Some things to consider when building up or modifying a vintage ATB

cover picture: my first ATB - Rossin Montare - Mallorca, 2016

The All Terrain Bikes, or mountain bikes as they are sometimes called, of the 80s and 90s have been The Alternative Bike Choice of the last decade or so and for good reason. They are usually cheap, sturdy and easy to convert to useful commuters or rough road tourers. I have personally owned about 8 of them over the years and have tried out various configurations. So I thought I’d share some insights from these projects of mine.

In general, I think the ideal ATB-tinkerer is someone with good basic mechanical skills and lots of motivation to put some work in to get a nice and special bike. Because you are probably going to use the bike in a somewhat different way than it was originally intended to be used, it is going to need some tinkering!

To start with, a whole bike or just a frame?

The projects of building or modifying ATBs can be divided into two categories, those that start with a complete bicycle and ones that start with a frame (and possibly fork) only. Usually it is always more economical to start with a whole bike, but for the “ultimate setup” a frameset gives you a blank canvas to start with.

The frame geometries of the 80s were more laid back than the 90s racing oriented style as you can see on this beautiful machine here. 80s all terrain bikes are quite rare in Finland though, as everything reaches here a little later than in the more civilized world...

Right away I would advise against buying a frame without a fork, or one with a suspension fork (that is useless in 95% of the cases). New or used suitable forks are not that easy to come by, and can be expensive or they might not fit the geometry of the frame. Often the higher end frames of the 90s have been sold with a suspension fork so you might have to find a fitting rigid fork. The Kona Project Two fork is almost always a safe choice and can be found used for around 80-100eu on eBay. They can be found in a few different axle-to-crown (AC) lengths, so if you can, find out what kind of fork your frame is meant for and try to find one with the correct AC. You can find most major bicycle manufacturers' old catalogues on retrobike.co.uk, where you can dig out information like the recommended fork length.

High(ish)-end aluminium Klein turned drop bar touring machine.

Another thing to consider before buying a bike or frame, or beginning to modify one is the quality of it. A lot of old ATBs have been made very cheaply, and might have very heavy frames of low quality steel or aluminium tubes. For some people this might not be a problem, but for me personally it makes the bike feel awfully sluggish and hard to pedal. A high quality racing frame might be under 2000g, whereas a cheap frame can weigh almost twice as much! The weight adds up and also stiffens the frame and makes it harsh and uninspiring to ride. Even the heaviest riders should be okay with a mid-weight quality frame.

So I would very much advise spending a hundred more euros, or whatever your currency is, for a mid-priced or high-end frame/bike. Of course if you’re building a bike just for the fun of having a project, and not really to use, it doesnt matter, but personally I like my bikes good and nice and ride them a lot.

A colleague's GT Tequesta in Mallorca, with some local white wine to go touring with. Note good frame size, very rideable even in the drops. Campagnolo 10s shifters with 3x8 Shimano derailleurs.

The size is of course of great importance, and I would usually recommend getting the largest size possible. These usually work better for both cruisy commuters with swept-back bars and also for fast drop-bar all terrain tourers. The MTB frames of the 90s usually dont grow much longer when they grow in size, but mostly only get taller. Also the geometry of the frames make them run smaller than the same size road frames. For me personally, at 178cms, a 60cm top tube is not yet too long, even though on a more road-ish frame I would pick a top tube of about 57cms. As an example Inka who is 162cm (but somehow has good reach) easily rides a 56 top tube (90s Kona geometry) with long reach drop-bars.

You should figure out your seat height (bottom bracket to top of saddle) and use that to calculate how tall of a seat tube you want. I’d say visually the most pleasing sloping-frame all terrain bikes have 10-20 cms of seat post showing above the frame. Often you see people (my old self included) having very small frames with even 30 centimeters of seatpost! The problem is worsened if you want to have the handlebar comfortably about the same height as the seat, as you would need to find a stem with LOTS of rise. This is probably suboptimal structurally and also just looks quite ugly to be honest.

A stash of parts I found (and left untouched) in a bush in Helsinki. With patience and drive one can also build an ATB for almost no money if needed!

