M A V

yeah, I found his first ride impression awhile back, pretty funny

Piff 

I realize this question has probably been asked multiple times before, but I would love to hear from some of you about how the conversion went and which frames worked well.

Specifically, I'm talking about top tube length, seat and head angle, stem height and length, and handlebar reach.

I'm thinking about finally getting around to doing this (10 years ago it's really what got me to do my first build, which never progressed to drop bars), and I've got my eyes on a frame with the following measurements:



​​​​My thoughts are that since my preferred top tube length on a road bike with steeper geometry (73/74) is roughly 54 or 55cm, and because bikes with slacker angles seem to be less affected by shorter stems, that this frame would be a good option for a conversion. Since I'll be needing to use a tall stem with a short extension to make it properly fit, the usual issue with these conversions.

But, I really have no idea since I've only just figured out what I prefer for road bikes.

What are your thoughts based on how your build has gone and what you would do differently, or what worked? Do you find yourself instead preferring the "alt-bar" route these days? Was the high bottom bracket annoying? Trail/rake values that worked well?

Here are the trail/rake/flop calcs. Trail seems awfully low... Jan, are you out there?

​​​​​​

base2 

The challenge in any conversion is getting the hand placement right. You can figure a road bar has a reach of probably ~80mm or so. Then tack on an additional 40-80mm of hoods on the brifters. So that adds up to 120-160mm further away the controls are in relation to a flat bar that can really only be accounted for by shortening the stem.

But you also have your rise/drop from saddle to bars to account for too. Because an aero road position is not an upright mountain bike position. So you'll need the stem to be an additional 2-4 inches taller, if not more to put your head/torso in more or less the same place to have proper front/rear weight distribution. You also won't have the proper arm bend to the controls due to the change in wrist orientation. You want a neutral wrist position with road controls to satisfy neck & shoulder muscles. Where as a mountain bike expects a horizontal wrist position which uses those muscles differently. Failure to get it right will mean not only will the bike handle funky, it won't be comfortable to ride either.

Factor in to that, that road bike handle bars tend to be narrower than mountain bike bars...That actually helps bring things closer. But you also need enough leverage to overcome the mountan bikes flop. So you can't actually have your narrow road bars if you want progressive, predictable handling. But you can have wide road bars. 46, 48, 50, etc...are becoming more common thanks to the rise in gravels popularity. So higher/closer still than you would probably think. Fortunately riser bars where the tops/hoods are 1-2cm higher than the clamping area are available from a variety of manufacturers to help with problematic conversions.

All that is to say that a bike with a higher stack and shorter head tube makes for an easier conversion. Short, highly angled stems (30-45 degree) starting higher are easier to find for workable solutions. Long top tubes with low stack simply need too much rise over too short of a run...Nobody makes a 90 degree stem. At least nobody I know of.

Piff 

Sorry, by higher stack and shorter head tube you are essentially saying a lower bottom bracket, right?

All of what you've said makes perfect sense and helps quite a bit, thank you. I'm wondering if my body type (quite long legs, short torso, average reach) simply is the wrong kind to try this kind of conversion except for the rare old frame that's more square. My body's dimensions exacerbates all of the issues present with low stack, long top tube vintage mountain bikes when considering a drop bar conversion...

I guess the reason all these old MTBs are still fun to run around with regular flat bars is because of their width. I loved my old 1988 Miyata Ridge Runner/Valley Runners setup with bullmoose handlebars + bar ends.

Well, this probably puts my dreams to bed except for perhaps getting another old MTB and keeping it for a do-anything flat bar bike...good enough I suppose, I had tons of fun with it like that anyways.

nathand

Looking for some advice around stems for a drop-bar conversion. I have a nearly-complete drop-bar conversion of a 1992 Trek Multitrack 790. It's a 17" frame, I'm 5'8", fits me pretty well but I'm stuck on the stem which is preventing me from getting cable housing cut to the final lengths and then wrapping the bar tape. I've experimented with several stems (my local co-op may be sick of me by now - I've stopped by 3 weeks in a row, picking out a different stem or two each time) and am having trouble finding one I'm completely happy with. A short stem - both vertically and horizontally - feels comfortable, but my knees bump the bars when standing on a steep climb, and my knees bump my elbows when riding in the drops. A long stem feels too stretched out. Also, I'm using cantilever brakes and trying to avoid a sharp bend in housing at the brake cable hanger. Here's photos of the stems I've tried. Anyone have advice on what's worked for them?

Tall adjustable stem - too long both horizontally and vertically, couldn't drop it any further

Quill stem - minimum height is a bit higher than I'd like, but otherwise comfortable

Quill stem adapter + 50mm high-angle stem: feels comfortable but my knees bump the bar, and forces a tight bend in the brake cable going to the cantilever hanger. Also, ugly.

CO_Hoya 

Perhaps a Nitto Dirt Drop? Comes in multiple lengths, clamp sizes and finish quality, and should be available locally and on-line (e.g. from Soma, also fancier version).



I'm not sure how much difference it would be versus your second option, but with the available specs on-line and measurement of your in-hand stem you may be able to guesstimate. At least it is a relatively attractive option.

I considered one for my MTB-to-drop conversion, but ended up using a Technomic instead.




Here's a pic of the stem on a completed bike with drop bars from another vendor.

mountaindave 

I’m not an expert, but it sounds like you’re running into fitment issues with the Trek Multitrack. I’m not sure a stem is going to solve your issue. It could be a frame size issue.

curbtender

https://www.jensonusa.com/Specialize...WFPVAvD05TTjaQ

base2 

Much good information has already been suggested about the stem situation.

