# Changing carbon hardtail suspension fork to rigid fork. Frame brakes more easily?



## empre (Aug 28, 2012)

Another carbon releated question 

Since carbon hardtails are designed to be used with suspension fork, will the frame break more easily if the suspension fork is replaced with rigid fork? Not planning to do jumps, just normal trail riding.

In this case it would be tapered head tube + non tapered aluminium fork with "adapter".


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## borabora (Feb 16, 2011)

Theoretically, yes but in reality no. A suspension fork does absorb energy and that absorption could prevent a failure that might occur with a rigid fork. But bikes are not designed with such small safety margins. You are more likely to break the rider than the bike under normal riding condition with or without a suspension fork. Carbon frames break either when they have a defect or if they impact a hard object. In either case the fork isn't an issue. Also rigid forks aren't inflexible -- they are also designed to absorb energy.
Rigids are a blast for climbing, trail riding and relatively smooth descending. They require careful riding at higher speeds. If the rider makes serious mistakes on a rigid at higher speeds he/she is more likely to lose control and crash. That can indeed result in a broken frame. But if you can stay on the bike, the frame will be fine.
The only case where I would be possibly concerned about frame failure would be with a very heavy rider.


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## empre (Aug 28, 2012)

Thanks for the info.

Is it possible to use rear rack with carbon hardtail MTB? The kind of rack that attaches to the (aluminium) seatpost and also to the rear axles with "dapters" similar to this:










My weight is 75kg and if I had 15kg of stuff in the panniers the total weight would be 90kg. Would there be too much stress to the frame? I would think no because all the weight from the panniers would be on the rear wheel, but some front/back and side to side force would be applied to the seatpost when driving and even though the aluminium seatpost will not break, could the carbon seat tube break?


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## StageHand (Dec 31, 2003)

empre said:


> Thanks for the info.
> 
> Is it possible to use rear rack with carbon hardtail MTB? The kind of rack that attaches to the (aluminium) seatpost and also to the rear axles with "dapters" similar to this:
> 
> ...


This adapter will put most (if not all) of the weight on the wheels, so it shouldn't be a problem. The stress of the stabilizers on the seatpost is very little compared to a full-grown (or even half-grown) person sitting on a seat at the top of the same seatpost, so again, not a problem.


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## jeffj (Jan 13, 2004)

empre said:


> Another carbon releated question
> 
> *Since carbon hardtails are designed to be used with suspension fork*, will the frame break more easily if the suspension fork is replaced with rigid fork?


Not sure I can agree with this as a blanket statement about carbon hardtail frames. Take the Niner Air 9 Carbon for example. They even make their own carbon fork that looks more at home on that frame than any suspension fork ever will.

I might agree that they design the geometry around the use of suspension forks, but I have no reason to believe that they are not designed to withstand any added stress a rigid fork might add.


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## borabora (Feb 16, 2011)

I think the panniers attached that way should be fine. But there is a bike packing forum and if I were you I'd bounce the idea around there for more experienced feedback.

You probably have a good reason why you want to use a carbon mountain bike for touring (e.g., you already own it). But if you don't, maybe consider an aluminum frame and spend the $1000+ savings on more touring specific toys. You won't be able to feel either the weight benefits of the carbon frame or the handling benefits (if any) when you are traveling with 35 lbs of stuff in the panniers. Maybe even consider a cross bike.


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## empre (Aug 28, 2012)

borabora said:


> I think the panniers attached that way should be fine. But there is a bike packing forum and if I were you I'd bounce the idea around there for more experienced feedback.
> 
> You probably have a good reason why you want to use a carbon mountain bike for touring (e.g., you already own it). But if you don't, maybe consider an aluminum frame and spend the $1000+ savings on more touring specific toys. You won't be able to feel either the weight benefits of the carbon frame or the handling benefits (if any) when you are traveling with 35 lbs of stuff in the panniers. Maybe even consider a cross bike.


Ok I will.

I don't own bike yet. I was asking because I only tour few weeks a year max and all other days I drive in a way where MTB is more suitable than road bike or hybrid. So I rather get a bike that works for me well in 50 weeks/year than a bike that works well for 2 weeks/year. Also my touring is more like exploring, not road cycling for 100km per day.

The carbon frame model costs the same as alu model. Carbon just doesn't have as good components. Both have still high quality components that are well enough for me (carbon XT and SLX, alu XO and so on). Just like with the most MTB's, either of the bikes don't have mounts for racks.


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## empre (Aug 28, 2012)

jeffj said:


> Not sure I can agree with this as a blanket statement about carbon hardtail frames. Take the Niner Air 9 Carbon for example. They even make their own carbon fork that looks more at home on that frame than any suspension fork ever will.
> 
> I might agree that they design the geometry around the use of suspension forks, but I have no reason to believe that they are not designed to withstand any added stress a rigid fork might add.


Me either  I meant more like most of the carbons are and the bike in question is too.


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