FastJake

I've been toying with the idea of making a 26" drop-bar mountain bike for winter riding. I have a 26" flat-bar MTB but I just can't get comfortable with the flat bars on long rides. I want to do drop bars but my concern is getting it to fit correctly. I'm worried that the short seat-tubes and long top-tubes of MTBs are not going to work.

So my question is: can I take measurements from my well-fitting road bikes to determine whether a MTB frame will work before buying it and trying to build it up? I have three road bikes that are quite different that fit me very well. A 1984 Fuji touring bike, a 1972 Fuji road bike converted to fixed gear, and a 1994 Trek 730 (700c hybrid) converted to drop bars.

Thanks!

jyl

I would simply stick a short-ish road stem and drop bars on your MTB and try sitting on it. It might feel fine. If it does, then convert over to road brakes and shifters.

FastJake

By measuring reach from the seatpost to the bars I know that my current MTB is quite a bit too long for drop bars. I have a known comfortable range for that dimension and it's simply too big. However, it's easy to measure because the bike is built up.

I guess my question is, if I'm looking at a frame only how can I tell? I'm used to classic road geometry with level top tubes. I can measure a bare road frame and instantly know if it will work for me. But MTBs often have sloping top tubes making things confusing. If I measure "effective top tube" will that get me what I need?

Squeeze

@FastJake - you might ask about this in the MTB drop bar conversion mega-thread here:

https://www.bikeforums.net/classic-vi...nversions.html

CliffordK

Each of my bikes seems to have a radically different fit, so I'm not convinced that one must have the perfect bar position.

My 26" to 700c conversion gives a long, low, very aggressive feeling bike.



In this case, the frame was short in height, but didn't have a sloping top tube.

However, if you start by setting the seat position, then you should be able to take all of your measurements relative to the seat.

due ruote 

I know it's an old thread, but what the heck.

In my experience, because of the proportionally longer tt as you noted, you need a "smaller" frame with an mtb. That results in more saddle to bar drop if you simply use a road quill and bars. This is why you often see riser/dirt drop stems on mtb conversions. Also, most mtb-designed drops (Midge, et al) have rather shallow drops, and the standard wisdom is to set them up with the drop as the default position. That's going to be very difficult to accomplish without a riser stem.

Be sure to spend some time on the thread referenced above. In addition to lots of pics, there is quite a bit of discussion of this and similar fit issues.

bikemig 

If your mountain bike has a longish top tube, then try a trekking bar. They work great and give you extra hand positions.

Best bikes for a drop bar mtb conversion tend to be mtbs from the 80s since they tend not to have as long a top tube.

I converted my 1988 stumpjumper comp to commuting duty with drop bars. It is a 20 inch frame with a 22 inch top tube. I pretty much copied my road bike set up when setting this up.

I did decide to use randonneur bars and a saddle with long rails (a selle anatomic nsx) to help deal with some of the set up problems. This has become my principal commuter. I use two commuters in winter. I use continental winter contact tires on the 1988 stumpjumper. They handle snow and ice reasonably well. it is also the bike I use for long distance rides in the winter (when the weather allows me to do longer rides). My heavy duty winter commuter is a bridgestone bb-1 with flat bars and studded tires. There is no reason I couldn't use studded tires on the drop bar mtb but then the bike would not work as well for longish rides (20 miles plus) so I prefer the continental winter contact tires for that bike.

I converted my 1991 team stumpjumper to a gravel bike with trekking bars. It has an 18 inch frame with a 22 inch top tube.

fietsbob

winter mostly wet, here cycle rain cape & trekking bars work fine , nothing to snag the hand loops..

Gripshifter IGH, so gearing, sequence of ratios, is linear..

ThermionicScott 

+1 for checking out the C&V thread. (I have an entry in it, after all.)

In a nutshell, a couple things to keep in mind are the long top tubes relative to the rest of the frame (since more standover clearance was a goal and a shorter stem would be used with flat bars), and the slacker angles you'll often find on 80's/90's MTBs. So you'll probably end up with a frame that's about one size smaller than your usual road bikes, as measured by the seat tube length, and the handlebars will end up higher relative to the frame. Unless you have short legs and a long torso, it's bound to end up looking a little dorky, but I made my peace with that long ago.

FastJake

I know this thread is getting old but thanks for all the advice. When I get around to it, I will sell my flat-bar winter MTB (too big for me) and keep these tips in mind when looking for a new frame.

ThermionicScott 

Looking forward to seeing the build! One thing you might consider is to measure the stack and reach of your current road bike(s). It's still kind of new to me, but those numbers seem to be very transferrable to other bikes. Once you have those, you can measure the positions of the saddle and the handlebars relative to them, and eliminate most of the guesswork when setting up the new bike: Technical FAQ: Setting your bikes up identically - VeloNews.com

Bikeforumuser0031

Bump: Any status updates on this?