All

I’m looking to get a new bike and was wondering what is more important to look for in the geometry between the eff TT and reach? I’ve always gone by eff TT in the past but reach seems to be quoted a lot more now.

I know the best way to tell is by trying the bike but I’m looking at one of the Canyons so can’t try it. It’s the Grand Canyon AL SLX and I’m between a L and XL. The L has a shorter TT of 610mm than my last hardtail which was 622mm but the reach is longer on the Canyon at 436mm Vs 428mm. The XL Canyon has a TT length of 630mm and the reach is at 452mm.

For reference I’m 6’5″ but have long legs and short body so might not really need an XL frame and I’m also concerned that the XL might be a bit of a gate!

Any suggestions would be appreciated.

I would have thought XL at 6ft5!

Effective TT is affected by the seatube angle, for every degree slacker it adds about 1cm to the ETT. So although the canyon is a cm shorter in ETT it’s a cm longer in reach, so I’m guessing the seatube is about 2deg steeper?

The net result is you’ll end up with a more laidback seapost to put the saddel back where it should be relative to the BB (assuming your current bike is perfect).

It’s more usefull on trail/enduro/AM bikes with droppers as they’re starting to get much slacker angles to compensate for the loss of any layback in the posts. Which would make the top tubes look artificialy long compared to a couple of yeas ago when layback posts were standard.

Of the two, reach is better for comparing two bikes. However, it’s only a small part of a much bigger picture.

Having said that, both my mountain bikes were bought from SPEC sheets and both at a time before reach and stack were commonly used. Both fit perfectly.

Consider the effect of combining stem lengths with your reach comparisons

Cheers for the replies. Some stuff to think about.

Spoon – My last hardtail was a C456 that has a seat tube angle of 72° IIRC so with the Canyon at 74° that might explain that difference.

Onza – The stem length for my old C456 was 90mm and the L Canyon comes with a 90mm stem and the XL 100mm. So I suppose in theory, reach wise, the L Canyon would still be longer?

Just looked up the spec of a Whyte 901 I had a few years back and that fit me well too and the eff TT of that was 610 the same as the L Canyon. No word on reach though unfortunately.

wilkij1975 – Member

I’m also concerned that the XL might be a bit of a gate!

dude, you’re 6’5″! – well into ‘gate’ territory.

if the XL is too long (i doubt it will be, a reach of 450mm isn’t ‘that’ long) you can always fit a shorter stem; big bike + short stem = all the rage nowadays dontchaknow.

Reach is the important measurement for when you’re out of the saddle. The BB / pedal postion to the centre of the head tube.

The effective TT is the important one when you’re sat pedalling.

As said above the arrival of non layback dropper posts has changed seat tube angles in the last couple of years. Stem length is for changing the handling and weight distribution over the front wheel as oposed to making a MTB fit properly.

Any way of finding out what the reach is of a bike if its not published?

My bike has a seat angle of 73.5 and so does my potential new bike, theres 3mm different in effective top tube length (new bike is longer), is it fair to assume that the reach will be similar as the bottom bracket is higher on the new bike by 9mm. All pretty close im guessing and will feel similar.

My bike is a 2013 stumpy evo, new bike is a 2014 orange alpine. Ive sat on one and it felt near enough the same!

At your height and with long legs (for your height) I would have thought Seat Tube length would be the limiting factor. With a 420mm Seat post would a size L (shorter ST) allow the saddle height you need?

Any way of finding out what the reach is of a bike if its not published?

Reach = ETT – ST Cos (SA)
Stack = ST Sin (SA)

where ST = seat tube length, SA = seat angle. Obvious caveats about how seat tube length is measured up to the point where ETT is defined.

Any way of finding out what the reach is of a bike if its not published?

Get the dimensions you can find and model it up here http://www.bikecad.ca/quickapplet to find others and start to understand the relationships between them.

This might be interesting

http://www.shedfire.com/2014/07/14/i-should-probably-do-some-diagrams-for-this-but-quickly/

Bikecad can help if used right.

Reach = ETT – ST Cos (SA)
Stack = ST Sin (SA)
where ST = seat tube length, SA = seat angle. Obvious caveats about how seat tube length is measured up to the point where ETT is defined.

Unfortunately this is incorrect. Stack is vertical distance between BB and top of head tube, reach is horizontal distance.