P-38 build

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UpWrong
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Location: Portsmouth, Hampshire

P-38 build

Post by UpWrong »

I don't have the frameset yet but my thoughts are turning to the build. I've got quite a lot of decent 9-speed bits in the spares box. One of the main deciders will be whether I keep the OEM handlebars, in which case bar-ends and Shimano compatible kit are the only option, or whether I try some alternative bars which allow me to use SRAM X series kit. The P-38 OEM bars are something of an oddity. There's no fore-aft adjustment (and the seat is fixed) and they require customised bent brake levers.

I've ordered hubs, rims and spokes to build the wheels. I'm quite keen to use a folding 37mm Vittoria Hyper Voyager on the rear wheel although there may not be enough clearance for that and a muduard in which case a 32mm GP5000 would be my choice. I've hedged my bets by ordering a DT Swiss disc R460 rim with an internal width of 18mm.
nobrakes
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Re: P-38 build

Post by nobrakes »

Looking forward to seeing how it progresses.
Blondie
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Re: P-38 build

Post by Blondie »

A 37mm rear will fit without a mudguard. With mudguard don’t go over 32mm. I have the Flinger F42 mudguard fitted with raw mudflaps attached. I run 32mm on rear and comfort is fine.

The front will go up to 40mm (possibly a bit more) with mudguard. I have a 40mm Marathon in winter 🥶 and something lighter and narrower this time of year.
Last edited by Blondie on 29 Jun 2021, 8:46pm, edited 1 time in total.
Blondie
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Re: P-38 build

Post by Blondie »

If you go bar ends and put them in friction mode then the rest of the gearing setup can be whatever you want. Friction works fine for 9 speed front and back.
belgiangoth
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Re: P-38 build

Post by belgiangoth »

If you are using ShimaNO I have some 9-speed bar end shifters somewhere and some microshift triggers that are apparenlty MTB compatible.
If you are using SRAM I have some twist shiters.

(I may have a problem)
If I had a baby elephant, I would put it on a recumbent trike so that it would become invisible.
UpWrong
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Re: P-38 build

Post by UpWrong »

Blondie wrote: 29 Jun 2021, 8:38pm A 37mm rear will fit without a mudguard. With mudguard don’t go over 32mm. I have the Flinger F42 mudguard fitted with raw mudflaps attached. I run 32mm on rear and comfort is fine.

The front will go up to 40mm (possibly a bit more) with mudguard. I have a 40mm Marathon in winter 🥶 and something lighter and narrower this time of year.
Yes, I suspect I'll go with a 32mm tyre on the rear with a mudguard fitted. I'd like to use the 37mm Voyager tyres but this isn't California so mudguards are pretty mandatory.. I am likely to cannibalise my Spa Wayfarer for crankset, disc brakes and rear mudguard but I could run into problems fitting the SKS mudguard with the disc brakes. I managed it on the Wayfarer but it depends on the disc tab location. Thanks for the letting me know about the Flinger F42. I'll need to sort out a 20" front mudguard. Will probably look at Tern and Dahon offerings.
UpWrong
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Re: P-38 build

Post by UpWrong »

belgiangoth wrote: 29 Jun 2021, 11:40pm If you are using ShimaNO I have some 9-speed bar end shifters somewhere and some microshift triggers that are apparenlty MTB compatible.
If you are using SRAM I have some twist shiters.

(I may have a problem)
Likewise I have a lot of 9-speed shifters and derailleurs lying around thanks. On this occasion I'm not adverse to switching bits around between bikes if I need to either.
nobrakes
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Re: P-38 build

Post by nobrakes »

You can make almost anything work together with a JTek Shiftmate. Very handy little things. I have sram road shifters going to shimano MTB derailleur.
UpWrong
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Re: Form vs Function

Post by UpWrong »

I plan on mainly using parts from my spares cupboard, cannibalising parts from my Spa Wayfarer or even swapping bits around between bikes. (I bought the Spa Wayfarer for riding some off-road trails but after doing the Guildford to Shoreham Downs Link I've no great appetite for doing more. I prefer to use quiet roads, easier and more comfortable. Also I hurt so much after a day riding an upright, even with a sprung saddle and wide tyres.)

The problem with re-using parts and spares is that the aesthetics suffer. Just realised the front rim is silver and the rear rim is black. The P-38 carbon forks are black and the riser is black. The Spa crankset I'm thinking of using is silver (160mm cranks). Might the bike end up looking like a dog's dinner? I've always been a function over form guy. However I am tempted to at least get the rims to match . I have a black 406 Alex DA16 wheel which I could take apart and use the rim with a disc hub.
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[XAP]Bob
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Re: P-38 build

Post by [XAP]Bob »

Form without function is meaningless, I'd get it working, and then decide if you want to start switching colours out.
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UpWrong
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Re: P-38 build

Post by UpWrong »

[XAP]Bob wrote: 30 Jun 2021, 1:49pm Form without function is meaningless, I'd get it working, and then decide if you want to start switching colours out.
I think you're right. Best thing is to get it up and running asap.

I've just been through my spares box. I don't have a spare SRAM RD so it will be a Shimano one with a matching shifter of some kind. Could be long cage Deore or medium cage R3000-GS SORA. Both will manage a 34T sprocket. The latter has a much stronger spring and is rated for 43T despite its shorter cage. I find that a bit odd.
https://bike.shimano.com/en-EU/product/ ... 00-GS.html
belgiangoth
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Re: P-38 build

Post by belgiangoth »

[XAP]Bob wrote: 30 Jun 2021, 1:49pm Form without function is meaningless, I'd get it working, and then decide if you want to start switching colours out.
^This, though I would probably get the wheels to match because swapping rims is probably the biggest faff of component change.
If I had a baby elephant, I would put it on a recumbent trike so that it would become invisible.
UpWrong
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Joined: 31 May 2009, 12:16pm
Location: Portsmouth, Hampshire

Deore M591 SGS vs Sora R-3000-GS

Post by UpWrong »

The Deore SGS is listed at 45T capacity, the SORA GS at 43T. However the cage length only differs by 1", which is 4 teeth when wrapped around the lower jockey wheel. The knuckle distances on the 2 RDs are the same. Arguably the Deore can cope with 47T so perhaps it's reasonable to list the SORA at 43T but that really should be regarded as an upper limit and it might be better sticking to 41T depending on whether or not you can tolerate any chain-wrap in small-small. I'm tempted to go with the medium cage for more precise shifiting but I would miss out a bit on range. Still 535% is possible as 20.3" to 108" with 41T utilised:
P38_gearing.png
But I might want lower.
EDIT: If I stretch it to 43T with a 34T bottom sprocket I can 565% of gear development as 19.1" to 108":
P38_gearing2.png
UpWrong
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Location: Portsmouth, Hampshire

Re: P-38 build

Post by UpWrong »

One last thought on gearing. I have an Alivio shadow RD and 12-36 cassette which is nicely spaced if a little heavy. Combined with the Deore SGS long cage I can get a range of 18.0" to 103.5" (575%) which is rather nice:
P38_gearing3.png
Blondie
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Re: P-38 build

Post by Blondie »

I had no difficulties with the rear mudguard stays of the Flinger F42 guards and my disc calliper.

I have silver rims on my wheels. Do they look out of place? Absolutely not. When riding you can’t see them anyway. If you already have suitable wheels just use them.
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