Author Topic: A bridge too far... (Read 3035 times)

EdinburghFixed · « **on:** 06 April, 2011, 01:12:55 pm »

Bicycle construction and use.

Exact tube angles, mm-precise bike fitting sessions, questions and concerns over whether you can safely run a 23mm tyre at one end and a 25mm at the other...

Yesterday, I replaced my 20" front wheel with a full sizer.

That's a 559x28mm, by the way. It will easily fit 700C but my legs are just slightly too stumpy with 175mm cranks (can you guess what the next purchase may be?), leading to a little bit of hard overlap, below:

Let me tell you, it's strange. Superficially I'm not any higher up (same back wheel) and the front end can only have risen by 3" or so, but suddenly it feels like the chainring is sawing threateningly at pedestros, I have to peer around my legs (and through the boom/mech) for potholes and I have an odd fear of falling over!

Luckily I can still handstand. With dual 700's I don't think this will be possible, making it less practical for the commute (unless I go back to MTB shoes, I suppose).

I was inspired by the thought of having something with two big wheels but retaining the "downness" of a lowracer - like the M5CHR. The question everybody wants to know (including me) is whether it goes any faster.

Good question. When I'm brave enough to give it some welly, I'll have an answer!!

(yes, I took the pics before I fitted the fork. Thanks

)

arvid · « **Reply #1 on:** 06 April, 2011, 03:15:57 pm »

Chain looks a bit tight.
And blimey, that's some crank overlap!

EdinburghFixed · « **Reply #2 on:** 06 April, 2011, 03:43:01 pm »

Obviously I have no need for a 70t ring with a big drivewheel - I'll be able to swap it to an ordinary double

Still you're right, it does need a couple of extra links.

I had to recable the disc caliper, but haven't done the rear mech yet (which is obviously struggling).

They say not to change anything before a big ride, and I am off to Mull it Over in 48 hours...

recumbentim · « **Reply #3 on:** 11 April, 2011, 07:29:33 pm »

I just realized yesterday what you had done on Saturday.
Wondered why you were mumbling on about gears and stuff.
I was in a bit of a 300 flying haze you know.
Looks like the mid racer???
So you had a 559mm on the fornt and 622mm rear ,Well how did it go?

?

recumbentim · « **Reply #4 on:** 11 April, 2011, 07:37:56 pm »

So that must be the midracer Fork?

EdinburghFixed · « **Reply #5 on:** 11 April, 2011, 08:01:09 pm »

Yeah, no midracer frames yet, but I saw Arnold had posted a prototype he made of this same thing, midracer fork on the lowracer...

It went well, really calmed the front end down over the rough stuff. I wasn't convinced it was much quicker until the last leg, when I went like an express train - 33 miles at an average of just under 19mph, with 150 miles in my legs. (To be honest, that was probably mainly haribo!)

I'm going to try for short cranks and dual 622, if at all possible. Then all my spares would match (although I've also discovered that a 700x28-38 inner tube will happily power a 26x1.5" tyre, so maybe it doesn't matter).

arvid · « **Reply #6 on:** 11 April, 2011, 10:02:01 pm »

Quote from: EdinburghFixed on 11 April, 2011, 08:01:09 pm

Yeah, no midracer frames yet,

I have seen a midracer for sale in my local recumbentshop.
I have seen and ridden a midracer on CycleVision last year.
So I wonder what you mean.

EdinburghFixed · « **Reply #7 on:** 11 April, 2011, 10:47:03 pm »

Well, LaidBack in Edinburgh have had one on back order for about a year now. So long that the buyer pulled out and it's now destined to be a demo ride! Perhaps it is being smuggled out preferentially round your way?

If you had only seen the prototype that would be different, as I know that has been around. But then it wouldn't be for sale in a shop. Confusing!

ruggtomcat · « **Reply #8 on:** 12 April, 2011, 02:35:11 am »

Its not so pretty anymore

Wendy · « **Reply #9 on:** 12 April, 2011, 07:13:09 am »

...still amazed!

EdinburghFixed · « **Reply #10 on:** 12 April, 2011, 08:39:33 am »

I commuted in today on crank shorteners borrowed from LaidBackBikes. 175 to 155mm is a bit of a shock to the system and at first I hated it, but bizarrely, this morning I was loving it.

Hmm. I can see some more upgrade-itis on the horizon!

EdinburghFixed · « **Reply #11 on:** 12 April, 2011, 08:54:05 am »

Also, how's this for weird...

On the bike as pictured above the seat angle became stupendously reclined - so much so that at its most extreme, I had to stop pedalling to look over one knee and see what was coming.

Yesterday I reshaped the front of the seat some more so that I could sit it up, more like the original angle with the 20" wheel. In the meantime I did pop out a 300km brevet so had got used to the "wind blowing under your sunglasses" look....

Now it feels like I'm sitting up too high, and being able to see over the boom feels daft!

The only ergonomic issue remaining is that my Edge, which sits between my knees, is now obscured by the brake levers. I either need to find somewhere else to position it or (oo-er) bend the aluminium handlebar column to raise the bars (!!!).

Wothill · « **Reply #12 on:** 12 April, 2011, 10:19:02 am »

That's an amazing looking conversion. Very brave to take it to Mull as a test run. I can see we are going to need tow ropes fitted to the back to keep you under the 30kph limit in future. Did you ride the 300 with the long cranks OK? How often did you use your 150" top gear?

Mike Burrows wrote an article somewhere where he strongly advocated short cranks. Never been convinced sufficiently to try them myself but you seem to have a similar reaction to what he described: strange at first but then really liking them.

I suppose there are (at least) three possible explanations for the increased speed: 1) bigger wheel (less rolling resistance) 2) more laid back (you might lose some of that having tilted the seat back up again) 3) you are still getting fitter. Probably all three but mostly the latter, I suspect.

EdinburghFixed · « **Reply #13 on:** 21 April, 2011, 02:09:35 pm »

Just a quick update with some 'side by side' pics:

In a related disaster to my wallet, I found someone to split a Planet X wheelset with, so it's going to have dual 80mm carbon tubulars on it.

Ultimate pub bike kudos. I'll be smoking the Halfords full sussers on the Roseburn at this rate

EdinburghFixed · « **Reply #14 on:** 26 April, 2011, 09:48:37 pm »

Oh dear, oh dear...

Anyone drilled an aluminium frame for internal cable routing before?

Wendy · « **Reply #15 on:** 26 April, 2011, 10:33:04 pm »

Oooooooh!!!!! A slip of the credit card, hope the boss approved that!!! Looks gorgeous mate, really lovely.

EdinburghFixed · « **Reply #16 on:** 27 April, 2011, 06:42:09 am »

"Yes, about those mysterious wheel bags dear..."

Valiant · « **Reply #17 on:** 27 April, 2011, 03:55:03 pm »

Tigerrr · « **Reply #18 on:** 28 April, 2011, 12:20:44 pm »

That is looking like a seriously fast roadbike.

EdinburghFixed · « **Reply #19 on:** 03 May, 2011, 09:54:36 pm »

I am a little worried that it upstages Arnold's midracer. Sure, that will handle like it was designed to have big wheels (!!) but I think I know which one will be the faster...

I had a terrifying commute this morning on these tricky carbon rims. I learned that you do, in fact, need carbon specific brake blocks

Author Topic: A bridge too far... (Read 3035 times)

ruggtomcat