Murray Missile 

I just finished a road bike for gravel riding, an old Schwinn World Sport fitted with 29inch MTB wheels and 47mm Continental tires. I really like the way it rides and it handles great in loose gravel.



I have this ('88?) GT Karakoram that's just a touch too small for me but I like the bike, given I already have a gravel bike that works well would there be any advantage to doing a drop bar conversion on the GT? I have all the parts. Would I just end up with more of the same or would there be enough difference in the ride and handling characteristics to justify the conversion?

bikemig 

I'm impressed that you managed to fit 47 mm tires on your schwinn world sport.

Rather than do a drop bar conversion, why not just use bar ends? They really help when riding long distances on a mtb by providing extra hand positions. I'm using my 1991 specialized team stumpjumper for a gravel event later this month set up like this.

Sir_Name 

I could see making a case for having both the World Sport and a drop bar conversion of the GT if the builds were toward opposite ends of the gravel spectrum. GT with fatter, knobbier tires and the Schwinn as a more smooth rolling machine. Maybe fenders if needed. How much wider a tire will the GT fit?

Henry III

I like dropbar mtb as they seem a little more versatile and more clearance.

USAZorro

I'm of a similar mind. I'd consider picking whichever is lighter (which also would hopefully be the one that also handles on the road better), and make that one a drop bar conversion and fit it out with tires that don't sacrifice much on the road, but which can also handle light-moderate gravel. I fitted out a Giant Iguana in this manner with Rat Trap Pass tires. It handles the bike trail and grass at the park very acceptably. Haven't really given it a gravel test, but reviews on the tires leave no doubt that they are up to the task.

danmyersmn

I have both.I have an all city space horse as a gravel bike and I have a early 90s specialized mtb that has been converted to a drop bar. They both run the same handlebars.the horse is tiagra with a brooks b17 and 700c wheels with clement ush tires. The Spech is claris with a brooks b67 36spoke sun rhino 26" rims with Continental Town & Country and full set of racks. If I'm out to put on miles I grab the Space Horse. For camping its the drop bar MTB. The combo works great.

Murray Missile 

The rear chainstays required some "finessing" but not all that much and HiTen is fairly malleable, also 1982 World Sports with beat up paint and decals don't have a lot of value so if it had gone wrong no great loss. It turned out quite well however. I have 3 other MTB's that fit me, the GT was a trade in that had some high end aftermarket components I swapped out. I built it back up with period correct Deore LX and it turned out nice enough I've taken a liking to it. Since it's a size or two too small I thought it might make a good drop bar conversion. Plus triple triangle GT's are not too common in my neck of the woods, I like "different".

Yeah, I have quite a variety of gravel I can ride and some dirt roads so that's a good case for doing the conversion with wider tires than 47's and having two similar bikes. It has 26 X 1.95's on it now which is about 49.5mm, not sure how much more tire I can squeeze in the GT but there is some room left. No "finessing" the frame on this one though, it's too nice, not doing any changes on it I can't undo with a wrench or screwdriver. The WS is getting Planet Bike SpeedEZ clip on fenders as soon as FedEx quits dragging them all over the Midwest.

Murray Missile 

I'd say they weigh pretty close to the same right now. The World Sport, which is a drop bar "road" bike, has proven itself to be a sweet ride on pavement, chip & oil and light gravel. It rolls over most irregularities very smoothly. There are some gravel roads around here that are pretty nasty, heavy washboarding on steep hills, deep loose gravel and soft as hell on the edges if you have to pull over, I haven't tried the WS on them yet.

I appreciate all the feedback guys, thanks everyone.

Chrome Molly

I ride lots of different roads that are collectively referred to as gravel. For limestone hard pack "racing" I have a road bike with 28c conti 4000s2's. Much faster than a comparable bike with 40c gravel tires. If the gravel is softer but not too loose than the cross bike with 40's is an ideal compromise. Sand, orv trails, or anything else that needs float will have me on a drop mtb with 2.1's.

Each is ideal for their own situation but of course you can't ride the 28's on sandy roads whereas the 2.1's are still reasonably fast on hard pack. Ymmv.

seedsbelize 

I am on the verge of building up a 78 Schwinn World similarly. We don't have anything here approaching a hill, and very little, if any gravel. I was gonna put upright bars on it, and use it for a town and short distance bike, so my mtb doesn't have to do double duty. Thanks for the 29er tip.

Sir_Name 

Sounds like a solid plan, enjoy! ...and pics please, curious to see how it turns out.

Murray Missile 

38's should fit no problem and I think 42's would as well without any chainstay modifications.

seedsbelize 

I can get mtb wheels with 126/120 spacing? Did you cold set, or just spread them to mount. I guess I could build my own with whatever hubs I have.

Murray Missile 

I used a rear wheel with 135 hub, I cold set for the hub, very easy to do on HiTen and then "massaged" the inside of the stays at the tire with a hammer and a 5/8" diameter brass bar as a punch. I only had to pickup about 2mm on each side in an area about 40mm long, it's not pretty but very effective and with a little paint touchup and the wheel and tire installed you can't see the carnage.

obrentharris 

My problem with drop bars on MTBs is the longer MTB top tube. Kind of negates the drop bar advantage of more hand positions if two of those positions (in the drops and on the hoods) require an uncomfortable stretch.

However I know nothing about the Karakorum geometry: Perhaps it has a shorter top tube than usual. You say that it's a little small for you. That may be a blessing if the top tube also is shorter.
Brent

smoothness 

i'll echo obrentharris' comment on the length of the top tube. i ended up having to buy a new fork and the second shortest thomson stem that they make it order to make my stumpjumper fit. even with the right amount of reach, it takes a bit of time to get used to the handling of a mountain bike with drops (even with road drops).

i would proceed with caution and the knowledge that it might not work for you at all. there's a reason why they build brand new bicycles with road geometry that fit fat tires.

wrk101

Typically, the earlier the MTB, the shorter the TT. By 1990, they got really long.

Murray Missile 

Top tube is short, especially compared to the World Sport, with the saddle all the way back I'm still scrunched up pretty good when I ride it. Heighth wise it's pretty decent, I still have a lot of seatpost in the frame but the bars definitely need to move forward.

Chr0m0ly 

I'm just curious, could this have been done with a C-clamp with the flat face removed? Or maybe a bench vice?

Murray Missile 

You'd need to support the outside of the stay and I'd leave the flat face in place as you are basically flattening the inside of the stay for tire clearance. In fact you might need to put something wider against the inside of the stay depending on the size of your C-clamp. A piece of steel pipe with an i.d. slightly larger than the stay cut lengthwise with an old chunk of leather belt lining it would probably work to protect the outer stay. If I ever did this on a better frame that's probably what I'd do, this one was already beat up some so no harm, no foul. If I didn't tell anyone what I did they wouldn't be able to tell by looking at it with the rear wheel in place.

Chr0m0ly 

I gotcha, I was thinking you were more dimpling than flattening but that makes sense.

Murray Missile 

In my case I was making flattish dimples LOL.

bikemig 

+ 1. I like the 80s MTBs for drop bar conversion for that reason.

tiredhands 

I got 42s in my 1980 World Sport no problem - I just had to make sure my rear wheel was very trued. In fact, I wouldn't mind getting another one of those frames - with the 42s it cruised like a Cadillac over Baltimore potholes. I bet that'd be a fun frame for a cheap monstercross build.

Murray Missile 

I like it. I paid $25 for mine in original rideable condition about 3 years ago. I had it on my stationary trainer until this Spring when I decided I wanted something better on the trainer. I haven't decided on a replacement for the trainer yet.