Possible problems and downsides

Like on any old bike, some of the most common problems are seized seatposts, quill stems or bottom brackets. So in that sense starting with a bare frame can be a safer choice. If you’re buying a used bike locally, it makes sense to try and remove the seatpost and stem before paying up! Usually even the stuck ones can be removed but they can be a real PITA.

Some bikes can have special old parts that are not so easy to replace. Especially if the bike has 6 or 7 speeds in the rear cogset, it might use an odd freewheel or cassette standard. Most 90s bikes will have 8 speed Shimano parts, and those usually are a safe choice. If the rear wheel has 7 speeds, you are most probably stuck with a 7s cassette due to the shorter freehub body, which cannot fit more modern cassettes. But then again the saying goes:

“Nine is fine, eight is great and seven is heaven!”

One of the finer geometry issues that I dislike a little bit on old ATBs is the bottom bracket height. The bikes have been designed with a 47 or 50mm tire in mind, and when you put on the biggest tyres possible, the BB height goes up. This isn’t a problem for everyone, but personally I prefer a lower bottom bracket, as it just feels better even though I’m not sure why. This is also a reason NOT to convert 26” bikes to use 650b/584 wheels, as some people seem to be doing, which makes the bottom bracket go even higher.

A downside to high quality light weight frames can be that they are specced with racing in mind, and might have no fender and rack eyelets. This is a problem if you want to attach those. There usually are workarounds but they are always hassles and the result usually sub-optimal.

Lastly, an ATB is not the fastest bike for road riding, even on rough gravel roads. They excel more in snow, on trails and at heavily loaded rough country riding. If you want more of an “all-road” bike project, I'd suggest looking at some 2010s cyclocross and gravel bikes and converting them into 650b all-road bikes. Or if you want the ultimate in smoothness and comfort, build up a 1940s 650b French touring frame 🙂

Handlebars

The handlebar is maybe the most important component after the frame that gives a bike its character. Do you want your bike to be relaxed and cruisy or fast and furious? Most people use a swept-back handlebar on their ATB, which often makes a lot of sense and fits the general feel of those bikes. But especially the more high-end bikes are good candidates for faster all-round use on varied terrain and might benefit from a straight-ish XC racing handlebar or even a drop bar.

Riser handlebar and added aerobars for multiple hand positions

Choosing a sweeping handlebar can be tricky as they vary a lot in rise, width and back- and upsweep angles. Most people will just have to find the correct one via trial and error. Trying out someone elses bike will probably be the best place to start. Swapping handlebars can be fun as well, and it’s not necessarily a question of better or worse, but of different styles. So don’t be afraid to just try something and see.

In some cases you need a lot of stem to get the bike fitted. A bit sub-optimal but that’s life sometimes!

Drop handlebars on ATBs are also a popular choice. After having tried various setups during the years I am personally wary of recommending one for ATB conversions. I feel that a lot of people see good looking drop-bar ATBs on the internet and then go ahead and put one on theirs, which might not be much at all suitable for it. Installing a drop bar on a heavy bike that has a low-but-long frame usually results in a poor coherence of the whole bicycle. Only some ATBs are well suited for drop-bars. What to look for is a frame that is as high as it is long, or preferably even taller than it is length-wise. These kind frames are quite rare as the general style in the 90s was to have a long and low frame. Like said on the frame section, look for a big enough frame!!

Gearing

If your bike came with gears, they are probably fine just the way they are. Just put on some new cables and cable housing. A 3x7 or a 3x8 system is still completely relevant in my opinion. A 2x front setup might make more sense, as it is a bit more simple to use and adjust. So if you already have a triple, stick to that, but if you need to get new cranks or chainrings anyhow, I’d go for a double. A 1x7 or 1x8 can be okay as well, but will limit loaded off-road touring capabilities somewhat. I’ve found a 42/28 double and 11-34 8 speed rear cassette to work great for everything from winter commuting to climbing Mount Etna.

If the old shifters seem stuck or the triggers are “hitting air” and not clicking, flushing the mechanisms with spray oil and vigorous pushing of the triggers will usually revive them back to life.

My unidentified Russian titanium bike, nicknamed Timofey, running a 42/28 double up front and 11-34 8 speed in the back. Note rear rack installation under quick release skewer due to lack of rack eyelets on a racing spec frame. This is not recommended for use with panniers, but works well with a saddle-mounted bag.

