Upgrades: Making the Thompson R9300 into a Gravel Bike

Thompson R9300 on a gravel track

The Thompson R9300 Gravel was, I concluded after a few thousand miles, more road bike with wide tyres than gravel bike, here’s how some upgrades changed that.

Those few thousand miles have been pretty varied. Commutes to the office, winter club runs and bikepacking trips. Tarmac, gravel and sand. Sun, rain and full on thunderstorms. There have been trials of broken parts and joys of exploring new places. I’ve got to know the Thompson R9300 pretty well, I still love it and it’s now more Gravel bike than before with the sprinkling of upgrades it’s had over the years. All discussed here as an update to the original review (here).

Thompson R9300 on a railway bridge

Knowing how I want to use the bike has allowed me to select upgrades that best suit that intended use. Though I’m still not entirely convinced i’ve got that down to just one thing. It’s a commuter, a winter hack, a gravel bike and a bikepacking rig. The upgrades all lean towards the latter two though. I think.

Upgrade One – Tyres

First up was the tyres. The supplied Schwalbe G-One, though giving excellent grip, lasted only 1500-2000 miles before appearing very worn. A well documented sacrifice for their renowned hold. These were replaced by the same tyre, but in the Allround MicroSkin TL-Easy form, allowing for a tubeless setup and lower pressures. More off-road grip for gravel riding. More comfort for road riding. Less worry about punctures on bikepacking trips. Win-win-win.

Once again, the tubeless version has not lasted more than 2000 miles. But I’ve been impressed with them. I trialled a set of the 700x38c G-Ones on instead of the 35’s, in the gravel bike cliché tan wall variety. The difference of the extra width is noticeable, especially in looser conditions. However, the rear tyre rubs the chainstay, so they had to come out again. Sadly 35mm really is about the tyre clearance limit with the Thompson R9300.

Upgrade Two – Wheels

Unfortunately this upgrade was born out of necessity due to a failure. The hub on the Novatec Thirty wheels failed and neither I, nor a local mechanic could strip it apart. So in came the Hunt 4-Season Gravel Disc Wheelset. Lighter than the original Novatec wheels and the lovely understated graphics match the Thompson R9300 well.

Thompson R9300 in the sun

I have been left wondering about their strength for rougher rides, after riding with a lower tyre pressure resulted in some dents to the rim. But they’re still holding up and sealing to tubeless, so the damage can’t be too bad.

Upgrade Three – Cassette and Rear Derailleur

I discussed in my first review how the gearing supplied was too road-oriented for this to be a true gravel bike. In particular the close ratio 12-28 cassette left me struggling on some loose and steep climbs. In order to increase the range, the short cage Tiagra rear derailleur needed replacing with the medium cage version. This also heralded the arrival of the 11-34 cassette. The 1:1 ratio of the 34 front ring and 34 sprocket definitely coming in useful when fully loaded cycling the Hebridean Way.

Upgrade Four – Chainrings and Front Derailleur

I rode with the first three upgrades for a long time, but still felt the R9300 was over-geared for most of how I used it. At the time I purchased the Thompson there wasn’t an easy alternative to the 50/34 chainset. It was after a broken shifter (more on that later) that left me with only the 34 tooth chainring that I came to a conclusion. For most of the riding I was doing, I never felt THAT limited without the 50 tooth.

So, while researching about gearing, I discovered Shimano have released their gravel specific GRX range of groupsets. I found the 46/30 2×10 chainset option. I knew I didn’t need a 50 and that the 30 would give me the lower gearing I wanted off-road. In fairness to Thompson, they appear to now spec this as an option (though not in the UK).

GRX 46/30 Chainset

One issue here is that the GRX chainrings sit further outboard by 2.5mm, so must be paired with the GRX front derailleur. Some discussions online have revealed this not to be entirely true, standard road dertailleurs working fine for many people.

However, on the Thompson frame, the braze-on mount does not sit low enough. The derailleur sits 3mm or more too high compared to Shimano’s recommendation. So far this does not appear to be causing any difficulties with shifting, but it might be attributable to a bit more chain rub though.

Upgrade Five – Shifters and Brakes

Once again, another upgrade out of necessity here. The plastic cable routing inside the Tiagra front shifter collapsed, making shifting the front chainring impossible. Chats with a mechanic have revealed this to be a common fault of a series of Shimano shifters. One that is not easily repaired.

So it was, having found out about the GRX groupset, that I found a steal of a deal on a set of GRX Shifters and Brakes at Rose Bikes. The brake blocks are almost identical in appearance. But the shifters are slimmer to hold, have a textured finish to improve grip and the pivot point of the lever has been moved for better braking power. I can definitely say I’ve noticed the benefits of the first two, not so sure on the latter.

Upgrade Six – Handlebars

There is a trend in gravel riding for wide flared handlebars, the extra width improving handling, much like in the mountain bike world. I had also found that, when bikepacking, the shift levers would often foul my handlebar bag. A further benefit of the flare and width then is the clearance for a handlebar roll.

Alpkit Love Mud Spitfire handlebars on the Thompson R9300

So the original bars have been replaced by a 2cm wider Alpkit Love Mud Spitfire bar. The 16° flare just enough to be useful without feeling excessive. The bar roll no longer interfering with shifting and off-road handling feels far superior too.

Upgrade Seven – Luggage

Not an upgrade as such this one, more some notes on carrying gear on the bike and some future plans. On smaller bikepacking trips (such as this Overnight trip to the Beach) I have utilised various combinations of a bar roll, top tube pouch, small frame bag and a seat pack all from Alpkit. I try to minimise using a backpack wherever possible.

Thompson R9300 with Alpkit Luggage on the Hebridean Way

When I toured the Outer Hebrides I added a rack and set of panniers. It worked, but was heavy. Next in line will be some larger bags, so I don’t need the rack and panniers for longer trips. Alpkit’s Stingray is a custom made full frame bag that is on it’s way to me soon.

Though with losing the inside of the main triangle, one missing puzzle piece of the Thompson R9300 will be the lack of mounting options. I currently get by by strapping two Blackburn Outpost Cages to the forks with cable-ties and an old inner tube. I really would like some mounting points on the fork. If the cable routing didn’t exit beneath the down tube where it did, then a mounting point under there would be useful too.

Upgrade Eight – 650B Wheels

This one was the one that didn’t happen. As standard the Thompson comes fitted with 700x35c tyres. A 38c does fit in, but as mentioned above, they foul the chainstay under effort. So I thought I’d look into a 650B conversion. The smaller wheel diameter allowing for the wider tyre.

I tried a 650B wheel with a 47mm tyre. It fitted fine up front and looked really good. Unfortunately at the back, the tyre sat hard-up against the chainstay. So even dropping to a 42 or 40, is likely to still foul the chainstay under effort. As such, 650B is not really worth pursuing as a gravel upgrade to the Thompson R9300 as it will provide no real tyre width benefit.

Conclusion

So there you go, a number of upgrades to make the Thompson R9300 into more of a gravel bike. It’s definitely taking on more of a gravel/adventure bike feel. But the beauty of replacing bits as they’ve worn out is I’ve made the bike into what I want. Now I just wait for then end of lockdown restrictions so adventures further afield can re-commence.

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