Hi there,

Trying to build up a (rigid) MTB for the summer, using parts I already have. (26er or 29er: have wheels and forks for both) The only part I need is a frame... (and maybe headset if frame had oversized head tube)....

At 5ft 8, I seem stuck between 16 inch or 18 inch. I've picked up a 16 inch On One Inbred frame (26er) for cheap but before I build it up, have measured my cycling inseam (book jammed into crotch method) + the length of the seat tube. My inseam is 80cm to pubic bone height.

On an old 26er 90s XC MTB which is 18 inch, I have around 20cm of seat post showing for full leg extension (for light trail use). So I'm thinking that on a 16 inch frame, I would end up with at least 25cm. This bike has an almost horizontal top tube and very low front end - 90s xc fit not v. comfy! Otherwise I'd just use this with a V on the rear as it's a decent cromo jobby.

On One's sizing puts me firmly in the 16 inch range, while other brands put me in the 17 - 18 inch range.

Not being an avid modern MTBer, just wondering if their sizing is on the assumption that people run their saddles a bit lower on MTBs.

Anyway, 25cm would seem like a lot of seat post!

Any thoughts appreciated!

I think REACH is at least as inportant if not moreso than frime height. Also, you need to consider headtube height.

Are you riding mostly pavment and or groomed trails? Off-road riding means a lower toptube so you don't crush the family jewels during an unexpected stop/dismount.

I toured fire/logging/mountain roads 2-weeks at a time and did a lot of that on a 21" mtb frame and was 5'9".

A por image due to being scanned from a 3"x5" photo.

#01 Ready to Ride by Miele Man, on Flickr

For off road trail riding i like more clearance between the toptube and groin.

Here's are some of my other MTBs although they're all converted to drop bas.

IMG_3433 by Miele Man, on Flickr

IMG_0561 by Miele Man, on Flickr

IMG_3366 by Miele Man, on Flickr

IMG_3332 by Miele Man, on Flickr

None of these has 25cm (nearly 10 inches) of seatpost showing.

I'd say a 18" to 20" frame size should fit you. However that does depend on your leg and torso lengths.

Cheers

Thanks for such a detailed reply - the bikes look great. I've not been able to get drop bars to work successfully on the couple of older MTB frames I have lying about, even with raised stems.

Anyway, I think you're right - stood over some 16s and 18s at work yesterday and 16s only fit with 25cm + seatpost when seat at correct height for reasonably flat terrain...

18s ok stand-over wise, apart from the 29ers. I will keep my eyes open for an 18 inch frame on 26 wheels - hopefully there's a 29er / 27.5 convert getting rid of one!

Pls help I'm using 17.5 frame my height is 5'5" what do you tink that's good for me tnx

sounds ok. how does it feel?

https://www.bicycle-guider.com/bike-...ke-size-chart/