Did a quick search, but didnt look like anyone had asked the question.
What are they there for? To help ensure good axle alignment within the dropouts?
Reason being -- I'm doing a restomod.....pics will be forthcoming....I just have to get a cassette, chain, and cables and I should be off and running.
Reason being, I'm obviously going to use a 130 rear in a 126 dropout. I did go to Sheldon Browns website; understood about spacing the frame, put a 2 x 4 on it, and didnt like the way it felt. I was putting some good weight on the lever, and only got the spacing to almost 127.5....so i am probably off a bit as far as how well centered.
Is that what I can use the dropout adjusters for? To counter this error? I can align the wheel fine in the dropout...(i.e. - there is plenty of room to get the wheel straight). Just making sure I'm not off base on what these things are for.
Pics to come once done, I promise....will show beginning garage sale find (that I rode for a summer), sanded frame, attempt to polish lugs, the paint job done on Christmas Day (while everyone was out of the paint shop), and the final assy.
All this just for a Schwinn Prelude -- but it rode soooooo great, I just wanted the same shifting / STIs as my much more expensive Felt. Almost wish I had found this bike first, might not have gotten the Felt.
dropout adjusters should only be necessary to fine tune the wheel alignment in a correctly aligned frame. They can also serve to optimise handling by altering the front to rear weight distribution.
an easy check is to tie a long piece of string from the right rear dropout face, running forward around the headtube and back to the left rear dropout face. measure the distance from the string to the seatube on each side of the bike. they should be the same.
I recently spread the rear frame spacing (first time for me) on a Miyata 610 circa 1986. I used a threaded rod with two nuts and fender washers to push the drop outs apart. I then used the string as described above to measure if they were equal distance.
To my horror I had pushed one side substantially and the other very little. I have since gone back and used Sheldon Browns method. It took a number of tweaks to get them closer. If I were you I would do the same just keep tweaking.
2010 Cannodale Hi Mod Synaspe, 2010 Sram Force, Mavic Kysirum SL Premium, Brooks Swallow 2011 Giant TCR Advanced SL Black Mavic SL Premiums, Full Sram Force, Fizik Aliante Carbon 15.33 lbs of pure adrenalin
Whay the need to coldset? You are only spreading 2 mm on each stay. There is enough flex in the stays to easily accomodate 130mm in a 126mm frame. Lp
The screw adjusters in the dropouts are for moving the rear wheel aft as far as necessary to keep the jockey pulley of the rear derailleur from clattering against the largest cog when the chain is on the small chainring. This adjustment is now performed by the "B" adjustment screw on modern derailleurs, but RDs of that era didn't have them. You get the adjuster on the drive side set first, then you fine-tune the off-side adjuster to lay the rim centred between the chainstays. Of course if you are using a modern RD, you can set the axle pretty much wherever you want as long as it's centred, then set the "B" adjustment as usual.
Only if the frame is aligned *and* the wheel centred in the frame will it track straight. The drop-out adjustment screws by themselves will not accomplish this. (Mind you, very small alignment errors are probably not detectable by mere mortals, but then I've never knowingly ridden a crooked bike, so I can't say for sure.) Remember the road has a crown (for drainage) that is going to make even a perfectly aligned bicycle tend to wander off to the shoulder, all else being equal.
Last edited by conspiratemus; 01-25-09 at 09:42 AM.
Reason: typos that survived proof-reading. Geez!
Sheldon's instructions for checking and adjusting alignment are on the same page as the cold setting instructions you were looking at.
As long as you are cold setting, you might as well do it right and spread it to the full 130mm. You can squeeze the wheel in, but it's so much nicer when it drops right in like it's supposed to. If you are afraid of damaging the seat tube using Sheldon's method, you can use a pad between the 2X4 and the tube. I have a length of foam pipe insulation that I use for that.