Cotic Roadrat conversion to 29er MTB?

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  • Cotic Roadrat conversion to 29er MTB?
  • Premier Icon soulwood
    Subscriber

    Okay so I have had an idea which revolves around the fork being really harsh on my commute and putting me off riding it in a recreational manner. I have seen the On One carbon rigid 29er fork and as I am now putting discs on the rat I figure it was time to go for it. I figure the fork would be more compliant than the steel fork and would allow me clearance to fit a 29×1.9 semi knob tyre on the front, also making the front end more comfy. I have today received the fork and fitted it quickly just to see what it looks like. I have now looked closer at the specs and see the Cotic fork is measured at 400mm from crown to axle, the One 0n is 470mm!. Now how much of a difference would this make to the ride? Specs for the Roadrat are 73 seat and 72 head. Should I just suck it and see or send them back while they are still new and fresh?

    I have a Pace 440 fork on mine and it is a bit too long.

    470 sounds waaaay to long. I would send back and swap it for a shorter one if poss

    MM

    Sounds like you're trying to make the RR into something it isn't?

    Premier Icon Clink
    Subscriber

    I fitted a Bonty 1.75 to the front of my RR last night for the current conditions. Was more comfy on the country roads but didn't stop me falling off on ice and sliding down hill!

    That fork will be way too long; send it back.

    Premier Icon soulwood
    Subscriber

    I think sending them back is the best option. I naively thought as it was 29er it would be the same as a 700c fork or thereabouts with a wider crown for a larger volume tyre. Looking at crown to axle lengths, it seems a Surly 1×1 with a length of 413mm would give clearance for a larger tyre.I would be also be able to run some sort of mudguard for its commuting duties. As for making the RR into something it isnt… I look at it as a modification to extend its usage, I can't afford or justify purchasing a specific 29er frame with all the other bits it would need.

    stealthcat
    Member

    Stupid question, but have you tried carbon bars on it? I used to suffer on long rides on my 'rat, until I put a set of carbon flats on it, and they take out enough of the harshness to make it OK for towpaths, gravel tracks and all-day road rides…

    Premier Icon soulwood
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    SC, I'm afraid to admit it but carbon bars scare me, I'm 101kg and 6'3" tall, been into this game since before spd's and rockshox forks and I've seen some horrendous accidents with carbon bars shearing apart. I was also sceptical about how much they could actually reduce the road bumps, I still recall the early Girvin Flexstems and how distracting they were. I know you will probably say that there are DH carbon bars now, but have you seen how much they cost?. I was thinking a different fork to allow a bigger tyre on front to reduce the road and open the rat up to more bridleway use on my more smoother routes would kill two birds with one outlay of cash.

    Premier Icon woody2000
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    You can fit a 700c wheel in the Roadhog fork and there's loads of tyre clearance, you don't need a longer one. I've got a Kinesis DC19 on mine though, that's pretty short A-C.

    grahamb
    Member

    +1 for carbon bars. They made a huge improvement to the ride comfort on my rat.

    JonEdwards
    Member

    +2 for the bars (although I'll admit I'm biased as I fitted stealthcat's!)

    Carbon is no more or less likely to fail than ally. In normal use a well designed carbon bar, fitted properly with the stem torqued up to correct spec is most likely far stronger than an ally one. Hell – you're happy to use carbon forks – what's the difference?

    Also, check out 18bikes website – they've built a fair few 'rats with big tyres – "monsterats", so will give you some ideas

    Premier Icon ourmaninthenorth
    Subscriber

    Okay so I have had an idea which revolves around the fork being really harsh on my commute and putting me off riding it in a recreational manner.

    I wonder if this isn't more of just noticing the contrasts between a rigid fork on tarmac with reasonably inflated tyres and the buzz and small bump reducing effect of suspension on your MTB. (Aka MTFU 😀 ).

    If you're riding it on the road and with the odd bridleway trip, then maybe some cross or slightly larger (say 32c or 35c) tryes would help. Actually, you are running 700c aren't you, rather than 26"?

    Also, from a position POV, do you have much weight on your hands? setting the bike up so your have an even weight distribution on hands, backside and feet ought to be more comfortable.

