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Question on those screws at the end of the rear dropouts.(16 posts)

Question on those screws at the end of the rear dropouts.kilimanjaro
Jun 27, 2002 10:59 AM
I imagine are used for changing effective chainstay length. Questions

1) What are the effects of changing my chainstay lenghth?

2) How do I make sure that offset on both dropouts are the same. I noticed that a plastic cap fell off the end of one of the screews. Do I just eyeball the rim relative to the insides of the two chainstays?

3) If I change my chainstay length do I need to adjust my chain length and or RD?
re: Question on those screws at the end of the rear dropouts.Sintesi
Jun 27, 2002 11:14 AM
Weird, second time this week for horizontal dropout questions. A hot hot topic.

1)Longer wheelbase generally means more stability shorter equals sharper handling. In the real world, I doubt you will be able to tell much difference with this adjustment unless you have really deep dropouts. It's just a tweak. experiment and see for yourself.

2)I just eyeball it. You can easily use a ruler to measure the distance between the rim and the chainstay tho.

3)Your derailleur should take up the slack just fine. I've never had a problem. Someone did say a little while ago that your shifting might get a little out of whack if you pull the wheel too far back. Again experiment but I would be surprised if you noticed any problems.
i had them on horizontal drop-outs, explain that nmishmael
Jun 27, 2002 11:16 AM
make that vertical. Which ever makes no sense nmishmael
Jun 27, 2002 11:17 AM
I have seen them on semi-vert(sorta in-between horz&vert) not v.curlybike
Jun 27, 2002 11:26 AM
Micro standover adjustment [nm]Leroy
Jun 27, 2002 1:18 PM
I call BSKerry
Jun 27, 2002 5:28 PM
I want to know the bike brand and model that has dropout adjustment screws on vertical dropouts. I do not believe this for one second.
guerciotti neuronishmael
Jun 27, 2002 6:22 PM the pic makes them look more slopping than they are. believe it now?
this pic is semi vert I must admitishmael
Jun 27, 2002 6:30 PM
but im not sure if this is even the same bike I had. Im pretty sure mine had more vert drops. the guerciotti neuron also comes with horizontal drops on a white frame, mine was blue and yellow.
A beneficial use in horizontal drop outsMel Erickson
Jun 27, 2002 11:31 AM
It's one way of compensating for slightly mis-aligned stays. I'm not talking about gross mis-alignment, something that would noticeably affect the tracking of the bike. However, these can come in handy when your wheel is slightly off center (either due to the wheel or stays, however, the wheel should then be trued properly). Once adjusted you can just slam in the wheel, throw the quick release and your off, wheel perfectly centered, brakes not rubbing, no fiddling with the quick release and rim, etc., etc., etc. Not alot of manufacturers build with this type of dropout now. Kinda miss them.
Mel's got it rightboneman
Jun 27, 2002 1:33 PM
Up until the last 10 years or so, most bikes, even those used by the pros, had horizontal drop outs. In fact Merckx, when he turned to making frames insisted on horizontal drop outs until finally sucumbing to market trends. His steel models are still made with them and he spec'd his Ti Ax and Ex models with them.

Mis-alignment from frame issues and also from wheel problems. A nice feature that in truth, I don't miss.
I really don't believe they are for adjusting the chain stay ...Pecos
Jun 27, 2002 11:35 AM
length as much as they are for adjusting the dropout alignment. They are generally found on steel frames with fixed dropouts that are not adjustable in themselves. The screw is a micro adjustment to allow for truing wheel spin in the the rear triangle.
Jun 27, 2002 11:42 AM
Horizontal dropouts don't have enough space to effectively change wheelbase. Back them out, install rear wheel and when it's centered properly screw the DO adjustors in until they both contact the axle. From then on wheel installation with horizontal DOs should be easier.
LBS guy told me those are a racing addition128
Jun 27, 2002 11:41 AM
so that when you have to replace the wheel during the race you just set it in against those stops and avoid adjustments. Isn't it a race bike thing?
re: Question on those screws at the end of the rear dropouts.brider
Jun 27, 2002 12:14 PM
1) Chainstay length can effect the percentage of the bike+rider weight that's held up by the rear wheel. How would you feel this? The most obvious effect would be rear wheel traction on wet pavement going up a hill. You'd usually only notice this when standing. The shorter chainstay length (within reason, there were some wickedly short chainstay bikes that utilized a split seat tube several years ago) will give better traction when standing riding uphill. For most conditions, you won't notice a difference.

2) An easier way to eye-ball the alignment is to look at the bike from behind and align the wheel with the seat-tube.

3) For most horizontal dropouts, you wouldn't be able to adjust it enough to need chain or derailleur adjustment. There was a Moots (I think) bike some years back that had what looked like doubled horizontal dropouts (one forward and one aft) as well as horizontal dropouts on the forks. Talk about wierd.
horizontal dropouts on the forklaffeaux
Jun 27, 2002 1:40 PM
I have an early '90s GT mountain bike that has horizontal dropouts with adjuster screws on the fork. According to the manual they are there to allow adjustment to the rake of the fork. Its the only bike I've ever seen like this, and it's no surprise that it came out during the height of the unemployeed aerospace engineers in the early '90s.