Sub 5kg Hillclimb Fixed

[JamieL]

Started a new build this year to keep me interested over the winter. The goal is to build up a sub-5kg fixed bike for some hillclimbs next year and maybe the odd training ride. My current set-up weights in at 6.3kg and i'm basically working to a budget of £1/gram saved over that.

Build is going to look something like this. Parts with a star are already in my garage.

Frame: Planet X Nanolight* 999g
Forks: Planet X Nanolight* 375g
Headset: Planet X Integrated* 65g

Seat Post: FRM ST-M10* 180g
Seat clamp: KCNC Road Lite 11g
Seat: Some ebay carbon shell 90g

Stem: Deda Zero 100 Servizio Corse* 120g
Bars: Deda Dabar* 174g

Chainset: Stronglight Pulsion (probably) 310g + 40g for the chainring
BB: Stronglight Twister Titanium BB 180g
Chain: KMC SL 250g

Front wheel:
Rim: Planet X 20mm 24h* 250g
Hub: Alchemy Elf 24h 66g
Spokes: Sapim Laser 110g

Rear Wheel:
Rim: Ebay Carbon Rim 28h 290g
Hub: White Industries Eccentric 330g
Spokes: Sapim Laser 130g
Fixed Cog: White Industries Splined 80g

Tyres: Tufo S3 lite 125g X 2* 250g

Skewers: Controltech Race 30g

F Brake: Planet X CNC 110g
Brake Lever: ?? maybe PX TT Carbon lever 50g
Cable+outer: Nokon* 40g

Pedals: Not decided. maybe Keywin Ti 200g

Total Weight 4.8kg ==> Realise this might be a bit hopeful but i should be able to get weight off the fork and seatpost

Frame arrived this morning so i'll post the odd update as parts trickle in. hope to have it finished by mid-March but it'll depend on work commitments. Once i've weighed stuff i'll post the confirmed weights for comparison.



Put this up as it seems a bit unique. there are not too many hillclimb specific fixed-gear builds on here...

[quattrings]

One thing on your build list to me spells "accident waiting to happen", that being light weight skewers.
On my SS the rear wheel sometimes budges ever so slightly with a closed cam skewer done up to the max. The forces on the rear wheel of a fixed gear are even greater and you wanna use superlight skewers???
I'd say it's a no no

[voodoojar]

Those skewers will be fine. I'm have a degree in fine arts so you know I know what I'm talking about.

[Fuchspk]

Sounds like it could be a nice bike. But I do not understand everything. Why using that velodrome tires but heavy wheels and cogs?
That vuma sounds heavy? With an 34 or what you use for your hills it should be more to 500g?

[octav]

Nice Maybe you post some weights of the frame and fork(real weights)
Good luck with your build!

[konky]

The tufo S3 lites are 215g each. You could go with the Elite Jets which are 160g each. According to people who have actually tried them they are durable and handle OK. They do have a harsh road feel though. They'll still take you over 5kg though.

[JamieL]

Some responses to the comments:

the frame has vertical dropouts so i'm sort of stuck with my choice of rearhub and cog. The front wheel will be coming in at around 400grams which isn't too bad for a £200 wheel. Regarding the rear wheel, i'm going to have another look at rims. not sure if i can find a lighter one without going into mad money.
Given the frame is vertical dropouts, i can't see why the control tech skewers should be more of a problem because it is fixed. they work just fine on my TT which takes some big forces at the start.
The tires are these and i've already (roughly) measured than at about 120g each (probably +/- 10g).

The vumaquad weight i gave is with a 53 and 39 chainrings. In most cases i'll be riding with a 34 so plenty of weight to come off there, just not sure how much so i didn't note it.

I'm getting a set of electronic scales today so i'll be able to start posting weights.

I'm fully aware that this is going to be a funny looking bike but when it's being build for such a specialist activity as hillclimb TTs that's going to happen. For a while i thought about cut down MTB bars and barends...

[Tallboy]

I love building hill climb bikes. My best build ever was a fixed wheel for a mate riding national hill climb. We used a track frame and hub then basically cut down everything possible- end of post, bars, half of seat, body of speedplay, etc!

Enjoy it, nothing like a hill climb race for fun!

[miltmaster3]

more photos please

[locktopus]

What do you think about that frame? I'm looking at going direct to source and buying one for a charity ride.

[euan]

Enjoy it, nothing like a hill climb race for fun!

Gotta agree. Shame that hillclimb season is cyclocross season.

[JamieL]

Hillclimb TTs are about the most horrible thing you can do to yourself. Doesn't stop them being one of the most fun things around either...
In October last year i did 4 in a weekend. At the begining of each i knew i was going to flat on my back, almost sick within 4 minutes and yet nothing stopped me going for it...

I'm mostly living in France while most of the parts are at my parent's place in the UK so i can photo/weigh the stem/seatpost/tires. I'll try to get some more pictures of the frame and Zipp chainset tonight.

I've got another Planet X frame in white and i love it. goes uphill well, sprints well, pretty twitchy on the downs though. The new one in black looks loads better.



Couple of things i'd like some advice on:
i've found a good deal on Stronlight Pulsion cranks. i'm inclined to leave the Zipp cranks on my other bike but want to get peoples' views on this swap.
Also, the rear hub i need to use to get the chain tension is the White Industries ENO Eccentric. This is a flip-flop design with white industries own splined system and a standard freewheel thread. What i would like to know is whether i can use the freewheel side with a threaded track cog. If i can then i can save loads of weight by using a lighter fixed cog.
Ie, can i use a threaded track cog such as this on the freewheel side or is the threading different?
Cheers

[euan]

the threading is the same its just you won't have it locked in place which is alright as you are only going up hill.

when I was doing fixed gear hillclimbs I rode out to them in a decent gear with cog that was on a fixed side. I would swap the wheel around to the climbing cog do the climb and then at the top swap back round for coming down the hill.

basically as long as you are only going up, yes you can.

[Tallboy]

Yes, just a bit of loctite and tighten it on well
I never use lock rings and have only pulled a sprocket off once in a big keirin crash!

[GZA]

saving a few grams of weight for increased crr of the tufo's makes no sense at all! get some quality tyres