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Which is faster for CX? A CX biker or MTB bike?(8 posts)

Which is faster for CX? A CX biker or MTB bike?LDF
Sep 10, 2001 3:48 AM
Here is what I am building up...

A Specialized S-Works MTB frame, with straight MTB handlebar. Gearing will be a single 46 tooth ring up front, moved to the middle ring position, thus allowing me to use the full range of gears in back. Ive managed to find a set of semi-slick 26" x 1.15 tires (I might go with a wider one up front). Also Im planning on putting a rigid fork on the front. It will have the full "weight wennie package" (ti-bolts, carbon fiber this and that, ect. ,ect.) and when its finished, I predict that it should come in at around 17 pounds, which will be lighter than almost any true CX bike.

Will this contraption be faster or slower than a CX bike? And why?
re: Which is faster for CX? A CX biker or MTB bike?MJ
Sep 10, 2001 4:05 AM
not to point out the obvious but speed is based on the rider not the weight of the bike - Tim Johnson could take you (and me) on a 30lb. cruiser

beware of the governing body of races you attend - some don't allow flat bars - and I think most ban bar ends

46 up front sounds a bit steep - most people with one front ring tend to go for the 42 as it's more realistic for cross terrain - but maybe you're an animal with huge legs!

the argument you need to have (with yourself) is whether you would receive a benefit or a penalty from using 26 in. rather than 700 wheels (that won't fit on a mtb. frame without 'major engineering work'

in any event it sounds like you've got a good rig built up/being built up - let us know if you are/your bike is faster or slower than people on traditional CX bikes
re: Which is faster for CX? A CX biker or MTB bike?LDF
Sep 10, 2001 7:33 AM
Very true,
Bikes are not fast, bikers are.

Actually I did mean 42, not 46. And in addition to that, I do tend to push a far bigger gear than most others. Im used to running XTR rings (46) and am very careful not to cross shift into the big/big gear combo. With this set up I will be running a much smaller chainring in front and will also beable to shift into the big in the back. If this works, I might actually set one of my race MTBs this way.

All of that said, I guess my real questions were how much will the fact that I dont have a CX specific geometry frame, drop handlebars, and 700cc wheels hurt me. Because the way I see it, those are the only differences I will be lacking.

By the way, my local series allows MTBs, but MTBs are not eligable to win series points. If the reasoning behind that is that the MTBs have an unfair advantage (???), I should have a real scream machine.
re: Which is faster for CX? A CX biker or MTB bike?MJ
Sep 10, 2001 9:02 AM
can't imagine the geometry/drop handlebars adding or detracting - it just seems different to me - maybe somebody else has an opinion on that though - Climbo is a regular on the board worth paging for input - he (I assume he) is very knowledgeable

for me I feel a bigger difference in the wheelset than geomtry/handlbars (though geomtery and handlbars take some getting used to for a pure cyclocross) - though again I can't say if it will hurt or help - to me, I ride both regularly, the 26 v the 700, again it just feels different rather than 'faster' -

I think terrain will make a difference in both regards - the more technical the better the small wheels seem to me - the faster (read non-technical) the terrain the better the 700's feel to me - in the end it's probably obvious physics
re: Which is faster for CX? A CX biker or MTB bike?climbo
Sep 11, 2001 10:54 AM
well thanks MJ. It's Mr. Climbo BTW.

I would say that a CX bike would be faster in most cases. i.e. if I rode the same CX race on a MTN and then a CX bike on different days I would be faster on my CX bike.

1. Faster wheels, skinnier tyres help. Usually flat and fast non-tech courses with a few hills each lap. Even a 1.5 is fatter than most CX tyres. Gary Fisher knows about how fast 700cc wheels are, look at his new line-up of 29" MTN bikes.
2. Getting in the drops on a CX bike makes sprinting/acceleration better than a MTN bike.
3. Carrying a MTN bike is not easy, CX frames are larger triangles and go over the shoulder better and quicker for uphill runs. Also, drop bars are very easy to hold when running as opposed to flat bars which are higher up and are in your face a bit when holding it.

I would think that with all the re-mounts and carries in one race alone, a CX bike will generally be faster for the same rider over the same course, unless it's an all out mud bog with technical singletrack in the course.

Either way, I hope your 17 lb'er does you well. Try a CX bike out at the races.
re: Which is faster for CX? A CX biker or MTB bike?climbo
Sep 11, 2001 11:02 AM
the no points for MTB's, I think is just a way to keep CX specific bikes in the sport at the top levels. MTN bikes are for the mountain bike races, CX bikes for CX races. UCI rules won't allow MTN bikes so you might need one eventually if you plan to race a lot.
re: Which is faster for CX? A CX biker or MTB bike?Joe C.
Sep 12, 2001 12:54 AM
But if MTBs are at a disadvantage over true CX bikes, there should be no problem with keeping CX specific bike in the sport at the top levels. What competitor would want to use a bike that gave him or her a disadvantage?
re: Which is faster for CX? A CX biker or MTB bike?climbo
Sep 12, 2001 11:58 AM
many folks who start in CX use a MTN bike from the cost point of view and keep using them. Not everyone can spend $1,000 or more just to get a faster bike. I was just proposing that race promoters might want to keep MTN bikes out for some reason. Don't know why but if you hit UCI or National levels you need a CX bike.