- This topic has 16 replies, 10 voices, and was last updated 9 years ago by devash.
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26 to 29 ETT numbers
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thepodgeFree MemberPosted 9 years ago
I’ve over thought this and confused myself.
I know reach & stack would be useful but I don’t have all the numbers & I know I should try before I buy but I’m looking second hand so it’s not always possible
If I’m comfortable on the following:
26″ wheels, ett 590, 65 stem
Fat bike, ett 610, 50 stemI should be fine with 29″ wheels & 600 ett shouldn’t I?
It’s my first go at 29ers so I’d like a little reassurance
thepodgeFree MemberPosted 9 years agoThat’s what I was thinking. I’ve just bamboozled my self with numbers
I can’t really see any reason why wheel size should make a difference, it was just quite a surprise how good the 610 ett felt when it’s supposed to be far too big for me and it happened to be on a different wheel size. Maybe I have long arms for my height or something
slackaliceFree MemberPosted 9 years agoFill yer boots. With a link to a good article from Transition Bikes.
thepodgeFree MemberPosted 9 years agoToo much arguing over things that don’t really matter in that thread
thepodgeFree MemberPosted 9 years agoNo but I suspect wheel size can affect the feel of the bike meaning I might not necessarily be looking for the same numbers
rickonFree MemberPosted 9 years agoWell, ETT will *generally* affect the wheelbase – which will *generally* be longer on a 29er.
Your Reach and Stack will *generally* want to be the same, regardless of what size wheels you’re on – it’s more to do with comfort, control and the type of riding you’ll be doing on the bike.
Obviously you can flex that Reach and Stack with using a different stem, but on a 29er you *generally* really dont want to be going much over 70mm or you’ll find the steering a bit slow and cumbersome – whereas on a 26er you can *generally* probably change that statement to 90mm.
Plus with stack, your Axle to Crown on the 29er fork will be *generally* longer, for the same given travel, compare to a 26er. So you have less room to lower the stack.
ShackletonFull MemberPosted 9 years agoFor what it’s worth I found that my 29ers generally had slightly longer TTs than my previous 26ers and I needed to use shorter stems (70mm down to 50mm) with wider bars (760mm up to 785mm) to get the same feeling of responsiveness.
But it all depends. If the bike is for similar usage then you are probably OK. If you are going from hardcore XC to big trail bike probably not.
Older 29ers also have slightly different geometries as they used fork offset designed for 26ers. If you are buying 2nd hand this is something to be aware of as this usually resulted in steeper HTA and all of the associated effects.
davewalshFree MemberPosted 9 years agoI think on a 29er you can get away with a bit more top tube length as the front is generally a bit higher, therefore bringing the bars closer to your shoulders. I ride a large soul and spitfire (610/55 & 615/50 ett/stem respectively) and they both feel good, however last year on holiday in the states I hired a 29er with 635 ett and 80mm stem and that also felt comfortable and I had no issues lifting the front wheel.
I’m testing a large Stanton Sherpa next week so should have more of an idea then !tenacious_dougFree MemberPosted 9 years agoBeen pondering this separately to this thread, then found the thread when trying to prove or disprove my theory!
Surely wheelsize will impact on ETT in that larger wheelsize almost always has a higher stack height. Given that both reach and ETT are influenced by stack height, being measured from the centre of the the top of the head tube.
On a lower stack frame, the riders saddle position will be raised further from the point at which the Reach/ETT measurement is taken than it will be on a high stack frame, thus lengthening the “effective” ETT for that given rider, since the angle of a seat tube means raising the saddle also moves that saddle backwards.
So taking the example from the OP above. Let’s say for arguments sake on the 26″ bike the saddle is 3cm above the top of the head tube, the point from which the ETT is measured, therefore the “effective ETT” when seated for the OP will be 590mm+ the amount the saddle moves backwards as it is raised to 3cm above the centre line, and backwards in the process. Then when you get your 29er, let’s say the stack height is 3cm higher, therefore the saddle will be run exactly in line with the top of the head tube, therefore the ETT will be bang on the quoted numbers. You’d be able to work the numbers out with some fairly simple maths, and knowing the seat tube angle, but it might actually be that the 600mm bike ends up in actual fact shorter than the 590mm bike.
Does that make sense? Am I right?
nemesisFree MemberPosted 9 years agoFWIW, I have the same position between 26 and 29. While 29ers do tend to have a higher stack height, you adjust for that with negative rise stems and/or flat bars if necessary.
thepodgeFree MemberPosted 9 years ago29ers do tend to have flat bars more than 26ers so I guess even if you work out the stack variations into it, you’ve still got cockpit changes which could be made.
I’ve always bought medium frames but having ridden a large and kind of preferred it I was wondering about sizing up.
Also found it odd that the 610 ett was the largest size from one manufacturer but the 600 ett was a medium in a range that went up to xl
Anyway I decided I need more miles not more bikes so didn’t buy the 29er.
devashFree MemberPosted 9 years agoI think on a 29er you can get away with a bit more top tube length as the front is generally a bit higher, therefore bringing the bars closer to your shoulders.
+1
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