Geometry for Trainer Bike

Question about bike geometry… I have a 2020 Trek Top Fuel. Absolutely love it.

One problem: Trainer is upstairs, Bike is in Garage.

Easy solution is to hike the bike up and down but the wife isn’t having all the marks on the walls as I try to move it up and down in our tight stairway. I am thinking about getting a hardtail to throw on the trainer and keep the top fuel for the trails. I am racing the Lutsen 99er and I feel like my ability to generate power is way off coming from a road bike (currently on the trainer) to the Top Fuel.

Questioin: What hardtails have similar geometry to the 2020 Trek Top Fuel? (Bonus if it is steel)

Geometry varies with size across most bikes (seat tubes tend to increase faster than stack height). What size are you?

If you’re thinking of getting a hard tail for dedicated trainer duty you don’t need it to be as perfect as your main bike. I have a hard tail on the turbo permanently and set the saddle height and fore aft to be as near to my road bike as possible. The bars are there or there abouts.

But I can feel the improvements on the road bike and my full suss when I take them out.

Don’t think it has to be perfect in my n=1 experience. You’re still working the fuel systems and your body is adapting.

You can try geometry geeks to find bikes with similar geos. For a dedicated trainer bike you don’t even need brakes. :joy:


Size Large. Sorry should have put that in there before.

no brakes needed Johnnyvee! I just need to get ballpark and maybe I just haven’t dove deep enough into it yet but it seems like the TopFuel is quite a bit different than most hardtails.

All that matters is the stack / reach / handler width / saddle and pedals. Match those, and ignore the rest of the geometry for a dedicated trainer bike.

Remember: you don’t care about on trail characteristics, so things like head tube / seat angle, slack, trail, chainstay length, etc are irrelevant


AlphaDog nailed it. If it’s a trainer bike, you could literally build up an extra small frame with some spacers under an up-turned 130mm stem, and a super long seat post. Outside, that would handle like crap, but inside it really only matters where the touch points are.

I’d find the cheapest used bike on Craigslist/FB marketplace and check its measurements versus your bike, then figure out what stem/spacers you’d need to make it mirror your outdoor bike. For example, if you were looking at an XL bike that had a reach 20mm longer and a stack 10mm higher, you’d run a 20mm shorter stem, with 10mm less spacers under it compared to your Trek. Match bar width, probably saddle shape, and set the saddle in the same spot relative to the bottom bracket, and you’ve mirrored your fit. (this assumes same crank length between bikes, but 99% of M, L, XL MTBs are going to have 175mm).


Thanks @AlphaDogCycling I’ll have to start doing some math… :thinking:

Try With that site you can select two bikes and see the comparison. There are others that have this same functionality, so no need to do the hard math yourself, as other people have built tools that will do it for you