Hi,
I’m considering changing my frame from a brother cycles big bro to a genesis longitude.
I like the big bro but the standover isn’t great, I’m 6’3″ so riding the XL which is fine length wise but it feels massive due to the standover.
Looking at the geometry charts for the genesis it looks on paper at least like it should cure that, it also has a 77mm bb drop Vs 60mm on the big bro which should make it feel a little more sat in than on if my understanding is correct.
So in a long way of putting it, should I swap or not?

I love mine, and from what you’ve said it probably is different from the Brother in the ways you want it to be. For reference, I’m 6’1″ and on a large, plenty of stand over and length. I’ve just put O-O loop bars on and it’s still roomy. It’s a very nice stable bike, good for loading touring but still lively enough to be fun on technical stuff. Looks like Genesis have dropped it this year though or maybe just not updated the website with a 2020 model? It would be a real shame if it’s gone, it’s such a great bike.

Thanks for the reply, sounds very promising.
Yeah I noticed there doesn’t seem to be a 2020 model on the genesis site, fortunately I quite like the orange of the 2019.

AFAIK they haven’t actually made any changes to the frame since they ditched the alloy fork in 2017, other than the paint jobs anyway. If you’re going frame only, all the parts from your Brother should move right over, it’s threaded BB, 100/135mm qr, 1⅛” steerer etc. It’ll take 27.5 X 3.0″ tyres but only with a 1x setup.

Yep frame only, I’ll be running it as a 29er as that’s what wheels I’ve got. The only thing I will need is a seatpost as the big bro is 30.9, hopefully everything else should swap straight over ( hopefully hoses and cables are long enough).

Measuring up my 2017 one the geometry chart bears no resemblance to actual geometry! Seat tube length is correct but literally everything else is different. Head tube is shorter, top tube horizontal is shorter and chainstays are longer compared to the spec sheet!

Well, that prompted me to go and measure mine (2017 XL). Not least because I’ve never quite figured out why it’s never ridden quite how I expected (and wanted) it to. Having bought it knowing the (alleged) geometry difference between it and my previous MTB, I’ve always been surprised with how high the front end felt, how unweighted the front wheel felt, how slack the steering felt, and how much I ended up pushing the saddle forward.

So…

ETT (667mm) and ST (520mm) and BB drop (77mm) all seem correct but then it all goes a bit awry.

Chainstays appear to be around 460mm (spec says 438), though that doesn’t bother me too much.

The top tube is 160mm (spec says 115), which in practice doesn’t give me a major problem but explains it feeling higher than expected.

The real issues come with the angles.

Seat angle should be 72.5, and admittedly it’s hard to measure because it’s a bent tube, but it looks to be somewhere around 71. Which explains why I’ve ended up sliding the saddle forward (something I’ve never needed to do on other bikes), losing precious saddle-to-bar reach in the process.

Head angle is specced as 70, but as far as I can measure it, it looks like 68. Which explains why I’m less able to weight the front wheel than I’d expected and why I’m finding the steering lazy. That’s always bugged me about this bike, it’s simply not the front end handling I like or had expected.

So on the one hand, thanks for pointing this out, because I now know I’m not going mad and there are good reasons for why it’s not riding the way I expected.

On the other, I’m now royally pissed off that I’ve been sold something that’s not what I thought I was buying. I’m unashamedly a fussy git when it comes to these details, I know many people would just suck it up and ride it, but this has been bugging me for 18 months now.

Ugh. Annoyed.

Ah bugger!
I guess I’m just going to have to suck it and see as I’ve ordered one now.
Well after reading Bez’s reply I at least know to get an inline seatpost.

I’ve the yellow frameset with the alloy fork and love it. Don’t know how the geo on that compares to the steel fork version but for me it’s a lovely versatile bike.

I went the other way, Longitude to BB. Both Medium

I needed seat post, front mech and cable and thru axle adapters for Pro 2 Evo. Big Bro is thru axle – Longitude QR

2018 big bro is qr

Aah, never realised that, I have the 2019 frame with TA

Interesting. I just happened to look at the 2019 Longitude geometry and I note it’s a match for what I measured my 2017 to be. Maybe they finally found a working tape measure? Or maybe they just read the forum 😀

https://www.genesisbikes.co.uk/bike/longitude-fs

Tempted to try and find a cheap 420mm fork to see if the tyre clearance and BB height are adequate. Should help bring the angles a little bit towards what they were originally claimed to be.