Thorn Cycles Forum

Technical => General Technical => Topic started by: PhilD28 on October 02, 2017, 08:38:16 am

Title: XTC SWB classic
Post by: PhilD28 on October 02, 2017, 08:38:16 am
I hope someone can help. I have an XTC short wheelbase classic (lugged) frame in Reynolds 725, size 500s and am curious about the frame tube wall thicknesses.
Does anyone have this information, frame angles and dimensions would also be useful.

I've had the bike from new bought in 2002 it's been a great bike and I intend keeping it but have had a few thoughts about changing the fork to one with a different rake to remove a little of the slightly twitchy low speed handling, although it's not really a problem and probably just a whim.

I could pester Thorn, but thought someone on here may have the info at hand.
Thanks
Phil
Title: Re: XTC SWB classic
Post by: PhilD28 on October 03, 2017, 03:22:23 pm
Sorted, Andy B from Thorn provided precise details.
thank you
Title: Re: XTC SWB classic
Post by: jags on October 03, 2017, 03:27:45 pm
is it not 725 thick ?
Dan will be sure to know or check the Reynolds tubing  website . ;)

jags.
Title: Re: XTC SWB classic
Post by: PhilD28 on October 04, 2017, 12:19:31 pm
.8/.5/.8 thick.
most tube sets are availble in different gauges.
Title: Re: XTC SWB classic
Post by: jags on October 04, 2017, 04:41:08 pm
wonder why it's called 725 then.  ::)

anto.
Title: Re: XTC SWB classic
Post by: Danneaux on October 04, 2017, 07:56:57 pm
Quote
wonder why it's called 725 then.
Anto,

725 describes the metallurgy and Reynolds' model designation for this tubing, which is cro-moly rather than the manganese-molybdenum of the earlier 531 series. Unlike 525, 725 is heat-treated.

As with Reynolds' other tubing, 725 is available in various wall thicknesses and diameters.

Best,

Dan.
Title: Re: XTC SWB classic
Post by: jags on October 04, 2017, 09:28:23 pm
Cheers Dan I've no idea what you just said but knowing you I bet your right ;)

Anto.
Title: Re: XTC SWB classic
Post by: David Simpson on October 05, 2017, 06:51:10 am
Cheers Dan I've no idea what you just said but knowing you I bet your right ;)

Anto,

"725" is the number that Reynolds gives to that "model" of tube. It mostly refers to the type of metal used to make the tube.

More info here, including a brief history of the Reynolds company:
https://en.wikipedia.org/wiki/Reynolds_Technology (https://en.wikipedia.org/wiki/Reynolds_Technology)

- DaveS
Title: Re: XTC SWB classic
Post by: PhilD28 on October 05, 2017, 08:23:33 am
I didn't realise that Anto was not being serious about not knowing that Reynolds type numbers didn't relate to wall thickness, otherwise I would have replied. As a chartered engineer, I'm guilty of making assumptions about other peoples level of knowledge of things engineering. Anyway, nicely explained by others.

Andy B was very helpful and provided full data including tube sizes, frame angles etc for my bike which had not previously been released due to commercial reasons.

It's still a great bike almost 20 years down the road with countless miles. The hubs (xt) are still perfect even after about 4 sets of bearings and I've rebuild the wheels with fresh rims 3 times only replacing with fresh spokes just this week. The bar end shifters and front mech are perfect but probably about time for a new rear mech, also xt.
This is a really nimble short wheelbase version of the standard XTC, it made a great audax bike as well as a fast tourer. The frame was nicely built at Bridgewater and is lugged and brazed. The design was fairly cutting edge at the time.

Bikes built for long term ownership for sure.
Title: Re: XTC SWB classic
Post by: jags on October 05, 2017, 04:08:02 pm
No worries Phil all this tech stuff goes over my head ,if i were to try and understand it all it would just be something else for me to worry about so i leave it to the experts  ;)

anto.
Title: Re: XTC SWB classic
Post by: PH on October 08, 2017, 10:05:50 pm
It's great to see someone still enjoying their 20 year old bike, is it your only bike?
Title: Re: XTC SWB classic
Post by: PhilD28 on October 09, 2017, 01:51:38 pm
No, I keep building them up. I have a 25 year old Dave Yates 26" wheeled Hosteller frame that was built for me that I built up into a bike also a Derailleur geared Nomad, again from new, alonside a fast road bike based upon a Genesis 725 frame.

The Dave Yates hosteller is a beautiful frame that handles most things well including loaded touring.

I build my own wheels and normally only buy F&F.

My wife has a Thorn XTC day tourer and a Roberts Roughstuff which she uses when we have extended tours abroad which is most summers. Normally average about 60 or 70 miles a day for our two month camping jaunts.
It's been a lifelong passion for me starting in 1963 when I joined the local cycling club, still peddalling every day at 65 despite having to take a year or two off after knee surgery a few years back but all's well now.
Title: Re: XTC SWB classic
Post by: jags on October 09, 2017, 05:28:29 pm
Wow Phil fair play to you and the  missus you guys certainly put in the miles ,
i have lower back problems these days so  no more big miles for this ould bird, tho if push came to shove i would manage it  ;)

Sounds like you have a great collection of quality bikes ,i just have 2 these days Thorn Audax and my Terry Dolan Le tape  class bike only use it for group rides with all the carbon warriors  ;D

anyway enjoy your cycling stay safe.

anto.
Title: Re: XTC SWB classic
Post by: PH on October 10, 2017, 11:48:50 am
Nice collection of bikes Phil.
I've built up a nice collection over the years but end up doing 90%+ of my miles on one.  Circumstances are such that it would be more practical to just have the one, but can't bring myself to do it and don't know anyone who has for any period of time. 
Title: Re: XTC SWB classic
Post by: PhilD28 on October 11, 2017, 06:12:48 pm
I know what you mean, I've tried having just one bike but it always seems too much of a compromise. Going away on a long camping tour needs a much heavier built frame and wheels than for riding a 100 mile Audax or going away for a few days in B&B's. Owning a few is a nice indulgence.