Forum menu
I have a 26" MTB, I like it but the options for tyres and rims etc are getting less and less.
So looking at options to replace the rims for 27.5".
The frame itself has loads of clearance at the rear and horizontal drops and should easily take the extra 1/2" of a 27.5" which is good.
The fork is a Rockshock Recon and it won't take a nobbly 27.5" tyre. And even if I did squeeze a low profile one in the clearance wouldn't be safe.
To take the front wheel up to 27.5" I need a new fork. But the head-tube is too narrow to take a tapered steerer fork. It will only take a straight steerer. RS don't make a straight steerer 27.5" or 29" fork except for the very bottom end of their range unless I'm missing somthing.
So the only option I can see is either going the Aliexpress route or getting my hands on an old 29" fork from before the tapered steerer became standard and servicing it.. I've been watching ebay for a decent example but no luck so far.
I can see some options for having the steerer tube replaced but it's very expensive and not done anywhere near me.
Has anyone else tackled this problem? It's not an immediate concern but I'd like to keep my eye out for parts.
Depending on the headtube, you may be able to replace the bottom headset to enable you to fit a tapered steerer fork which will open up more options. Similar discussion here.
Yes, double check the headtube first.
RSF put straight steerers in modern forks
34mm ID head tube which was common on many 26 inch bikes with straight steerers will be a no go.
44mm ID can run an external lower cup headset for a tapered steerer.
I’ve an Xc 30 29er fork with straight steerer and qr which is adequate for tame stuff. Beware bb height though
Unless it’s got a very low BB, long reach and very steep seat angle, the handling will be compromised by these changes. If you keep the fork travel the same, then 27.5 front and rear will raise the BB by about 15mm and slacken the angles by about 1.5 deg. 29/27.5 mullet will raise the BB by about 30mm and slacken it by about 3 deg. Full 29 will raise the BB by almost 50mm and slacken it about 2 deg.
I really wouldn’t bother, I’d just spend time finding some 26” rims and tyres that suit.
I don't think it's panic stations for 26" tyres yet.
https://www.chainreactioncycles.com/tyres/mtb-tyres?f=4294957536,2247
Saying that, if you're desperate to switch to 650b you could always buy a tapered fork and replace the steerer.
https://www.ndtuned.com/en/tubo-de-direccao.php
27.5 front and rear will raise the BB by about 15mm and slacken the angles by about 1.5 deg.
Those numbers don't add up. I think it will jack the front up by about 15 mm which will slacken it by about 3/4 of a degree. If you mulleted it with 27.5 front and 26 rear, it would slacken it by about 1.5 degrees.
I've nearly always overforked my bikes and the predicted dire changes to handling have never occurred. You do need to crank the saddle forward though to get over the pedals for climbing.
A low end rockshox fork is prob the least worst option.
I'd avoid those aliexpress forks personally. Look v cheap and nasty.
“I think it will jack the front up by about 15 mm which will slacken it by about 3/4 of a degree.”
Depends on the fork but the A2C on most recent forks is a lot longer than many older ones - partly for the bigger wheel but also for the bigger tyres and stiffer crowns etc.
It all sounds a bit of a bodge - maybe it’s time to just pickup a new frame?
I have a 100mm travel, 27.5" DT Swiss fork with an 1 1/8" steerer. It's bloody good! Not for sale either. Just letting you know decent forks are out there...
There used to be a few Manitou tower forks knocking about with straight steerers for around £150. 100mm xc fork which can take a 2.25 tyre.
They get a bit noodly on fast rocky bits but in the main a decent fork