If you look throughout this thread you will notice most saddles are moreorless centered on the saddle rails. Your saddle is as far at the back extreme as is possible. This causes all kinds of issues. Proper leg extension when riding and fore/aft saddle position in relation to the crank set is paramount. It is the first step to any fit related issue. The handlebars, stem and whatever else is part 2 of the equation.

I don't know your proportions but to me, your saddle looks to low and too far aft. You should be able to take your hands off the bars while riding using only your core to support your torso in otherwise the same position and your placement on the saddle should remain the same as you ride. If you find yourself sliding forward or back while pedaling, you are not balanced. Nothing else will be right or comfortable. No stem will fix the issue because the stem isn't the problem.

The low saddle height probably is contributing to your knee/elbow collisions when in the drops. Your butt, torso and shoulders and thus your elbows are too low in relation to your knees that come up too high in relation...If that makes any sense.

Assuming you adjust the saddle position to be "correct" and you then get the bars where they need to be... if you still have a knee/elbow collision problem, 170 crank arms may help. Mountain cranks usually come in 170mm or 175mm lengths. If you have the longer, your knees will come up a centimeter higher. Which may be just that nth bit enough to be a factor.

nathand

Thanks for suggesting I look at seat adjustment. The seat clamp is nearly centered on the saddle rails; it's just there's a fair amount of setback. I may have adjusted the saddle forward slightly since I took that photo, though. It's a 26.8mm seatpost (as opposed to something more common like 27.2) so I don't really want to go hunting for one with less setback unless that's really an issue. My pedaling position feels comfortable to me, so I think I have the saddle positioned properly (and I've had a professional fit done before, admittedly years ago on a bike that was since stolen, but at least I have an idea of how a bike "should" fit from riding that bike).

daywood 

I don’t know if this would be helpful or not but, some time ago when I got a drop bar conversion set up so it felt right to me, I took measurements that I use to make the initial setup on subsequent conversions. So with the saddle set somewhat in the center of the rails, I adjust the saddle height to my preferred setting (~36”) as measured from the top of a peddle when at the bottom of a peddle stroke to the area on the top of the saddle where my sit bones sit. I then know that my preferred distance from that sit bone place on the saddle (not a precise location, I know) to the cross tube of the drop bar is around 28”. That distance, along with my preference for having the cross bar and the saddle at about the same height, guides my selection of stem length and rise. Also knowing that my old bod does not enjoy laying out too far when on the hoods, I always use compact drops with a short forward section. These measurements are starting points and I’ll fiddle with things (although not the saddle height) on each bike because each has its own character. Once I get it to where it feels right, I log the measurements in case I want to use it as a new reference down the road or if I ever disassemble and reassemble the bike. Also, if l’m honest, I just like keeping track of stuff like that. I’ve also taken to logging measurements of the trail and the chain stays. 😀

base2 

The pic doesn't show where you've moved your saddle to since the pic was taken. What I mean is the middle of the clamping area of the rails, not the middle of the entire length of the rails.

In any case, it may be an artifact of the photo but your saddle in that pic also looks a bit nose down. Saddle angle has a profound effect on how your hips are rotated and thus weight on your hands to compensate; complicating any stem selection. Leveling the saddle is a great place to start. Any ol' level or smartphone level app set on a hardcover book, set upon the saddle will do the trick.

If because of seatpost limitations you are forced to pick nose up or nose down with no option to select an angle in between...Nose up is probably the better choice. If that still doesn't work, then a 2 bolt seat post with a continuously variable infinite number of angles will get your saddle level for a nominal sum. maybe ~$20 or so. Well worth the cost to eliminate that variable from the equation.

acoustophile

1996 Cannondale m400 CAD2 work in progress. Waiting for replacement brakes and it'll be complete.

nathand

Here's a pair of photos of my Jamis Renegade, a purpose-built gravel bike that fits me well (I've comfortably done many 50-75 mile rides on it over varied terrain) and the Trek 790, in the same location for comparison. I want to roughly match the position on that bike, maybe with the handlebars a little higher on the Trek since I'll be doing more riding around town on it where I'd like to be a little more heads-up. The challenge is that the seat -and head-tube angles and lengths are different, such that I need a short stem on the Trek to match the Renegade (which has a fairly short 90mm stem). Given the choice between a short stem that allows me to more closely match the Renegade, versus a longer one that doesn't result in bumping my knees on the bars, which would you recommend? And, thoughts on a quill stem versus a threadless stem adapter? I only seem to see either very short threadless adapters like the one I have, or very long ones. Thanks for the thoughts!

acoustophile

Bergz

Here's the latest iteration of my Trek (Wrek?) 950 rat rod. I posted earlier about the frame stripping and rust/oil finish, which is holding up very well...
I intended this bike to be a go anywhere/any surface bike with great ability. The drop bars certainly make it versatile. With the lush riding Michelin semi-slick tires it rolls very well, I just don't know what I will replace them with... The lowered bottom bracket and bars level with the saddle give it great comfort. It seems the secret to a successful drop bar conversion of old MTB's is to get a frame with as tall a head tube as you can find. Original Shimano LX cranks swapped for Tourney XT with straight arms to narrow the "Q".
26 lbs 3 oz as pictured with mudguards. I've built it up with salvaged parts wherever possible and probably have around $70.00 NZ "invested"