Thorn Cycles Forum
Community => Thorn General => Topic started by: pt88 on June 26, 2011, 06:16:13 PM
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Steering problem on RST
Took delivery of a new RST 4 weeks ago bike looks fantastic well put together etc, on my first ride about 10 miles I found the steering very twitchy stopped and checked to make sure everything was tight ,no problem with the wheel all looked in order. I put it down to being unfamiliar with this type of bike I have now coverer 120miles, 57miles yesterday cycled round Arran lots of very steep hills did not need to get off and walk so the gearing looks ok, but again the steering is very wobbly/twitchy, going up hill front end lifted of the ground a few times leaving me with no control over the bike also when going at about 8-10 mph
I find I am fighting with the handlebars all the time. Don’t feel confident or safe riding this bike on a busy road not even a quiet road.
I have tried the following
Reduced the pressure in the front tyre
Adjusted the handlebars up down turned the stem so it points up
Adjusted the saddle back and forward
No panniers fitted just a small 5lts bag on the back even took that off no difference
Any help or advice on how I can resolve this issue would be much appreciated
Thanks Alastair
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Hi Alaistair
From a fellow RST owner, I don't think there's anything wrong - I think you are coming to terms with the very "responsive" nature of the RST, which is sold as being for the "experienced" rider, because of this reason (I think!) and I am not suggesting you are inexperienced, simply this is the nature of the beast. I found the steering twitchy on my first tour, disconcertingly so and have occassionally experienced front wheel lift when in a very easy gear. It does take some getting to used to.
When you do get around to doing loaded cycle touring, I would make sure you do distribute some weight to front if carrying over 12Kg. My advice is your bike should be adjusted so that it is comfortable for you to ride and not to counteract any of above - I'd stick with it - 120 miles isn't very far - I am sure you'll gain in confidence and appreciate the responsiveness more as you clock up the miles. Hope this reassures.
Fred
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What is your handlebar set up? A short stem or a high upright position may be a contributing factor?
As another happy RST owner I can only sing praises for it's handling particularly on technical descents... The best bike I've owned.
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Hi Thanks for the reply
RST 511L
I have a 110mm Ahead Stem +17 DEG
The bike arrived with the stem straight on , thorn flat track bars cut to 580mm 10 Deg pull back ergon grips with bar ends fitted. have tried it in the +17 DEG ie took it off and reversed it. still very twitchy, got off the blike and pushed it along the road holding the saddle all over the place, can't go with no hands bike fitted with 1.6 Schwalbe Marathon Supreme's on DT Swis XR425 wheels would fatter tyres help?
THanks Alastair.
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I find having a bar bag with my dslr camera kit in definitely nullifies the steering response a bit. In fact for years I rode my RST like this, recently I've been riding it with nothing on the front (got a smart new saddlebag) and I'm kind of kicking myself for missing out on the responsiveness without it.
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I wouldn't fit anything fatter than what you have tyre wise - it will only serve to slow you down which IMO defeats the purpose of going for the RST. Stick with it for a few hundred more miles, and try even to enjoy the twitchiness, it's there for a purpose - Joatamon's suggestion ref bar bag is a sensible one if you're carrying weight on the back.
If you don't find it getting any easier, you could always go for a Thorn Raven, assuming Thorn still do their 100 day satisfaction guarantee?
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Thanks Fred
Will give Thorn a phone ask there advice
" It's there for a purpose " this is my first real bike so a bit inexperienced please can you explane, I have been reading this forum for months so value your experience
would fitting a bar bag help cut down the twichyness,
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I dont find it twitchy on mine. As others mentioned if your in a very low gear on a steep climb (eg, out of Sliddery) the front wheel can come up, the gears are that low. (I run 40*16) If you'd been used to a steep head angle before (on a racing bike) I may have thought that while wheeling it around could be a prob as the RST is comparatively relaxed angle, and the steering wants to turn.
On fast descents mine weaves a wee bit: Not sure if its the weight in the rack bag I used, but above 30mph, I become very careful.
Could it be just a case of very light steering compared to what your used to ? I'd persevere with your current setup for a bit before changing any bags, tyres etc.
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I've had several nice bikes over the years. I bought a Legnano around 1976 from a friend who'd had it a few years. That was a nice racing bike - sew-up tires, etc. Very twitchy, though - I could never ride that bike no-hands. Super responsive, though!
I bought a Trek 520 in 1996. Not so responsive, but still not stable enough to let me ride it confidently no-hands.
Just last November, 2010, my Thorn Nomad MkII arrived. I've got a 38x16 setup on the gears, so I can climb the mountains. Very easy to get the front wheel off the ground! But also very stable steering. I can ride that bike no-hands easily, which I like. A nice way to relieve stress.
Whether your RST is the right bike for you, I have no idea. But many very fine bicycles have skittish steering - that makes them responsive, which has upsides and downsides. As for the wheel coming off the ground, that's mostly just low gears. Both attributes are things you can learn to work with. I agree with advice you've already been given - another couple hundred miles should help you see more accurately if the bike will work for you.
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Just a quick follow on from JimK, I've never been able to ride my RST no-hands either - I've often wondered whether the wide steerers supplied (my only criticism of the RST, not particularly fond of them) affected this, but the conclusion I came to was that Thorn simply didn't intend the RST to be ridden with no hands when designing it - and why would they?
The RST is a responsive bike without a shadow of a doubt - it's not much lighter than the Thorn Raven, and not that much faster either from what I gather, but it is as described, a light tourer - if you bought it for that purpose, I'm fairly certain you will feel the benefits over the RT in that capacity. I appreciate it may come as a shock to the relatively unitinitiated, as it did me, but stick with it for another month of getting miles under your belt, and then if you're not feeling any happier, swap it for the Thorn Raven.