For alternative handlebar setups, like a swept back handlebar or a drop-bar, you might have to replace the original shift levers. On swept-back bars there isn’t always space for the shifter to go next to the brake lever. On my Tunturi I solved this problem by installing the shifters next to the stem. This looks fun(ny) and works well enough. Things don’t always need to make perfect sense!

Another great option is to use bar-end shifters. Their tactile feel is in a sphere of its own when it comes to bodily sensations in cycling, and they are easy to manipulate with thick winter mittens as well. For sweepy bars make sure to check that the handlebar end is large enough to accommodate the shifter, which often isnt the case! It is possible to drill out the inner part of the bar, but I have no personal experience of this procedure. Many Nitto bars are designed to fit bar ends, and virtually all drop-bars will be bar-end compatible as well. Whether to go with indexed or friction-based levers is up to you.

One of my favourite drop-bar shifting setups is to pair 10 speed Campagnolo Ergopower brake/shift levers with old 8 speed Shimano derailleurs (that your ATB probably already has). By chance the shifter pull ratios and the derailleur side-to-side movement ratios in this combination work perfectly. The plus sides are that Campy front shifters use a micro-ratchet mechanism instead of indexing like Shimanos, so you can easily run either 2x or 3x on the crank. I also just like the look and feel of the Campagnolo levers better than Shimano brifters. And mixing up things that aren’t supposed to be mixed gives me some weirdo aesthetic pleasure! Just make sure not to put normal Shimano gear cables in or they might get stuck in the lever!

Brakes

Like for the gears, if your bike has brakes, they will most probably be perfectly fine with some fresh Kool Stop salmon brake pads. Old cantilevers can be a bit tricky to set up at first if you are not initiated into their adjustment, but properly adjusted they are some of the best brakes available. A good starting point with ATB-style “low-profile” cantilevers is to set the straddle cable as low as possible.

V-brakes are also good, but I dislike them a little bit for their on/off type of braking that lacks modulation. They are easier to adjust and to keep adjusted though. Just be sure to match your brake levers to your brakes, ones meant for cantilevers wont work for v-brakes and vice versa! If you want to use a drop-bar, levers for V-brakes do exist but they are more rare. Examples are the Dia-Compe 287v and EVO-V.

This bike has some Dia-Compe V-brake levers. Pretty sure that is the Kona P2 fork mentioned earlier.

If you wish to use integrated brake/shift levers meant for road bikes, then pretty much your only option is to go with cantilever brakes. Lever/brake pull ratio modifying units that allow mating the brifters with V-brakes do exist, but I am a bit suspicious of adding more moving parts to something as critical as brake cables. They probably will work fine until they get corroded or dirty. All in all, I personally prefer cantilevers anyway due to their superior modulation and feel.

Tire choice

Another thing that affects the handling and characteristics of the bike greatly is the tires. ATBs are of course picked in the first place due to their good tire clearance, so wide tires are usually the only relevant option. But not always the very widest possible tire is best for everyone.

These bikes basically always use 26”, or more scientifically said 559mm Bead Set Diameter tires. A 50-54mm (true width) tire will suit most people. The Gravelking SK 2,2” (about 52mm) is a good general all-round tyre that I can recommend, and that I have personally used in the past. For summer use I dont really see much benefit in using a tire with larger knobs, except if you use your bike mostly for actual forest/mountain biking on WET trails. The only situation where knobs are really useful in my opinion is when it's wet or snowy. If your location has lots of snow in the winter, run the widest moderately knobby tire you can fit, except if you are using mudguards be sure to leave at least 10mm of space between tire and fender, even more is beneficial.

My Tunturi Equillar with a 2,4” Furious Fred up front and 2,2” Nobby Nic in the back. Summer mode so no fenders. I am 178cms tall, about 84cm PBH, and the frame is the XL size I think, about 21”, 600mm top tube and a 535mm C-T seattube. Shown here with a completely rack free double Carradice setup: the rear did sway a little bit and both needed to be set up correctly not to hit the tires. But it was fine and the tour was a success.

