General Cycling Discussion - karate monkey as a speedy lightweight bike?

Looking to build up a fixed gear bike with a rim rear brake, disc front brake and with a nice lightweight wheelset. The karate monkey frame fits the bill perfectly, except for the fact that it is a MTB frame and slightly heavier than, say, the crosscheck.

I know that wheel weight matters far more than frame weight. But I'd like to know if it is possible to build up the karate monkey into a fairly lightweight fixed gear for commuting. I want something that feels good to ride, and is suited to fixed gear (i.e. isn't too heavy).

Thanks

Daven

i don't understand why you want to build up a fixed gear out of a mountain bike when you can just get a fixed gear bike. i also don't understand why you want a fixed gear with such heavy duty front and rear brakes. why not just ride a singlespeed? or, if you really want to ride a fixed gear, why not get a fixed gear with a front brake? do you want the burly-ness of a mountainbike frame? i love my steamroller, and i'm pretty sure it's lighter than a KM, and the frame is quite stout and sturdy. all that said, if you are dead set on the karate monkey frame, then yeah, you can make it work. i don't see it as a "speedy lightweight bike" though.

I built my Surly 1x1 with Rhynolites,BB7 front,Nexus 7/roller brake rear,and skinny 1.3" tires. It's a 18" and weighs 28lbs 1oz. Ditching the gear hub for a fixed one would drop a couple pounds,but it would still be over 25lbs. Not super heavy,but not exactly light. The KM frame is a little heavier I believe,so I think you'd be in the same ballpark. If you're not going to be riding off road,then a road frame will be alot lighter than a MTB frame,and you can always go with an aftermarket fork to run a front disc.

I did look at the 1x1 but I want 700C wheels! Also the reason for having a rear brake is redundancy - sure I probably won't use it much, but it doesn't weigh much and isn't a huge hassle so might as well have one. The reason for a disc brake is I find them much more responsive and better in wet weather. As this will be an all weather bike I'd prefer them.

Might see if I can find a frame out there onto which I can put a disc fork. Although not much of a fork selection. Also the frame will need to be able to take 35mm tyres.

Thanks - will keep looking!

What about making a SS out of a Surly Instigator frame?

i don't understand why you want to build up a fixed gear out of a mountain bike when you can just get a fixed gear bike. i also don't understand why you want a fixed gear with such heavy duty front and rear brakes. why not just ride a singlespeed? or, if you really want to ride a fixed gear, why not get a fixed gear with a front brake? do you want the burly-ness of a mountainbike frame? i love my steamroller, and i'm pretty sure it's lighter than a KM, and the frame is quite stout and sturdy. all that said, if you are dead set on the karate monkey frame, then yeah, you can make it work. i don't see it as a "speedy lightweight bike" though.

I don't understand why you must criticize the OP's choice in bike instead of being remotely helpful.

well the frame is what it is , a rugged off road capable steel frame, to survive rough service it will have some heavier tube selections,, should survive the errant pothole.
the weight savings will come from not putting much on it. your fixed gear..
Discs not the lightest thing but you gotta stop, on short notice in traffic, on a commute.

I'd get a hub capable of fitting a disc on the back too , then you can fit a second stopper,
later, if your legs are not capable of bringing the rear wheel to a stop.

Mudguards, of course, or you wear the road gunk into the job.
mudguards will fill up some of the generous space allowing for big 29er Knobbys when you put a more modest, faster , 35 wide tire on.

yeah was definitely going for mudguards - not a disc at the back due to wanting a standard rear brake as I understand you have to loosen the calipers if you get a flat - not what I want to be doing first thing in the morning!

I was thinking light wheels will make it nippy enough, and I do ride on some crap roads so maybe fat tyres will be used in the future.

Thanks :)

I don't understand why you must criticize the OP's choice in bike instead of being remotely helpful.

The OP asked for advice on the frame. He gave his honest opinion. I happen to agree with his opinion and it should make the OP look for a lighter frame.

The OP asked for advice on the frame. He gave his honest opinion. I happen to agree with his opinion and it should make the OP look for a lighter frame.

Get the monkey...it's a Surly:D

But crap roads will beat up light wheels and tires, which when they flat will make you late for the job,
unless you start early on the commute.. allowing for puncture mending.. sort of negates some of the go fast..
then touring strong wheels and some Schwalbe big apples or similar types will be the way to go

But crap roads will beat up light wheels and tires, which when they flat will make you late for the job,
unless you start early on the commute.. allowing for puncture mending.. sort of negates some of the go fast..
then touring strong wheels and some Schwalbe big apples or similar types will be the way to go

well i currently have a road bike with 23mm armadillo tyres which are fine - wheels stay true etc. and a hybrid with big apples - noticeably slower but also more comfortable. For a fixed gear bike I don't want to put a ridiculously low ratio on there, hence wanting it to be light so I can get up to speed quickly etc. and not spin out on downhills, and be able to get up the hills with no problem!

I have a fixed gear which is 42T and 18T, this is just slightly too high for my riding so I want something equivalent to a 42T and 20T. But that bike is my beater so I don't want to be upgrading it!

Just want a frame like the steamroller, that has cable guides for the rear brake (is it really a big issue not to have them - how would I route the cable?) and disc brake mounts.

Thanks

I don't understand why you must criticize the OP's choice in bike instead of being remotely helpful. and i don't understand why you feel the need to criticize me instead of being remotely helpful to the OP. i'm not criticizing him. i just don't understand why, and i was pointing out, that he was, to me, trying something less efficient than was already out there, and i at least recommended the steamroller, so i was being more helpful than you.