Size choice – Trek Fuel EX 8 GX 2021 – on the fence with ML and L

Hi,

I’ve decided to buy new Trek Fuel EX 8 GX (2021 version). But I have a problem with deciding which size should I order. Unfortunately stores near me don’t have this one on in their stock, so I cannot try it.

My dimensions are as below:

* Height: 180 cm heigh (5’11)
* Inseam leg length: 79 cm (31.1 inches) (measured with no shoes)
* Arm span: 170 cm (5’7) so ape index < 1

Apparently my arms and legs are shorter than average.

Trek on their website recommend this dimensions:

ML (18.5 virtual / 17.5 actual) – height 165.5 – 179.0 cm and inseam leg length 77.0 – 84.0 cm
L (19.5 virtual / 18.5 actual) – height 177.0 – 188.0 cm and inseam leg length 83.0 – 88.0 cm

So I match for both L (looking at height) and ML (looking at inseam leg length), and therefore I’m not sure which one should I choose.

Here are all dimensions for that bike: https://www.trekbikes.com/gb/en_GB/gb/en_GB/bikes/mountain-bikes/trail-mountain-bikes/fuel-ex/fuel-ex-8-gx/p/33001/

Is here anyone with similar dimension who use Fuel and can share your experience?

I will just add, that my intention is to buy the bike that will be as universal as possible, as I’m planning to use it in various routes with a both uphill and downhill parts, short and long routes.

Thanks
Adrian

I’m 1cm shorter with similar inseam. I went for ML Top Fuel. L would have been too big (not enough room for a 150cm dropper)

Inseam is more important than overall height when choosing a frame size IMO.

I’d say body and arm length is more important than inseam, you can adjust saddle height a huge amount but you’ve only really got a few cms stem length to adjust. A 150mm dropper is good but not on a frame that’s too short.
Looking at your dimensions I’d probably go ML though as shorter arms means you might find the L a bit of a stretch. If needed you could add a bit of stem length to increase the reach a bit.

Looking at the dimensions, it looks a couple of years out-of-date.

A bit shorter, steeper head, slacker seat etc. If you size ‘up’ how long a dropper can you actually run if you’ve “short legs”?

Tried a large ex 2020 and loved it.
I’m 6foot, just

I thought that Trek stopped all that Virtual and actual sizing about 3 years ago . 6ft with a 33 inside leg riding a large 2020 fuel EX 8 and I have a fair bit of post out of the frame and the fit is great . Just remember to make sure if you go for a large that you can get the dropper low enough in the frame to fit otherwise you will need to buy a shorter dropper . Also remember when measuring your inside leg to actually measure without clothes on and don’t just go by what size jeans that you wear . Great bike .

I just went through similar with buying a Remedy. Luckily the shop had a Med and Large so I got to try them both. Med felt just a wee bit cramped for me but the L was spot on.
I bought the L and as I went back in to pay for it someone else was buying the M, crazy corona ike demands!
I’m 5ft 10, no idea of inseam etc.

183cm here on a large. Fits great

I’ve always found a bike that’s slightly too small is much better than one that’s slightly too large. Depends on where you ride though.

Descriptions like “Medium” and “Large” are completely useless. A lot of Small sized frames now seem to be as long as many Large frames were 10 years ago. Getting a tape out and measuring up your current bike, then comparing it to the dimensions of the new bikes is probably the best you can do if you can’t ride them. Other people who are of similar height to you might have different proportions or preferences, so not really much use.

Found myself in a similar predicament when I wanted to buy a Remedy 8 last year. My height is 181cm and inseam is about 32 inch. Ended up with a large which ime quite happy with. Reach wise it doesn’t feel that big but I’ve got bad knees so do feel it getting on and off on inclines but a touch on the dropper sorts that.

What is your current bike? If you are comfortable on it I’d be happy to help with a comparison against the M/L and L.

Trek seem to do their geometry and sizing a bit more traditionally and less Pinkbike cool bro. You can probably make both work so it depends how you see yourself using it. If you would normally go smaller and more nimble then M/L. If you want 1.5cm more reach and longer wheelbase then go for the L.

Trek are very good with their advice so see what they say. I went with the advice to size down as I could fit M/L or L which wasn’t my first instinct but I am very happy I did.

The other thing to bear in mind aside from dropper length is that the actual seat tube is very slack so if you run a lot of post the saddle may end up too far back on a smaller frame. Trek should be able to advise at what height they measure this virtual STA and which size helps you get closest to the 75 degree virtual STA for your saddle height to avoid it being miles behind the BB.

Thanks everyone for your advices. I managed to find a shop that had similar bikes in both sizes (other version, but the same frame).

Reach in both seems to be ok, although I slightly prefer L. It gave me the feeling of having more space. Would a longer stem help with that?

But the dropper height was too high for me. When I put the dropper fully in frame and extend it, I was barely touching the pedals. In M/L with the same setting the height was in point.

So although I still have some doubts, I think I will buy M/L. For L I would definitely need to swap the dropper to shorter one. For M/L I may need to buy longer stem, maybe 70mm rather than original 50mm to get some more reach.

What is your current bike? If you are comfortable on it I’d be happy to help with a comparison against the M/L and L.

The last one that I used didn’t have any marks about size, I bought it just be trying it. One of my older bike that I remember was B’Twin Rockrider 520, size L which was good size. Bot completely different geometry and different usage. Here’s the geometry of it https://contents.mediadecathlon.com/p1969850/k$7dbe52fe42d6acefb052002ab55a3b28/geometria%20ST520%20530%20540%20jpg.jpg

I’m 5’11 and the large is Bob on! My legs are also shorter than average apparently 🙄