Thorns: design and handling

[lb1dej]

I don't have a Thorn but have a number of road bikes - tourers, racers, and an MTB. Nevetheless I've spent some time considering them in both 700c and 26 inch.

The reviews that I've read of Thorns generally comment positively on how well the bikes handle.

Having become increasingly cautious as I grow older, under strict instructions to come home in one piece, and doing most of my cycling around the Peak District's hilly lanes this is an important factor for me in choice of bike.

Among the crucial design elements are frame angles and wheelbase, though quality of brakes is also a factor in one's confidence at speed downhill.

Thorn do not publish frame angles though told me on enquiring that the club tour 576S bike had a head angle of 70.5 which is much shallower than the "standard" tourer's 72.

I certainly seem to feel more confident and go faster downhill on my Kona MTB (head angle 69 degrees) and Schwalbe marathon tyres than on my 72 degree tourer with 28mm tyres.

The key factors would seem to be:
-frame angles
-wheelbase
-brake stopping power
-flat vs. drop bars

Just wondered what comments Thorn users might have on this?

Thanks

David

[john28july]

Hello,
In my opinion as a three Thorn bikes owner, the bikes are superb. Comfortable, safe and sure handling. I believe angles of frames are variable to frame size. I do not think that you should concern yourself further. I need a safe bike due to disabilty and I am more than happy with the confidence the bikes install.
John.
www.pbase.com/john28july

[stutho]

As I understand it the 2 main criteria for stability are 'trail' and 'chain stay length'.

Trail is the distance between the projected headset angle and the contact point of the front tyre. It is dependent on headset angle, fork length, fork rake, wheel size and tyre size. (Imagine looking down the head tube to a spot on the ground this spot must be in front of the point that the tyre makes contact)

Chain stay length is important to ensure  load is distributed between the front and back wheels (similar to your comment on wheel base)

I own a Raven Sport Tour.  I also live in a very hilly part of the world.  On my commute I get up to 40+ mph - downhill. (Unfortunately I have to cycle back up on the way home.)  I have also (once) touched 60mph on a steep and straight hill near Cardiff.  At no time have I experienced any instability due to speed.

Brake stopping power - V brakes are obviously the way to go if you are in a hilly part of the world. I use Avid ultimate (SJSC don't stock them) they are expensive but nothing else IMHO come close.  I also use ceramic rims although I am not entirely convinced by them.

flat vs drop bars - Long ongoing debate.  I like drops others like flat.  I think that you probably do have 'slightly' more authority over the bike when using flat BUT drops are comfortable to use.  You haven’t mentioned if you are looking at a Rohloff equipped model, if you are DONT be put off drops there are several solutions to using the Rohloff shifter with drops.

[geocycle]

The handling on my raven tour is far, far better than on any other bike I have owned.  Of course it is also the most expensive bike i have owned, but I think the 26 wheels and the frame geometry helps.  Going downhill off road it handles like an mtb, and there were no twitches on the tarmac at 37mph fully loaded.  I use flat (comfort) bars which I find great.  They are quite wide, so the extra leverage takes some getting used to, but you can be precise.  If you go down this route I'd recommend the ergogrips -very nice.

[Piglit]

I think stability can be just as much a matter of rider adaptation and preference as it can be bike design.
I got back into cycling 2 and a half years ago with an old Trex hybrid. When I got some money I bought what I really wanted - a fast tourer in the form of the Brevet. This initially felt twitchy on the downhills of the Peak, and looking over my shoulder to check the traffic was a bit of a wobble. A few weeks down the line and no probs and the extra speed and precision of this bike make it much safer - though when I hopped back on the trek the other day it felt well wobbly for a moment!
As for brakes - if the rx100s can cope with 15st of yours truly and panniers filled with all the requirements for a piglit's day out then no probs.
Straights v drops - well since I got back on a well set up drop bar bike I've had no numbness in the wrist or aches in the back and long runs are a pleasure.
Hope this helps. We'll prbably pass each other sometime.

[Roberto]

Wheelbase of my 533S Club Tour is 103.5 cm. Chainstays are 44 cm. and forks rake is 50 mm. I use old XT cantis with lots of stopping power. My daily ride is through a winding mountain road with a fast long (approx 12 kms) descent. After several years, I still smile with satisfaction when I reach home. Stability of the CT is perfect, so much so that I can even pass cars on my way down.
I also own a Kona MTB (Kilauea) with rigid (P2) forks. Stability is also very good, but the only improvement over the CT is the stopping power provided by the V-brakes.

[lb1dej]

Thanks very much everyone.
It seems difficult to pin down the key ingredients and as people have said it can be a mix of both design and, say, quality of brakes - the latter giving more confidence on the descents.
My experience is that the qualities of any one bike or piece of kit are subjectively assessed in comparison to others that have been or are being used, and that once you've experienced an improvement, then what used to be acceptable no longer is.
An example is brakes where 20 years ago Campag record side pulls with non aero levers were the best road brake and one got used to them. Going back to them after dual pivots you realise that by present standards they required an awful lot of hand effort and were poor stoppers.
After riding MTBs converted for road use (e.g. Kona Cindercone with rigid forks), I've found that 73 parallel road frames are twitchy - if I only used the latter then I'd get used to them again I suppose.
Anyway the latest C+ has a glowing account of the Club Tour's handling though the top tube length options would make it a less than straightforward choice for me (long legs and short upper body).
Thanks very much again.
David

[john28july]

quote:Originally posted by lb1dej

Thanks very much everyone.
It seems difficult to pin down the key ingredients and as people have said it can be a mix of both design and, say, quality of brakes - the latter giving more confidence on the descents.
My experience is that the qualities of any one bike or piece of kit are subjectively assessed in comparison to others that have been or are being used, and that once you've experienced an improvement, then what used to be acceptable no longer is.
An example is brakes where 20 years ago Campag record side pulls with non aero levers were the best road brake and one got used to them. Going back to them after dual pivots you realise that by present standards they required an awful lot of hand effort and were poor stoppers.
After riding MTBs converted for road use (e.g. Kona Cindercone with rigid forks), I've found that 73 parallel road frames are twitchy - if I only used the latter then I'd get used to them again I suppose.
Anyway the latest C+ has a glowing account of the Club Tour's handling though the top tube length options would make it a less than straightforward choice for me (long legs and short upper body).
Thanks very much again.
David

Hello,
I have long legs short body and a poorly spine! Mt Thorn bikes fit to perfection.
Nomad 525S, Audax 853 550S, Brevet 533S.
John.
www.pbase.com/john28july