My personal go-to tire used to be the Schwalbe Furious Fred, which was available even in a 62mm 2,4” version. I like fast and light tires and I’m not afraid of punctures! But as that tyre is unfortunately discontinued I believe that the no. 1 fast ATB tire widely available is now the Continental Speed King 2,2”. It is very light, fast rolling and has micro knobs for that little bit of extra traction on wet ground. Probably the Rene Herse Rat Trap Pass is even faster and more comfortable in road/touring use, but the cost is very high and the completely smooth tread is not as suitable for all terrains. For those looking for a cheap but decent tire, Michelin has a good selection of 26”/559 tires for modest prices. As a side note, those tanwall tires some of you are eyeing are starting to be out of fashion now!

Mudguards

As many people build up their ATB as an allround commuting or touring machine, rather than for pure trail use, mudguards are an important thing to consider. The choices are not that plentiful, and the differences are not very pronounced. As no great aluminium 559-sized fenders are easily available, I would suggest using either the SKS Bluemels in 60 or 65mm widths, or the Gilles Berthoud stainless fenders in 60mm. The first is lighter but wobblier, and the second is heavier but sturdier and offers a little more coverage lenghtwise. Whichever you pick, be sure to install some mud flaps as well!

Some fiddlings with another titanium frame: front rack and rear fender mounted with hose clamps, rear rack under QR-skewer etc. This bike also has the Kona P2 fork, in the threaded 1&⅛” triple butted version.

Carry capacity

Every good bike used for everyday life needs a carry solution. Luckily pretty much all ATBs come with rear rack mounts at least. Only racing-spec frames have these left out. A normal aluminium rear rack bought from a recyclery like Uusix-verstas would be my choice if I was on a budget. Add a large Carradice bag like the Camper or Super C, with or without the quick release, and you have a very decent everyday/day tripping bag setup. If you are tall enough and have your handlebar set up high you can usually run a Carradice saddlebag in the front as well. I’ve done camping trips with just two Super Cs and a pair of large water bottles. Most forks do not have front rack mounts, which makes these bikes less easy to convert to full-on camping bikes. The Pelago commuter front rack is a decent choice but it is quite heavy, the side pannier mounts are too far forward for optimal weight distribution and it’s not the cheapest either. A fork with lowrider eyelets works great for fitting more bags, even though the low-mounted panniers can be a problem if you do real off-road touring as they tend to hit obstacles constantly.

Rear rack simply works everytime!

You could also drill your front fork for some side mounted cargo cages, or even just fix them on with tape or twine. I have even made pannier mounts out of wooden sticks I fixed with twine onto a front rack that I made out of a cheap rear rack. The mindset of the ATBer should be that of creative play, and thus you shouldn’t be afraid to try some wacky stuff!

A two-ATB tour in southern Italy with compact luggage, containing everything for wild camping and cooking.

Other parts

One more important piece is the pedals. If you’re really going to go off-road, I suggest you get some good pedals that are grippy, light and durable. Don’t get those 20 euro cool looking CNC machined pedals off of AliExpress, the bearings will most probably wear out fast or the axle will break just on that critical moment as you’re cresting the first hill on your big tour. Any mass produced decent MTB flat pedal will probably work well, but be prepared to spend around 50 euros. My personal choice is the MKS Allways: light, good looking, has crazy nice bearings and the shape fits my size 43 shoes just perfectly.

Brooks saddles: easy comfort and with proper use you get that inimitable beausage-look! Note clamped on racks due to race spec frames.

Like on any bike, the saddle can cause you horrible pain or it can be actually pretty nice. I prefer leather saddles, as they act as a simple spring between you and the bike. A well worn-in leather saddle gives you 5-10 millimeters of suspension, and with less techy parts than a suspension seat post. But if the original saddle on your bike works well, then why not use that.

A dynamo lighting system is extremely useful on any bike, and I would argue it is basically always worth the expense. If possible, get a dynamo hub&light combination that produces light even at low speeds, so you can climb hills even on nights when the moon is not lighting your path.

Some well deserved rest after all is done.

Conclusion

So now you hopefully have a great decent quality ATB with most of its original parts possibly still in place, fitted with a cool handlebar, comfortable saddle, some nice tires, mudguards, possibly dynamo lighting and a carry bag. Time to pack some useful items with you and get out there and see some birds/make some tea/read a book/get lost! (Or if your bike is still missing some vital parts, we probably will have it in stock)

-Aki