Why were all riding bikes that are too small

[Craig Stubbs]

http://www.mbr.co.uk/news/size-matters-why-were-all-riding-bikes-that-are-too-small/

 

Really interesting read that I thought id share. For years its been drilled into people that if you are on the "size cusp", then rather go for the smaller frame, but when you apply this logic to technical MTB, the dynamics change.

 

Craig

[MTBeer]

WE'RE

 

just saying.

[Mousea]

Mmm think I will have to put some wheels on the next Farm gate I see

[TrackGuy]

I just see really headtube angle difference in the illustrations, size doesn't really have all that much to do with it.

[Brian Fantana]

I just see really headtube angle difference in the illustrations, size doesn't really have all that much to do with it.

The illustrations are not there to indicate different sizes. They are there to show the difference between classic geometry (short top tube, short wheelbase, long stem steep head angle) and forward geometry (long wheelbase, long top tube, short stem, slack head angle).

 

It makes a lot of sense. If you look how sketchy your average south african mountain biker rides, a longer wheelbase with a slacker head angle will help riders to descend with confidence without wearing down brake pads at an alarming rate. A shorter stem will also make you steering more controlled.

 

This is probably not for your weight weenie type marathon and XCO riders but it is very relevant to trail/All Mountain/Enduro riders.

[Hairy]

Mmm think I will have to put some wheels on the next Farm gate I see

 

 

I just see really headtube angle difference in the illustrations, size doesn't really have all that much to do with it.

coming off bikes that have always been a medium where I should rather have just gone for a large and nice short stem, I can fully agree with NOT getting the smaller frame.

 

having moved to a larger frame, or rather just a frame with a longer top tube and running a shorter stem has been a revelation for me.

 

the first signs I got that this was the way to go, was with the On-Ones I have had. They have always advocated a longer TT with a shorter stem. On the medium here I measure my On-One at the 600mm C/C of headset to seatpost and ridden with a 60mm stem.

 

Previous bikes in the medium sizes have all been on the 585/590mm mark. This led to beeing too cramped on the bike if running anything less than a 70mm stem and it always felt like the stem would be in the way of my knees on out of the saddle sprints.

 

My last duallie was a large with a 613ish mm C/C TT and a 50mm stem and it was really really a great feeling to finally "fit" on a bike.

 

For reference I am 1.78m tall and am usually slap bang on the mid point between a medium and a large based on most manufacturers fit guide.

 

So longer TT and a nice low stand and low seat tube could get more people fitted right on a bike.

 

In the article the author does really push his figures to the limit, but I believe there is merit in what he is wanting to promote.

 

In the illustration, please note the increase in distance of the riders knees and the stem

 

http://www.mbr.co.uk/wp-content/uploads/sites/11/2014/05/FORWARD-GEOMETREY-IMAGE.jpg

[Captain Fastbastard Mayhem]

The illustrations are not there to indicate different sizes. They are there to show the difference between classic geometry (short top tube, short wheelbase, long stem steep head angle) and forward geometry (long wheelbase, long top tube, short stem, slack head angle).

 

It makes a lot of sense. If you look how sketchy your average south african mountain biker rides, a longer wheelbase with a slacker head angle will help riders to descend with confidence without wearing down brake pads at an alarming rate. A shorter stem will also make you steering more controlled.

 

This is probably not for your weight weenie type marathon and XCO riders but it is very relevant to trail/All Mountain/Enduro riders.

Thing is, BF - it's not even highlighting the slacker head tube side of it all... just the longer TT / shorter stem combo! Throw in a slacker head tube and it just makes so much more sense.

[Hairy]

be careful not to get too caught up in super slack HA's

 

67deg is still a nice point for a trail / am bike in SA and 68/69 is nice XC and Marathon.

 

why are people afraid of bikes that can steer

[Craig Stubbs]

Interestingly enough, I popped into a large and well known Durban bike shop last week as im currently looking for a frame.

 

The chap who assisted me, looked at me, and said, you will be a large. Now, I'm 6'3 with a 94cm inseam, so pretty much an XL all the way. When i said that i wasnt too sure about his guess at a large frame, he responded, "a large will be perfect if you fit a 110mm Stem (this is for a 140mm trail bike with a 67 degree head angle).

 

Made me think how many people are sold lemons like this every day.

[Brian Fantana]

Interestingly enough, I popped into a large and well known Durban bike shop last week as im currently looking for a frame.

 

The chap who assisted me, looked at me, and said, you will be a large. Now, I'm 6'3 with a 94cm inseam, so pretty much an XL all the way. When i said that i wasnt too sure about his guess at a large frame, he responded, "a large will be perfect if you fit a 110mm Stem (this is for a 140mm trail bike with a 67 degree head angle).

 

Made me think how many people are sold lemons like this every day.

 

This is a good example why I think the article above is very good.  It highlights the very important fact that on a trail/AM bike, the frame cannot be compensated for by fitting a longer stem.  Sure you can play around between say 40-70mm stem length, but before you go longer than a 70mm stem for a trail bike, you should rather go for a longer frame.

[Hairy]

Interestingly enough, I popped into a large and well known Durban bike shop last week as im currently looking for a frame.

 

The chap who assisted me, looked at me, and said, you will be a large. Now, I'm 6'3 with a 94cm inseam, so pretty much an XL all the way. When i said that i wasnt too sure about his guess at a large frame, he responded, "a large will be perfect if you fit a 110mm Stem (this is for a 140mm trail bike with a 67 degree head angle).

 

Made me think how many people are sold lemons like this every day.

[CMK]

http://1.bp.blogspot.com/-AT--0EIE_cQ/UCgDpM4euRI/AAAAAAAABIw/SV4ZDQK5UME/s400/R+17.JPG

http://kanebikes.com/wp-content/uploads/2012/10/buy-bikes-online_oversize-bike-300x159.jpg

[nolipoli]

be careful not to get too caught up in super slack HA's

 

67deg is still a nice point for a trail / am bike in SA and 68/69 is nice XC and Marathon.

 

why are people afraid of bikes that can steer

and yet some of the newer trail bikes are coming out with 65 degree Head Angles.  Modern geometry seems to include fiddling with the offset of the fork to get a bike that steers well in spite of a slack head angle.

[LongDonkey]

http://1.bp.blogspot.com/-AT--0EIE_cQ/UCgDpM4euRI/AAAAAAAABIw/SV4ZDQK5UME/s400/R+17.JPG

 

Yup, thats what i look like..... sorta

[Hairy]

and yet some of the newer trail bikes are coming out with 65 degree Head Angles.  Modern geometry seems to include fiddling with the offset of the fork to get a bike that steers well in spite of a slack head angle.

critical factor

[Klipspringer]

Very interesting. Also 1,78 m like Hairy and measures according to bike shops between Medium and Large frame and have always been advised to go for Medium. With my last purchase when I went for an independant setup on my current medium bike,  I hade to add a longer stem and was told the large frame would have suited me better!  wish I had read this before buying.