss you or anyone else here. My intent was to suggest that the OP get some more replies. Those who do this day in and day out for a living would be a good addition to the replies already posted, including yours.

Again, my sincerest apologies!

Btw, kenhill3, cold setting (a steel frame!) just 4 or 5mm won't affect dropout alignment enough to worry about. I'm not a professional, but again I've done it and it works fine. I've also cold set greater distances, like from 126 to 135. For that, it's probably enough to matter, I re-aligned the dropouts for that. As pointed out in Sheldon's instructions (remember, he's a professioal, so this should carry a great amount of weight), if the dropouts were misaligned in the other direction than they are during cold setting, there would be a greater chance of broken axles.

Sorry, I was typing while you were posting-

Great information, I don't claim to know everything, I appreciate learning from you. Thanks.

And, yes, Sheldon DOES carry a lot of weight in my book.

+1 for not cold setting this frame. Plus think of re-sale value. Would anyone want to buy this frame after you have cold set it and weakened it? You can always re set a hub OLD but the damage/cold set you do on the frame will be forever.

I'm not worried about resale value. I got the frame for $40, shipping included, on Ebay.

That said, lengthening the axle (http://harriscyclery.net/itemdetails.cfm?ID=2436) seems pretty trivial by comparison. A nut or two from the hardware store should get that all up ons.

So, a follow-up question: is this a 135mm axle, or a 135mm OLD axle? Should I be adding, I dunno, 10mm to the OLD to get the total axle length?

Er, never mind. As usual, Sheldon has the answer (http://www.sheldonbrown.com/frame-spacing.html).

I'm not worried about resale value. I got the frame for $40, shipping included, on Ebay.

That said, lengthening the axle (http://harriscyclery.net/itemdetails.cfm?ID=2436) seems pretty trivial by comparison. A nut or two from the hardware store should get that all up ons.

So, a follow-up question: is this a 135mm axle, or a 135mm OLD axle? Should I be adding, I dunno, 10mm to the OLD to get the total axle length?

I figure dropouts to be on the average 5mm thick. So add 10mm to 135mm would be too much. Let's say 142-143mm.

Edit: Here's what Sheldon says:Axle Length
Typical quick-release axles are 11 or 12 mm longer than the spacing of the hub locknuts. This gives 5.5-6 mm of axle protrusion on each side. You don't actually need nearly this much, so for respacing hubs to wider spacing, if you're not adding more than, say, 5-6 mm of spacers, you don't need a new axle. As long as you have 2 or 3 mm sticking out on each side, that's plenty.

Silly me for trying. Sheldon is da man. Does that answer your question?

Indeed!

you can live dangerously and just cinch the 130 into the frame (i've done it before, its just a lot of qr nut tightening) or respace the hub. I would just respace the hub. Probably $20-30 at a shop, less if you have junk hubs and spare washers/locknuts around

Aluminum loses and incredible amount of strength if it is bent, even a LITTLE bit. Give your hub/axle 135mm spacing, ( if that's the spacing for the dropouts, not all hybrids have/had mtn spacing . Don't forget to re-check your "dish", if it's "off " the bike wil feel like it's trying to lean over to one side. (I was a "pro" mechanic )

you can live dangerously and just cinch the 130 into the frame (i've done it before, its just a lot of qr nut tightening) or respace the hub.

Cinching it up doesn't get tight enough, and the spring of the stays has a tendency to squirt the wheel out before it's all the way in place, anyway.

So I'm lengthening the axle. I don't anticipate the dish being off. It's correct now and I'm not going to do anything to make it off-center. Is that what you mean?

So I'm lengthening the axle. I don't anticipate the dish being off. It's correct now and I'm not going to do anything to make it off-center. Is that what you mean?
If you respace the hub correctly you will make the rim off-center. You want to keep the distance from the drive-side locknut to the cassette lock ring the same so you don't change the chainline. Therefore, you will have to add the 5 mm spacer to the non-drive side of the hub and recenter the axle so it protrudes evenly on both ends. That will shift the rim a bit toward the drive side and you will have to redish it to get it back to center.

If you respace the hub correctly you will make the rim off-center. You want to keep the distance from the drive-side locknut to the cassette lock ring the same so you don't change the chainline. Therefore, you will have to add the 5 mm spacer to the non-drive side of the hub and recenter the axle so it protrudes evenly on both ends. That will shift the rim a bit toward the drive side and you will have to redish it to get it back to center.

It's a matter of compromise. The by-the-book way is to keep chainline intact, add spacers on the left side, and re-dish. The simple-and-dirty way is to add the spacers evenly in both sides, accept 2.5mm offset to chainline, and not re-dish the wheel. If this was a short-chainstay with 10sp, the simple-and-dirty would be probably not great. But with a former hybrid that probably has longish chainstays, and 8sp setup, you can probably squeeze by with the cheap-and-dirty. Check the chainline first, with some luck you have some offset the other way to start with, and if not, at least you'll know.

Put the spacers on the non drive side & redish the wheel. That will be fairly simple and will give you a stronger wheel.

I'd do the above, getting a longer axle, if necessary. Easy to do, and your best, cheap solution.

Thanks so much, everyone. This gives me a little more wheel tweaking experience, to boot!

It turns out, Sheldon's got the axle I need on sale for 10 bucks. Awesome.

Even simpler, this thread (http://www.bikeforums.net/showthread.php?t=362258) solved my problem 100%!

I just tried it and everything works out great with no odd stresses at all. There's ~1mm of axle on either side.

The chain line may, in fact, be odd. I don't have a BB yet to find out. But if that's the case, I'll just move the nut I put on the right over to the left and redish.

Can't go wrong with Sheldon advice.