Thursday, September 13, 2007

Q&A: Rear dropout spacing frame alignment cold setting

I am back for another consult: I have a new frame for buildup (Kogswell Porteur- ordered raw w/o paint). It is spaced 135mm in rear, but I am thinking of using 130mm hub (Campy Centaur or Veloce- with 10 speed ergo drive train). I have years of experience as a bicycle wrestler and know how hard it is to re-space rear triangles as the frame is essentially a big spring. I have one bike currently that is spaced about 122mm, and accepts 126mm six speed hubs with just a little spread action. I have tried to get the stays to move those extra 4mm, but the stays return to original position after many attempts (which is good).

So can I, with a clear conscience, run a 130mm hub in a 135mm rear triangle without any liability other than the hassle of wheel removal and installation? I will attempt to add some spacers to the rear axle; and I know it is possible to run Shimano 135mm hub with Shimano cassette with
Campy ergo shifters- the J-tek thingamabob or some such.

Thank you,

Hi Michael,
You'll probably be okay running your 130mm wheel in your 135mm frame. It won't hurt the frame to squeeze it those 5mm, 2.5 on each side. The risk is that, with the squeezed dropouts holding your axle, the dropouts are slightly out of parallel. And, because they're clamped tightly against the axle locknuts they will be applying a steady bending force on the axle. Over time this force could cause the axle to bend, or maybe break. Fortunately, most modern quick-release axles are made out of chrome moly steel, which is tough stuff, so it's likely that the force from the dropouts
won't bend your axle, but there are no guarantees, I've seen some bend and some break, it depends on your axle, how much your frame actually distorts when compressed, how hard you ride, what kind of load you carry on your bike - and whether you're lucky.

If it was me, I'd realign the frame's rear end to 130 or get a 135 hub or re-space the hub you want to use to 135, or if you can't do that, just
adding anything, even 1 or 2mm will help.

That Kogswell frame is steel so it should be relatively easy to cold set. I would stand behind the bike, put one hand on each dropout and push my hands together. If you have large hands, you might be able to reach across the stays with your fingers and squeeze your hands together. No? You could also use woodworking clamps to gently squeeze the rear end down to 130.

Or, you could have a friend come over and you could do it together. Ideally, you'll do it carefully and not overdo it. You want to bend it only once if possible, not back and forth. But, it shouldn't be all that difficult to do it.

I did visit the Kogswell Porteur website
read about your bike and learned that it was designed for 26-inch wheels and that's probably why they went with the 135 spacing. So, my last comment is that maybe you might want to reconsider building your bike up with road equipment and use mountain stuff since that sounds like what it was made for? That's just a suggestion. It's possible yours is a custom model built for the parts you plan to use, but if that's the case, I don't understand why it didn't come with 130 spacing.

Hope something here helps you build up that cool bike in style,

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