Show Your Vintage MTB Drop Bar Conversions
12-04-18, 01:15 PM
#6302
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More thots on fit...
IMHO the best case scenario is to work off a fit which you want to duplicate. For example a touring bike which is comfy for long rides.
The two key dimensions on that bike are going to be the reach and stack. Once you have these it is fairly straight forward to reproduce the fit on the new bike.
Fit is simply a triangle: Saddle - Bottom bracket - Bars (I'm assuming the same length crank so use the pedal if the crank arms are a different length)
As mentioned by others, MTB geometries vary A LOT. Early MTB's were more like road bikes in that they had shorter top tubes. This is important to for account for the additional reach in moving from a flat bar to the brake hoods on a drop bar.
The top tube length is also the reason why may drop bar conversions require one to use a smaller frame to get the proper length and then compensate for the small frame by using a tall stem and long seat post.
Bike makers started moving to longer top tubes in the early 90's. Also note that the high end bikes targeted for racers tended to have longer top tubes than the lower end models where the target market might prefer a more upright position. All this is guideline info whenever I'm shopping for a vintage mtb I take a tape measure and plumb bob to measure the frame. Many catalogs from the 80's had frame geometry info, but nobody in the day was using Reach and Stack so it is more difficult to determine how well a frame will fit.
One last thot...
Here's a web site which allows one to compare fit between bikes. It's great if one can find the frame geometry (read: more useful for newer bike than vintage)
Bike Geometry/Fit Comparison
Hope this helps and happy shopping,
Greg
12-09-18, 01:01 AM
#6305
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I've been wanting to build one of these for a while. ~87ish Fisher Mountain Bikes Hoo Koo e Koo. Sort of a tribute bike to folks like Repack Rider and all those folks from the early mtb days that are my heroes. I am calling this one Jacquie after Jacquie Phelan.
Deore derailleurs, Dura Ace barends in friction mode, nitto dirt drop stem, junk wheels I had lying around, Specialized knobby tires that came with the frame when I bought it from the co-op Warehouse sale.
Pending upgrades: new Diatech Hombre u-brake, switch to 10 speed indexed shifting. And some folding tires once I can bring myself to spend >$50 a tire.
Deore derailleurs, Dura Ace barends in friction mode, nitto dirt drop stem, junk wheels I had lying around, Specialized knobby tires that came with the frame when I bought it from the co-op Warehouse sale.
Pending upgrades: new Diatech Hombre u-brake, switch to 10 speed indexed shifting. And some folding tires once I can bring myself to spend >$50 a tire.
Last edited by tricky; 12-09-18 at 03:19 PM.
12-09-18, 03:25 PM
#6306
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Made some last minute changes for the build.
Went with SRAM Red levers instead of Rival.
Sram XO rear derailleur instead of Rival.
Avid Shorty Ultimate brakes inssead of TRP Revox.
Also changed to a SRAM Red crankset over the Bontrager. Something was wrong with the BB for that crankset.
The 90mm stem is too long. I am thinking 70mm with 6* rise. How do stems shorter than 70mm work out for folks? A 50 or 60mm might just make for a perfect fit.
Love the looks of it. How’s the handling? I’ve read (on the internet so I take it with a grain of salt) that the Colnago mountain bikes had weird geos. It’s a little jingoistic of me, but it made me wonder if all the Italian mtbs were a little strange in that department. That said, might make it perfect for a drop bar conversion!
12-10-18, 03:40 AM
#6307
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Belated reply but hope this helps...
IMHO the best case scenario is to work off a fit which you want to duplicate. For example a touring bike which is comfy for long rides.
The two key dimensions on that bike are going to be the reach and stack. Once you have these it is fairly straight forward to reproduce the fit on the new bike.
Fit is simply a triangle: Saddle - Bottom bracket - Bars (I'm assuming the same length crank so use the pedal if the crank arms are a different length)
As mentioned by others, MTB geometries vary A LOT. Early MTB's were more like road bikes in that they had shorter top tubes. This is important to for account for the additional reach in moving from a flat bar to the brake hoods on a drop bar.
The top tube length is also the reason why may drop bar conversions require one to use a smaller frame to get the proper length and then compensate for the small frame by using a tall stem and long seat post.
