The Trek Y Series Introduction

During 1995 Trek released a bike design that would revolutionise the design of mountain bikes for several years. It was called the Y33, and was made from what Trek called OCLV, or Optimum Compaction Low Void. In plain English, that's Carbon Fibre. This would have been one of the most expensive top of the range mountain bikes then available. The revolutionary aspect of design was the Y frame with a URT (Unified Rear Triangle), which was the ultimate in simplicity for a full suspension design.
It also won an industrial design award.
It wasn't long before everyone else was copying it, though usually with only a two piece "Y" or variants thereof, and differing pivot points for the URT. There was some mention of Trek attempting to seek compensation from GT for infringing their patent.  So, next time you see a Y frame bike, remember it came from Trek's Y33.

From July 1996 Popular Mechanics. The Trek Y33 was being compared against five other bikes and came out top.

Trek didn't stop with the Y33 for there was a whole series of Y frame OCLV bikes and to make the Y design more affordable to the masses, a series of aluminium models were released.
The last of Trek's Y frame mountain bikes were released in 2001.

The OCLV Frames
These were produced from 1995 to 1999 but developed a reputation for problems with the initial models. The main one was the rear shock mount would become detached; it was only glued on to the frame. There were also a few incidents with the carbon fibres delaminating. Some riders complained of the frame being noisy; apparently the hollow carbon fibre frame had some sort of amplifying effect.  These problems were overcome for the 1998-1999 models, with a change of frame design. The improved Y series carbon fibre frames look more like a wedge shape than a Y, and the rear shock mount is much stronger; being moulded into the frame itself.

1997 Y11 in large size. The "Y11" is a two tone yellow/black decal on the upper arm near the seat tube.

1995 medium Y22. The most popular of the OCLV Y bikes. 1996 saw a nude carbon finish while for 1997 it version was available in cream with the "Y22" decal being two tone red/black.

1997 Y50 (Y Five O) in large size...named after the "Hawaii Five O" TV series. Top of the range for 1997. Note the unusual body graphics.

The models in the initial OCLV Y frame series were the Y50 (pronounced Y Five-0),Y33, Y22, and Y11. The Y33 was intially the top of the range bike, but was overtaken by the Y50 in 1997. All these models used the same frame and differed only in the body graphics and components fitted.  The Y50 did not appear with the new frame in 1998. Instead, the "Y Superlite", YSL200, and YSL300 took its place, and were then the top of the range. The URT for all these models was 6061 aluminium. The 1995-1997 URT's are made of rectangular section tubing, with a replaceable derailleur hanger for the 1997 models. With the new frame in 1998, the URT was now made of oval section tubing, also with a replaceable derailleur hanger. The URT's are interchangeable and some of the new style frames were fitted with the older URT's. Note that the Gary Fisher Joshua uses the same URT. Hardly suprising, since Gary Fisher is owned by Trek.
Trek also created a road bike at the time called the "Y Foil". This had no suspension and looks nothing like the mountain bikes. Its production was short as it was banned from competition for being too light. One of the Tour de France commentators mentioned that the bikes had to be a minimum weight of 6.8kg.

The new style OCLV frame introduced in 1998. Applicable to Y11, Y22, Y33, YSL, YSL200 and YSL300. It eliminated rear shock mount failure. The YSL's were made of OCLV-HC (Honeycomb) construction reducing weight by 10%. The YSL300 pictured is a medium size 1999 model.

The Aluminium Y Frames
While the OCLV framed Y bikes had been in production since 1995, the aluminium models came later. Initial attempts to create an alloy Y bike resulted in the ST120 which uses the same URT as the OCLV bikes.

1996 large size ST120 has the same URT as the OCLV and later aluminium Y bikes. The 1996 catalog states that, "Our new ST120 incorporates all the functional advantages of our Y-bikes into an Easton aluminum design at a shockingly low price."

It existed until 1997 when the true Y bikes; the Y5 and Y3, and later Y1 and Y-Glide/ Y-Glide Deluxe came into existance. For these bikes, the frames were identical throughout their production. The main part of the frame (the Y shaped part) is made of 6061 Aluminium. The Y5 and Y-Glide/Y-Glide Deluxe have their URT made from the same material, and used the same URT's as the OCLV bikes. For the Y1 and Y3's, their URT is chromoly and are made from round section tubing. The chromoly and alloy URT's are therefore interchangeable, but of course the chromoly URT is heavier (and stronger if you're into rough treatment). The Y5 weighs 12.7kg and the Y3 is 13.2kg. As before, it's the quality of components that determine the model, with the Y1 being the cheapest. Gripshift gear shifters were used on some models at various times, but mostly various forms of Shimano Rapid Fire shifters were used. V brakes were standard except for the Y Glide Deluxe which was factory fitted with disc brakes. Cantilever brakes were used on the 1995 OCLV models.

