Boardman rear chainstay upgrade

NaughtyNige78

Hi all this is my first post on here and am looking for some help and advice. I have recently bought a 2011 Boardman team fs frame unfortunately the rear chainstay has a very small crack in the small bar that sits just behind the bottom pivot joint the one with the two holes in it. To get it repaired is £30 as its not a load bearing part of the chainstay I’m happy the get it done. My question is will a 650b chainstay fit ie just a simple bolt on job so then I can put my 27.5s on it, iv do have 26ers but my 27.5s are much better. Is there anybody on here or do u know of anybody that has done this and if anyone has a Boardman 650b would it be possible for you to take some measurements of ur rear frame so that I can compare with mine some pics of the rear would but cool to any help would be very much appreciated.

kirkymtb

I had a similar issue with a Voodoo Canzo 26er. The cross piece joining the 2 sides of the chain stay eventually snapped. I fabricated a copy in steel and it transformed the handling. It was so much less flexible so the bike lost the vague feeling it had always had.
I have a 2016 FS Pro so I'll give it a measure and get back to you.

kirkymtb

The distance from the pivot above the BB to the pivot near the rear axle is approx. 37.5cm. The pivot is about 4 cm wide. The back wheel of the FS Pro has a through axle and is a 148mm boost (I think!).
I read recently that 27.5" tyres are actually only 27" in diameter. Utter rubbish! My Conti Trail King 2.4 is 28" compared to the same tyre on a 26er which is a 2.2 version which measures at 26". In other words you need a full inch of extra space to fit a 27.5" tyre, not the 3/4" you might expect.
The 650b Team is, of course, a skewer, not a through axle so would be the one to get for your frame. I'm not sure it would fit but reckon there's a good chance.

steve_sordy

Is the 2011 Boardman frame a 26er? A quick Google suggests that it is.

If so, I'm assuming that you intend putting 27.5 wheels on front as well as the rear, otherwise the geometry of the bike will be affected, and not in a good way. Rear only will make the head angle steeper. Both will be better, but I believe that having a larger front wheel alters the amount of trail. Trail is something I always have to bone up on, so I'll leave it there.

KirkyMTB makes a good point about tyre diameters, and it is interesting that he points to the large size of the Continental Trail Kings. A friend of mine and I used to to ride 26ers with 2.2" Conti TKs fitted front and rear. He replaced his bike with 27.5 Lapierre. I asked him how it felt and he said he couldn't tell he was on a 27.5 wheel compared to his previous 26er. I measured my 26x2.2 TKs and got 26.75". His 27.5x2.25 Schwalbe Nobby Nics were 27.25" in diameter. No wonder he couldn't tell the difference when the diameter was less then 2% bigger. It is interesting to hear from KirkyMTB that some 27.5 tyres inflate even smaller, to 27".

Not all tyres are the same, some are bigger than others.