Bike Dork Question

[DirtyHarry]

Dave, anyone else -

 

Have any experience with "cold setting" a steel bike frame? I have an old Italian steel frame with rear spacing of 120 mm.

 

I'd like to make it go to 130mm, since freehub / cassettes are easy and available.

 

Recomendations / Suggestions ????

[olyclimber]

you mean bending the hell out of it AKA dorking it? my bro brah Sheldon Brown knows his bike shizzle:

 

http://www.sheldonbrown.com/frame-spacing.html

[tomtom]

Just shove the wheel in there and be done with it.

 

[crackers]

Oly beat me to it. Read Sheldon's page, it really explains pretty much everything you need to know. Its really rather simple. The string alignment thing works very well.

[DirtyHarry]

Intersting. Thanks.

 

Anyone here actually done this?

[crackers]

oh, one other thought: physically and permanently bend it out to only 128 and then see how it rides, if it's okay then just bend it the 2mm when you're putting on the wheel, not permanent like...

[downfall]

Just get a 120mm hub threaded for a singlespeed freewheel. These are readily available. You only have one speed but that's what all the kids are doing anyway.

 

With the cold setting (I haven't done it but usually trust sheldon that what he says can be done can) it seems that you are liable to end up with the following unwanted results:

1) seat/chain stays bent at the bridges (maybe the distance isn't big enough to make this noticable though)

2) if you have horizontal drop outs, which you probably do giving the description of the frame, they won't be parallel anymore and you'd have to bend them too.

[DirtyHarry]

Seems like if you did it right, you could mitigate those possibilities. Do you mean, the rear dropouts would be bent so they wouldn't allign with the rest of the frame?

[downfall]

I meant that if you have horizontal drop outs which are parallel to each other to begin with but then bend the stays outward the dropouts are no longer parallel to each other and you'd have to rebend them where they meet the stay so that they are parallel again or else you might have problems getting your skewer to sit correctly.

 

Sheldon goes in to the framealignment problem (i.e., each stay needs to be the same distance from the center) and that seems easy to adjust. Bending the dropout tabs where they go in to the stays seems harder. I know framebuilders do this but I don't know how hard it is to get right.

Edited March 29, 2006 by downfall

[DirtyHarry]

I see what you're saying. But you think 10mm will make that much of a noticeable difference though?

 

Alas, it will be somewhat of a risky endeavor, but its an old frame and somewhat useless to me with 120mm spacing.

[Dave_Schuldt]

If it's a nice frame think twice.

[DirtyHarry]

It was a nice frame 30 years ago.

[jon]

I think the biggest problem with doing this is getting the derailer hanger aligned so your shifting is smooth.

[RogerJ]

I'm with downfall on the single speed idea. Of the 5 bikes I own, only 2 have gears (for racing). Fixed or single speed makes maintenenace simple. I ride 100 milers in the hills on a fixed gear. It's not so bad once you get into the groove.

 

If you really want to fiddle with it, I'd read Sheldong's pages like mentioned and if push came to shove, I am sure some local frame builder would help for cheap.

 

-r

[jon]

I ride 100 milers in the hills on a fixed gear.....

 

.......in the snow with a headwind both ways.

[DirtyHarry]

I'm way too lightweight for that shit. I need gears. Thnx for the advice.

[RogerJ]

.......in the snow with a headwind both ways.

 

with 2 flats and a dry chain.

 

OK I know I would take shit for that

[downfall]

I see what you're saying. But you think 10mm will make that much of a noticeable difference though?

 

I don't know. Horizontal drops outs do require the skewer to be set tight and flush againt them so the torque while pedaling doesn't shift the wheel

 

I'd recommend trying to trade the frame with something equivalent on craigs list with 130 spacing since conversion frames for single speeds are hot and it would be better satisfying some messenger wannabe with that frame than fucking it up and you would have something which satisfies your need too

[ashw_justin]

fixed gear = bouldering

 

all the cool kids are doin it, but there's really no point.

 

Can you get 7spd road parts anymore? 7 is plenty of speeds and that would require less distortion.

[ken4ord]

As mentioned before just put the wheel in the frame. It is 1cm we talking about. Don't bother with trying to bend the frame, it will cost you more than it is worth and you actually might have problem with allignment of your bike even if you have it done professionally. I have done this many time while working a shop and retro fitting older frames with more modern components.

 

Once the wheel is in place, it is worthwhile to check the alignment, run a string from the outside of the dropout to the head tube on both sides of the bike. The space inbetween the string and the seat tube should be the same for both sides. Everytime I have retro fitted a bike, maybe 10 or times the stays have spread evenly and there was no effect on allignment.

 

So I just looked at Sheldon's page, that has the DIY frame spreading suggestion, it should work no problem at all, but I still would just shove the wheel in the frame and be done with it. If you do go the route of spreading your frame it might be worthwhile to bring in your bike to have the dropouts checked and alligned if needed.

Edited March 30, 2006 by ken4ord

[ken4ord]

I know framebuilders do this but I don't know how hard it is to get right.

 

Not hard at all most decent sized shops will have allignment tool. Drop out allignment tool are really easy to use. They have arms that bolt onto the outside of the frame, cups in the center that are used to gauge the allignment. 2 minutes tops to allign.

[ken4ord]

I think the biggest problem with doing this is getting the derailer hanger aligned so your shifting is smooth.

 

Very easy to do as well, though I highly doubt it would be needed. The tool that is used is call an R-tool. It threads into the hanger and has a bar rotates around the wheel that is used for alligning assessment and bending. It uses the wheel to assess whether the hanger is alligned (you need to make sure that your wheel is true before beginning). Most shops have R-tools even the very small shops, it is the most frequently used allignment tool. Again most likely your hanger will not be affected by bending your frame or just shoving the wheel in place.

 

Bicycles are not rockets, they do not have very strick tollerances.

[dbb]

Bicycles are not rockets, they do not have very strick tollerances.

 

YOUR bicycle may not be, but Pax's girl-bike sure is!

[olyclimber]

nah...pax got a new bike. it is pretty pimp.

 

[DirtyHarry]

 

Thanks for all the advice kids. Local bike shop guy is going to help me with it - he's got all the spreading and allignment shit.

 

Ken, I would just stretch it out by hand, but I'm already spreading it quite a bit just to get a 5-speed Shimano freewheel in there. It was originally made for a 1970's era 5-speed campi free wheel cog set up, which is WAY narrow. Bike shop guy obviously has some modern 130 mm spaced hubs we can try to horseshoe in there by hand to see how it works before spreading it permanently.

 

BTW, isn't it kind of funny that the allignment tool used for spreading the rear dropouts is called a FAG-2.