Bike makers started moving to longer top tubes in the early 90's. Also note that the high end bikes targeted for racers tended to have longer top tubes than the lower end models where the target market might prefer a more upright position. All this is guideline info whenever I'm shopping for a vintage mtb I take a tape measure and plumb bob to measure the frame. Many catalogs from the 80's had frame geometry info, but nobody in the day was using Reach and Stack so it is more difficult to determine how well a frame will fit.
One last thot...
Here's a web site which allows one to compare fit between bikes. It's great if one can find the frame geometry (read: more useful for newer bike than vintage)
Bike Geometry/Fit Comparison
Hope this helps and happy shopping,
Greg
IMHO the best case scenario is to work off a fit which you want to duplicate. For example a touring bike which is comfy for long rides.
The two key dimensions on that bike are going to be the reach and stack. Once you have these it is fairly straight forward to reproduce the fit on the new bike.
Fit is simply a triangle: Saddle - Bottom bracket - Bars (I'm assuming the same length crank so use the pedal if the crank arms are a different length)
As mentioned by others, MTB geometries vary A LOT. Early MTB's were more like road bikes in that they had shorter top tubes. This is important to for account for the additional reach in moving from a flat bar to the brake hoods on a drop bar.
The top tube length is also the reason why may drop bar conversions require one to use a smaller frame to get the proper length and then compensate for the small frame by using a tall stem and long seat post.
Bike makers started moving to longer top tubes in the early 90's. Also note that the high end bikes targeted for racers tended to have longer top tubes than the lower end models where the target market might prefer a more upright position. All this is guideline info whenever I'm shopping for a vintage mtb I take a tape measure and plumb bob to measure the frame. Many catalogs from the 80's had frame geometry info, but nobody in the day was using Reach and Stack so it is more difficult to determine how well a frame will fit.
One last thot...
Here's a web site which allows one to compare fit between bikes. It's great if one can find the frame geometry (read: more useful for newer bike than vintage)
Bike Geometry/Fit Comparison
Hope this helps and happy shopping,
Greg
thanks for your long answer. i also tihnk working from a known fit, might be the best solution. the problem is often buying a bike online from guys, where you don't trust their measurements aka non bike people
that's where that bike fit comparison tool comes in handy! thanks for that!
12-10-18, 03:43 AM
#6308
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Made some last minute changes for the build.
Went with SRAM Red levers instead of Rival.
Sram XO rear derailleur instead of Rival.
Avid Shorty Ultimate brakes inssead of TRP Revox.
Also changed to a SRAM Red crankset over the Bontrager. Something was wrong with the BB for that crankset.
The 90mm stem is too long. I am thinking 70mm with 6* rise. How do stems shorter than 70mm work out for folks? A 50 or 60mm might just make for a perfect fit.
12-10-18, 09:20 AM
#6309
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Love the looks of it. How’s the handling? I’ve read (on the internet so I take it with a grain of salt) that the Colnago mountain bikes had weird geos. It’s a little jingoistic of me, but it made me wonder if all the Italian mtbs were a little strange in that department. That said, might make it perfect for a drop bar conversion!
12-10-18, 10:26 AM
#6310
Senior Member
Hey Jay,
interested in in the Avid ultimate brakes you have used. Love to get a feedback after some serious use. You have a sweet looking ride there!
interested in in the Avid ultimate brakes you have used. Love to get a feedback after some serious use. You have a sweet looking ride there!
12-11-18, 01:28 PM
#6311
Virgo
Though a hybrid by definition, I hope this is acceptable as the concept/result is very similar. I use this for commuting and it's very well suited for the task. Like others have noted, it takes some care to figure out the right stem. This top tube is 57.5. I usually ride a about a 56/57TT on a road frame but I'm tall and seem to prefer a little more reach. My road stems are 100-130mm no rise, this one is 100mm 25 deg. I rode it with the stock 105/45deg and reach was a little short and bars a little too high. It handles a little better with the pictured stem. When riding on hoods and in the drops, looking down the front hub is still in front of the stem. On the roadies it was usually hidden.
Note: I went back and forth between 23" and 25" road frames, this setup (23" frame) seems to be a good compromise for me.
Note 2: If I were to do another and wanted something a little more nimble, I'd start with a smaller frame, like a 21. This one is out on the open road a lot so I like being able to stretch out.
