# How much abuse can MTB wheels take?



## aserota (26 Oct 2008)

I know this is a very general question, but how much abuse will carbon MTB wheels take, before buckling/puncturing?

I reguaraly cycle off road, going through forests, over pot holes, tree roots etc. but wondered if the wheels would buckle if the bike was ridden down steps and other harsher surfaces. Also regarding tyre pressure, how low is too low?


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## RedBike (26 Oct 2008)

From memory the Spin wheels use a standard aluminium box section rim that is bonded to carbon 'spokes'. They were known for being very strong (and heavy) so I wouldn't have any worries about pot-holes / tree-roots. (They should also be perfectly fine being ridden down steps.)

As for tyre pressure. If you're not pinch flatting then your tyres are not too low. Pinch flatting is when the rim strikes the ground punching two holes/slits in the inner tube. (Pinch flats are often falled snake-bites. )

The pressure needed to avoid pinch flats depends on how wide yoiur tyres are (wider tyres can be run at a lower pressure) how heavy you are and how aggresively you ride rough terrain. I used to have my 2.5" tyres about 40psi.


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## mickle (26 Oct 2008)

Your SPIN whels are possbly the strongest XC wheels ever made. I've seen people lay them on the ground and jump on them with no ill effect. That said, the rims themselves are still dentable if you hit an edge too hard with not enough air pressure in the tyre. Since the rims aren't replaceable it makes good sense to protect them from wear so replace your pads regularly and keep the rims clean.


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## Panter (26 Oct 2008)

> Also regarding tyre pressure, how low is too low?



Very much depends on your weight, your tyres and what you want to do with them.

If you're heavy and aggressive (fast over rock sections etc) then you'll need to run at a decent pressure to avoid pich flats. Unless of course you're running tubeless then you can go a fair bit lower. The bigger your tyres are, the lower presure you can safely run too.

As a very rough guide, 25-30psi would be IMO about the lowest you'd want to be at (assuming tubed tyres) with a lightweight rider running over fairly modest courses but 35-45 as a safer value for anything more severe or heavier rider.

As a heavy rider, I can't drop below 40psi without risking snakebites and even then I need to run a larger tyre when on a rocky trail.

HTH


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## aserota (26 Oct 2008)

tbh im not sure what a heavyweight rider is classed as im 13st and generally very aggressive in my riding style. 

Im running the tyres at 55 psi. but that is because my roadbike is on the tt and im doing 20 miles a day on average (on the road) and a bit off road aswell.


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## RedBike (26 Oct 2008)

55psi is fine for on the road but off-road i'm suprised you haven't found this way too high. 

I've just switched to tubeless so that I can drop below 40 (Which I thought was too high!) without pinch flatting. 

Very aggressive on a rigid v-braked MTB - Respect!


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## aserota (26 Oct 2008)

its soo much fun and a good release from road cycling. At the moment i can see why you actually need suspension, although it is a little bumpy at times!


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## RedBike (27 Oct 2008)

> At the moment i can see why you actually need suspension



If you're worried about a pot hole and can't see the need for suspension then you're probably not riding rough terrain aggresively. 

You should be able to get away with dropping your tyre pressure for the off-road sections to as low as 30psi without striking the rim.


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## aserota (28 Oct 2008)

Well i have spoken to Pace and the model of carbon forks i have can not have the steerer changed.

So i will need a new set of forks

Any recommendations for under £150?


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## mickle (28 Oct 2008)

I can't tell from your pictures but there may be enough meat on the head-tube to allow some material to be faced off, which, combined with a headset and a stem with a lower stack heights might save the day. How many mms too short is your steerer? 5mm here, 8mm there, it all adds up.


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## RedBike (28 Oct 2008)

IMO it's time to start getting tough with the seller. He's charged you an absolute fortune for a poorly (dangerously?) assembled bike, thats been tarted up with old parts that he's trying to pass off as new. *Demand* he sorts this problem out!

Here's the frame you've got
http://cgi.ebay.co.uk/Kinisis-Alloy...39:1|66:2|65:12|240:1318&_trksid=p3286.c0.m14

For £150 you should be able to easily find a similar fork second-hand 
http://sports.shop.ebay.co.uk/items...5&_fromfsb=&_trksid=m270&_odkw=&_osacat=36135
or something similar new like this
http://www.planet-x-warehouse.co.uk/acatalog/Online_Catalogue_Mountainbike_Rigid_365.html
Maybe even a suspension fork like this 
http://www.merlincycles.co.uk/?fn=product&productId=1156&categoryId=17

The trouble is the sort of fork you'd typically get on a £1000 bike is well out of your £150 budget and they don't often come with V-brakes.


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