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Obviously not if you don't mind V brake bosses, straight steerer, 100mm wheel spacing a weird range of A2C measurements.... There's loads of them.
I've searched the forum for previous threads, of which there are quite a few. But couldn't find my answers.
So are there any rigid carbon forks that are:
1) for 29ers
2) Have an A2C of approx 465mm (this is my info from this forum on the right length to replace a 100mm sus fork)
3) Have a Tapered Steerer
4) Boost spaced
I naively thought that the biggest current market for a rigid MTB fork would be to replace a 100mm travel, boost spaced, tapered steerer fork on an XC 29er....?? I mean that's the kind of bike that would still ride in a manner it was designed to with a rigid fork. Unlike a slack trail bike etc. In my mind, I have often passed by svelt looking XC guys on a racey 29er with rigid forks. Or at peast I thought I had.
Anyway, that's what I want to do. My local off road loops in Bristol are so tame, that I want to spice them up by loosing the sus. Looking at the likes of a Spesh Chisel, swapping out the 100mm Judys (boost spaced and tapered steerer) for some carbon rigids. Should be easy I thought....
But the A2C on a lot of higher end stuff seems to be 485mm and up, which is too long from my understanding. The exotic forks that have a 465mm A2C only come in straight steerer and non boost. CRC has really expensive Ritchys with 470mm A2C butthey also have a straight steerer, non boost and cost £450!!!
Thanks in advance for any indulgence, advice, sympathy etc
Why are carbon rigid forks so hard to find?
Because they are niche basically,
The On-One / Planet X rigid carbon fork would almost do it if it weren't for the boost spacing. 480mm axle to crown, tapered or straight steerer. I doubt you'd notice the AC tbh, you could always drop the bars slightly or go for a lower rise bar or stem. Given that they're only 100 quid, you could always just buy a non-boost front wheel.
Axle to crown 445mm
Axle to crown race 490mm
?
Whisky?
The Boost spaced part of your requirement is where you are expecting too much
Travers prong
I bought some off ebay for a Boost front B+ hardtail. It otherwise runs with 120 Rebas (though it was originally designed for 100mm Rebas).
Similar to these
Edit: these ones: https://www.ebay.com/itm/Carbo-Fork-27-5-650B-29-MTB-Rigid-Boost-Fork-Tapered-Thru-Axle-110mm-with-Lever/283165054210
Genesis tarn fork might suit although they are corrected for 120mm.
Axle to crown 445mm
Axle to crown race 490mm
?
Some specs list the height to the underside of the crown as well so you can judge if 29+ tyres will fit.
Tideace forks off AliExpress. I know it's a risk with cheap Chinese carbon but I got a pair (non-boost though boost is available) for £70+£20 P&P. Arrived in 8 days with the express postage. Visually I can't find any faults/anything to indicate they're not well made. Over 400km on them in the last 3 weeks now and they ride well.
Up to you whether you take the risk with cheap direct carbon, but I'd happily but another pair.
￡88.18 31%OFF | Tideace 110*15mm MTB fork 1-1/2 mountain bike fork 29er MTB boost disc Brake fork Carbon Bicycle Fork Tapered 160mm disc
https://s.click.aliexpress.com/e/tLlPTNW
BadlyWiredDog - those kinesis ones look amazing... Bit dear (when compared to a full sus fork), thanks. But yes that Axle 2 Crown or Axle 2 Crown Race thing is really confusing. I sort of get what thisisnotaspoon is saying, 29+ tyre clearance etc... but does it mean that the forks are 445 or 490? I mean if axle to crown means the centre point of the axle to the lowest point of the crown (ie the bit that effects tyre clearance) and axle to crown is 445, then what is the axle to crown race for? Or do most A2C measurements actually mean axle to crown race..? So these are actually 490 in relation to other A2C measurements? ;-/???
Have you measured the a2c of your current forks?
My 26" Reba u-turn (85-115) that i recently replaced with a rigid fork were 495 at 115 and 465 in 85mm.
I ended up getting the 465 length.
I would have thought for a 29er, 495 would be fine.
Unless mentioned otherwise, I thought a2c was always the crown race to the axle?
Unless mentioned otherwise, I thought a2c was always the crown race to the axle?
It is
Those CarbonCyles eXotic ones are really confusing!
The A2C is available at 470mm if you choose a 650b fork and jumps to 490mm if you choose a 29er. Any thoughts on using a 650b fork if the A2C measurement is more appropriate?
Are they speccing 490 for a 29er beacuse they are assuming more people are replacing 120mm forks?
Don't get too hung up on the exactitude of the A2C. Different forks of the same travel will have slightly different A2C measurements anyway.
The A2C for a 29er Reba of 100mm travel is 506mm. Allowing for 20% sag would bring that to 486mm.
The A2C for a 29er Reba of 120mm travel is 526mm. Allowing for 20% sag would bring that to 502mm.
