Not exactly a vintage bike but just received my new crosscheck. Since horizontal dropouts were more common on vintage bikes, thought I would ask here and sorry if this is a dumb question.

I am having trouble getting early 90s xt 7 speed derailleur to work in that it rubs against the largest cog on the cassette no matter how the B screw is adjusted. Is there an ideal position (towards the rear, middle, front...) for the wheel/axle on horizontal dropouts when using a derailleur or does it matter?

Hello. normally the wheel is positioned as far forward in the dropouts as possible. how big is your largest cog? is the derailluer new or used? pics? OH are there adjusting screws in the dropouts?

I think Bianchigirl is referring to real Horizontal dropouts aka Track Dropouts.

On the Semi-Horizontal drops on your crosscheck you'll want to pull the rear wheel as far rearwards as possible. If the derailleur is rubbing on the largest cog, and you've tried all the adjustments it usually means you are trying to use a larger cog than the derailleur is capable of handling.

like Bianchigirl asked: Whats the size of the big cog, and what Rear Derailleur are we talking about?

Thanks for the responses so far. Unfortunately I am home for the long weekend in Canada right now and the bike is back in WA state so I can't show a photo but, I found a picture of my derailleur on ebay. It's an old 7 speed XT from the late 80s/early 90s I believe.

I have the axle about centered in the dropout mostly because that is as far as the adjustment screws would go. I wanted it as far forward as possible thinking quicker handling but sounds like that's not the way to go according to CravenM. The large cog on the cassette is a 32 and I believe it is a 26-36-46 in front.

Perhaps this might indicate something: when the chain is in the large rear and large front, there is barely enough chain to make the shift and the derailleur is reaching way forward. However, when in the small rear and small front, there is too much chain and the derailleur is bottomed out meaning it can't take up anymore slack. This really has me scratching my head. I have built a few bikes and never had this problem. Hope I am clear and again, sorry for no photos of the bike.

Sounds like the derailleur doesn't have enough chain wrap to handle the gear range you want to use. That means you'll need a derailleur with a longer cage to handle the extra chain wrap.


Calculate your chain wrap like this (Large Rear Cog + Large Front Chainring) - (Small Rear Cog + Small Front Chainring)...for you thats (32+46)-(??+26)

without knowing your small cog size (in teeth) I'd venture a guess that you'll need a Rear Derailleur with at least a 40 Tooth capacity, and it will need to handle a cog of at least 32. Shouldn't be too hard to find.

ok that statement has me really Honestly curious. We're talking about 2-3cm of adjustment room there. I know a shorter Wheelbase = Quicker Handling, but is that enough of a distance to make a difference?

There are a lot of variables here, including the length of the slot, the make of the dropout, the distance from the centerline of the axle to the centerline of the derailleur hanger, the type of derailleur, the length of your chain, and the cogs you are using.

I've never been able to tell the difference, but some people swear it's night-and-day.

A few things that you need to look (in this order - easy to hard) :

check the spacing of the rear, if it is less that 130mm you cannot have an MTB 7 freewheel there and it is probably the frame that is the problem and not the RD

if that is the case, manually (i.e. don't use derailleurs, but with the derailleurs on - and wear gloves btw) put the chain on the biggest cog up front and on the biggest cog in the back. If there is not enough room to do this, the chain is the limiting factor and you need a different chain. (and, yes, this is not 'textbook' because you are running cross gears at this point, but the chain should be able to do that)

If you can do that manually, you have to adjust your RD in a way to be able to do it physically...

Unless you are running something in the 30s this XT RD should be able to handle at least 28 teeth...

I suspect that this is not an issue, this puppy is probably as long caged as they come...

oh, yeah. It IS night and day, but the OP's way is not the way to do it... It's in the frame geometry (short TT, short stays)

Long dropout


short


semi vertical


vertical


track end


Raleigh 3-speed

Chainwrap! I completely forgot the the small ring is a stainless steel 22 not a 26 which means (46+32)-(22+12)=44. That would explain the too much/not enough chain situation. I really hope the derailleur will work since it is a long cage.

CravenM, I agree the position probably doesn't matter but wanted to try since the seller recommended it. I also thought that if the axle position didn't effect shifting, I might as well have it forward even if the benefit was slight. Just to confirm, the wheel all the way to the rear is the way to go for a derailleur set up, right?? If so, I will remove the screws and pull the wheel back. However, if you haven't see the dropouts on a Crosscheck, they are looooong.

huh?

Shimano makes a 126mm spaced 7-speed freehub. OP didn't specify whether it was a Freewheel or Freehub but I assumed Freehub as it was stated to be 'early 90's'.



As long as the wheel is in the dropouts enough for the Skewer or Bolt to get a good solid grip you should be able to safely put the wheel pretty much wherever you want in the drops.

I think i might try this whole moving the wheel forward business and see for myself if I can tell the difference. If its one of those 'princess and the pea' kinda things though I will fail the test.

Here's the important part:

"The large cog on the cassette is a 32 ...."

I suspect back when XT was a 7s group they didn't plan on 32t cogs or the amount of chain wrap you have. XT did come in different cage lengths and that will be a big factor in how much chain wrap is permitted.

I think you nailed it.

The rear derailleur was taken off of an old Univega Alpina Sport, as were most of the parts, and it worked great but it had a 7 speed freewheel w/ a 28 large sprocket. I am now using a cassette (sorry I didn't specify this but didn't think it was significant) w/ the large being 32. Combined w/ a 24 difference up front was creating havoc. I bought the Cross Check hoping to use all used parts that I had and I came close. I found an inexpensive Deore long cage at Jenson that I think will make things right but also might have to get a larger small chainring.

Anyway, thanks everyone for your help.

Surly responded to my email and in regards to the wheel position and for what it's worth, they recommended setting it up as far forward as possible for two reasons: it makes the wheelbase shorter and the bike will handle a "shade" quicker and also it is less likely the screws will get bent since they won't be sticking out as far.

A modern Deore long cage should have no problem with your big cog and should be able to wrap just about any combination you can get a front der to shift. A 22 tooth difference up front is very common on the mountain bikes that the Deore is built for so I would expect it to work fine on your 24. Most Shimano stuff is spec'd pretty conservatively and can usually handle a couple more teeth than advertised.

As soon as I saw 26-36-46, I figured your 32t cog is too big. Not because I know any better, but only because I have a 28-40-48 and it simply doesn't work with a 13-32 rear freewheel, 7-sp.

It works fine with what the OEM bike shipped with, and that's a 13-28. Chain length is much more manageable, too.

I tried the same setup with a Bontrager Race 53/42/30, and the FD cage couldn't handle it, either it was rubbing the bottom of the rear cage bolt on the 30, or it couldn't be raised high enough to get over the 53t ring.

Shimano shipped it 28-40-48 with a 13-28 rear, 3x7 brifters, and I decided to leave well enough alone. So far, so good.