Ye olde mtb frame size help

[macp]

So I’m pretty much settled on a Haibike Alltrack 6 hard tail. But I’m struggling with frame size. I’m 5 11” with about a 33” inside leg. Overall though I’m pretty average size wise everywhere else. My selection is M or L. But I’m concerned about feeling stretched out. And getting neck or shoulder pain. Also there is the question of wheel size 27.5 or 29. Although 29 is only available in the large. Where you can select 27.5 or 29 in M size. My riding is light off road and some road riding/commuting.

Thoughts or comment are very welcome please guys

[dave123456]

I’d say your inside leg : height ratio is on the higher side. I’d go medium with 29” wheels.

[macp]

Thanks Dave im also coming down on the side of medium. I dont think I have ever gone large on bike sizing before. I swang my leg over a large. And although the dealer seem convinced I was a large. Particularly as he put it because of the height of the bottom bracket. But it stlll seemed too big. I guess if I feel cramped on a medium I can at least get a longer stem.

[Regbuser]

You might find this useful > https://www.bikester.co.uk/guides/frame-sizes/1080...

[bobbo89]

Reach is the number you want to be looking at if your worried about being stretched out.

I'd say that at your height you want something with a reach of around 480ish but could maybe go lower.

You need to try bikes and see how they feel really.

[macp]

Regbuser said:

You might find this useful > https://www.bikester.co.uk/guides/frame-sizes/1080...

Thanks it reckons 47 to 48cm (18-19") frame size.

[macp]

bobbo89 said:

Reach is the number you want to be looking at if your worried about being stretched out.

I'd say that at your height you want something with a reach of around 480ish but could maybe go lower.

You need to try bikes and see how they feel really.

I guess I may just have to find some time and get my ass out there quite literally and sit on a few bikes. I did just this weekend sit on a large Haibike. It just gave me the impression of being big. But as we all know it could be an expensive mistake to get it wrong.

[GravelBen]

bobbo89 said:

Reach is the number you want to be looking at if your worried about being stretched out.

Reach number for being stretched out while standing on the pedals, top tube number for being stretched out while sitting. They can be quite different depending on seat tube angle.

bobbo89 said:

I'd say that at your height you want something with a reach of around 480ish but could maybe go lower.

I'd suggest going a bit shorter for a hardtail, because hardtails effectively get a bit longer as the suspension sags.

For a reference point I'm 5'10" (1" shorter than the OP) and have found a nominal reach of around 450-455 suits me on a hardtail - my current one is 455 (622 effective top tube), which from memory equates to a sagged reach of 472. I wouldn't want to go any longer than that, I swapped from 50mm to 35mm stem to make that size fit me better.

bobbo89 said:

You need to try bikes and see how they feel really.

Absolutely agree, proportions and preference/riding style etc make a big difference as well as overall height.


ETA: just looked up that Haibike geometry, looks like the M is 432 reach / 674 stack / 625 top tube. L is 452 / 683 / 648 - they have quite a slack seat tube angle (ie seatpost leans further back) which means longer top tube relative to reach, and quite a tall stack for a more upright position.

OP while the reach number would put you on the L for standing descending, I suspect you might find the L feels too stretched out while sitting pedalling. But a test ride is the only way to be sure.

Edited by GravelBen on Monday 31st July 01:03

[dave123456]

Talk around changing stems - this can make a difference to the handling.

It’s hard to tell someone else what size they need, as I said in my earlier post height is one thing, upper body : leg ratio is another issue, my legs are proportionally longer so I have always tended to size down which results in a lower front end for me - coming from a 90’s mtb background that’s not an issue…

I have 2 bikes I use on the road now, a canyon ultimate and a ribble gravel sl, the canyon is more stretched and I find more comfortable, although most people would likely prefer the more upright ribble.

My advice was based on the relatively long leg length and the OP question.

[macp]

GravelBen said:

Absolutely agree, proportions and preference/riding style etc make a big difference as well as overall height.


ETA: just looked up that Haibike geometry, looks like the M is 432 reach / 674 stack / 625 top tube. L is 452 / 683 / 648 - they have quite a slack seat tube angle (ie seatpost leans further back) which means longer top tube relative to reach, and quite a tall stack for a more upright position.

OP while the reach number would put you on the L for standing descending, I suspect you might find the L feels too stretched out while sitting pedalling. But a test ride is the only way to be sure.

Edited by GravelBen on Monday 31st July 01:03

Fantastic bit of analysis Ben. Very much appreciate your time & comments.

[macp]

dave123456 said:

Talk around changing stems - this can make a difference to the handling.

It’s hard to tell someone else what size they need, as I said in my earlier post height is one thing, upper body : leg ratio is another issue, my legs are proportionally longer so I have always tended to size down which results in a lower front end for me - coming from a 90’s mtb background that’s not an issue…

I have 2 bikes I use on the road now, a canyon ultimate and a ribble gravel sl, the canyon is more stretched and I find more comfortable, although most people would likely prefer the more upright ribble.

My advice was based on the relatively long leg length and the OP question.

Agreed Dave and actually my thinking is more towards a medium. I had a specialized rockhopper in a M/L frame I think it was and it felt fine in my book. Of course though it would be very typical of me to overthink this.

[macp]

Watching a really good video on YouTube last night as others have said reach is the key. It went on to say in order to get your reach or RAD take your height multiplied by 2.5. So in my case that is 451. To get a minus RAD it’s height x 2.45. So that is 442.

The bike shop have replied to say you could run a medium and deal with the under reach and lower front end of the medium with a longer /taller handlebar stem.

I’m even now wondering if I should be looking at gravel ebikes. But I doubt I will be able to get the same size of battery that you can on an emtb. And with a flat bar ?

Edited by macp on Monday 31st July 17:21

[macp]

Just spotted a new old stock 2022 Trek Powerfly in large that has the juices flowing. Frame sizes in the large dont seem as severe as on the Haibike. And im reading that the Trek quality is very good.

[macp]

So just an update. I bought the Trek and im blown away by the difference in torque from the Performance CX motor as opposed to the Active Line Plus. I thought the ALP was pretty good. But the PCX is so much better. The only slight negative is that the CX is a good bit noisier than the almost silent ALP motor. Not a biggy though. Im also happy with the L frame size. The original bars were virtually flat and 750mm wide. I changed to a 720mm bar with a 30mm rise. And the comfort has improved. I may yet go up to a 50mm rise. But I will wait and see.