1998 Y Glide Deluxe. Note the disc brakes.

It is important to realise that some of these bikes are getting on in years, and some have had components replaced. Important to realise this when buying a Y bike, because what came with the bike from the factory might not necessarily be what's on the bike now. These bikes were handmade in Wisconsin, which always made them more expensive than their imported competitors. A Chinese made bike with the same components will therefore be cheaper.
It is interesting to note that there were 3rd party manufacturers of the rear derailleur hanger and alloy URT since Trek no longer makes these. Unfortunately, new replacement Y frames are not made, so don't break yours! Carbon fibre is not repairable. Pivot bushings and URT's were still available as a spare part from Trek in the mid 2000's but would be difficult to find now. In 2007, I paid $50 for a pivot bushing and was told an alloy URT would be $500. As mentioned before, the Gary Fisher Joshua URT is another source for spares, and presumably the pivot bushing. Although the original purchaser of a Trek bike gets a lifetime warranty on the frame, if that frame is no longer available you get given something else; invariably the frame used on a current production dual suspension model. You get no warranty if you buy second hand.

Radical New Design
Although it was seen as a radical new design that got people's attention, the Y frame concept was not seen favourably by some. The problem was bio pacing, otherwise known as the "pogo stick" effect or "pedal bob", which has been a contentious issue with dual suspension bikes since day one.  Basically, the rear suspension caused loss of power, particularly riding up hill. As the rider pedalled, the URT would be moving up and down relative to the mainframe, using valuable energy. The main reason for this is that the distance between the rider and the pedals varies with frame movement.
Most of the manufacturers who were using the design experimented with pivot point location to compromise between rider comfort and bio pacing.  Usually, this was done by moving the pivot point, and also GT's I Drive system which used a unique bottom bracket design. Some rear suspension designs (eg. Trek 9300) were very bad in that the chain length would vary as the URT moved. With these bikes, the bottom bracket is on the main part of the frame and not the URT.
Trek claimed to have found the ideal pivot point and patented their design. This is why you won't see other bikes with the pivot point part way up the URT.
Many gave up trying to perfect rear suspension designs, feeling that if they couldn't make it work the best thing was to eliminate it altogether. Thus, the creation of the hardtail. Strange logic wouldn't buy a car without rear suspension would you? There is an ever so simple solution however, which Trek applied to the top of the range models. These had lockout shocks to completely eliminate the problem. However, if the rider is out of the saddle whilst pedalling, without a lockout shock, the problem is again eliminated. The critics don't really have any valid complaints.
The critics would also be hard pressed to give examples of bikes lighter than the Y series. How many alloy dual suspension bikes are lighter than the 12.7kg of a Y5? The OCLV models are even better at just on 11kg for the Y50. Even the relatively heavy Y3 is still lighter than many dual suspension bikes of today.
Something you won't find on other bikes is the welder's initials stamped into the bottom bracket...further illustration of Trek's pride in what they built.
The last of the real Trek Y bikes came out in 2001 with the Y1 finishing up fitted with cheap components.
Trek kept the "Y" name going for a while after,  with the much cheaper bikes, the Y26 and Y24. These are not in the same league as their predecessors and bear little resemblance to the original bikes in quality and appearance, and are known as "entry level" bikes. Although they continued with URT rear suspension, the URT's are not the same.

Trek Y Bike Chronology - How to Date Your Y bike

1995: Y33 and Y22 OCLV models with cantilever brakes. Y33 was Indigo Blue and Y22 Ice Red

1996: Y33 in now Judy Yellow, (i.e. frame colour matched to the Judy SL forks). Y22  fitted with V brakes and now nude carbon. Y11 released in Dry Ice Blue.  Alloy ST120 released.

1997: Y33, Y22, Y11 now have the "Yxx" logo on the upper arm of the frame printed on a two tone decal. Y33 is Nude Carbon, Y22 is Gloss Cream and Y11 is Gloss Ice Inkwell. Y50 takes over as top of the range OCLV with its unique red/white/blue graphics. ST120 replaced by Y5  in polished aluminium with black URT.  Y3 introduced as a cheaper version of the Y5. It had a red frame with white chromoly URT. Alloy URT's now have replaceable derailleur hangers. Later versions of the Y50 are nude carbon.

1997 Y5. First of the alloy Y bikes. This and the Y Glide/Y Glide Deluxe have an alloy URT unlike the cheaper Y3 and Y1. It was fitted with Deore LX standard of components. The pic shows medium size.