    +3

    Carbon bars and forks on mine (90kg)

    Premier Icon soulwood
    Subscriber

    Hmmm I hear you, the carbon forks I saw on ones test and saw that the crown failed after so many thousand whatevers so figured it wouldn't be as sudden and catastrophic as a bar going. I occasionally go to work on my Soul and notice the comfort and on the flip the side I notice how much slower it is. I saw the picture on cotics site of the monster rat upgrade, there appeared to be next to no clearance on the fork crown for any kind of guard. Yes I run 700x 42 tyres, 50 psi in the front and 60 in the rear. The position set up on the rat is pretty identical to my soul, sometimes I forget which bike I am one (my soul has a thumbshifter for the front mech – old skool I know).

    Premier Icon Vortexracing
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    I asked the question about the difference between carbon forks and steel ones, the answer back from most on here is that the design of the fork makes as much as a difference as the material it is made from.

    Just as an aside on-one don't have any 440mm forks in stock (I looked for my Cotic), so I think it will be money back.

    and the head angle will be slacker by approx 3degrees. (working of roughly 25mm/degree)

    Which will be very noticable

    Premier Icon ourmaninthenorth
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    I run 700x 42 tyres, 50 psi in the front and 60 in the rear.

    If you're not comfy on those big fat squidgy things, then deffo a case of MTFU is required…! 😀

    HTH 😉

    Premier Icon soulwood
    Subscriber

    I never knew what MTFU or HTH meant on other threads, it is only when it applies to you that you are bothered to check. I just did. I shall use the only "urban" word I know, LOL.

    grahamb
    Member

    I looked around for a disk tab carbon fork with the right a-c & couldn't find one. When i bought my rat Cy warned me off putting an rc31 on it – the ones they were selling at the time were the wrong geometry.

    Premier Icon woody2000
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    grahamb – http://kinesisbikes.co.uk/product.php?id=50

    Just the job at 400mm A-C, and black and white to match the 'Rat

    Premier Icon soulwood
    Subscriber

    Grahamb, was Cy referring to the A-C length or the fork rake? I have found some forks that would give clearance for a bigger tyre and a guard with A-C lengths of 413 and 420mm. The Rats original one is 400mm. The question is will this slight length increase have a detrimental effect on the ride?

    grahamb
    Member

    All they said to me was "Basically, Pace RC31's are not suitable for use on a Roadrat frame as they are about 2 inches too long which will cause undue stress on the headtube aswell as impairing the geometry."

    woody2000 that Kinesis fork seems to be just the job. Loads lighter than the standard fork and a good price too. Are you running one ?.

    Premier Icon woody2000
    Subscriber

    Yep – only issue I've had is getting a mudguard to fit, the eyelets seem in a strange place. I haven't tried too hard mind!

    chunkypaul
    Member

    i'd probably just done this and deal with the rain

    but a 440mm fork will fit a larger 29er tyre such as a halo twin rail 2.2 tyre

    Premier Icon cy
    Subscriber

    440mm forks will make the bike slow witted and rubbish IMO, and it's not designed for forks that long so you may damage your frame if you hit things hard like kerbs or pot holes. Something in the 410-420 range would work OK if you have to have 'guards, but the big tyres will fit in the current forks and with such a big tyre you're probably better off with a Crud Catcher type fender, or certainly something 2-piece that doesn't need to fit under the crown of the fork.

    Premier Icon cy
    Subscriber

    PS – We have the Monster Cross Upgrade in stock: 29 x 1.75" Bontrager XDX tyres + tubes. £60 posted.

    Premier Icon Clink
    Subscriber

    PS – We have the Monster Cross Upgrade in stock: 29 x 1.75" Bontrager XDX tyres + tubes. £60 posted

    I tried the Dry x on the front yesterday (old version of xdx?); was impressed how well they rolled and the extra comfort on country roads – will probably leave it on and get another.

    Premier Icon oldagedpredator
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    What was the outcome of this one? Was thinking carbon forks but have read through might just go bars.

    Premier Icon Woody
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    IME carbon forks are still pretty rigid, far better with wide twangy bars eg. Salsa's or ti if carbon is too scary and a few less psi in the tyres

    Premier Icon Seamus
    Subscriber

    I got some alpina carbon cross forks for my rat and was amazed by the improvement in ride. They save a load of weight as well.

Viewing 28 posts - 1 through 28 (of 28 total)

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