P-38 build

DIscuss anything relating to non-standard cycles and their equipment.
UpWrong
Posts: 1694
Joined: 31 May 2009, 12:16pm
Location: Portsmouth, Hampshire

Re: P-38 build

Post by UpWrong »

The front derailleur was badly bent in a chain suck incident. Examination of the chain rings showed no obvious cause but the 24T inner ring is steel with minimal shaping of the teeth. So I'll switch it for a 26T Spa Zicral ring and put the 11-34 cassette back on to compensate. Will also change the crankset to one with short cranks by pinching the 150mm crankset off the Paseo. I have an Altus FD to install but it needs a longer cable for its dual pull mechanism. That's quite a bit of work to be done. And I'll need to replace the Paseo cranks with something too.
UpWrong
Posts: 1694
Joined: 31 May 2009, 12:16pm
Location: Portsmouth, Hampshire

Re: P-38 build

Post by UpWrong »

Altus FD installed and adjusted. Seemed to work better with the 44T outer with a bigger gap than the standard 2mm. I realise now that the P-38 came configured for a dual-pull 34.9 top clamp FD because of the cable stop position and the supplied shim for the skinny derailleur tube. Which meant that my 110mm titanium BB would not work. The chain wouldn't make the inner ring reliably. I'm sure 113mm would work but I've changed the BB to an 116mm FSA one I had which seems to run very smoothly. Also had to extend the boom 10mm because of the shorter cranks.

Now pondering which cassette to use now I have short cranks and a larger inner chainring. 11-32 doesn't give a low enough bottom gear, 11-34 is a bit gappy, wondering whether to try a 12-36. This would reduce the top gear but really would give me a 17.7" bottom gear and the spacing of the gears is pretty consistent. I can balance at low speed on the P-38 but I struggle to restart on hills more than 8% or so. I'll be able to climb steeper but if I have to stop I'll probably have to get off and push until I can find some flatter road to restart.

Edit: I tightened the boom bolts very carefully, alternating between them whilst gradually increasing the torque, finishing at 8.8Nm. It's tricky on the P-38 because one bolt is where the support tube is welded to the boom. Both the boom and the support tube have slots so they can be pinched. Lightning don't give a torque setting but warn against overtightening!
Last edited by UpWrong on 28 Aug 2022, 8:42am, edited 1 time in total.
UpWrong
Posts: 1694
Joined: 31 May 2009, 12:16pm
Location: Portsmouth, Hampshire

Re: P-38 build

Post by UpWrong »

Completed a longer test ride. All good. The smaller wheels suit me better and the shorter cranks have opened my body position out a bit when riding. I've got the seat stays about 75% of the way to their shortest setting, about 1 cm away from shortest. I do slide forward a bit so I reckon my angle of recline is not far off 45 degrees in practice. I'm going to leave the cassette alone for now. The gearing is from about 20" to 100" and the steps on the cassette and on the ring changes are nice. I can use all combinations of gears.

No more planned changes. This is probably as good as it's going to get for me on an SWB. I'm going to turn my attention to the Paseo now and make a decision whether to keep or move it on. I love the engineering but I've been finding it a bit too reclined for me to ride it confidently in traffic. I'm going to try some longer cranks on it to close the hip angle a little.
UpWrong
Posts: 1694
Joined: 31 May 2009, 12:16pm
Location: Portsmouth, Hampshire

Re: P-38 build

Post by UpWrong »

Did another ride on the P-38 and feeling very at one with it. Think I will change the cassette to 11-34 after all. I don't want to give up the 44/11 ratio but could do with something a bit lower than 26/32. Also the bigger steps will be welcome, sometimes. Swings and roundabouts.

I have some awful front disc brake squeal at the moment to resolve.

Although I felt at one with the bike, there were no personal Strava segment records. I think this confirms that I'm no quicker on the P-38 than I am on the Stratus. The Lightning is lighter but I'm generating more power on the RANS I think.
UpWrong
Posts: 1694
Joined: 31 May 2009, 12:16pm
Location: Portsmouth, Hampshire

Re: P-38 build

Post by UpWrong »

Changed the cassette to 11-34 and have largely eliminated the front disc squeal by moving the fixed pad closer to the rotor and cleaning the disc rotor with white spirit.

I felt stronger on the bike today, so I think I have the right set up for me. It was a stress free ride inspite of encountering heavy traffic and horses.
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