So looking at a new bike but struggling to get my head around the sizing numbers. Im 6ft 2 with 34″ leg. Never able to sit on XL or XXL bikes as rarely in stock.

Looking at Hightower LT in XXL, reach marginally longer than current T130 XL, but EFF TT way longer!

If I buy on reach then im happy, however the +40mm EFF TT concerns me.

Other posts suggest to size up on SC.

Thoughts please?

Eff TT is affected by seat angle whereas reach is independent of seat angle. Does the hightower have a slack seat tube angle compared with the t130?

No…both very similar. Stack is taller on Hightower so guess saddle is out further when EFF TT is measured.

I guess EFF TT will be felt when seated and reach when out the saddle?

No…both very similar. Stack is taller on Hightower so guess saddle is out further when EFF TT is measured.

I guess EFF TT will be felt when seated and reach when out the saddle?

If the reach and seat angles are the same then the true seated reach at your pedalling height will be the same too.

ETT being measured level with the top centre of the head tube causes massive confusion when stack heights can vary so much. Really ETT should be measured at a standardised pedalling height for each size.

ETT = how long the bike feels when you’re sat down. Can be changed by moving the saddle a bit without affecting your pedalling too much.

Reach = how long the bike feels when you’re stood up. Can only be changed by modifying the cockpit setup, longer/shorter stem, lower rise bars, lower stack.

Now that’s all pretty simple. Now for the slightly more complex part.

Pay attention to stack, or headtube length. A short headtube may have you running many spacers to raise the bar. This shortens the reach the more spacers you add, and is exacerbated by slack headtube angles.

Generally, you should buy a bike based on the reach you need. Manufacturers have started to clock on this, as you’ll see most bikes are sold by size, not by seatube length. Then check you have enough seatube, then check the seatangle is enough so you don’t end up with your ass over the rear wheel.

All that said, until you sit on a bike, it’s just numbers on paper.

Pay attention to stack, or headtube length. A short headtube may have you running many spacers to raise the bar. This shortens the reach the more spacers you add, and is exacerbated by slack headtube angles.

I forgot about this aspect! Basically, if stack and reach are the same, then the standing fit is the same. But, the following geometries will all have the same fit, you just need more spacers and/or higher rise bars on the lower stack bikes (assuming you can get your bars low enough for your liking on the higher stack bikes).

Head Angle = 65 deg
Stack = 580 & Reach = 458
Stack = 600 & Reach = 450
Stack = 620 & Reach = 442
Stack = 640 & Reach = 434