This version of the Y50 appeared later in 1997 and closely resembles the Y33 of the same year. It is not shown in the catalog. This one is a large frame.

1998: This was definitely the year of the Y bike! The OCLV frame shape is changed with a more rugged rear shock mount. This years OCLV models are a Y33 in Platinum Pearl, Y22 in Blaze Red, and the Y11 in Team Yellow.
The alloy bikes are the Y Glide Deluxe in Black Mercury Pearl, Y Glide in Ice Inkwell, Y5 in Team Purple and the Y3 in Ice RC Blue. There is no longer a Y50. Although they do not appear in the catalog, it appears that the Y Superlite (24spd), and possibly the Y Superlite 200 (27spd) are introduced later in the year. Other versions of the 1998 Y bikes which did not make the catalog included a yellow Y33, a nude carbon Y33, and a blue Y22.
The alloy URT's are now using oval section tubing and begin to feature disc brake mounts. Y Glide and its disc brake counterpart, the Y Glide Deluxe are now the top of the range alloy models.  "Trek" decals are now 3D except the YSL and YSL200.

1998 was definitely the year of the Y bike. From left to right is a medium Y22, a small Y33 which resembles the Y11, a small nude carbon Y33, and a medium Y SuperLite. Note that Trek were still using the Rocket Boy logo as seen on the YSL. None of these bikes appear in the catalog for 1998. This makes 11 versions of Y bike for 1998!

1999: The decline of the Y bike is now imminent with only the YSL300, YSL200, and Y3. 3D decals are dropped on all models. The Y3 has lesser quality components compared to the previous year. The YSL300 is now top of the range. It and the YSL200 are using OCLVHC frames; 10% lighter than the standard OCLV.

Y3 was the only alloy frame Y bike for 1999. It's fitted with Acera grade components and came in Inkwell Blue.

2000: Y1 is a cheap version of the Y3 introduced this year. It has lesser quality components. Y3 also remains.

2001: Y1 is the last of the Y bikes.

Y1 was fitted with relatively low grade components.

Sizing your Y bike

From the 1999 Catalog.

Note that the OCLV and aluminium frames have the same dimensions despite the different appearance. Get the size wrong and you end up with knee pain. Get the reach (C) wrong and you'll have neck and shoulder pain. It is interesting to note the seat angle (B). Is this the actual angle of the URT or is it the chainstay (D) relative to the seat? If the former, then it indicates that there are 3 variations of URT. I find it hard to imagine that one degree is going to make a signifigant difference. Interestingly, prior to 1999 the URT's are all the same size and have the same seat angle. When I queried buying a replacement URT for my Y22 I wasn't asked what size I needed either. And I don't believe the 3rd party Boulton URT came in S,M & L sizes.

What are the actual sizes?
The only time Trek actually list the frame size in the catalog is in 1995.

Some of the early bikes had a size sticker on the frame also with the measurement. From 1996 onwards, the bikes were simply listed as S,M, or L, although the size stickers continued on the actual frame for a short time.
Note that the above Trek measurement is from the crank centre to the top of the top tube. Most people measure from crank centre to top of the seat post clamp, so the above sizes are then slightly larger. Trek must have realised this, for in the 1997 Retail Technical Manual they have changed their method of measuring to the top of the seat post clamp, which they call "seat tube length". Now the sizes are:

From time to time there are supposed "XL" size bikes for sale. These are just ordinary large size with a longer stem fitted.

In case you think it's a weak design....

These pics came from Brian Sutherland in the UK who owns this 1995 Y11. It has been converted to single speed and has other components replaced. As can be clearly seen, it is being used as a BMX bike in these pics. It's obvious that the Y frame is not a weak design! Note also that this is the early OCLV frame, which is supposedly the weakest.

Trek Y Bikes Yahoo Group.
Yahoo discontinued group hosting at the end of 2019. The files for the Trek Y Bikes group were downloaded from Yahoo prior to the deletion of the group. They are available here: The messages file is in two sections with an obscure file extension. I found it possible to read the messages by changing the file extension to html and opening in a web browser.

1997 Trek Y5. My first Y bike. Top of the range alloy model.

1999 Trek YSL200. The third Y bike to enter my collection. This was top of the range for 1999.

1998 Trek Y33. The fourth Y bike was this 1998 model. It looked nice so I had to have it.

1996 Trek Y33. The fifth bike to join the collection, but the first I've had in medium size and with the early style OCLV frame.

1995 Trek Y22. The sixth Y bike I've bought. Classic original Y bike technology on what is the earliest model.

1998 Trek Y11.  My seventh Y bike..

1999 Trek Y3.  Medium grade alloy model were  my final two Y bikes.

(The 2nd bike was a lemon and I sold it).