Last edited by Phamilton; 12-11-18 at 02:29 PM.
12-18-18, 07:30 PM
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That Tiramisu is one of the 2 or 3 hottest bikes in this thread/this site. Really nice build.
12-19-18, 07:24 AM
#6313
Thrifty Bill
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The present stem is relatively flat. So even one the same length but at a much steeper angle would be an improvement. I would find a co op or a shop that will let you try out various stem lengths and get it dialed in.
12-19-18, 09:03 AM
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12-20-18, 04:19 PM
#6315
Senior Member
Cougar is up and rolling. Bought this as a frame and fork this past summer. Brakes were moved and the yellow paint was rough. Went blue with new decals. Not rushing the build but wanted try the fit as it’s a big bike in drop form. After a spin it feels spot on. ( I’m 6’1). So back to shop for the winter where I’ll finish up loose ends. Cheers, Kevin. 
Rack is old but sturdy
As found. U brakes moved to seat stay.
Rack is old but sturdy
As found. U brakes moved to seat stay.
12-22-18, 09:47 AM
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Cougar is up and rolling. Bought this as a frame and fork this past summer. Brakes were moved and the yellow paint was rough. Went blue with new decals. Not rushing the build but wanted try the fit as it’s a big bike in drop form. After a spin it feels spot on. ( I’m 6’1). So back to shop for the winter where I’ll finish up loose ends. Cheers, Kevin.
As found. U brakes moved to seat stay.
As found. U brakes moved to seat stay.
12-22-18, 06:06 PM
#6317
Senior Member
Yes Underneath chainstays. U brakes. Common I believe for that era of mountain bikes. I personally like the cantilever style of brake better.
12-23-18, 09:03 AM
#6318
Senior Member
Hey K, who did the work? I have a GT with seat stay U brake I want to convert to regular cantilever.
12-23-18, 10:54 AM
#6319
Senior Member
3speed, previous owner had the work done. The frame and fork was listed on cl for quite awhile before I took a chance on it.
12-30-18, 09:34 AM
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I picked up a Nishiki Ariel the other day. Its the elevated chainstay model, a 19.5" frame with a 22.5" top tube, which is about right for me on a road bike. Looks like it will take 2.35 tires with room for fenders with a short "effective" chainstay leangth. I have a pseudo LD quill stem the will get the bars up abit so that there's a 1 1/2" of drop, and the distance from the top of the seat post to the stem/handlebar connection is also about the same as my road bike.
I figure with the 1 1/12" drop and my "conditioning" level I will want to ride primarily on the handlebar hoods. I was thinking that the 52mm Nitto RM-013 Dirt Drop bars might be a good match. I've got a set of barends and a set of command shifters to choose from. The bike will see 80% rural pavement/chipseal and 20% gravel and occasional logging roads. For tires I was going to go with Maxxis 2.35 DTH's. I'll try and get some pictures up. This bike's forth in line right now so I'm this is very much a request for suggestions for the planning and parts gathering process.
I figure with the 1 1/12" drop and my "conditioning" level I will want to ride primarily on the handlebar hoods. I was thinking that the 52mm Nitto RM-013 Dirt Drop bars might be a good match. I've got a set of barends and a set of command shifters to choose from. The bike will see 80% rural pavement/chipseal and 20% gravel and occasional logging roads. For tires I was going to go with Maxxis 2.35 DTH's. I'll try and get some pictures up. This bike's forth in line right now so I'm this is very much a request for suggestions for the planning and parts gathering process.
12-30-18, 02:03 PM
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Here it is after a "successful" test ride. The bars might be a little short and a little narrow, but I'll probably use them for round one. The guy I got it from had had it serviced and then didnt realy ride it again, so it looks to have new stainless brake cables, so i didn't just cut them off for the experiment.
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12-30-18, 02:04 PM
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12-30-18, 02:06 PM
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Should have held a ruler up but there's plenty of clearance for fat tires and fenders.
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12-30-18, 02:22 PM
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And here's a little ghetto lightbox geometry comparison. If it works out the bike may be dubbed the PFB
01-09-19, 09:56 PM
#6325
Full Member
Schwinn Dropbar
Probably my favorite ride. Mid 80’s Schwinn Mtb that started as a 5.00 frame set at a swap meet. Here it is in front of the Alamo by the Christmas tree.