It's axle to crown race.
Lockout lever?
Kinesis do some.
Not sure on axle to crown but been working fine on my XC Hardtail.
Thanks,
Max.
100mm 29 suspension is 485 a-c when sagged shirley?
I was wondering about the 'Lockout' situation. If one uses a sus fork in lockout, there is no sag.... so the bike is running at the max A2C.
Andy, why do you say 485 when others say 465? A fork with 485 is defo an easier option to find.
Andy, why do you say 485 when others say 465? A fork with 485 is defo an easier option to find.
Look at my figures above...
Unless mentioned otherwise, I thought a2c was always the crown race to the axle?
It is. That’s what sets the geometry when installed in the frame.
The other measuremt dictates what tyres will fit. Two differ things really.
Sorry, didnt see Scotroutes detailed explaination. As said it is 485mm for 100mm 29 sagged. No idea where the 465 comes from but its wrong. Fyi 470 is 80mm 29er sagged - ish. Aliexpress and ebay has loads of the forks Scotroutes linked earlier. Good forks. Just buy from a trader on either site with good history. My only reservation with those is the 15m axle nut isnt bonded to the fork, but I had a pair on Scotroutes recommendation for a while and they were fine.
Thanks Andy and Scotroutes.... I had picked up other numbers from other threads that stated the A2C was much lower at around 465mm. That was one reason for asking these questions, as it seemed odd that there wouldn't be a little more choice for that size.
I'll check those links now. Cheers all.
I'm not sure if this is relevant or not but I've recently fitted 120 Rebas to my chisel and it's brilliant.
I read a lot of stuff on the mtbr chisel thread beforehand as it's available as a frame only in the states and quite a few people built them with 120 forks
Probably because a thru axle on a rigid fork is unnecessary. They are to tie the ends of the fork lowers together, on a rigid fork they are rigidly held by the crown!
Also the riding on a rigid fork will be much less GNAR, so no need for the minor strength advantage of boost or a tapered head tube.
How about a crown race adapter to straight and then use a front wheel to match the fork.
I only know steel rigids, but:
465-470mm axle-to-crown is the length that matches a 80mm travel 29er fork
480-490mm matches a 100mm travel 29er fork
Like Scotroutes says, don't get hung up on 10mm.
The other thing is that it seems like people often use a slightly shorter fork when rigid and it works fine. So if you currently had an 100mm travel sus for and swapped it for an 80mm corrected rigid fork, that'd be fine.
I assume this is because the sus fork would frequently be much shorter, i.e. when deeper into the travel, but a rigid never is.
As @benp1 says: Travers Prong - https://www.traversbikes.com/store.html#!/Travers-XC-Prong-Boost-Carbon/p/73904492/category=15761046
I've the non-boost version on my Solaris and my fat bike came with the fat version.
Your cheapest option would be something like this:
https://www.tritoncycles.co.uk/frames-forks-c6/rigid-forks-c51/xct-boost-tapered-mtb-fork-p18064
Obviously you're not going to get the same weight savings as you would with a carbon fork, but if you just want to spice up non-techy local trails they'd do just fine.
I've got the non-boost on my rigid mtb and they do the job. Probably a bit stiff, but that's nothing a 2.6 front tyre can't solve.
Obviously you’re not going to get the same weight savings as you would with a carbon fork,
1.6kg? That's not much lighter than my Rebas which I can flip a lever to lock out.
wzzzz
Member
Probably because a thru axle on a rigid fork is unnecessary. They are to tie the ends of the fork lowers together, on a rigid fork they are rigidly held by the crown!
Prefer thru axle on rigid forks on road, gravel and offroad as even with closed cam QRs or DT Swiss RWS the QR wheel is more likely to flex in the forks when cornering and make the steering more vague. But I am 90kgs so thats maybe just me, but Im about as far away from being gnarly as you can get!
+1 Carbon Cycles/Exotic
490 C2A - tick
boost - tick
carbon - tick
decent - tick
I have first refusal on a set of 2016 NINER RDOs. They have apparently got a 470mm A2Cand are 100mm spaced.
So I'd need a new front wheel... and I'm 10-20mm out of the ideal zone. But they are £200 and by all accounts a pretty high end fork and normally £450 new.
Many have said to ignore slight discrepancies like a degree of slackness etc. I'm concerned that the Chisel (the bike I'm about to buy) is fairly aggressive (not slack) by modern standards, so thinking that I'm more inclined to go 490 on some eXotics if I was basing it on geo.
Unless anyone with any experience, says that the carbon quality on a NINER is just too good to pass up.
Thanks
Shorter than you ideally need, the wrong hub size AND more expensive?
The A2C is available at 470mm if you choose a 650b fork and jumps to 490mm if you choose a 29er.
Are they speccing 490 for a 29er beacuse they are assuming more people are replacing 120mm forks?
Err....