Yellow & purple 650b conversion... or something

Howdy y'all. Got a bit inspired the other day by the approaching spring weather and this photo posted by @spotter in the FBNPNA thread.

So I went and bought his yesterday.

It just about clears 700x25mm and looks identical to the turquise one so I figured 650bx35mm would fit nicely. I converted my wife's mixte last year (https://www.lfgss.com/conversations/289257/) and borrowed a wheel off it to check:

Lots of room in the rear (ooohh) and no problems height wise in the front but not enough width for a bigger tyre. Upon closer inspection the turquoise one doesn't seem to have a unicrown fork. Bummer.

Meaning if I go down this route I'd lower the BB by 10-15 mm, is this lethal?

Also - the one in, one out rule applies. Which one should I let go? I've my sweet fixeh commuter, that's staying. And the road bike has to stay too, I'd never get my money back. Keep fooling myself 'I'm going to use it more next year'. That leaves my functional disc cross commuter in the shape of a moss green PX london road. Built it up last october and it has spent the winter waiting for actual winter to arrive so I'd get any use out of it, studded tyres and all. Have ridden it maybe 10 times in total, somehow always end up taking the fixed gear instead.

It does of course seem idiotic to replace a modern fully functional alu/carbon/disc brake thing with a steel relic from the 80's topped with weird size wheels and rim brakes. But that's the way I'm leaning right now... Decisions decisions.

Will at any rate be a slow project so I've time to think this through. Opinions welcome.

Can fork blades be crimped (If that's the right term) to make room, like chainstays? @coldharbour et al

Edit: called dimpling, apparently

Talk to Patrik Tegnér, he's a local framebuilder in Gbg.

Bb height not lethal unless you like cycling hard into corner with big fuck-off old school MTB pedals without a single care in the world.

You can always get a chrome flat crown fork for it to improved clearance, but 35mm is pretty good, still lighter than a similar 700c option.

(My BB on the 650b is very low, even if you put 700c on it, it still a lots lower!).

cycling hard into corner with big fuck-off old school MTB pedals without a single care in the world

Unlikely. More like really slow riding, shortness of breath and a creased brow above my greying stubble, muttering incoherently at the above variety.

Re dimpling forks, found this forum thread.

https://groups.google.com/forum/#!topic/internet-bob/BLbcu91U9s4

Apparently a tandem fork only survives ~65 years of presumably rough condiditions after being dimpled so maybe I shouldn't.

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Got hold of a local framebuilder (thanks @Thrust ) who thinks "dimpling a little should be ok".

Also started hoarding parts and simultaneously clearing out the basement.

You looking to go for long drop brakes or get canti's welded on, since its going to a framebuilder anyway? Looking forward to seeing how it turns out!

Welding on canti mount probably will cost more than a Tektro long drop calipers.

No sweat, glad to have helped!

Subbed.

Tektro long drop calipers. And it's not going to a framebuilder ;-)

Plan is to shape a block of mahogany and use a small bench vise. Maybe.

Very true, I had considered exactly this myself on my current commuter but gave up after not finding any brake surface rims in the right budget. I mean I didn't look crazy hard but it was enough to put me off my whimsical search

Now, wheels. Will be using the same schurmann yak rims as I did on the mixte, probably 36h as I don't want to worry about the wheels once they're done. I have a 700c wheel with a SP-8 disc dynohub already so probably unlacing that and putting on this build instead. Could sell the wheel and buy a new hub instead I suppose but probably won't be economical. Rear will be some bog standard shimano hub. Getting stuff from cnc-bike.de and sella-berolinum.de.

Sprayed the inside of the frame with linseed oil, drilled a drainage hole in the BB and took it down to the LBS for respacing to 130mm + facing/chasing the BB.

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Probably picking this up later in the week. I know, I know. Plan is oven cleaner and polish + silver 46 outer I have lying around. Could look ok, could look horrible. But they're cheap and I got inspired by (I think) @Jaap 's budget sscx project.

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Why not just fit a 46t only and run 46/34? much more practical.

Sorry, meant 46/34. Edited.

Oh yes! pump peg, get yourself a Zefal HPX in the correct length, it will fit very very well in your frame (just saw the pump peg).

Yeah I guess I have to make use of the peg. Zefal HPX eh? Comes in silver, isn't too expensive and works all right? Wouldn't want it to get stolen, so maybe not if I need to leave the bike locked up (commuting) but for longer rides it could be handy I suppose.

it work great, it's the exact same pump I use for proper long distance shit, and been quite reliable.

It's difficult to find better for the money too.

Nice project and cool looking frame!

Yeah I used oven cleaner to turn a crankset grey (picture below) and you'll probably need some benzine to clean off the branding.

What's the plan for the brakes? Since the braketrack on 650b rims is lower than 700c, how are you gonna fill that gap?

Yeah that's the pic I was thinking of! Thanks. Re brakes I'm planning to use these

I found those to be reasonably powerful despite the long arm, recommend going for Swissstop BXP or Koolstop Salmon.

PM re: hub

@edscoble do you know how they compare to centre pull long reach like the dia compe 750? The tektros are fine, used them on the mixte build and am impressed by them. But the Dia Compes would mean a) full on rando wankery and b) ability to mount one of the specific front racks for centre pulls.