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Sorry to sound like a smart arse, but I can ride my RST with no hands & have no qualms about taking my hands off the bars to take off a gillet etc- though the RST steering is quite sensitive & I'd imply that it is steered by the seat of ones pants ! On descents It likes to be leant into corners & steered with the hips ( best way I can describe it ! ) & 'counter steering' too seems to work on gentle bends... I'm sure Andy B. the designer would back this up.
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Hi
4 years ago I had exactly the same problem - I emailed Andy Blance for advice and whether or not I should swap the RST for the RT.
Here's his reply:
"The RT is more stable than the RST, which is designed to have sportier steering characteristics. The RT is also a bit heavier than the RST and, IMO, requires 1.75” tyres to be as comfortable as the RST is with 1.5” tyres…having said that I would certainly have recommended that you have 1.75” tyres (Pasela) on your RST…they are much more comfortable. The greater width allows the running of lower pressures without increasing the risk of impact punctures. Lower pressures are not only more comfortable, they are also much more efficient on bumpy surfaces".
I kept the RST and learned to live with the twitchiness of the steering - which I don't notice now to be honest. The recommendation for 1.75" tyres was because part of my commute is on towpath/loose gravel.
I did make 2 changes - I run Marathon Supremes 1.6" and I swapped the Thorn comfort bars for On-One Mary bars. It seems to work for me.
Talk to Andy.
Ian
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Hi Ian, spoke to Robin Thorn today about the steering problems I am having with the RST he said he would like to have the bike back to check in over, alignment of the frame forks etc and take it from there.
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"I've never been able to ride my RST no-hands either" - Just to qualify, I should have inserted the word comfortably. I tried on the way home - Ok on a smooth tarmac but otherwise pretty hazardous, but stand by statement that riding no-hands clear wasn't a prominent design objective for the RST - otherwise it would simply have the responsiveness of a Raven Thorn, of which I've never heard anyone complain ref twitchiness.
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Sent the bike back last week, phone call from Andy Blance confirmed that the steering was more responsive than normal this was due to the front forks being slightly out of tollerance after a long chat with Andy he sugusted a complete frame swap to the Raven Tour being more stable etc would suit me better, new bike ariver 2 days latter fantastic service. (800mile round trip)
Done about 50 miles so far, no twitchyness bike very stable although feels a bit heavy going up hill compared to the sport tour, I got the gearing changed from 44 to 40 so hopfully this will help in the big hills can manage 20mph on the flat in gear 14 without spinning out ( not for long though) need to get my fitness lever up.
Dont need the load capacity of the bike as most of my cycling will be day trips thats why I opted for the sports tour in the first place but will give it a go.
Alastair.
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Glad to hear Thorn sorted you out OK, though I never thought they wouldn't. Based on what you say, I think the Raven will turn out to be the better choice for you - enjoy!
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can manage 20mph on the flat in gear 14 without spinning out ( not for long though) need to get my fitness lever up.
This puzzles me a bit! That seems like a slow cadence. I might ride 14 mph on the flat.. but that is in gear 9 or 10 - and I have a 38 tooth chainring. I find gear 14 useful above 25 mph, and spin out at maybe 32 mph. At 20 mph I am likely in gear 12.
I think a steady 20 mph on the flat is out of my reach in this lifetime!
Jim
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hi Jim,
It probably is quite a slow cadence, I am relatively new to cycling and cycle most of the time by myself
so don't really know what the cadence should be, I just change down when it starts to get hard to pedal
the cateye computer fitted to the bike only shows mph distance covered average milage etc, how do you calculate the cadence I have a 40 tooth chainring so to give me an idea, If on the flat in gear 12 and want to travel at 20 mph what would the cadence be, is there an optimum cadence to aim for ?
any info would be much appreciated
Thnks Alastair
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Here's a good start:
http://www.kenkifer.com/bikepages/touring/gears.htm
80 rpm is a good cadence to shoot for, as a ballpark figure. You can multiply numbers a variety of ways to get speeds in different gears for that. To get precise about it... it even depends on your tire pressure!
Jim
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http://www.rohloff.de/en/products/speedhub/sprocket_ratios/
is another nice page, plus
http://www.schwalbetires.com/tech_info/tire_dimensions#circumference
Note that circumference is a tricky affair. More weight on the bike and/or lower pressure will squish the tire more and reduce the effective circumference.
Rohloff says gear 12 is a 1.135 internal ratio. 40 teeth on the front and 16 on the rear means one turn of the pedals gives 2.8375 turns of the wheel.
Suppose you're running something like a 26x2 Marathon Supreme, i.e. a 5-559 tire: Schwalbe says the circumference is 2.075 meters. So one rotation of the pedals moves the bike 5.888 meters.
80 revolutions per minute would then be 471 meters per minute which is 28.26 km per hr which is 17.5 mph.
Try that yourself to check my math and to get the hang of it!
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My bike has a 38 tooth chainring with a 16 tooth sprocket. I find I like a cadence of 90 rpm. I am riding Marathon Supreme 2.0 tires, which I measured to have an effective circumference of 2010 mm with my usual load & pressure. This gives a gear to speed relationship of:
1: 4.46 mph
2: 5.06 mph
3: 5.76 mph
4: 6.55 mph
5: 7.42 mph
6: 8.45 mph
7: 9.61 mph
8: 10.92 mph
9: 12.39 mph
10: 14.10 mph
11: 16.01 mph
12: 18.17 mph
13: 20.68 mph
14: 23.49 mph
Probably I spin even a bit above 90 - my experience is that I tend to downshift if I get below these speeds. Except with 1st gear, of course. But once I am below 4.1 or so mph then I have entered the realm of slogging. It happens!
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thanks Jim for the info
think I have been pedaling too slow
Alastair.